Papers by Alejandro Vázquez-Martín
Cell Cycle, 2015
Tumour cellular senescence induced by genotoxic treatments has recently been found to be paradoxi... more Tumour cellular senescence induced by genotoxic treatments has recently been found to be paradoxically linked to the induction of "stemness". This observation is critical as it directly impinges upon the response of tumours to current chemoradio-therapy treatment regimens. Previously, we showed that following etoposide (ETO) treatment embryonal carcinoma PA-1 cells undergo a p53-dependent upregulation of OCT4A and p21Cip1 (governing self-renewal and regulating cell cycle inhibition and senescence, respectively). Here we report further detail on the relationship between these and other critical cell-fate regulators. PA-1 cells treated with ETO display highly heterogeneous increases in OCT4A and p21Cip1 indicative of dis-adaptation catastrophe. Silencing OCT4A suppresses p21Cip1, changes cell cycle regulation and subsequently suppresses terminal senescence; p21Cip1-silencing did not affect OCT4A expression or cellular phenotype. SOX2 and NANOG expression did not change following ETO treatment suggesting a dissociation of OCT4A from its pluripotency function. Instead, ETO-induced OCT4A was concomitant with activation of AMPK, a key component of metabolic stress and autophagy regulation. p16ink4a, the inducer of terminal senescence, underwent autophagic sequestration in the cytoplasm of ETO-treated cells, allowing alternative cell fates. Accordingly, failure of autophagy was accompanied by an accumulation of p16ink4a, nuclear disintegration, and loss of cell recovery. Together, these findings imply that OCT4A induction following DNA damage in PA-1 cells, performs a cell stress, rather than self-renewal, function by moderating the expression of p21Cip1, which alongside AMPK helps to then regulate autophagy. Moreover, this data indicates that exhaustion of autophagy, through persistent DNA damage, is the cause of terminal cellular senescence.
International journal of oncology, 2011
KRAS mutation status is being used as the sole biomarker to predict therapeutic efficacy of cetux... more KRAS mutation status is being used as the sole biomarker to predict therapeutic efficacy of cetuximab in metastatic colorectal cancer (mCRC). A significant number of mCRC patients with KRAS wild-type (WT) tumors, however, do not benefit from cetuximab. We are also lacking efficacy predictors in head and neck squamous cell carcinomas with an intact KRAS signaling and in non-small cell lung cancer in which KRAS mutations do not predict cetuximab efficacy. We recently established pre-clinical models of EGFR gene-amplified KRAS WT A431 squamous carcinoma cells chronically adapted to grow in the presence of cetuximab. We employed the ingenuity pathway analysis software to functionally interpret data from Agilent's whole human genome arrays in the context of biological processes, networks, and pathways. Cetuximab-induced activation of the interferon (IFN)/STAT1 appeared to switch from 'growth inhibitory' in acutely-treated cells to…
Scientific Reports, 2012
The antidiabetic drug metformin efficiently circumvents the dilemma that in reducing the tumourig... more The antidiabetic drug metformin efficiently circumvents the dilemma that in reducing the tumourigenicity of stem cells, their essence, specifically their pluripotency, must also be sacrificed. Metformin prevents the occurrence or drastically reduces the size and weight of teratoma-like masses after the transplantation of induced pluripotent stem (iPS) cells into immunodeficient mice. Yet, iPS cells implanted into metformin-treated mice retain full pluripotency, as they produce the same number of distinct tissue types derived from the three embryonic germ layers that is observed in untreated mice. Mechanistically, metformin appears to suppress the Oct4-driven compartment of malignant stem cells responsible for teratocarcinoma growth while safeguarding an intact, Oct4-independent competency to generate terminally differentiated tissues. Metformin's ability to efficiently and specifically control the tumourigenic fate of teratoma-initiating iPS cells without interfering with their pluripotency not only has implications for the clinical use of iPS cells but also in stem cell biology, cancer and ageing.
PLoS ONE, 2013
Tumors are heterogeneous at the cellular level where the ability to maintain tumor growth resides... more Tumors are heterogeneous at the cellular level where the ability to maintain tumor growth resides in discrete cell populations. Floating sphere-forming assays are broadly used to test stem cell activity in tissues, tumors and cell lines. Spheroids are originated from a small population of cells with stem cell features able to grow in suspension culture and behaving as tumorigenic in mice. We tested the ability of eleven common breast cancer cell lines representing the major breast cancer subtypes to grow as mammospheres, measuring the ability to maintain cell viability upon serial non-adherent passage. Only MCF7, T47D, BT474, MDA-MB-436 and JIMT1 were successfully propagated as long-term mammosphere cultures, measured as the increase in the number of viable cells upon serial non-adherent passages. Other cell lines tested (SKBR3, MDA-MB-231, MDA-MB-468 and MDA-MB-435) formed cell clumps that can be disaggregated mechanically, but cell viability drops dramatically on their second passage. HCC1937 and HCC1569 cells formed typical mammospheres, although they could not be propagated as long-term mammosphere cultures. All the sphere forming lines but MDA-MB-436 express E-cadherin on their surface. Knock down of E-cadherin expression in MCF-7 cells abrogated its ability to grow as mammospheres, while re-expression of E-cadherin in SKBR3 cells allow them to form mammospheres. Therefore, the mammosphere assay is suitable to reveal stem like features in breast cancer cell lines that express E-cadherin.
Ejc Supplements, Nov 1, 2006
Friday 10 November Poster Session-Signal transduction modulators to generate blood concentration ... more Friday 10 November Poster Session-Signal transduction modulators to generate blood concentration plots. TEMSR Cmax in BrCA was 53% higher but transient while SIR Cmax decreased 11.9% compared with other subjects. SIR C trough at 168 hr was unchanged. Effect of nonwhite race on Cmax in RCC was less than effect for BrCA. No other covariates affected TEMSR or SIR disposition. Conclusions: Saturable distribution model for TEMSR adequately predicted concentrations through wide (1-250 mg) dosing range. Collectively, data suggest no PK basis for modifying TEMSR dose in pts with RCC receiving 25 mg IV. 553 POSTER B-RAF mutation is associated with altered patterns of negative feedback of MAPK signaling that correlate with increased output of the pathway and increased sensitivity to MEK inhibition
Advances in Experimental Medicine and Biology, 2008
Identification of genes/proteins that are differentially expressed in HER2overexpressing breast c... more Identification of genes/proteins that are differentially expressed in HER2overexpressing breast carcinomas (BC) is essential in elucidating the mechanistic basis of their increased metastastic potential. With the goal of identifying a unique HER2-induced "cytokine signature" in BC, Human Cytokine Array III (RayBiotech, Inc.) simultaneously detecting 42 cytokines and growth factors on one membrane was used to determine the profile of cytokines in conditioned media obtained from MCF-7/Her2-18 cells, a MCF-7-derived clone engineered to stably express the full-length human HER2 cDNA, and from the MCF-7/neo control sub-line. We identified two inflammatory and proangiogenic CXC chemokines with at least a 10-fold increased expression in MCF-7/Her2-18 transfectants when compared with matched control MCF-7/neo cells: CXCL8 (IL-8; interleukin-8) and CXCL1 and (GRO; growth-related oncogene). HER2 up-regulation of IL-8 and GRO was validated by ELISA and further confirmed by switching off the HER2 signaling. Treatment with the tyrosine kinase inhibitor gefitinib (Iressa™) returned the expression levels of IL-8 and GRO back to the baseline observed in HER2-negative MCF-7 BC cells. Moreover, IL-8 and GRO circulating levels were significantly higher in sera from HER2-positive BC patients. These findings reveal for the first time that (a) Enhanced synthesis and secretion of members of the IL-8/GRO chemokine family, which have recently been linked to estrogen receptor (ER) inaction, increased cell invasion, and angiogenesis, may represent a new pathway involved in the metastatic progression and endocrine resistance of HER2overexpressing breast carcinomas; and (b) Circulating levels of IL-8 and GRO cytokines may represent novel biomarkers monitoring BC responses to endocrine treatments and/or HER2-targeted therapies.
European Journal of Cancer Supplements, 2006
Friday 10 November Poster Session-Signal transduction modulators to generate blood concentration ... more Friday 10 November Poster Session-Signal transduction modulators to generate blood concentration plots. TEMSR Cmax in BrCA was 53% higher but transient while SIR Cmax decreased 11.9% compared with other subjects. SIR C trough at 168 hr was unchanged. Effect of nonwhite race on Cmax in RCC was less than effect for BrCA. No other covariates affected TEMSR or SIR disposition. Conclusions: Saturable distribution model for TEMSR adequately predicted concentrations through wide (1-250 mg) dosing range. Collectively, data suggest no PK basis for modifying TEMSR dose in pts with RCC receiving 25 mg IV. 553 POSTER B-RAF mutation is associated with altered patterns of negative feedback of MAPK signaling that correlate with increased output of the pathway and increased sensitivity to MEK inhibition
European Journal of Cancer Supplements, 2006
Journal of Clinical Oncology, 2004
9690 Background: Fatty acid synthase (FAS) is the enzyme responsible for the de novo synthesis of... more 9690 Background: Fatty acid synthase (FAS) is the enzyme responsible for the de novo synthesis of fatty acids, and is overexpressed in 20% of human breast carcinomas. The inhibition of FAS induces apoptosis, and has shown significant antitumor activity against human breast, prostate and ovarian cancer xenografts. We have previously observed that inhibition of FAS acts synergistically with trastuzumab inhibiting the proliferation of HER2-positive, FAS positive breast cancer cells. We have also shown that inhibition of FAS enhances the effectiveness of paclitaxel, docetaxel and vinorelbine, and reverses anthracyclin resistance on breast cancer cells. We have now tested the effects of cerulenin, an inhibitor of FAS, on gene expression analysis of the breast cancer cell lines SK-Br-3, BT-474, and MCF-7, which express different levels of FAS (++, +, and negative). METHODS Using 10,000-spot human cDNA microarrays, we have evaluated the time course of the transcriptional response of breast cancer cells to FAS inhibition (6 to 24h). RESULTS Gene response paralelled the magnitude and time-course of FAS enzymatic inhibition. In FAS-positive cells, significant up-regulation (>6-fold) was observed for osteonectin, TGF-β2, and genes involved in the insulin signalling pathway (IGFBP-1, IGFBP-2, IGFBP-3 and IGF5), apoptosis (caspase-7, Gas-7, Gas-1), and metastasis inhibition (thrombospondin, osteoprotegirin, kiss-1). Significant down-regulation (>6-fold) was observed for Grb7 (involved in HER2-signalling pathway), FGF5, inhibin, and IL-11. CONCLUSIONS The observed changes on the gene expression pattern provide new insights in the molecular mechanisms of the inhibition of FAS, and will help in the development of new inhibitory molecules. No significant financial relationships to disclose.
Background: A low incidence of breast cancer in the Mediterranean basin suggests that a high cons... more Background: A low incidence of breast cancer in the Mediterranean basin suggests that a high consumption of Extra Virgin Olive Oil (EVOO) might confer this benefit. While the anti-HER2 oncogene effects of the main ω-9 fatty acid present in EVOO triacylglycerols (i.e., oleic acid) have been recently described, the anti-breast cancer activities of EVOO non-glyceridic constituentswhich consist of at least 30 phenolic compounds-, remained to be evaluated. Methods: Semi-preparative HPLC was used to isolate EVOO polyphenols (i.e., tyrosol, hydroxytyrosol, oleuropein). Both the anti-proliferative and the pro-apoptotic effects of EVOO phenolics were evaluated by using MTT-based quantification of metabolically viable cells and ELISAbased detection of histone-associated DNA fragments, respectively. The nature of the interaction between oleuropein aglycone and the anti-HER2 monoclonal antibody trastuzumab (Herceptin™) was mathematically evaluated by the dose-oriented isobologram technique. HER2-specific ELISAs were employed to quantitatively assess both the basal cleavage of the HER2 extracellular domain (ECD) and the expression level of total HER2. The activation status of HER2 was evaluated by immunoblotting procedures using a monoclonal antibody specifically recognizing the tyrosine phosphorylated (Phosphor-Tyr1248) form of HER2. Results: Among EVOO polyphenols tested, oleuropein aglycone was the most potent EVOO phenolic in decreasing breast cancer cell viability. HER2 gene-amplified SKBR3 cells were ~5-times more sensitive to oleuropein aglycone than HER2-negative MCF-7 cells. Retroviral infection of the HER2 oncogene in MCF-7 cells resulted in a "SKBR3-assimilated" phenotype of hypersensitivity to oleuropein aglycone. An up to 50-fold increase in the efficacy of trastuzumab occurred in the presence of oleuropein aglycone. A preclinical model of acquired autoresistance to trastuzumab (SKBR3/Tzb100 cells) completely recovered trastuzumab sensitivity (> 1,000-fold sensitization)
PLoS ONE, 2009
Autophagy has been emerging as a novel cytoprotective mechanism to increase tumor cell survival u... more Autophagy has been emerging as a novel cytoprotective mechanism to increase tumor cell survival under conditions of metabolic stress and hypoxia as well as to escape chemotherapy-induced cell death. To elucidate whether autophagy might also protect cancer cells from the growth inhibitory effects of targeted therapies, we evaluated the autophagic status of preclinical breast cancer models exhibiting auto-acquired resistance to the anti-HER2 monoclonal antibody trastuzumab (Tzb). We first examined the basal autophagic levels in Tzb-naive SKBR3 cells and in two pools of Tzb-conditioned SKBR3 cells (TzbR), which optimally grow in the presence of Tzb doses as high as 200 mg/ml Tzb. Fluorescence microscopic analyses revealed that the number of punctate LC3 structures-a hallmark of autophagy-was drastically higher in Tzbrefractory cells than in Tzb-sensitive SKBR3 parental cells. Immunoblotting analyses confirmed that the lipidation product of the autophagic conversion of LC3 was accumulated to high levels in TzbR cells. High levels of the LC3 lipidated form in Tzbrefractory cells were accompanied by decreased p62/sequestosome-1 protein expression, a phenomenon characterizing the occurrence of increased autophagic flux. Moreover, increased autophagy was actively used to survive Tzb therapy as TzbR pools were exquisitely sensitive to chemical inhibitors of autophagosomal formation/function. Knockdown of LC3 expression via siRNA similarly resulted in reduced TzbR cell proliferation and supra-additively interacted with Tzb to resensitize TzbR cells. Subgroups of Tzb-naive SKBR3 parental cells accumulated LC3 punctate structures and decreased p62 expression after treatment with high-dose Tzb, likely promoting their own resistance. This is the first report showing that HER2-overexpressing breast cancer cells chronically exposed to Tzb exhibit a bona fide up-regulation of the autophagic activity that efficiently works to protect breast cancer cells from the growth-inhibitory effects of Tzb. Therapeutic targeting autophagosome formation/function might represent a novel molecular avenue to reduce the emergence of Tzb resistance in HER2-dependent breast carcinomas.
International Journal of Molecular Medicine, 2008
Inhibitors of fatty acid synthase (FASN), a key enzyme involved in the anabolic conversion of die... more Inhibitors of fatty acid synthase (FASN), a key enzyme involved in the anabolic conversion of dietary carbohydrates to fat in mammals, are receiving increasingly more attention as they may provide therapeutic moieties for the treatment of human malignancies. Natural compounds, such as the green tea polyphenol epigallocatechin-3-gallate, have been shown to induce anti-cancer effects by suppressing FASN, which may account for the epidemiologically observed inverse correlation between green-tea drinking and cancer risk in Oriental populations. Since extra-virgin olive oil (EVOO)-derived phenolics have been suggested to possess biological activities that may explain the health-promoting effects of the 'Mediterranean diet', we evaluated their effects on the expression of FASN protein in human breast epithelial cell lines. First, we developed a reverse phase protein microspot array (RPPA) capable of rapidly assessing the relative amount of FASN protein in whole lysates from cultured human cells. Then we tested the effects of phenolic fractions from EVOO and its main constituents including single phenols (i.e. tyrosol, hydroxytyrosol, vanillin), phenolic acids (i.e. caffeic acid, p-coumaric acid, vanillic acid, ferulic acid, elenolic acid), lignans (i.e. 1-[+]-pinoresinol, 1-[+]-acetoxy-pinoresinol), flavonoids (i.e. apigenin, luteolin), or secoiridoids (i.e. deacetoxyoleuropein aglycone, ligstroside aglycone, oleuropein glycoside, oleuropein aglycone) on FASN protein expression. EVOO polyphenols lignans, flavonoids and secoiridoids were found to drastically suppress FASN protein expression in HER2 gene-amplified SKBR3 breast cancer cells. Equivalent results were observed in MCF-7 cells engineered to overexpress the HER2 tyrosine kinase receptor, a well-characterized up-regulator of FASN expression in aggressive sub-types of cancer cells. EVOOderived lignans, flavonoids and secoiridoids were significantly more effective than the mono-HER2 inhibitor trastuzumab (~50% reduction) and as effective as the dual HER1/HER2 tyrosine kinase inhibitor lapatinib (≥95% reduction) at suppressing high-levels of FASN protein in HER2overexpressing SKBR3 and MCF-7/HER2 cells. EVOO single phenols and phenolic acids failed to modulate FASN expression in SKBR3 and MCF-7/HER2 cells. These findings reveal for the first time that phenolic fractions, directly extracted from EVOO, may induce anti-cancer effects by suppressing the expression of the lipogenic enzyme FASN in HER2-overexpressing breast carcinoma cells, thus offering a previously unrecognized mechanism for EVOO-related cancer preventive effects.
Advances in Experimental Medicine and Biology, 2008
Identification of genes/proteins that are differentially expressed in HER2overexpressing breast c... more Identification of genes/proteins that are differentially expressed in HER2overexpressing breast carcinomas (BC) is essential in elucidating the mechanistic basis of their increased metastastic potential. With the goal of identifying a unique HER2-induced "cytokine signature" in BC, Human Cytokine Array III (RayBiotech, Inc.) simultaneously detecting 42 cytokines and growth factors on one membrane was used to determine the profile of cytokines in conditioned media obtained from MCF-7/Her2-18 cells, a MCF-7-derived clone engineered to stably express the full-length human HER2 cDNA, and from the MCF-7/neo control sub-line. We identified two inflammatory and proangiogenic CXC chemokines with at least a 10-fold increased expression in MCF-7/Her2-18 transfectants when compared with matched control MCF-7/neo cells: CXCL8 (IL-8; interleukin-8) and CXCL1 and (GRO; growth-related oncogene). HER2 up-regulation of IL-8 and GRO was validated by ELISA and further confirmed by switching off the HER2 signaling. Treatment with the tyrosine kinase inhibitor gefitinib (Iressa™) returned the expression levels of IL-8 and GRO back to the baseline observed in HER2-negative MCF-7 BC cells. Moreover, IL-8 and GRO circulating levels were significantly higher in sera from HER2-positive BC patients. These findings reveal for the first time that (a) Enhanced synthesis and secretion of members of the IL-8/GRO chemokine family, which have recently been linked to estrogen receptor (ER) inaction, increased cell invasion, and angiogenesis, may represent a new pathway involved in the metastatic progression and endocrine resistance of HER2overexpressing breast carcinomas; and (b) Circulating levels of IL-8 and GRO cytokines may represent novel biomarkers monitoring BC responses to endocrine treatments and/or HER2-targeted therapies.
International Journal of Oncology, 2008
The marked clinical anticancer activity of the paclitaxel (PTX) and gemcitabine (GEM) combination... more The marked clinical anticancer activity of the paclitaxel (PTX) and gemcitabine (GEM) combination has suggested that the two drugs may interact more than additively. We have analyzed the in vitro growth and molecular interactions of the two chemotherapy drugs in a panel of human breast cancer cells. We evaluated cell viability in four breast cancer cell lines (i.e., MCF-7, MDA-MB-231, MDA-MB-468, and SKBR3) that were treated with PTX and GEM combined either simultaneously (PTX + GEM) or sequentially (PTX→GEM; GEM→PTX). PTX-GEM interactions at the cellular level were assessed mathematically employing both the isobologram analysis (Berenbaum) and the combination index (Chou-Talalay) method. PTX-GEM molecular interactions on the apoptotic markers PARP, Bcl-2 and Bax were analyzed by immunoblotting procedures. Apoptosis was detected using a DNA ladder assay. We observed significant synergistic growth inhibitory interactions when PTX was administered before GEM. Additive interactions were observed when both the simultaneous regimen and the GEM followed by PTX regimen were used. DNA ladder and Western blotting results in the PTX followed by GEM sequence revealed a significant increase in the apoptotic cell death of breast cancer cells related to the Bax/Bcl-2 apoptotic pathway. In summary, the occurrence of clinically relevant synergism between PTX and GEM suggests a sequence-dependent nature in human breast cancer cells. This synergistic interaction on the PTX→GEM schedule appears to be related to an increase in the Bcl-2-related mitochondrial apoptotic pathway. The synergism that we have observed may explain the favorable clinical responses that have been achieved in clinical studies, in which patients are administered PTX first, and then GEM.
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Papers by Alejandro Vázquez-Martín