title: Histone deacetylases and their inhibitors as potential therapeutic drugs for cholangiocarcinoma - cell line findings.
abstract: Histone deacetylation mediated by histone deacetylases (HDACs) has been reported as one of the epigenetic mechanisms associated with tumorigenesis. The poor responsiveness of anticancer drugs found with cholangiocarcinoma (CCA) leads to short survival rate. We aimed to investigate mRNA expression of HDACs class I and II, and the effect of HDAC inhibitors, suberoylanilide hydroxamic acid (SAHA) and valproic acid (VPA), in CCA in vitro. Expression of HDACs was studied in CCA cell lines (M213, M214 and KKU-100) and an immortal cholangiocyte (MMNK1) by semi-quantitative reverse transcription-PCR. SAHA and VPA, as well as a classical chemotherapeutic drug 5-fluorouracil (5-FU) were used in this study. Cell proliferation was determined by sulforhodamine assay. IC50 and IC20 were then analyzed for each agent and cell line. Moreover, synergistic potential of VPA or SAHA in combination with 5-FU at subtoxic dose (IC20) of each agent was also evaluated. Statistic difference of HDACs expression or cell proliferation in each experimental condition was analyzed by Student's t-test. The result demonstrated that HDACs were expressed in all studied cell types. Both SAHA and VPA inhibited cell proliferation in a dose-dependent manner. Interestingly, KKU-100 which was less sensitive to classical chemotherapeutic 5-FU was highly sensitive to HDAC inhibitors. Simultaneous combination of subtoxic doses of HDAC inhibitors and 5-FU significantly inhibited cell proliferation in CCA cell lines compared to single agent treatment (P ≤ 0.01), while sequentially combined treatments were less effective. The present study showed inhibitory effects of HDACIs on cell proliferation in CCA cell lines, with synergistic antitumor potential demonstrated by simultaneous combination of VPA or SAHA with 5-FU, suggesting a novel alternative therapeutic strategy in effective treatment of CCA.
authors.affiliation: Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Liver Fluke and Cholangiocarcinoma Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Ruethairat
authors.initials: R
authors.lastname: Sriraksa
authors.forename: Temduang
authors.initials: T
authors.lastname: Limpaiboon
mesh_terms: D001650:Bile Duct Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D001653:Bile Ducts, Intrahepatic / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects*; D018281:Cholangiocarcinoma / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006655:Histone Deacetylases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
chemical_list: D056572:Histone Deacetylase Inhibitors; D012333:RNA, Messenger; D006655:Histone Deacetylases