title: Silencing A7-nAChR levels increases the sensitivity of gastric cancer cells to ixabepilone treatment.
abstract: Gastric cancer is an important health issue worldwide. Currently, improving the therapeutic efficacy of chemotherapy drugs is an important goal of cancer research. Alpha-7 nicotine acetylcholine receptor (A7-nAChR) is the key molecule that mediates gastric cancer progression, metastasis, and therapy responses; however, the role of A7-nAChR in the therapeutic efficacy of ixabepilone remains unclear. A7-nAChR expression was silenced by small interfering RNA (siRNA) technology. The cytotoxicity of ixabepilone was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and ixabepilone-induced apoptosis was analyzed by flow cytometry and annexin V/propidium iodide (PI) apoptotic assay. The expression patterns of anti-apoptotic proteins (AKT, phospho-AKT, Mcl-1, and Bcl-2) and pro-apoptotic proteins (Bad and Bax) were determined by western blot. Our study found that A7-nAChR knockdown (A7-nAChR-KD) AGS cells were more sensitive to ixabepilone administration than scrambled control AGS cells. We found that A7-nAChR knockdown enhanced ixabepilone-induced cell death as evidenced by the increased number of annexin V-positive (apoptotic) cells. After scrambled control and A7-nAChR-KD cells were treated with ixabepilone, we found that pAKT and AKT levels were significantly reduced in both groups of cells. The levels of Bcl-2 and the anti-apoptotic Mcl-1 isoform increased dramatically after ixabepilone treatment in scrambled control cells but not in A7-nAChR-KD cells. Bad and Bax levels did not change between the treatment group and vehicle group in both A7-nAChR-KD and scrambled control cells, whereas cleaved PARP levels dramatically increased in ixabepilone-treated A7-nAChR-KD cells. Our results demonstrated that knockdown of A7-nAChR enhanced the sensitivity of gastric cancer cells to ixabepilone administration. Thus, the A7-nAChR expression level in patients with gastric cancer may be a good indicator of ixabepilone sensitivity.
authors.affiliation: Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.|Division of General Surgery, Department of Surgery, New Taipei Hospital, Taipei, Taiwan.
authors.forename: Chao-Chiang
authors.initials: CC
authors.lastname: Tu
authors.affiliation: Division of General Surgery, Department of Surgery, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan.
authors.forename: Chien-Yu
authors.initials: CY
authors.lastname: Huang
authors.affiliation: Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Wan-Li
authors.initials: WL
authors.lastname: Cheng
authors.affiliation: Cancer Research Center, Taipei Medical University Hospital, Taipei Medical University, 250 Wu-Xin Street, Taipei City, 110, Taiwan.
authors.forename: Chin-Sheng
authors.initials: CS
authors.lastname: Hung
authors.affiliation: Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan. r5424012@tmu.edu.tw.|Cancer Research Center, Taipei Medical University Hospital, Taipei Medical University, 250 Wu-Xin Street, Taipei City, 110, Taiwan. r5424012@tmu.edu.tw.
authors.forename: Yu-Jia
authors.initials: YJ
authors.lastname: Chang
authors.affiliation: Department of Surgery, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan. poliwei@tmu.edu.tw.|Division of General Surgery, Department of Surgery, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan. poliwei@tmu.edu.tw.|Cancer Research Center, Taipei Medical University Hospital, Taipei Medical University, 250 Wu-Xin Street, Taipei City, 110, Taiwan. poliwei@tmu.edu.tw.
authors.forename: Po-Li
authors.initials: PL
authors.lastname: Wei
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D034261:Epothilones / Q000494:pharmacology*; D005434:Flow Cytometry; D006801:Humans; D034741:RNA, Small Interfering / Q000235:genetics*; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D050257:Tubulin Modulators / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D064569:alpha7 Nicotinic Acetylcholine Receptor / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
chemical_list: D034261:Epothilones; D034741:RNA, Small Interfering; D050257:Tubulin Modulators; D064569:alpha7 Nicotinic Acetylcholine Receptor; C430592:ixabepilone
keywords: Gastric cancer; Ixabepilone; Nicotine acetylcholine receptor