title: Nrf2 inhibition sensitizes cholangiocarcinoma cells to cytotoxic and antiproliferative activities of chemotherapeutic agents.
abstract: Nuclear factor erythroid 2-related factor 2 (Nrf2), a key transcription factor regulating antioxidant, cytoprotective, and metabolic enzymes, plays important roles in drug resistance and proliferation in cancer cells. The present study was aimed to examine the expression of Nrf2 in connection with chemotherapeutic drug sensitivity on cholangiocarcinoma (CCA) cells. The basal levels of Nrf2 protein in cytosol and nuclear fractions of CCA cells were determined using Western blot analysis. Nrf2 mRNA expression of KKU-M156 and KKU-100 cells, representatives of low and high-Nrf2-expressing CCA cells, were silenced using siRNA. After knockdown of Nrf2, the sensitivity of those cells to the cytotoxicity of cisplatin (Cis) was enhanced in association with the increased release of AIF and downregulation of Bcl-xl in both cells. Also, knockdown of Nrf2 suppressed the replicative capability of those cells in colony-forming assay and enhanced their sensitivity to antiproliferative activity of Cis and 5-fluorouracil. The chemosensitizing effect was associated with the suppressed expression of Nrf2-regulated and Cis-induced antioxidant and metabolic genes including NQO1, HO-1, GCLC, TXN, MRP2, TKT, and G6PD. In cell cycle analysis, Nrf2 knockdown cells were arrested at G0/G1 phase and combination with Cis increased the accumulation of cells at S phase. The suppression of KKU-M156 cell proliferation was associated with the downregulation of cyclin D1 and increased level of p21. Inhibition of Nrf2 could be a novel strategy in enhancing antitumor activity of chemotherapeutic agent in control of resistant cancer.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand.
authors.forename: Papavee
authors.initials: P
authors.lastname: Samatiwat
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand.|Liver Fluke and Cholangiocarcinoma Research Center, Khon Kaen University, Khon Kaen, 40002, Thailand.
authors.forename: Auemduan
authors.initials: A
authors.lastname: Prawan
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand.|Liver Fluke and Cholangiocarcinoma Research Center, Khon Kaen University, Khon Kaen, 40002, Thailand.
authors.forename: Laddawan
authors.initials: L
authors.lastname: Senggunprai
authors.affiliation: Department of Physiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand.
authors.forename: Upa
authors.initials: U
authors.lastname: Kukongviriyapan
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand. veerapol@kku.ac.th.|Liver Fluke and Cholangiocarcinoma Research Center, Khon Kaen University, Khon Kaen, 40002, Thailand. veerapol@kku.ac.th.
authors.forename: Veerapol
authors.initials: V
authors.lastname: Kukongviriyapan
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001650:Bile Duct Neoplasms / Q000378:metabolism / Q000473:pathology*; D001653:Bile Ducts, Intrahepatic / Q000473:pathology; D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018281:Cholangiocarcinoma / Q000378:metabolism / Q000473:pathology*; D002945:Cisplatin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D005434:Flow Cytometry; D055785:Gene Knockdown Techniques; D006801:Humans; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D016133:Polymerase Chain Reaction
chemical_list: D000970:Antineoplastic Agents; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D002945:Cisplatin
keywords: Antioxidant; Antiproliferation; Chemosensitizing; Cholangiocarcinoma; Cisplatin; Nrf2