INTRODUCTION:
Increasing evidence suggests that prostate cancer cells undergo unique metabolic r... more INTRODUCTION:
Increasing evidence suggests that prostate cancer cells undergo unique metabolic reprogramming during transformation. A master regulator of cellular homeostasis, 5'-AMP-activated protein kinase (AMPK), directs metabolic adaptation that supports the growth demands of rapidly dividing cancer cells. The utilization of AMPK as a therapeutic target may therefore provide an effective strategy in the treatment of prostate cancer. AREAS COVERED:
Our review describes the regulation of AMPK by androgens and upstream kinases including the calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) in prostate cancer. Oncogenic, AMPK-regulated pathways that direct various metabolic processes are also addressed. Furthermore, we discuss the role of AMPK in growth arrest and autophagy as a potential survival pathway for cancer cells. In addition, by regulating non-metabolic pathways, AMPK may stimulate migration and mitosis. Finally, this review summarizes efforts to treat prostate cancer with pharmacological agents capable of modulating AMPK signaling. EXPERT OPINION:
Current research is primarily focused on developing drugs that activate AMPK as a treatment for prostate cancer. However, oncogenic aspects of AMPK signaling calls for caution about employing such therapies. We think that inhibitors of CaMKK2 or AMPK, or perhaps the modulation of downstream targets of AMPK, will gain importance in the clinical management of prostate cancer.
Papillary thyroid cancer (PTC) is the most prevalent of all endocrine cancers. In recent studies,... more Papillary thyroid cancer (PTC) is the most prevalent of all endocrine cancers. In recent studies, the presence of receptors for pituitary-type growth hormone-releasing hormone (pGHRH-R) has been demonstrated in various human cancers, including human prostate, brain, and other cancer lines. Thyroid malignancies, however, have not yet been investigated in this regard. In this study, we found that pGHRH-R and its functional splice variant, SV1, are present in normal thyroid and PTC cells. We also treated seven normal and PTC tumor thyroid cells in vitro with a GHRH antagonist, MIA-602, to compare its anti-proliferation and anti-invasion potential against vehicle-treated cells. We found that treatment with GHRH antagonist increases the expression of SV1 and pGHRH-R in tumor cells compared to tumor cells exposed to vehicle only, a response which may alter the sensitivity of signaling kinases within the cells. GHRH antagonist treatment of tumor cells also reduced activity of the tumor invasion marker, matrix metalloproteinase (MMP)-2, compared to tumor cells exposed to vehicle only. The expression of pGHRH-R and SV1, as well as MMP-2 activity, in normal thyroid cells remained unaffected by GHRH antagonist treatment. Similarly, cell proliferation rates for tumor or normal thyroid cells were not affected by GHRH antagonist treatment. Our findings have important implications for the therapeutic use of GHRH antagonist in cases of aggressive PTC refractory to conventional treatment modalities, and in which protein expression and MMP-2 activity in normal thyroid tissue is left unaltered
Dyslipidemia associated with triglyceride-rich lipoproteins (TRLs) represents an important residu... more Dyslipidemia associated with triglyceride-rich lipoproteins (TRLs) represents an important residual risk factor for cardiovascular and chronic kidney disease in patients with type 1 diabetes (T1D). Levels of growth hormone (GH) are elevated in T1D, which aggravates both hyperglycemia and dyslipidemia. The hypothalamic growth hormone-releasing hormone (GHRH) regulates the release of GH by the pituitary but also exerts separate actions on peripheral GHRH receptors, the functional role of which remains elusive in T1D. In a rat model of streptozotocin (STZ)-induced T1D, GHRH receptor expression was found to be up-regulated in the distal small intestine, a tissue involved in chylomicron synthesis. Treatment of T1D rats with a GHRH antagonist, MIA-602, at a dose that did not affect plasma GH levels, significantly reduced TRL, as well as markers of renal injury, and improved endothelial-dependent vasorelaxation. Glucagon-like peptide 1 (GLP-1) reduces hyperglucagonemia and postprandial TRL, the latter in part through a decreased synthesis of apolipoprotein B-48 (ApoB-48) by intestinal cells. Although plasma GLP-1 levels were elevated in diabetic animals, this was accompanied by increased rather than reduced glucagon levels, suggesting impaired GLP-1 signaling. Treatment with MIA-602 normalized GLP-1 and glucagon to control levels in T1D rats. MIA-602 also decreased secretion of ApoB-48 from rat intestinal epithelial cells in response to oleic acid stimulation in vitro, in part through a GLP-1-dependent mechanism. Our findings support the hypothesis that antagonizing the signaling of GHRH in T1D may improve GLP-1 function in the small intestine, which, in turn, diminishes TRL and reduces renal and vascular complications.
We previously showed that growth hormone-releasing hormone (GHRH) agonists are cardioprotective f... more We previously showed that growth hormone-releasing hormone (GHRH) agonists are cardioprotective following myocardial infarction (MI). Here, our aim was to evaluate the in vitro and in vivo activities of highly potent new GHRH agonists, and elucidate their mechanisms of action in promoting cardiac repair. H9c2 cells were cultured in serum-free medium, mimicking nutritional deprivation. GHRH agonists decreased calcium influx and significantly improved cell survival. Rats with cardiac infarction were treated with GHRH agonists or placebo for four weeks. MI size was reduced by selected GHRH agonists (JI-38, MR-356, MR-409); this accompanied an increased number of cardiac c-kit+ cells, cellular mitotic divisions, and vascular density. One week post-MI, MR-409 significantly reduced plasma levels of IL-2, IL-6, IL-10 and TNF-α compared to placebo. Gene expression studies revealed favorable outcomes of MR-409 treatment partially result from inhibitory activity on pro-apoptotic molecules and...
Treatment of colon cancer with an antagonist of growth hormone-releasing hormone (GHRH), JMR-132,... more Treatment of colon cancer with an antagonist of growth hormone-releasing hormone (GHRH), JMR-132, results in a cell cycle arrest in S-phase of the tumor cells. Thus, we investigated the effect of JMR-132 in combination with S-phase-specific cytotoxic agents, 5-FU, irinotecan and cisplatin on the in vitro and in vivo growth of HT-29, HCT-116 and HCT-15 human colon cancer cell lines. In vitro, every compound inhibited proliferation of HCT-116 cells in a dose-dependent manner. Treatment with JMR-132 (5 μM) combined with 5-FU (1.25 μM), irinotecan (1.25 μM) or cisplatin (1.25 μM) resulted in an additive growth inhibition of HCT-116 cells in vitro as shown by MTS assay. Cell cycle analyses revealed that treatment of HCT-116 cells with JMR-132 was accompanied by a cell cycle arrest in S-phase. Combination treatment using JMR-132 plus a cytotoxic drug led to a significant increase of the sub-G 1 fraction, suggesting apoptosis. In vivo, daily treatment with GHRH antagonist JMR-132 decreased the tumor volume by 40-55% (p < 0.001) of HT-29, HCT-116 and HCT-15 tumors xenografted into athymic nude mice. Combined treatment with JMR-132 plus chemotherapeutic agents 5-FU, irinotecan or cisplatin resulted in an additive tumor growth suppression of HT-29, HCT-116 and HCT-15 xenografts to 56-85%. Our observations indicate that JMR-132 enhances the antiproliferative effect of S-phase-specific cytotoxic drugs by causing accumulation of tumor cells in S-phase.
Previously, we have shown that the targeted cytotoxic somatostatin (sst) analogue AN-162 [AZSE-12... more Previously, we have shown that the targeted cytotoxic somatostatin (sst) analogue AN-162 [AZSE-124] inhibits the growth of MDA-MB-231 human breast cancers xenografted into nude mice. In this study, we examined the trafficking of AN-162 into the cell, the expression of the somatostatin receptors (sstr) in specimens of human triple-negative breast cancers (TNBC), and the effect of AN-162 on HCC 1806 human TNBC xenografts. The expression of sstr in TNBC tumor samples was investigated by immunohistochemical staining. The expression of sstr in HCC 1806 was evaluated by reverse transcription PCR. Internalization studies with I-labeled AN-162 were carried out and the autofluorescence sign of doxorubicin moiety in the cell nucleus after incubation with AN-162 was measured using a fluorescence assay. The effects of AN-162 on the growth of HCC 1806 xenografted into nude mice were studied. A fluorescence microscopy cytotoxicity assay in vitro to detect cell death after treatment with AN-162 was also carried out. About 28% of TNBC tumor specimens showed a positive staining for sstr subtype 2a. HCC 1806 expresses all five subtypes of sstr. In the fluorescence cytotoxicity assay, dead HCC 1806 cells were found 24 h after incubation with AN-162. The growth of HCC 1806 tumors in nude mice was significantly inhibited by treatment with AN-162. AN-162 was internalized into the HCC 1806 cells and doxorubicin moiety was detected in the cell nuclei. This study is the first to show that the trafficking of the cytotoxic sst analogue AN-162 into the cell is mediated by sstr. Our work shows that the growth of xenografted HCC 1806 TNBCs can be effectively inhibited in vivo with AN-162. This investigation provides information on the mechanism of action and efficacy of this new targeted cytotoxic sst analogue and identifies in this relation the sstr as a favorable therapeutic target in TNBC.
Malignant melanoma is the deadliest form of skin cancer; the treatment of advanced and recurrent ... more Malignant melanoma is the deadliest form of skin cancer; the treatment of advanced and recurrent forms remains a challenge. It has recently been reported that growth hormone-releasing hormone (GHRH) receptor is involved in the pathogenesis of melanoma. Therefore, we investigated the effects of our new GHRH antagonists on a human melanoma cancer cell line. Antiproliferative effects of GHRH antagonists, MIA-602, MIA-606 and MIA-690, on the human melanoma cell line, A-375, were studied in vitro using the MTS assay. The effect of MIA-690 (5 μg/day 28 d) was further evaluated in vivo in nude mice bearing xenografts of A-375. Subcellular localization of p27 was detected with Western blot and immunofluorescent staining. MIA-690 inhibited the proliferation of A-375 cells in a dose-dependent manner (33% at 10 μM, and 19.2% at 5 μM, P < 0 .05 vs. control), and suppressed the growth of xenografted tumors by 70.45% (P < 0.05). Flow cytometric analysis of cell cycle effects following the administration of MIA-690 revealed a decrease in the number of cells in G2/M phase (from 19.7% to 12.9%, P < 0.001). Additionally, Western blot and immunofluorescent studies showed that exposure of A-375 cells to MIA-690 triggered the nuclear accumulation of p27. MIA-690 inhibited tumor growth in vitro and in vivo, and increased the translocation of p27 into the nucleus thus inhibiting progression of the cell cycle. Our findings indicate that patients with malignant melanoma could benefit from treatment regimens, which combine existing chemotherapy agents and novel GHRH-antagonists.
Recent findings suggest that BPH has an inflammatory component. Clinical trials have documented t... more Recent findings suggest that BPH has an inflammatory component. Clinical trials have documented that therapy with LHRH antagonist Cetrorelix causes a marked and prolonged improvement in LUTS in men with symptomatic BPH. We investigated the mechanism of action and effect of Cetrorelix in a rat model of BPH. Adult male Wistar rats were used. BPH was induced in rats by subcutaneous injections of TE 2 mg/day for 4 weeks. Control animals received injections of corn oil. After induction of BPH, rats received depot Cetrorelix pamoate at the doses of 0.625, 1.25, and 12.5 mg/kg on days 1 and 22 and TE-control rats received vehicle injections. Whole prostates were weighed and processed for RNA and protein. Real-time RT-PCR assays for numerous inflammatory cytokines and growth factors were performed. Quantitative analyses of prostatic LHRH receptor, LHRH, androgen receptor (AR) and 5α-reductase 2 were done by real-time RT-PCR and immunoblotting; serum DHT, LH, PSA, and IGF-1 by immunoassays. mRNA levels for inflammatory cytokines IFN-γ, IL-3, IL-4, IL-5, IL-6, IL-8, IL-13, IL-15, and IL-17 and for growth factors EGF, FGF-2, FGF-7, FGF-8, FGF-14, TGF-β1, and VEGF-A were significantly reduced by Cetrorelix 0.625 mg/kg (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05). Prostate weights were also significantly lowered by any dose of Cetrorelix. This study suggests that Cetrorelix reduces various inflammatory cytokines and growth factors in rat prostate and, at doses which do not induce castration levels of testosterone, can lower prostate weights. Our findings shed light on the mechanism of action of LHRH antagonists in BPH.
Antibiotic treatment of patients infected with G − or G + bacteria promotes release of the toxins... more Antibiotic treatment of patients infected with G − or G + bacteria promotes release of the toxins lipopolysaccharide (LPS) and pneumolysin (PLY) in their lungs. Growth Hormone-releasing Hormone (GHRH) agonist JI-34 protects human lung microvascular endothelial cells (HL-MVEC), expressing splice variant 1 (SV-1) of the receptor, from PLY-induced barrier dysfunction. We investigated whether JI-34 also blunts LPS-induced hyperpermeability. Since GHRH receptor (GHRH-R) signaling can potentially stimulate both cAMP-dependent barrier-protective pathways as well as barrier-disruptive protein kinase C pathways, we studied their interaction in GHRH agonist-treated HL-MVEC, in the presence of PLY, by means of siRNA-mediated protein kinase A (PKA) depletion.
Novel drugs are required for the treatment of
CRPC. The best option may not be the agents
that ... more Novel drugs are required for the treatment of
CRPC. The best option may not be the agents
that target androgen receptors or compounds
which inhibit enzymes involved in androgen
biosynthesis. This is because the androgen
deprivation created by these compounds
can be overcome by mutations in androgen
receptors, the appearance of splice variants
of these receptors or alternate biochemical
pathways.
The use of currently available cytotoxic
analogs of LHRH, or somatostatin that can
be targeted to prostate cancers may lead to
an improvement in the treatment of CRPC
and an increase in the survival rate. A new
modality based on GHRH antagonists also
appears to be useful for the treatment of
metastatic CRPC.
BACKGROUND:
Androgen deprivation therapy (ADT) has been the standard of care for treating pati... more BACKGROUND:
Androgen deprivation therapy (ADT) has been the standard of care for treating patients with hormone-sensitive advanced prostate cancer (PCa) for 3 decades. The agonists of luteinizing hormone-releasing hormone (LHRH), also called gonadotropin-releasing hormone, are still the most frequently used form of medical ADT.
ADT AND LHRH ANALOGS: The application of agonists of LHRH has improved and modernized the treatment of advanced PCa; millions of patients have benefited from therapy with LHRH agonists as a preferred alternative to surgical castration, as the psychological effects and perpetuity of orchiectomy are undesirable for most men. Despite their efficacy, agonists of LHRH have several shortcomings, including initial surge in testosterone, producing exacerbation of clinical symptoms, and microsurges in testosterone that might occur after each administration. A new, alternate approach to ADT is emerging with the improvements in antagonists of LHRH. This class of LHRH analogues produces a direct and immediate blockade of pituitary LHRH receptors and leads to a more rapid suppression of testosterone without an initial surge or subsequent microsurges. Degarelix, a third-generation LHRH antagonist, is the only antagonist with a low histamine-releasing activity that is currently on the market for clinical use in advanced PCa with improved testosterone suppression, better control of follicle-stimulating hormone and prostate-specific antigen, and which offers a prolonged delay to progression and more favorable effects on serum alkaline phosphatase.
CONCLUSIONS: Although LHRH agonists are still the mainstay for treatment of advanced PCa, antagonists of LHRH offer an alternative as a pharmacological approach.
THE AMERICAN JOURNAL OF HEMATOLOGY/ONCOLOGY. 2014 December 22;10(6):5-13., Dec 22, 2014
This article describes relationships between follicle-stimulating
hormone (FSH), vascular endoth... more This article describes relationships between follicle-stimulating
hormone (FSH), vascular endothelial growth factor (VEGF), and other modulators of prostatic cancer, in order to help optimize treatment decisions. A comprehensive literature search of PubMed and relevant congress abstract databases was conducted using combinations of the key words prostate cancer, follicle-stimulating hormone, vascular endothelial growth factor, inhibins/activins, gonadotropin-releasing hormone (GnRH)/luteinizing hormone-releasing hormone (LHRH) receptor agonists/antagonists, and angiogenesis/neogenesis. This was followed by a consensus meeting of prostate cancer experts to discuss current knowledge surrounding FSH and the relevant evidence for its role in the development and progression of prostate cancer.
Our understanding of prostate cancer and its progression
indicate an increase in levels of FSH and the FSH receptor, along with alterations in key modulatory proteins that regulate FSH synthesis and receptor signaling. Elevations in VEGF and differential modulation of testosterone with GnRH/LHRH agonists and antagonists may contribute to treatment outcomes. Considerable evidence supports the hypothesis that dysregulation of the FSH system plays a role in both the development and progression of prostate cancer. Data indicate that FSH can be modulated by the choice of treatment intervention, especially when androgen-deprivation therapy
is used.
World J Clin Urol. 2014 November 24; 3(3): 184-194. , Nov 24, 2014
Benign prostatic hyperplasia (BPH) is a pathologic condition of the prostate described as a subst... more Benign prostatic hyperplasia (BPH) is a pathologic condition of the prostate described as a substantial increase in its number of epithelial and stromal cells. BPH may significantly reduce the quality of life due to the initiation of bladder outlet obstruction and lower urinary tract syndromes. Current medical therapies mostly consist of inhibitors of 5α-reductase or α1-adrenergic blockers; their efficacy is often insufficient. Antagonistic analogs of neuropeptide hormones are novel candidates for the management of BPH. At first, antagonists of luteinizing hormone-releasing hormone (LHRH) have been introduced to the therapy aimed to reduce serum testosterone levels. However, they have also been found to produce an inhibitory activity on local LHRH receptors in the prostate as well as impotence and other related side effects. Since then, several preclinical and clinical studies reported the favorable effects
of LHRH antagonists in BPH. In contrast, antagonists of growth hormone-releasing hormone (GHRH) and gastrin-releasing peptide (GRP) have been tested only in preclinical settings and produce significant reduction in prostate size in experimental models of BPH. They act at least in part, by blocking the action of respective ligands produced locally on prostates through their respective receptors in the prostate, and by inhibition
of autocrine insulin-like growth factors-Ⅰ/Ⅱ and epidermal growth factor production. GHRH and LHRH antagonists were also tested in combination resulting in a cumulative effect that was greater than that of each alone. This article will review the numerous studies that demonstrate the beneficial effects of antagonistic analogs of LHRH, GHRH and GRP in BPH, as well as
suggesting a potential role for somatostatin analogs in experimental therapies.
Introduction: This study evaluated the effects of an ntagonistic analog of growth hormone-releasi... more Introduction: This study evaluated the effects of an ntagonistic analog of growth hormone-releasing hormone, MIA-602, on tumor growth, response to doxorubicin, expression of drug resistance genes, and efflux pump function in human triple negative breast cancers.
Methods: HCC1806 (doxorubicin-sensitive) and MX-1 doxorubicin-resistant), cell lines were xenografted into nude mice and treated with MIA-602, doxorubicin, or their combination. Tumors were evaluated for changes in volume and the expression of the drug resistance genes MDR1 and NANOG. In-vitro cell culture assays were used to analyze the effect of MIA-602 on efflux pump function.
Results: Therapy with MIA-602 significantly reduced tumor growth and enhanced the efficacy of doxorubicin in both cell lines. Control HCC1806 tumors grew by 435%, while the volume of tumors treated with MIA-602 enlarged by 172.2% and with doxorubicin by 201.6%. Treatment with the combination of MIA-602 and doxorubicin resulted in an increase in volume of only 76.2%. Control MX-1 tumors grew by 907%, while tumors treated with MIA-602 enlarged by 434.8% and with doxorubicin by 815%. The combination of MIA-602 and doxorubicin reduced the increase in tumor volume to 256%. Treatment with MIA-602 lowered the level of growth hormonereleasing hormone and growth hormone-releasing hormone receptors and significantly reduced the expression of multidrug resistance (MDR1) gene and the drug resistance
regulator NANOG. MIA-602 also suppressed efflux pump function in both cell lines.
Conclusions: We conclude that treatment of triple negative breast cancers with growth hormone-releasing hormone antagonists reduces tumor growth and potentiates the effects of cytotoxic therapy by nullifying drug resistance.
Oncotarget. 2014 Jun 29;5(12):4567-4578., Jun 29, 2014
Management of castration-resistant prostate cancer (CRPC) is challenging due to lack of efficacio... more Management of castration-resistant prostate cancer (CRPC) is challenging due to lack of efficacious therapy. Luteinizing hormone-releasing hormone (LHRH) analogs appear to act directly on cells based on the LHRH receptors on human prostate adenocarcinoma cells. We explored anticancer activity of a cytotoxic analog of LHRH, AEZS-108, consisting of LHRH agonist linked to doxorubicin. Nude mice bearing DU-145 tumors were used to compare antitumor effects of AEZS-108 with its individual constituents or their unconjugated combination. The tumor growth inhibition of conjugate was greatest among treatment groups (90.5% inhibition vs. 41% by [D-Lys(6)]LHRH+DOX). The presence of LHRH receptors on DU-145 cells was confirmed by immunocytochemistry. In vitro, AEZS-108 significantly inhibited cell proliferation (61.2% inhibition) and elevated apoptosis rates (by 46%). By the detection of the inherent doxorubicin fluorescence, unconjugated doxorubicin was seen in the nucleus; the conjugate was perinuclear and at cell membrane. Autophagy, visualized by GFP-tagged p62 reporter, was increased by AEZS-108 (7.9-fold vs. 5.3-fold by DOX+[D-Lys(6)]LHRH. AEZS-108 more effectively increased reactive oxygen species (ROS, 2-fold vs. 1.4-fold by DOX+[D-Lys(6)]LHRH) and levels of the apoptotic regulator p21 in vivo and in vitro. We demonstrate robust inhibitory effects of the targeted cytotoxic LHRH analog, AEZS-108, on LHRHR positive castration-resistant prostate cancer cells.
World J Gastroenterol. 2014 May 28;20(20):6102-6112. Review., May 28, 2014
The introduction of new cytotoxic substances as well as agents that target vascular endothelial g... more The introduction of new cytotoxic substances as well as agents that target vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) signaling has improved clinical outcome of patients with metastatic colorectal cancer (mCRC). In this review we summarize the most relevant clinical data on VEGF and EGFR targeting regimens in mCRC. The effects of available treatment strategies for mCRC are often temporary, with resistance and disease progression developing in most patients. Thus, new treatment strategies are urgently needed. Some GI peptides including gastrin and gastrin releasing peptide, certain growth factors such as insulin-like growth factor-I and II and neuropeptides such as growth hormone releasing hormone (GHRH) are implicated in the growth of CRC. Experimental investigations in CRC with antagonistic analogs of bombesin/gastrin-releasing peptide, GHRH, and with cytotoxic peptides that can be targeted to peptide receptors on tumors, are summarized in the second part of the review.
In view of the recent findings of stimulatory effects of GHRH analogs, JI-34, JI-36 and JI-38, on... more In view of the recent findings of stimulatory effects of GHRH analogs, JI-34, JI-36 and JI-38, on cardiomyocytes, pancreatic islets and wound healing, three series of new analogs of GHRH(1-29) have been synthesized and evaluated biologically in an endeavor to produce more potent compounds. "Agmatine analogs", MR-356 (N-Me-Tyr(1)-JI-38), MR-361(N-Me-Tyr(1), D-Ala(2)-JI-38) and MR-367(N-Me-Tyr(1), D-Ala(2), Asn(8)-JI-38), in which Dat in JI-38 is replaced by N-Me-Tyr(1), showed improved relative potencies on GH release upon subcutaneous administration in vivo and binding in vitro. Modification with N-Me-Tyr(1) and Arg(29)-NHCH3 as in MR-403 (N-Me-Tyr(1), D-Ala(2), Arg(29)-NHCH3-JI-38), MR-406 (N-Me-Tyr(1), Arg(29)-NHCH3-JI-38) and MR-409 (N-Me-Tyr(1), D-Ala(2), Asn(8), Arg(29)-NHCH3-JI-38), and MR-410 (N-Me-Tyr(1), D-Ala(2), Thr(8), Arg(29)-NHCH3-JI-38) resulted in dramatically increased endocrine activities. These appear to be the most potent GHRH agonistic analogs so far developed. Analogs with Apa(30)-NH2 such as MR-326 (N-Me-Tyr(1), D-Ala(2), Arg(29), Apa(30)-NH2-JI-38), and with Gab(30)-NH2, as MR-502 (D-Ala(2), 5F-Phe(6), Ser(28), Arg(29),Gab(30)-NH2-JI-38) also exhibited much higher potency than JI-38 upon i.v. administration. The relationship between the GH-releasing potency and the analog structure is discussed. Fourteen GHRH agonists with the highest endocrine potencies were subjected to cardiologic tests. MR-409 and MR-356 exhibited higher potency than JI-38 in activating myocardial repair in rats with induced myocardial infarction. As the previous class of analogs, exemplified by JI-38, had shown promising results in multiple fields including cardiology, diabetes and wound healing, our new, more potent, GHRH agonists should manifest additional efficacy for possible medical applications.
Proc Natl Acad Sci U S A. 2014;111(2):781-6, Jan 14, 2014
The dismal prognosis of malignant brain tumors drives the development of new treatment modalities... more The dismal prognosis of malignant brain tumors drives the development of new treatment modalities. In view of the multiple activities of growth hormone-releasing hormone (GHRH), we hypothesized that pretreatment with a GHRH agonist, JI-34, might increase the susceptibility of U-87 MG glioblastoma multiforme (GBM) cells to subsequent treatment with the cytotoxic drug, doxorubicin (DOX). This concept was corroborated by our findings, in vivo, showing that the combination of the GHRH agonist, JI-34, and DOX inhibited the growth of GBM tumors, transplanted into nude mice, more than DOX alone. In vitro, the pretreatment of GBM cells with JI-34 potentiated inhibitory effects of DOX on cell proliferation, diminished cell size and viability, and promoted apoptotic processes, as shown by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide proliferation assay, ApoLive-Glo multiplex assay, and cell volumetric assay. Proteomic studies further revealed that the pretreatment with GHRH agonist evoked differentiation decreasing the expression of the neuroectodermal stem cell antigen, nestin, and up-regulating the glial maturation marker, GFAP. The GHRH agonist also reduced the release of humoral regulators of glial growth, such as FGF basic and TGFβ. Proteomic and gene-expression (RT-PCR) studies confirmed the strong proapoptotic activity (increase in p53, decrease in v-myc and Bcl-2) and anti-invasive potential (decrease in integrin α3) of the combination of GHRH agonist and DOX. These findings indicate that the GHRH agonists can potentiate the anticancer activity of the traditional chemotherapeutic drug, DOX, by multiple mechanisms including the induction of differentiation of cancer cells.
Advanced hormone-sensitive prostate cancer responds to androgen-deprivation therapy (ADT); howeve... more Advanced hormone-sensitive prostate cancer responds to androgen-deprivation therapy (ADT); however, therapeutic options for recurrent castration-resistant disease are limited. Because growth hormone-releasing hormone (GHRH) and GHRH receptor (GHRH-R) are regulated in an autocrine fashion in prostate cancer, inhibition of GHRH-R represents a compelling approach to treatment. We investigated the effects of the latest series of improved, highly potent GHRH antagonists--MIA-602, MIA-606, and MIA-690--on the growth of androgen-dependent as well as castration-resistant prostate cancer (CRPC) cells in vitro and in vivo. GHRH-R and its splice variant, SV1, were present in 22Rv1, LNCaP, and VCaP human prostate cancer cell lines. Androgen-dependent LNCaP and VCaP cells expressed higher levels of GHRH-R protein compared with castration-resistant 22Rv1 cells; however, 22Rv1 expressed higher levels of SV1. In vitro, MIA-602 decreased cell proliferation of 22Rv1, LNCaP, and VCaP prostate cancer cell lines by 70%, 61%, and 20%, respectively (all P < 0.05), indicating direct effects of MIA-602. In vivo, MIA-602 was more effective than MIA-606 and MIA-690 and decreased 22Rv1 xenograft tumor volumes in mice by 63% after 3 wk (P < 0.05). No noticeable untoward effects or changes in body weight occurred. In vitro, the VCaP cell line was minimally inhibited by MIA-602, but in vivo, this line showed a substantial reduction in growth of xenografts in response to MIA-602, indicating both direct and systemic inhibitory effects. MIA-602 also further inhibited VCaP xenografts when combined with ADT. This study demonstrates the preclinical efficacy of the GHRH antagonist MIA-602 for treatment of both androgen-dependent and CRPC.
Oncogene advance online publication, 4 November 2013; doi:10.1038/onc.2013.463
Prostate cancer is the most commonly diagnosed malignancy among men in industrialized countries, ... more Prostate cancer is the most commonly diagnosed malignancy among men in industrialized countries, accounting for the second
leading cause of cancer-related deaths. Although we now know that the androgen receptor (AR) is important for progression to the
deadly advanced stages of the disease, it is poorly understood what AR-regulated processes drive this pathology. Here we
demonstrate that AR regulates prostate cancer cell growth via the metabolic sensor 50-AMP-activated protein kinase (AMPK),
a kinase that classically regulates cellular energy homeostasis. In patients, activation of AMPK correlated with prostate cancer
progression. Using a combination of radiolabeled assays and emerging metabolomic approaches, we also show that prostate
cancer cells respond to androgen treatment by increasing not only rates of glycolysis, as is commonly seen in many cancers, but
also glucose and fatty acid oxidation. Importantly, this effect was dependent on androgen-mediated AMPK activity. Our results
further indicate that the AMPK-mediated metabolic changes increased intracellular ATP levels and peroxisome proliferatoractivated
receptor gamma coactivator 1-alpha (PGC-1a)-mediated mitochondrial biogenesis, affording distinct growth advantages
to the prostate cancer cells. Correspondingly, we used outlier analysis to determine that PGC-1a is overexpressed in a
subpopulation of clinical cancer samples. This was in contrast to what was observed in immortalized benign human prostate cells
and a testosterone-induced rat model of benign prostatic hyperplasia. Taken together, our findings converge to demonstrate that
androgens can co-opt the AMPK-PGC-1a signaling cascade, a known homeostatic mechanism, to increase prostate cancer cell
growth. The current study points to the potential utility of developing metabolic-targeted therapies directed toward the
AMPK-PGC-1a signaling axis for the treatment of prostate cancer.
INTRODUCTION:
Increasing evidence suggests that prostate cancer cells undergo unique metabolic r... more INTRODUCTION:
Increasing evidence suggests that prostate cancer cells undergo unique metabolic reprogramming during transformation. A master regulator of cellular homeostasis, 5'-AMP-activated protein kinase (AMPK), directs metabolic adaptation that supports the growth demands of rapidly dividing cancer cells. The utilization of AMPK as a therapeutic target may therefore provide an effective strategy in the treatment of prostate cancer. AREAS COVERED:
Our review describes the regulation of AMPK by androgens and upstream kinases including the calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) in prostate cancer. Oncogenic, AMPK-regulated pathways that direct various metabolic processes are also addressed. Furthermore, we discuss the role of AMPK in growth arrest and autophagy as a potential survival pathway for cancer cells. In addition, by regulating non-metabolic pathways, AMPK may stimulate migration and mitosis. Finally, this review summarizes efforts to treat prostate cancer with pharmacological agents capable of modulating AMPK signaling. EXPERT OPINION:
Current research is primarily focused on developing drugs that activate AMPK as a treatment for prostate cancer. However, oncogenic aspects of AMPK signaling calls for caution about employing such therapies. We think that inhibitors of CaMKK2 or AMPK, or perhaps the modulation of downstream targets of AMPK, will gain importance in the clinical management of prostate cancer.
Papillary thyroid cancer (PTC) is the most prevalent of all endocrine cancers. In recent studies,... more Papillary thyroid cancer (PTC) is the most prevalent of all endocrine cancers. In recent studies, the presence of receptors for pituitary-type growth hormone-releasing hormone (pGHRH-R) has been demonstrated in various human cancers, including human prostate, brain, and other cancer lines. Thyroid malignancies, however, have not yet been investigated in this regard. In this study, we found that pGHRH-R and its functional splice variant, SV1, are present in normal thyroid and PTC cells. We also treated seven normal and PTC tumor thyroid cells in vitro with a GHRH antagonist, MIA-602, to compare its anti-proliferation and anti-invasion potential against vehicle-treated cells. We found that treatment with GHRH antagonist increases the expression of SV1 and pGHRH-R in tumor cells compared to tumor cells exposed to vehicle only, a response which may alter the sensitivity of signaling kinases within the cells. GHRH antagonist treatment of tumor cells also reduced activity of the tumor invasion marker, matrix metalloproteinase (MMP)-2, compared to tumor cells exposed to vehicle only. The expression of pGHRH-R and SV1, as well as MMP-2 activity, in normal thyroid cells remained unaffected by GHRH antagonist treatment. Similarly, cell proliferation rates for tumor or normal thyroid cells were not affected by GHRH antagonist treatment. Our findings have important implications for the therapeutic use of GHRH antagonist in cases of aggressive PTC refractory to conventional treatment modalities, and in which protein expression and MMP-2 activity in normal thyroid tissue is left unaltered
Dyslipidemia associated with triglyceride-rich lipoproteins (TRLs) represents an important residu... more Dyslipidemia associated with triglyceride-rich lipoproteins (TRLs) represents an important residual risk factor for cardiovascular and chronic kidney disease in patients with type 1 diabetes (T1D). Levels of growth hormone (GH) are elevated in T1D, which aggravates both hyperglycemia and dyslipidemia. The hypothalamic growth hormone-releasing hormone (GHRH) regulates the release of GH by the pituitary but also exerts separate actions on peripheral GHRH receptors, the functional role of which remains elusive in T1D. In a rat model of streptozotocin (STZ)-induced T1D, GHRH receptor expression was found to be up-regulated in the distal small intestine, a tissue involved in chylomicron synthesis. Treatment of T1D rats with a GHRH antagonist, MIA-602, at a dose that did not affect plasma GH levels, significantly reduced TRL, as well as markers of renal injury, and improved endothelial-dependent vasorelaxation. Glucagon-like peptide 1 (GLP-1) reduces hyperglucagonemia and postprandial TRL, the latter in part through a decreased synthesis of apolipoprotein B-48 (ApoB-48) by intestinal cells. Although plasma GLP-1 levels were elevated in diabetic animals, this was accompanied by increased rather than reduced glucagon levels, suggesting impaired GLP-1 signaling. Treatment with MIA-602 normalized GLP-1 and glucagon to control levels in T1D rats. MIA-602 also decreased secretion of ApoB-48 from rat intestinal epithelial cells in response to oleic acid stimulation in vitro, in part through a GLP-1-dependent mechanism. Our findings support the hypothesis that antagonizing the signaling of GHRH in T1D may improve GLP-1 function in the small intestine, which, in turn, diminishes TRL and reduces renal and vascular complications.
We previously showed that growth hormone-releasing hormone (GHRH) agonists are cardioprotective f... more We previously showed that growth hormone-releasing hormone (GHRH) agonists are cardioprotective following myocardial infarction (MI). Here, our aim was to evaluate the in vitro and in vivo activities of highly potent new GHRH agonists, and elucidate their mechanisms of action in promoting cardiac repair. H9c2 cells were cultured in serum-free medium, mimicking nutritional deprivation. GHRH agonists decreased calcium influx and significantly improved cell survival. Rats with cardiac infarction were treated with GHRH agonists or placebo for four weeks. MI size was reduced by selected GHRH agonists (JI-38, MR-356, MR-409); this accompanied an increased number of cardiac c-kit+ cells, cellular mitotic divisions, and vascular density. One week post-MI, MR-409 significantly reduced plasma levels of IL-2, IL-6, IL-10 and TNF-α compared to placebo. Gene expression studies revealed favorable outcomes of MR-409 treatment partially result from inhibitory activity on pro-apoptotic molecules and...
Treatment of colon cancer with an antagonist of growth hormone-releasing hormone (GHRH), JMR-132,... more Treatment of colon cancer with an antagonist of growth hormone-releasing hormone (GHRH), JMR-132, results in a cell cycle arrest in S-phase of the tumor cells. Thus, we investigated the effect of JMR-132 in combination with S-phase-specific cytotoxic agents, 5-FU, irinotecan and cisplatin on the in vitro and in vivo growth of HT-29, HCT-116 and HCT-15 human colon cancer cell lines. In vitro, every compound inhibited proliferation of HCT-116 cells in a dose-dependent manner. Treatment with JMR-132 (5 μM) combined with 5-FU (1.25 μM), irinotecan (1.25 μM) or cisplatin (1.25 μM) resulted in an additive growth inhibition of HCT-116 cells in vitro as shown by MTS assay. Cell cycle analyses revealed that treatment of HCT-116 cells with JMR-132 was accompanied by a cell cycle arrest in S-phase. Combination treatment using JMR-132 plus a cytotoxic drug led to a significant increase of the sub-G 1 fraction, suggesting apoptosis. In vivo, daily treatment with GHRH antagonist JMR-132 decreased the tumor volume by 40-55% (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001) of HT-29, HCT-116 and HCT-15 tumors xenografted into athymic nude mice. Combined treatment with JMR-132 plus chemotherapeutic agents 5-FU, irinotecan or cisplatin resulted in an additive tumor growth suppression of HT-29, HCT-116 and HCT-15 xenografts to 56-85%. Our observations indicate that JMR-132 enhances the antiproliferative effect of S-phase-specific cytotoxic drugs by causing accumulation of tumor cells in S-phase.
Previously, we have shown that the targeted cytotoxic somatostatin (sst) analogue AN-162 [AZSE-12... more Previously, we have shown that the targeted cytotoxic somatostatin (sst) analogue AN-162 [AZSE-124] inhibits the growth of MDA-MB-231 human breast cancers xenografted into nude mice. In this study, we examined the trafficking of AN-162 into the cell, the expression of the somatostatin receptors (sstr) in specimens of human triple-negative breast cancers (TNBC), and the effect of AN-162 on HCC 1806 human TNBC xenografts. The expression of sstr in TNBC tumor samples was investigated by immunohistochemical staining. The expression of sstr in HCC 1806 was evaluated by reverse transcription PCR. Internalization studies with I-labeled AN-162 were carried out and the autofluorescence sign of doxorubicin moiety in the cell nucleus after incubation with AN-162 was measured using a fluorescence assay. The effects of AN-162 on the growth of HCC 1806 xenografted into nude mice were studied. A fluorescence microscopy cytotoxicity assay in vitro to detect cell death after treatment with AN-162 was also carried out. About 28% of TNBC tumor specimens showed a positive staining for sstr subtype 2a. HCC 1806 expresses all five subtypes of sstr. In the fluorescence cytotoxicity assay, dead HCC 1806 cells were found 24 h after incubation with AN-162. The growth of HCC 1806 tumors in nude mice was significantly inhibited by treatment with AN-162. AN-162 was internalized into the HCC 1806 cells and doxorubicin moiety was detected in the cell nuclei. This study is the first to show that the trafficking of the cytotoxic sst analogue AN-162 into the cell is mediated by sstr. Our work shows that the growth of xenografted HCC 1806 TNBCs can be effectively inhibited in vivo with AN-162. This investigation provides information on the mechanism of action and efficacy of this new targeted cytotoxic sst analogue and identifies in this relation the sstr as a favorable therapeutic target in TNBC.
Malignant melanoma is the deadliest form of skin cancer; the treatment of advanced and recurrent ... more Malignant melanoma is the deadliest form of skin cancer; the treatment of advanced and recurrent forms remains a challenge. It has recently been reported that growth hormone-releasing hormone (GHRH) receptor is involved in the pathogenesis of melanoma. Therefore, we investigated the effects of our new GHRH antagonists on a human melanoma cancer cell line. Antiproliferative effects of GHRH antagonists, MIA-602, MIA-606 and MIA-690, on the human melanoma cell line, A-375, were studied in vitro using the MTS assay. The effect of MIA-690 (5 μg/day 28 d) was further evaluated in vivo in nude mice bearing xenografts of A-375. Subcellular localization of p27 was detected with Western blot and immunofluorescent staining. MIA-690 inhibited the proliferation of A-375 cells in a dose-dependent manner (33% at 10 μM, and 19.2% at 5 μM, P < 0 .05 vs. control), and suppressed the growth of xenografted tumors by 70.45% (P < 0.05). Flow cytometric analysis of cell cycle effects following the administration of MIA-690 revealed a decrease in the number of cells in G2/M phase (from 19.7% to 12.9%, P < 0.001). Additionally, Western blot and immunofluorescent studies showed that exposure of A-375 cells to MIA-690 triggered the nuclear accumulation of p27. MIA-690 inhibited tumor growth in vitro and in vivo, and increased the translocation of p27 into the nucleus thus inhibiting progression of the cell cycle. Our findings indicate that patients with malignant melanoma could benefit from treatment regimens, which combine existing chemotherapy agents and novel GHRH-antagonists.
Recent findings suggest that BPH has an inflammatory component. Clinical trials have documented t... more Recent findings suggest that BPH has an inflammatory component. Clinical trials have documented that therapy with LHRH antagonist Cetrorelix causes a marked and prolonged improvement in LUTS in men with symptomatic BPH. We investigated the mechanism of action and effect of Cetrorelix in a rat model of BPH. Adult male Wistar rats were used. BPH was induced in rats by subcutaneous injections of TE 2 mg/day for 4 weeks. Control animals received injections of corn oil. After induction of BPH, rats received depot Cetrorelix pamoate at the doses of 0.625, 1.25, and 12.5 mg/kg on days 1 and 22 and TE-control rats received vehicle injections. Whole prostates were weighed and processed for RNA and protein. Real-time RT-PCR assays for numerous inflammatory cytokines and growth factors were performed. Quantitative analyses of prostatic LHRH receptor, LHRH, androgen receptor (AR) and 5α-reductase 2 were done by real-time RT-PCR and immunoblotting; serum DHT, LH, PSA, and IGF-1 by immunoassays. mRNA levels for inflammatory cytokines IFN-γ, IL-3, IL-4, IL-5, IL-6, IL-8, IL-13, IL-15, and IL-17 and for growth factors EGF, FGF-2, FGF-7, FGF-8, FGF-14, TGF-β1, and VEGF-A were significantly reduced by Cetrorelix 0.625 mg/kg (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05). Prostate weights were also significantly lowered by any dose of Cetrorelix. This study suggests that Cetrorelix reduces various inflammatory cytokines and growth factors in rat prostate and, at doses which do not induce castration levels of testosterone, can lower prostate weights. Our findings shed light on the mechanism of action of LHRH antagonists in BPH.
Antibiotic treatment of patients infected with G − or G + bacteria promotes release of the toxins... more Antibiotic treatment of patients infected with G − or G + bacteria promotes release of the toxins lipopolysaccharide (LPS) and pneumolysin (PLY) in their lungs. Growth Hormone-releasing Hormone (GHRH) agonist JI-34 protects human lung microvascular endothelial cells (HL-MVEC), expressing splice variant 1 (SV-1) of the receptor, from PLY-induced barrier dysfunction. We investigated whether JI-34 also blunts LPS-induced hyperpermeability. Since GHRH receptor (GHRH-R) signaling can potentially stimulate both cAMP-dependent barrier-protective pathways as well as barrier-disruptive protein kinase C pathways, we studied their interaction in GHRH agonist-treated HL-MVEC, in the presence of PLY, by means of siRNA-mediated protein kinase A (PKA) depletion.
Novel drugs are required for the treatment of
CRPC. The best option may not be the agents
that ... more Novel drugs are required for the treatment of
CRPC. The best option may not be the agents
that target androgen receptors or compounds
which inhibit enzymes involved in androgen
biosynthesis. This is because the androgen
deprivation created by these compounds
can be overcome by mutations in androgen
receptors, the appearance of splice variants
of these receptors or alternate biochemical
pathways.
The use of currently available cytotoxic
analogs of LHRH, or somatostatin that can
be targeted to prostate cancers may lead to
an improvement in the treatment of CRPC
and an increase in the survival rate. A new
modality based on GHRH antagonists also
appears to be useful for the treatment of
metastatic CRPC.
BACKGROUND:
Androgen deprivation therapy (ADT) has been the standard of care for treating pati... more BACKGROUND:
Androgen deprivation therapy (ADT) has been the standard of care for treating patients with hormone-sensitive advanced prostate cancer (PCa) for 3 decades. The agonists of luteinizing hormone-releasing hormone (LHRH), also called gonadotropin-releasing hormone, are still the most frequently used form of medical ADT.
ADT AND LHRH ANALOGS: The application of agonists of LHRH has improved and modernized the treatment of advanced PCa; millions of patients have benefited from therapy with LHRH agonists as a preferred alternative to surgical castration, as the psychological effects and perpetuity of orchiectomy are undesirable for most men. Despite their efficacy, agonists of LHRH have several shortcomings, including initial surge in testosterone, producing exacerbation of clinical symptoms, and microsurges in testosterone that might occur after each administration. A new, alternate approach to ADT is emerging with the improvements in antagonists of LHRH. This class of LHRH analogues produces a direct and immediate blockade of pituitary LHRH receptors and leads to a more rapid suppression of testosterone without an initial surge or subsequent microsurges. Degarelix, a third-generation LHRH antagonist, is the only antagonist with a low histamine-releasing activity that is currently on the market for clinical use in advanced PCa with improved testosterone suppression, better control of follicle-stimulating hormone and prostate-specific antigen, and which offers a prolonged delay to progression and more favorable effects on serum alkaline phosphatase.
CONCLUSIONS: Although LHRH agonists are still the mainstay for treatment of advanced PCa, antagonists of LHRH offer an alternative as a pharmacological approach.
THE AMERICAN JOURNAL OF HEMATOLOGY/ONCOLOGY. 2014 December 22;10(6):5-13., Dec 22, 2014
This article describes relationships between follicle-stimulating
hormone (FSH), vascular endoth... more This article describes relationships between follicle-stimulating
hormone (FSH), vascular endothelial growth factor (VEGF), and other modulators of prostatic cancer, in order to help optimize treatment decisions. A comprehensive literature search of PubMed and relevant congress abstract databases was conducted using combinations of the key words prostate cancer, follicle-stimulating hormone, vascular endothelial growth factor, inhibins/activins, gonadotropin-releasing hormone (GnRH)/luteinizing hormone-releasing hormone (LHRH) receptor agonists/antagonists, and angiogenesis/neogenesis. This was followed by a consensus meeting of prostate cancer experts to discuss current knowledge surrounding FSH and the relevant evidence for its role in the development and progression of prostate cancer.
Our understanding of prostate cancer and its progression
indicate an increase in levels of FSH and the FSH receptor, along with alterations in key modulatory proteins that regulate FSH synthesis and receptor signaling. Elevations in VEGF and differential modulation of testosterone with GnRH/LHRH agonists and antagonists may contribute to treatment outcomes. Considerable evidence supports the hypothesis that dysregulation of the FSH system plays a role in both the development and progression of prostate cancer. Data indicate that FSH can be modulated by the choice of treatment intervention, especially when androgen-deprivation therapy
is used.
World J Clin Urol. 2014 November 24; 3(3): 184-194. , Nov 24, 2014
Benign prostatic hyperplasia (BPH) is a pathologic condition of the prostate described as a subst... more Benign prostatic hyperplasia (BPH) is a pathologic condition of the prostate described as a substantial increase in its number of epithelial and stromal cells. BPH may significantly reduce the quality of life due to the initiation of bladder outlet obstruction and lower urinary tract syndromes. Current medical therapies mostly consist of inhibitors of 5α-reductase or α1-adrenergic blockers; their efficacy is often insufficient. Antagonistic analogs of neuropeptide hormones are novel candidates for the management of BPH. At first, antagonists of luteinizing hormone-releasing hormone (LHRH) have been introduced to the therapy aimed to reduce serum testosterone levels. However, they have also been found to produce an inhibitory activity on local LHRH receptors in the prostate as well as impotence and other related side effects. Since then, several preclinical and clinical studies reported the favorable effects
of LHRH antagonists in BPH. In contrast, antagonists of growth hormone-releasing hormone (GHRH) and gastrin-releasing peptide (GRP) have been tested only in preclinical settings and produce significant reduction in prostate size in experimental models of BPH. They act at least in part, by blocking the action of respective ligands produced locally on prostates through their respective receptors in the prostate, and by inhibition
of autocrine insulin-like growth factors-Ⅰ/Ⅱ and epidermal growth factor production. GHRH and LHRH antagonists were also tested in combination resulting in a cumulative effect that was greater than that of each alone. This article will review the numerous studies that demonstrate the beneficial effects of antagonistic analogs of LHRH, GHRH and GRP in BPH, as well as
suggesting a potential role for somatostatin analogs in experimental therapies.
Introduction: This study evaluated the effects of an ntagonistic analog of growth hormone-releasi... more Introduction: This study evaluated the effects of an ntagonistic analog of growth hormone-releasing hormone, MIA-602, on tumor growth, response to doxorubicin, expression of drug resistance genes, and efflux pump function in human triple negative breast cancers.
Methods: HCC1806 (doxorubicin-sensitive) and MX-1 doxorubicin-resistant), cell lines were xenografted into nude mice and treated with MIA-602, doxorubicin, or their combination. Tumors were evaluated for changes in volume and the expression of the drug resistance genes MDR1 and NANOG. In-vitro cell culture assays were used to analyze the effect of MIA-602 on efflux pump function.
Results: Therapy with MIA-602 significantly reduced tumor growth and enhanced the efficacy of doxorubicin in both cell lines. Control HCC1806 tumors grew by 435%, while the volume of tumors treated with MIA-602 enlarged by 172.2% and with doxorubicin by 201.6%. Treatment with the combination of MIA-602 and doxorubicin resulted in an increase in volume of only 76.2%. Control MX-1 tumors grew by 907%, while tumors treated with MIA-602 enlarged by 434.8% and with doxorubicin by 815%. The combination of MIA-602 and doxorubicin reduced the increase in tumor volume to 256%. Treatment with MIA-602 lowered the level of growth hormonereleasing hormone and growth hormone-releasing hormone receptors and significantly reduced the expression of multidrug resistance (MDR1) gene and the drug resistance
regulator NANOG. MIA-602 also suppressed efflux pump function in both cell lines.
Conclusions: We conclude that treatment of triple negative breast cancers with growth hormone-releasing hormone antagonists reduces tumor growth and potentiates the effects of cytotoxic therapy by nullifying drug resistance.
Oncotarget. 2014 Jun 29;5(12):4567-4578., Jun 29, 2014
Management of castration-resistant prostate cancer (CRPC) is challenging due to lack of efficacio... more Management of castration-resistant prostate cancer (CRPC) is challenging due to lack of efficacious therapy. Luteinizing hormone-releasing hormone (LHRH) analogs appear to act directly on cells based on the LHRH receptors on human prostate adenocarcinoma cells. We explored anticancer activity of a cytotoxic analog of LHRH, AEZS-108, consisting of LHRH agonist linked to doxorubicin. Nude mice bearing DU-145 tumors were used to compare antitumor effects of AEZS-108 with its individual constituents or their unconjugated combination. The tumor growth inhibition of conjugate was greatest among treatment groups (90.5% inhibition vs. 41% by [D-Lys(6)]LHRH+DOX). The presence of LHRH receptors on DU-145 cells was confirmed by immunocytochemistry. In vitro, AEZS-108 significantly inhibited cell proliferation (61.2% inhibition) and elevated apoptosis rates (by 46%). By the detection of the inherent doxorubicin fluorescence, unconjugated doxorubicin was seen in the nucleus; the conjugate was perinuclear and at cell membrane. Autophagy, visualized by GFP-tagged p62 reporter, was increased by AEZS-108 (7.9-fold vs. 5.3-fold by DOX+[D-Lys(6)]LHRH. AEZS-108 more effectively increased reactive oxygen species (ROS, 2-fold vs. 1.4-fold by DOX+[D-Lys(6)]LHRH) and levels of the apoptotic regulator p21 in vivo and in vitro. We demonstrate robust inhibitory effects of the targeted cytotoxic LHRH analog, AEZS-108, on LHRHR positive castration-resistant prostate cancer cells.
World J Gastroenterol. 2014 May 28;20(20):6102-6112. Review., May 28, 2014
The introduction of new cytotoxic substances as well as agents that target vascular endothelial g... more The introduction of new cytotoxic substances as well as agents that target vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) signaling has improved clinical outcome of patients with metastatic colorectal cancer (mCRC). In this review we summarize the most relevant clinical data on VEGF and EGFR targeting regimens in mCRC. The effects of available treatment strategies for mCRC are often temporary, with resistance and disease progression developing in most patients. Thus, new treatment strategies are urgently needed. Some GI peptides including gastrin and gastrin releasing peptide, certain growth factors such as insulin-like growth factor-I and II and neuropeptides such as growth hormone releasing hormone (GHRH) are implicated in the growth of CRC. Experimental investigations in CRC with antagonistic analogs of bombesin/gastrin-releasing peptide, GHRH, and with cytotoxic peptides that can be targeted to peptide receptors on tumors, are summarized in the second part of the review.
In view of the recent findings of stimulatory effects of GHRH analogs, JI-34, JI-36 and JI-38, on... more In view of the recent findings of stimulatory effects of GHRH analogs, JI-34, JI-36 and JI-38, on cardiomyocytes, pancreatic islets and wound healing, three series of new analogs of GHRH(1-29) have been synthesized and evaluated biologically in an endeavor to produce more potent compounds. "Agmatine analogs", MR-356 (N-Me-Tyr(1)-JI-38), MR-361(N-Me-Tyr(1), D-Ala(2)-JI-38) and MR-367(N-Me-Tyr(1), D-Ala(2), Asn(8)-JI-38), in which Dat in JI-38 is replaced by N-Me-Tyr(1), showed improved relative potencies on GH release upon subcutaneous administration in vivo and binding in vitro. Modification with N-Me-Tyr(1) and Arg(29)-NHCH3 as in MR-403 (N-Me-Tyr(1), D-Ala(2), Arg(29)-NHCH3-JI-38), MR-406 (N-Me-Tyr(1), Arg(29)-NHCH3-JI-38) and MR-409 (N-Me-Tyr(1), D-Ala(2), Asn(8), Arg(29)-NHCH3-JI-38), and MR-410 (N-Me-Tyr(1), D-Ala(2), Thr(8), Arg(29)-NHCH3-JI-38) resulted in dramatically increased endocrine activities. These appear to be the most potent GHRH agonistic analogs so far developed. Analogs with Apa(30)-NH2 such as MR-326 (N-Me-Tyr(1), D-Ala(2), Arg(29), Apa(30)-NH2-JI-38), and with Gab(30)-NH2, as MR-502 (D-Ala(2), 5F-Phe(6), Ser(28), Arg(29),Gab(30)-NH2-JI-38) also exhibited much higher potency than JI-38 upon i.v. administration. The relationship between the GH-releasing potency and the analog structure is discussed. Fourteen GHRH agonists with the highest endocrine potencies were subjected to cardiologic tests. MR-409 and MR-356 exhibited higher potency than JI-38 in activating myocardial repair in rats with induced myocardial infarction. As the previous class of analogs, exemplified by JI-38, had shown promising results in multiple fields including cardiology, diabetes and wound healing, our new, more potent, GHRH agonists should manifest additional efficacy for possible medical applications.
Proc Natl Acad Sci U S A. 2014;111(2):781-6, Jan 14, 2014
The dismal prognosis of malignant brain tumors drives the development of new treatment modalities... more The dismal prognosis of malignant brain tumors drives the development of new treatment modalities. In view of the multiple activities of growth hormone-releasing hormone (GHRH), we hypothesized that pretreatment with a GHRH agonist, JI-34, might increase the susceptibility of U-87 MG glioblastoma multiforme (GBM) cells to subsequent treatment with the cytotoxic drug, doxorubicin (DOX). This concept was corroborated by our findings, in vivo, showing that the combination of the GHRH agonist, JI-34, and DOX inhibited the growth of GBM tumors, transplanted into nude mice, more than DOX alone. In vitro, the pretreatment of GBM cells with JI-34 potentiated inhibitory effects of DOX on cell proliferation, diminished cell size and viability, and promoted apoptotic processes, as shown by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide proliferation assay, ApoLive-Glo multiplex assay, and cell volumetric assay. Proteomic studies further revealed that the pretreatment with GHRH agonist evoked differentiation decreasing the expression of the neuroectodermal stem cell antigen, nestin, and up-regulating the glial maturation marker, GFAP. The GHRH agonist also reduced the release of humoral regulators of glial growth, such as FGF basic and TGFβ. Proteomic and gene-expression (RT-PCR) studies confirmed the strong proapoptotic activity (increase in p53, decrease in v-myc and Bcl-2) and anti-invasive potential (decrease in integrin α3) of the combination of GHRH agonist and DOX. These findings indicate that the GHRH agonists can potentiate the anticancer activity of the traditional chemotherapeutic drug, DOX, by multiple mechanisms including the induction of differentiation of cancer cells.
Advanced hormone-sensitive prostate cancer responds to androgen-deprivation therapy (ADT); howeve... more Advanced hormone-sensitive prostate cancer responds to androgen-deprivation therapy (ADT); however, therapeutic options for recurrent castration-resistant disease are limited. Because growth hormone-releasing hormone (GHRH) and GHRH receptor (GHRH-R) are regulated in an autocrine fashion in prostate cancer, inhibition of GHRH-R represents a compelling approach to treatment. We investigated the effects of the latest series of improved, highly potent GHRH antagonists--MIA-602, MIA-606, and MIA-690--on the growth of androgen-dependent as well as castration-resistant prostate cancer (CRPC) cells in vitro and in vivo. GHRH-R and its splice variant, SV1, were present in 22Rv1, LNCaP, and VCaP human prostate cancer cell lines. Androgen-dependent LNCaP and VCaP cells expressed higher levels of GHRH-R protein compared with castration-resistant 22Rv1 cells; however, 22Rv1 expressed higher levels of SV1. In vitro, MIA-602 decreased cell proliferation of 22Rv1, LNCaP, and VCaP prostate cancer cell lines by 70%, 61%, and 20%, respectively (all P < 0.05), indicating direct effects of MIA-602. In vivo, MIA-602 was more effective than MIA-606 and MIA-690 and decreased 22Rv1 xenograft tumor volumes in mice by 63% after 3 wk (P < 0.05). No noticeable untoward effects or changes in body weight occurred. In vitro, the VCaP cell line was minimally inhibited by MIA-602, but in vivo, this line showed a substantial reduction in growth of xenografts in response to MIA-602, indicating both direct and systemic inhibitory effects. MIA-602 also further inhibited VCaP xenografts when combined with ADT. This study demonstrates the preclinical efficacy of the GHRH antagonist MIA-602 for treatment of both androgen-dependent and CRPC.
Oncogene advance online publication, 4 November 2013; doi:10.1038/onc.2013.463
Prostate cancer is the most commonly diagnosed malignancy among men in industrialized countries, ... more Prostate cancer is the most commonly diagnosed malignancy among men in industrialized countries, accounting for the second
leading cause of cancer-related deaths. Although we now know that the androgen receptor (AR) is important for progression to the
deadly advanced stages of the disease, it is poorly understood what AR-regulated processes drive this pathology. Here we
demonstrate that AR regulates prostate cancer cell growth via the metabolic sensor 50-AMP-activated protein kinase (AMPK),
a kinase that classically regulates cellular energy homeostasis. In patients, activation of AMPK correlated with prostate cancer
progression. Using a combination of radiolabeled assays and emerging metabolomic approaches, we also show that prostate
cancer cells respond to androgen treatment by increasing not only rates of glycolysis, as is commonly seen in many cancers, but
also glucose and fatty acid oxidation. Importantly, this effect was dependent on androgen-mediated AMPK activity. Our results
further indicate that the AMPK-mediated metabolic changes increased intracellular ATP levels and peroxisome proliferatoractivated
receptor gamma coactivator 1-alpha (PGC-1a)-mediated mitochondrial biogenesis, affording distinct growth advantages
to the prostate cancer cells. Correspondingly, we used outlier analysis to determine that PGC-1a is overexpressed in a
subpopulation of clinical cancer samples. This was in contrast to what was observed in immortalized benign human prostate cells
and a testosterone-induced rat model of benign prostatic hyperplasia. Taken together, our findings converge to demonstrate that
androgens can co-opt the AMPK-PGC-1a signaling cascade, a known homeostatic mechanism, to increase prostate cancer cell
growth. The current study points to the potential utility of developing metabolic-targeted therapies directed toward the
AMPK-PGC-1a signaling axis for the treatment of prostate cancer.
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Papers by Ferenc Rick
Increasing evidence suggests that prostate cancer cells undergo unique metabolic reprogramming during transformation. A master regulator of cellular homeostasis, 5'-AMP-activated protein kinase (AMPK), directs metabolic adaptation that supports the growth demands of rapidly dividing cancer cells. The utilization of AMPK as a therapeutic target may therefore provide an effective strategy in the treatment of prostate cancer.
AREAS COVERED:
Our review describes the regulation of AMPK by androgens and upstream kinases including the calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) in prostate cancer. Oncogenic, AMPK-regulated pathways that direct various metabolic processes are also addressed. Furthermore, we discuss the role of AMPK in growth arrest and autophagy as a potential survival pathway for cancer cells. In addition, by regulating non-metabolic pathways, AMPK may stimulate migration and mitosis. Finally, this review summarizes efforts to treat prostate cancer with pharmacological agents capable of modulating AMPK signaling.
EXPERT OPINION:
Current research is primarily focused on developing drugs that activate AMPK as a treatment for prostate cancer. However, oncogenic aspects of AMPK signaling calls for caution about employing such therapies. We think that inhibitors of CaMKK2 or AMPK, or perhaps the modulation of downstream targets of AMPK, will gain importance in the clinical management of prostate cancer.
CRPC. The best option may not be the agents
that target androgen receptors or compounds
which inhibit enzymes involved in androgen
biosynthesis. This is because the androgen
deprivation created by these compounds
can be overcome by mutations in androgen
receptors, the appearance of splice variants
of these receptors or alternate biochemical
pathways.
The use of currently available cytotoxic
analogs of LHRH, or somatostatin that can
be targeted to prostate cancers may lead to
an improvement in the treatment of CRPC
and an increase in the survival rate. A new
modality based on GHRH antagonists also
appears to be useful for the treatment of
metastatic CRPC.
Androgen deprivation therapy (ADT) has been the standard of care for treating patients with hormone-sensitive advanced prostate cancer (PCa) for 3 decades. The agonists of luteinizing hormone-releasing hormone (LHRH), also called gonadotropin-releasing hormone, are still the most frequently used form of medical ADT.
ADT AND LHRH ANALOGS: The application of agonists of LHRH has improved and modernized the treatment of advanced PCa; millions of patients have benefited from therapy with LHRH agonists as a preferred alternative to surgical castration, as the psychological effects and perpetuity of orchiectomy are undesirable for most men. Despite their efficacy, agonists of LHRH have several shortcomings, including initial surge in testosterone, producing exacerbation of clinical symptoms, and microsurges in testosterone that might occur after each administration. A new, alternate approach to ADT is emerging with the improvements in antagonists of LHRH. This class of LHRH analogues produces a direct and immediate blockade of pituitary LHRH receptors and leads to a more rapid suppression of testosterone without an initial surge or subsequent microsurges. Degarelix, a third-generation LHRH antagonist, is the only antagonist with a low histamine-releasing activity that is currently on the market for clinical use in advanced PCa with improved testosterone suppression, better control of follicle-stimulating hormone and prostate-specific antigen, and which offers a prolonged delay to progression and more favorable effects on serum alkaline phosphatase.
CONCLUSIONS: Although LHRH agonists are still the mainstay for treatment of advanced PCa, antagonists of LHRH offer an alternative as a pharmacological approach.
hormone (FSH), vascular endothelial growth factor (VEGF), and other modulators of prostatic cancer, in order to help optimize treatment decisions. A comprehensive literature search of PubMed and relevant congress abstract databases was conducted using combinations of the key words prostate cancer, follicle-stimulating hormone, vascular endothelial growth factor, inhibins/activins, gonadotropin-releasing hormone (GnRH)/luteinizing hormone-releasing hormone (LHRH) receptor agonists/antagonists, and angiogenesis/neogenesis. This was followed by a consensus meeting of prostate cancer experts to discuss current knowledge surrounding FSH and the relevant evidence for its role in the development and progression of prostate cancer.
Our understanding of prostate cancer and its progression
indicate an increase in levels of FSH and the FSH receptor, along with alterations in key modulatory proteins that regulate FSH synthesis and receptor signaling. Elevations in VEGF and differential modulation of testosterone with GnRH/LHRH agonists and antagonists may contribute to treatment outcomes. Considerable evidence supports the hypothesis that dysregulation of the FSH system plays a role in both the development and progression of prostate cancer. Data indicate that FSH can be modulated by the choice of treatment intervention, especially when androgen-deprivation therapy
is used.
of LHRH antagonists in BPH. In contrast, antagonists of growth hormone-releasing hormone (GHRH) and gastrin-releasing peptide (GRP) have been tested only in preclinical settings and produce significant reduction in prostate size in experimental models of BPH. They act at least in part, by blocking the action of respective ligands produced locally on prostates through their respective receptors in the prostate, and by inhibition
of autocrine insulin-like growth factors-Ⅰ/Ⅱ and epidermal growth factor production. GHRH and LHRH antagonists were also tested in combination resulting in a cumulative effect that was greater than that of each alone. This article will review the numerous studies that demonstrate the beneficial effects of antagonistic analogs of LHRH, GHRH and GRP in BPH, as well as
suggesting a potential role for somatostatin analogs in experimental therapies.
Methods: HCC1806 (doxorubicin-sensitive) and MX-1 doxorubicin-resistant), cell lines were xenografted into nude mice and treated with MIA-602, doxorubicin, or their combination. Tumors were evaluated for changes in volume and the expression of the drug resistance genes MDR1 and NANOG. In-vitro cell culture assays were used to analyze the effect of MIA-602 on efflux pump function.
Results: Therapy with MIA-602 significantly reduced tumor growth and enhanced the efficacy of doxorubicin in both cell lines. Control HCC1806 tumors grew by 435%, while the volume of tumors treated with MIA-602 enlarged by 172.2% and with doxorubicin by 201.6%. Treatment with the combination of MIA-602 and doxorubicin resulted in an increase in volume of only 76.2%. Control MX-1 tumors grew by 907%, while tumors treated with MIA-602 enlarged by 434.8% and with doxorubicin by 815%. The combination of MIA-602 and doxorubicin reduced the increase in tumor volume to 256%. Treatment with MIA-602 lowered the level of growth hormonereleasing hormone and growth hormone-releasing hormone receptors and significantly reduced the expression of multidrug resistance (MDR1) gene and the drug resistance
regulator NANOG. MIA-602 also suppressed efflux pump function in both cell lines.
Conclusions: We conclude that treatment of triple negative breast cancers with growth hormone-releasing hormone antagonists reduces tumor growth and potentiates the effects of cytotoxic therapy by nullifying drug resistance.
leading cause of cancer-related deaths. Although we now know that the androgen receptor (AR) is important for progression to the
deadly advanced stages of the disease, it is poorly understood what AR-regulated processes drive this pathology. Here we
demonstrate that AR regulates prostate cancer cell growth via the metabolic sensor 50-AMP-activated protein kinase (AMPK),
a kinase that classically regulates cellular energy homeostasis. In patients, activation of AMPK correlated with prostate cancer
progression. Using a combination of radiolabeled assays and emerging metabolomic approaches, we also show that prostate
cancer cells respond to androgen treatment by increasing not only rates of glycolysis, as is commonly seen in many cancers, but
also glucose and fatty acid oxidation. Importantly, this effect was dependent on androgen-mediated AMPK activity. Our results
further indicate that the AMPK-mediated metabolic changes increased intracellular ATP levels and peroxisome proliferatoractivated
receptor gamma coactivator 1-alpha (PGC-1a)-mediated mitochondrial biogenesis, affording distinct growth advantages
to the prostate cancer cells. Correspondingly, we used outlier analysis to determine that PGC-1a is overexpressed in a
subpopulation of clinical cancer samples. This was in contrast to what was observed in immortalized benign human prostate cells
and a testosterone-induced rat model of benign prostatic hyperplasia. Taken together, our findings converge to demonstrate that
androgens can co-opt the AMPK-PGC-1a signaling cascade, a known homeostatic mechanism, to increase prostate cancer cell
growth. The current study points to the potential utility of developing metabolic-targeted therapies directed toward the
AMPK-PGC-1a signaling axis for the treatment of prostate cancer.
Increasing evidence suggests that prostate cancer cells undergo unique metabolic reprogramming during transformation. A master regulator of cellular homeostasis, 5'-AMP-activated protein kinase (AMPK), directs metabolic adaptation that supports the growth demands of rapidly dividing cancer cells. The utilization of AMPK as a therapeutic target may therefore provide an effective strategy in the treatment of prostate cancer.
AREAS COVERED:
Our review describes the regulation of AMPK by androgens and upstream kinases including the calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) in prostate cancer. Oncogenic, AMPK-regulated pathways that direct various metabolic processes are also addressed. Furthermore, we discuss the role of AMPK in growth arrest and autophagy as a potential survival pathway for cancer cells. In addition, by regulating non-metabolic pathways, AMPK may stimulate migration and mitosis. Finally, this review summarizes efforts to treat prostate cancer with pharmacological agents capable of modulating AMPK signaling.
EXPERT OPINION:
Current research is primarily focused on developing drugs that activate AMPK as a treatment for prostate cancer. However, oncogenic aspects of AMPK signaling calls for caution about employing such therapies. We think that inhibitors of CaMKK2 or AMPK, or perhaps the modulation of downstream targets of AMPK, will gain importance in the clinical management of prostate cancer.
CRPC. The best option may not be the agents
that target androgen receptors or compounds
which inhibit enzymes involved in androgen
biosynthesis. This is because the androgen
deprivation created by these compounds
can be overcome by mutations in androgen
receptors, the appearance of splice variants
of these receptors or alternate biochemical
pathways.
The use of currently available cytotoxic
analogs of LHRH, or somatostatin that can
be targeted to prostate cancers may lead to
an improvement in the treatment of CRPC
and an increase in the survival rate. A new
modality based on GHRH antagonists also
appears to be useful for the treatment of
metastatic CRPC.
Androgen deprivation therapy (ADT) has been the standard of care for treating patients with hormone-sensitive advanced prostate cancer (PCa) for 3 decades. The agonists of luteinizing hormone-releasing hormone (LHRH), also called gonadotropin-releasing hormone, are still the most frequently used form of medical ADT.
ADT AND LHRH ANALOGS: The application of agonists of LHRH has improved and modernized the treatment of advanced PCa; millions of patients have benefited from therapy with LHRH agonists as a preferred alternative to surgical castration, as the psychological effects and perpetuity of orchiectomy are undesirable for most men. Despite their efficacy, agonists of LHRH have several shortcomings, including initial surge in testosterone, producing exacerbation of clinical symptoms, and microsurges in testosterone that might occur after each administration. A new, alternate approach to ADT is emerging with the improvements in antagonists of LHRH. This class of LHRH analogues produces a direct and immediate blockade of pituitary LHRH receptors and leads to a more rapid suppression of testosterone without an initial surge or subsequent microsurges. Degarelix, a third-generation LHRH antagonist, is the only antagonist with a low histamine-releasing activity that is currently on the market for clinical use in advanced PCa with improved testosterone suppression, better control of follicle-stimulating hormone and prostate-specific antigen, and which offers a prolonged delay to progression and more favorable effects on serum alkaline phosphatase.
CONCLUSIONS: Although LHRH agonists are still the mainstay for treatment of advanced PCa, antagonists of LHRH offer an alternative as a pharmacological approach.
hormone (FSH), vascular endothelial growth factor (VEGF), and other modulators of prostatic cancer, in order to help optimize treatment decisions. A comprehensive literature search of PubMed and relevant congress abstract databases was conducted using combinations of the key words prostate cancer, follicle-stimulating hormone, vascular endothelial growth factor, inhibins/activins, gonadotropin-releasing hormone (GnRH)/luteinizing hormone-releasing hormone (LHRH) receptor agonists/antagonists, and angiogenesis/neogenesis. This was followed by a consensus meeting of prostate cancer experts to discuss current knowledge surrounding FSH and the relevant evidence for its role in the development and progression of prostate cancer.
Our understanding of prostate cancer and its progression
indicate an increase in levels of FSH and the FSH receptor, along with alterations in key modulatory proteins that regulate FSH synthesis and receptor signaling. Elevations in VEGF and differential modulation of testosterone with GnRH/LHRH agonists and antagonists may contribute to treatment outcomes. Considerable evidence supports the hypothesis that dysregulation of the FSH system plays a role in both the development and progression of prostate cancer. Data indicate that FSH can be modulated by the choice of treatment intervention, especially when androgen-deprivation therapy
is used.
of LHRH antagonists in BPH. In contrast, antagonists of growth hormone-releasing hormone (GHRH) and gastrin-releasing peptide (GRP) have been tested only in preclinical settings and produce significant reduction in prostate size in experimental models of BPH. They act at least in part, by blocking the action of respective ligands produced locally on prostates through their respective receptors in the prostate, and by inhibition
of autocrine insulin-like growth factors-Ⅰ/Ⅱ and epidermal growth factor production. GHRH and LHRH antagonists were also tested in combination resulting in a cumulative effect that was greater than that of each alone. This article will review the numerous studies that demonstrate the beneficial effects of antagonistic analogs of LHRH, GHRH and GRP in BPH, as well as
suggesting a potential role for somatostatin analogs in experimental therapies.
Methods: HCC1806 (doxorubicin-sensitive) and MX-1 doxorubicin-resistant), cell lines were xenografted into nude mice and treated with MIA-602, doxorubicin, or their combination. Tumors were evaluated for changes in volume and the expression of the drug resistance genes MDR1 and NANOG. In-vitro cell culture assays were used to analyze the effect of MIA-602 on efflux pump function.
Results: Therapy with MIA-602 significantly reduced tumor growth and enhanced the efficacy of doxorubicin in both cell lines. Control HCC1806 tumors grew by 435%, while the volume of tumors treated with MIA-602 enlarged by 172.2% and with doxorubicin by 201.6%. Treatment with the combination of MIA-602 and doxorubicin resulted in an increase in volume of only 76.2%. Control MX-1 tumors grew by 907%, while tumors treated with MIA-602 enlarged by 434.8% and with doxorubicin by 815%. The combination of MIA-602 and doxorubicin reduced the increase in tumor volume to 256%. Treatment with MIA-602 lowered the level of growth hormonereleasing hormone and growth hormone-releasing hormone receptors and significantly reduced the expression of multidrug resistance (MDR1) gene and the drug resistance
regulator NANOG. MIA-602 also suppressed efflux pump function in both cell lines.
Conclusions: We conclude that treatment of triple negative breast cancers with growth hormone-releasing hormone antagonists reduces tumor growth and potentiates the effects of cytotoxic therapy by nullifying drug resistance.
leading cause of cancer-related deaths. Although we now know that the androgen receptor (AR) is important for progression to the
deadly advanced stages of the disease, it is poorly understood what AR-regulated processes drive this pathology. Here we
demonstrate that AR regulates prostate cancer cell growth via the metabolic sensor 50-AMP-activated protein kinase (AMPK),
a kinase that classically regulates cellular energy homeostasis. In patients, activation of AMPK correlated with prostate cancer
progression. Using a combination of radiolabeled assays and emerging metabolomic approaches, we also show that prostate
cancer cells respond to androgen treatment by increasing not only rates of glycolysis, as is commonly seen in many cancers, but
also glucose and fatty acid oxidation. Importantly, this effect was dependent on androgen-mediated AMPK activity. Our results
further indicate that the AMPK-mediated metabolic changes increased intracellular ATP levels and peroxisome proliferatoractivated
receptor gamma coactivator 1-alpha (PGC-1a)-mediated mitochondrial biogenesis, affording distinct growth advantages
to the prostate cancer cells. Correspondingly, we used outlier analysis to determine that PGC-1a is overexpressed in a
subpopulation of clinical cancer samples. This was in contrast to what was observed in immortalized benign human prostate cells
and a testosterone-induced rat model of benign prostatic hyperplasia. Taken together, our findings converge to demonstrate that
androgens can co-opt the AMPK-PGC-1a signaling cascade, a known homeostatic mechanism, to increase prostate cancer cell
growth. The current study points to the potential utility of developing metabolic-targeted therapies directed toward the
AMPK-PGC-1a signaling axis for the treatment of prostate cancer.