Papers by Wei-Chien Huang
Oncotarget, Nov 16, 2015
Poor prognosis of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) involves HBV ... more Poor prognosis of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) involves HBV X protein (HBx)-induced tumor progression. HBx also contributes to chemo-resistance via inducing the expressions of anti-apoptosis and multiple drug resistance genes. However, the impact of HBx expression on the therapeutic efficacy of various receptor tyrosine kinase inhibitors remains unknown. In this study, our data showed that HBx overexpression did not alter the cellular sensitivity of HCC cell lines to sorafenib but unexpectedly enhanced the cell death induced by EGFR family inhibitors, including gefitinib, erlotinib, and lapatinib due to ErbB3 up-regulation. Mechanistically, HBx transcriptionally up-regulates ErbB3 expression in a NF-κB dependent manner. In addition, HBx also physically interacts with ErbB2 and ErbB3 proteins and enhances the formation of ErbB2/ErbB3 heterodimeric complex. The cell viability of HBx-overexpressing cells was decreased by silencing ErbB3 expression, further revealing the pivotal role of ErbB3 in HBx-mediated cell survival. Our data suggest that HBx shifts the oncogenic addiction of HCC cells to ErbB2/ErbB3 signaling pathway via inducing ErbB3 expression and thereby enhances their sensitivity to EGFR/ErbB2 inhibitors.
Molecular Carcinogenesis, Nov 1, 2009
MAX dimerization protein 1 (MAD1) is a transcription suppressor that antagonizes MYCmediated tran... more MAX dimerization protein 1 (MAD1) is a transcription suppressor that antagonizes MYCmediated transcription activation, and the inhibition mechanism occurs mainly through the competition of target genes' promoter MYC binding sites by MAD1. The promoter binding proteins switch between MYC and MAD1 affects cell proliferation and differentiation. However, little is known about MAD1's regulation process in cancer cells. Here, we present evidence that AKT inhibits MAD1-mediated transcription repression by physical interaction with and phosphorylation of MAD1. Phosphorylation reduces the binding affinity between MAD1 and its target genes' promoter and thereby abolishes its transcription suppression function. Mutation of the phosphorylation site from serine to alanine rescues the DNA-binding ability in the presence of activated AKT. In addition, AKT inhibits MAD1 mediated target genes (hTERT and ODC) transcription repression and promotes cell cycle and cell growth. However, mutated S145A MAD1 abrogates the inhibition by AKT. Thus, our results suggest that phosphorylation of MAD1 by AKT inhibits MAD1-mediated transcription suppression and subsequently activates the transcription of MAD1 target genes.
Oncotarget, Jul 17, 2015
Maspin suppresses tumor progression by promoting cell adhesion and apoptosis and by inhibiting ce... more Maspin suppresses tumor progression by promoting cell adhesion and apoptosis and by inhibiting cell motility. However, its role in tumorigenesis of hepatocellular carcinoma (HCC) remains unclear. The gene regulation of maspin and its relationship with HCC patient prognosis were investigated in this study. Maspin expression was specifically reduced in HBV-associated patients and correlated with their poor prognosis. Maspin downregulation in HCC cells was induced by HBx to promote their motility and resistance to anoikis and chemotherapy. HBx-dependent induction of microRNA-7,-107, and-21 was further demonstrated to directly target maspin mRNA, leading to its protein downregulation. Higher expressions of these microRNAs also correlated with maspin downregulation in HBV-associated patients, and were associated with their poor overall survival. These data not only provided new insights into the molecular mechanisms of maspin deficiency by HBx, but also indicated that downregulation of maspin by microRNAs confers HBx-mediated aggressiveness and chemoresistance in HCC.
Journal of Biomedical Science, 2013
IκB kinase (IKK) complex, the master kinase for NF-κB activation, contains two kinase subunits, I... more IκB kinase (IKK) complex, the master kinase for NF-κB activation, contains two kinase subunits, IKKα and IKKβ. In addition to mediating NF-κB signaling by phosphorylating IκB proteins during inflammatory and immune responses, the activation of the IKK complex also responds to various stimuli to regulate diverse functions independently of NF-κB. Although these two kinases share structural and biochemical similarities, different sub-cellular localization and phosphorylation targets between IKKα and IKKβ account for their distinct physiological and pathological roles. While IKKβ is predominantly cytoplasmic, IKKα has been found to shuttle between the cytoplasm and the nucleus. The nuclear-specific roles of IKKα have brought increasing complexity to its biological function. This review highlights major advances in the studies of the nuclear functions of IKKα and the mechanisms of IKKα nuclear translocation. Understanding the nuclear activity is essential for targeting IKKα for therapeutics.
Oncogene, 2021
The tyrosine kinase inhibitors (TKIs) targeting epidermal growth factor receptor (EGFR) have been... more The tyrosine kinase inhibitors (TKIs) targeting epidermal growth factor receptor (EGFR) have been widely used for non-small cell lung cancer (NSCLC) patients, but the development of acquired resistance remains a therapeutic hurdle. The reduction of glucose uptake has been implicated in the anti-tumor activity of EGFR TKIs. In this study, the upregulation of the active sodium/glucose co-transporter 1 (SGLT1) was found to confer the development of acquired EGFR TKI resistance and was correlated with the poorer clinical outcome of the NSCLC patients who received EGFR TKI treatment. Blockade of SGLT1 overcame this resistance in vitro and in vivo by reducing glucose uptake in NSCLC cells. Mechanistically, SGLT1 protein was stabilized through the interaction with PKCδ-phosphorylated (Thr678) EGFR in the TKI-resistant cells. Our findings revealed that PKCδ/EGFR axis-dependent SGLT1 upregulation was a critical mechanism underlying the acquired resistance to EGFR TKIs. We suggest co-targetin...
Oncogene, 2020
Smoker patients with non-small cell lung cancer (NSCLC) have poorer prognosis and survival than t... more Smoker patients with non-small cell lung cancer (NSCLC) have poorer prognosis and survival than those without smoking history. However, the mechanisms underlying the low response rate of those patients to EGFR tyrosine kinase inhibitors (TKIs) are not well understood. Here we report that exposure to cigarette smoke extract enhances glycolysis and attenuates AMP-activated protein kinase (AMPK)-dependent inhibition of mTOR; this in turn reduces the sensitivity of NSCLC cells with wild-type EGFR (EGFRWT) to EGFR TKI by repressing expression of liver kinase B1 (LKB1), a master kinase of the AMPK subfamily, via CpG island methylation. In addition, LKB1 expression is correlated positively with sensitivity to TKI in patients with NSCLC. Moreover, combined treatment of EGFR TKI with AMPK activators synergistically increases EGFR TKI sensitivity. Collectively, the current study suggests that LKB1 may serve as a marker to predict EGFR TKI sensitivity in smokers with NSCLC carrying EGFRWT and ...
Molecular oncology, 2018
Cigarette smoking is one of the leading risks for lung cancer and is associated with the insensit... more Cigarette smoking is one of the leading risks for lung cancer and is associated with the insensitivity of non-small cell lung cancer (NSCLC) to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). However, it remains undetermined whether and how cigarette smoke affects the therapeutic efficacy of EGFR TKIs. In this study, our data showed that chronic exposure to cigarette smoke extract (CSE) or tobacco smoke-derived carcinogen benzo[α]pyrene, B[α]P, but not nicotine-derived nitrosamine ketone (NNK), reduced the sensitivity of wild-type EGFR-expressing NSCLC cells to EGFR TKIs. Treatment with TKIs almost abolished EGFR tyrosine kinase activity but did not show an inhibitory effect on downstream Akt and ERK pathways in B[α]P-treated NSCLC cells. CSE and B[α]P transcriptionally upregulate c-MET and activate its downstream Akt pathway, which is not inhibited by EGFR TKIs. Silencing of c-MET reduces B[α]P-induced Akt activation. The CSE-treated NSCLC cells are sensi...
Gastroenterology, Jun 15, 2018
Hepatic stellate cells (HSCs) contribute to desmoplasia and stiffness of liver metastases by diff... more Hepatic stellate cells (HSCs) contribute to desmoplasia and stiffness of liver metastases by differentiating into matrix-producing myofibroblasts. We investigated whether stiffness due to the presence of tumors increases activation of HSCs into myofibroblasts and their tumor-promoting effects, as well as the role of E1A binding protein p300 (EP300 or p300), a histone acetyltransferase that regulates transcription, in these processes. HSCs were isolated from liver tissues of patients, mice in which the p300 gene was flanked by 2 loxP sites (p300F/F mice), and p300+/+ mice (controls). The HSCs were placed on polyacrylamide gels with precisely defined stiffness, and their activation (differentiation into myofibroblasts) was assessed by immunofluorescence and immunoblot analyses for alpha-smooth muscle actin. In HSCs from mice, the p300 gene was disrupted by cre recombinase. In human HSCs, levels of p300 were knocked down with small hairpin RNAs or a mutant form of p300 that is not phos...
Oncotarget, Jan 16, 2015
Poor prognosis of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) involves HBV ... more Poor prognosis of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) involves HBV X protein (HBx)-induced tumor progression. HBx also contributes to chemo-resistance via inducing the expressions of anti-apoptosis and multiple drug resistance genes. However, the impact of HBx expression on the therapeutic efficacy of various receptor tyrosine kinase inhibitors remains unknown. In this study, our data showed that HBx overexpression did not alter the cellular sensitivity of HCC cell lines to sorafenib but unexpectedly enhanced the cell death induced by EGFR family inhibitors, including gefitinib, erlotinib, and lapatinib due to ErbB3 up-regulation. Mechanistically, HBx transcriptionally up-regulates ErbB3 expression in a NF-κB dependent manner. In addition, HBx also physically interacts with ErbB2 and ErbB3 proteins and enhances the formation of ErbB2/ErbB3 heterodimeric complex. The cell viability of HBx-overexpressing cells was decreased by silencing ErbB3 expression, ...
Oncotarget, Jan 17, 2015
Maspin suppresses tumor progression by promoting cell adhesion and apoptosis and by inhibiting ce... more Maspin suppresses tumor progression by promoting cell adhesion and apoptosis and by inhibiting cell motility. However, its role in tumorigenesis of hepatocellular carcinoma (HCC) remains unclear. The gene regulation of maspin and its relationship with HCC patient prognosis were investigated in this study. Maspin expression was specifically reduced in HBV-associated patients and correlated with their poor prognosis. Maspin downregulation in HCC cells was induced by HBx to promote their motility and resistance to anoikis and chemotherapy. HBx-dependent induction of microRNA-7, -107, and -21 was further demonstrated to directly target maspin mRNA, leading to its protein downregulation. Higher expressions of these microRNAs also correlated with maspin downregulation in HBV-associated patients, and were associated with their poor overall survival. These data not only provided new insights into the molecular mechanisms of maspin deficiency by HBx, but also indicated that downregulation of...
BioMedicine, 2011
Epidermal growth factor receptor (EGFR) was identified as a major oncogenic factor in various typ... more Epidermal growth factor receptor (EGFR) was identified as a major oncogenic factor in various types of cancer, and thereby has been considered as an attractive therapeutic target for cancer therapy. The well-characterized classic function of this plasma membrane-bound receptor is transduction of extracellular mitogenic signals to a variety of intracellular downstream signaling cascades associated with tumorigenesis. Aberrantly expressed EGFR also undergoes direct nuclear translocation to induce transcription of genes associated with cell proliferation, cell cycle regulation, and tumor progression. Emerging evidence suggests the existence of a new role of nuclear EGFR signaling in conferring acquired resistance in response to various anticancer therapies. In this review, we summarize the current understanding of how EGFR translocates into the nucleus in response to ionizing radiation, chemotherapy, and anti-EGFR target agents. The emerging impact of nuclear EGFR in modulating the cellular sensitivity of cancer cells to these anticancer treatments will also be discussed. A better understanding of the nuclear EGFR pathways in response to anticancer therapies will facilitate the development of novel strategies to overcome the acquired resistance.
BioMed research international, 2014
Lapatinib, a dual EGFR/HER2 tyrosine kinase inhibitor, has been shown to improve the survival rat... more Lapatinib, a dual EGFR/HER2 tyrosine kinase inhibitor, has been shown to improve the survival rate of patients with advanced HER2-positive breast cancers. However, the off-target activity of lapatinib in inducing EGFR expression without tyrosine kinase activity was demonstrated to render HER2-negative breast cancer cells more metastatic, suggesting a limitation to the therapeutic effectiveness of this dual inhibitor in HER2-heterogeneous tumors. Therefore, targeting EGFR expression may be a feasible approach to improve the anticancer efficiency of lapatinib-based therapy. Inhibition of HDAC has been previously reported to epigenetically suppress EGFR protein expression. In this study, however, our data indicated that treatment with HDAC inhibitors trichostatin A (TSA), but not suberoylanilide hydroxamic acid (SAHA) or HDAC siRNA, can attenuate both protein and mRNA expressions of EGFR in lapatinib-treated triple-negative breast cancer cells, suggesting that TSA may suppress EGFR exp...
Molecular biology of the cell, 2005
Inhibition of ubiquitin-proteasome pathway has been shown to be a promising strategy for the trea... more Inhibition of ubiquitin-proteasome pathway has been shown to be a promising strategy for the treatment of inflammation and cancer. Here, we show that proteasome inhibitors MG132, PSI-1, and lactacystin induce COX-2 expression via enhancing gene transcription rather than preventing protein degradation in the human alveolar NCI-H292 and A549, and gastric AGS epithelial cells. NF-IL6 and CRE, but not NF-kappaB elements on the COX-2 promoter were involved in the gene transcription event. The binding of CCAAT/enhancer binding protein (C/EBP)beta and C/EBPdelta to the CRE and NF-IL6 elements, as well as the recruitment of CBP and the enhancement of histone H3 and H4 acetylation on the COX-2 promoter was enhanced by MG132. However, it did not affect the total protein levels of C/EBPbeta and C/EBPdelta. MG132-induced DNA-binding activity of C/EBPdelta, but not C/EBPbeta was regulated by p38, PI3K, Src, and protein kinase C. Small interfering RNA of C/EBPdelta suppressed COX-2 expression, fu...
PLoS ONE, 2011
Epidermal growth factor receptor (EGFR), a receptor tyrosine kinase which promotes cell prolifera... more Epidermal growth factor receptor (EGFR), a receptor tyrosine kinase which promotes cell proliferation and survival, is abnormally overexpressed in numerous tumors of epithelial origin, including colorectal cancer (CRC). EGFR monoclonal antibodies have been shown to increase the median survival and are approved for the treatment of colorectal cancer. Histone deacetylases (HDACs), frequently overexpressed in colorectal cancer and several malignancies, are another attractive targets for cancer therapy. Several inhibitors of HDACs (HDACi) are developed and exhibit powerful antitumor abilities. In this study, human colorectal cancer cells treated with HDACi exhibited reduced EGFR expression, thereby disturbed EGF-induced ERK and Akt phosphorylation. HDACi also decreased the expression of SGLT1, an active glucose transporter found to be stabilized by EGFR, and suppressed the glucose uptake of cancer cells. HDACi suppressed the transcription of EGFR and class I HDACs were proved to be involved in this event. Chromatin immunoprecipitation analysis showed that HDACi caused the dissociation of SP1, HDAC3 and CBP from EGFR promoter. Our data suggested that HDACi could serve as a single agent to block both EGFR and HDAC, and may bring more benefits to the development of CRC therapy.
PLoS ONE, 2012
Hepatocellular carcinoma (HCC), a major cause of cancer-related death in Southeast Asia, is frequ... more Hepatocellular carcinoma (HCC), a major cause of cancer-related death in Southeast Asia, is frequently associated with hepatitis B virus (HBV) infection. HBV X protein (HBx), encoded by a viral non-structural gene, is a multifunctional regulator in HBV-associated tumor development. We investigated novel signaling pathways underlying HBx-induced liver tumorigenesis and found that the signaling pathway involving IkB kinase b (IKKb), tuberous sclerosis complex 1 (TSC1), and mammalian target of rapamycin (mTOR) downstream effector S6 kinase (S6K1), was upregulated when HBx was overexpressed in hepatoma cells. HBx-induced S6K1 activation was reversed by IKKb inhibitor Bay 11-7082 or silencing IKKb expression using siRNA. HBx upregulated cell proliferation and vascular endothelial growth factor (VEGF) production, and these HBx-upregulated phenotypes were abolished by treatment with IKKb inhibitor Bay 11-7082 or mTOR inhibitor rapamycin. The association of HBx-modulated IKKb/mTOR/S6K1 signaling with liver tumorigenesis was verified in a HBx transgenic mouse model in which pIKKb, pS6K1, and VEGF expression was found to be higher in cancerous than noncancerous liver tissues. Furthermore, we also found that pIKKb levels were strongly correlated with pTSC1 and pS6K1 levels in HBV-associated hepatoma tissue specimens taken from 95 patients, and that higher pIKKb, pTSC1, and pS6K1 levels were correlated with a poor prognosis in these patients. Taken together, our findings demonstrate that HBx deregulates TSC1/ mTOR signaling through IKKb, which is crucially linked to HBV-associated HCC development.
The signaling pathway involved in TNF-α-induced COX-2 expression was further studied in human NCI... more The signaling pathway involved in TNF-α-induced COX-2 expression was further studied in human NCI-H292 epithelial cells. A protein kinase C (PKC) inhibitor (staurosporine), tyrosine kinase inhibitors (genistein and herbimycin A), or a Src kinase inhibitor (PP2) attenuated TNF-α-or TPA-induced COX-2 promoter activity. TNF-α− or TPA-induced IKK activation was also blocked by these inhibitors, which reversed IκBα degradation. Activation of c-Src and Lyn kinases, two Src family members, was inhibited by the PKC, tyrosine kinase, or Src kinase inhibitors. The dominant-negative c-Src (KM) mutant inhibited induction of COX-2 promoter activity by TNF-α or TPA. Overexpression of the constitutively active PKCα (PKCα A/E) or wild-type (wt) c-Src plasmids induced COX-2 promoter activity, and these effects were inhibited by the dominant-negative c-Src (KM), NIK (KA), or IKKβ (KM) mutant. The dominant negative PKCα (K/R) or c-Src (KM) mutant failed to block induction of COX-2 promoter activity caused by wt NIK overexpression. In co-immunoprecipitation experiments, IKKα/β was found to be associated with c-Src and to be phosphorylated on its tyrosine residues after TNF-α or TPA treatment. Two tyrosine residues, Tyr 188 and Tyr 199 , near the activation loop of IKKβ were identified to be crucial for NF-κB activation. Substitution of these residues with phenylalanines attenuated COX-2 promoter activity and c-Src-dependent phosphorylation of IKKβ induced by TNF-α or TPA. These data suggest that, in addition to activating NIK, TNF-α also activates PKC-dependent c-Src. These two pathways cross-link between c-Src and NIK and converge at IKKα/β, and go on to activate NF-κB, via serine phosphorylation and degradation of IκB-α, and, finally, to initiate COX-2 expression.
Nature Cell Biology, 2008
The RAS-ERK pathway is known to play a pivotal role in differentiation, proliferation and tumour ... more The RAS-ERK pathway is known to play a pivotal role in differentiation, proliferation and tumour progression. Here, we show that ERK downregulates Forkhead box O 3a (FOXO3a) by directly interacting with and phosphorylating FOXO3a at Ser 294, Ser 344 and Ser 425, which consequently promotes cell proliferation and tumorigenesis. The ERK-phosphorylated FOXO3a degrades via an MDM2-mediated ubiquitin-proteasome pathway. However, the non-phosphorylated FOXO3a mutant is resistant to the interaction and degradation by murine double minute 2 (MDM2), thereby resulting in a strong inhibition of cell proliferation and tumorigenicity. Taken together, our study elucidates a novel pathway in cell growth and tumorigenesis through negative regulation of FOXO3a by RAS-ERK and MDM2.
Molecular Carcinogenesis, 2009
MAX dimerization protein 1 (MAD1) is a transcription suppressor that antagonizes MYC‐mediated tra... more MAX dimerization protein 1 (MAD1) is a transcription suppressor that antagonizes MYC‐mediated transcription activation, and the inhibition mechanism occurs mainly through the competition of target genes' promoter MYC binding sites by MAD1. The promoter binding proteins switch between MYC and MAD1 affects cell proliferation and differentiation. However, little is known about MAD1's regulation process in cancer cells. Here, we present evidence that AKT inhibits MAD1‐mediated transcription repression by physical interaction with and phosphorylation of MAD1. Phosphorylation reduces the binding affinity between MAD1 and its target genes' promoter and thereby abolishes its transcription suppression function. Mutation of the phosphorylation site from serine to alanine rescues the DNA‐binding ability in the presence of activated AKT. In addition, AKT inhibits MAD1‐mediated target genes (hTERT and ODC) transcription repression and promotes cell cycle and cell growth. However, mut...
Journal of the Formosan Medical Association, 2009
Phosphoinositide 3-kinase (PI3K)/Akt has emerged as an important pathway in regulating the signal... more Phosphoinositide 3-kinase (PI3K)/Akt has emerged as an important pathway in regulating the signaling of many fundamental biological processes, such as cell proliferation, survival and apoptosis, glucose metabolism, ribosomal function, gene transcription, and cell migration, via phosphorylation of a variety of substrates by the crucial serine/threonine kinase Akt. Dysregulation of the PI3K/Akt pathway is associated with the development of many human malignancies. Constitutive activation of the PI3K/Akt pathway occurs in tumor cells via several mechanisms, such as oncogene activation, gene amplification, and inactivation of tumor suppressors. Activated Akt contributes to tumor progression by modulating the function of numerous substrates related to the regulation of cell proliferation, antiapoptosis and angiogenesis, and therefore, is a valid target for anti-cancer therapy. PI3K/Akt signaling plays a major role not only in tumor growth, but also in the potential response of tumors to anti-cancer treatment. Accumulating evidence has indicated that activation of Akt promotes acquired resistance to treatment with radiation, chemotherapy,
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Papers by Wei-Chien Huang