摘要
AIM:To assess the role and mechanism of metformin in inducing apoptosis of pancreatic cancer cells.METHODS:The human pancreatic cancer cell lines ASPC-1,BxPc-3,PANC-1 and SW1990 were exposed to metformin.The inhibition of cell proliferation and colony formation via apoptosis induction and S phase arrest in pancreatic cancer cell lines of metformin was tested.RESULTS:In each pancreatic cancer cell line tested,metformin inhibited cell proliferation in a dose dependent manner in MTS(3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assays).Flow cytometric analysis showed that metformin reduced the number of cells in G1 and increased the percentage of cells in S phase as well as the apoptotic fraction.Enzymelinked immunosorbent assay(ELISA) showed that metformin induced apoptosis in all pancreatic cancer cell lines.In Western blot studies,metformin induced poly-ADP-ribose polymerase(PARP) cleavage(an indicator of caspase activation) in all pancreatic cancer cell lines.The general caspase inhibitor(VAD-fmk) completely abolished metformin-induced PARP cleavage and apoptosis in ASPC-1 BxPc-3 and PANC-1,the caspase-8 specific inhibitor(IETD-fmk) and the caspase-9 specific inhibitor(LEHD-fmk) only partially abrogated metformin-induced apoptosis and PARP cleavage in BxPc-3 and PANC-1 cells.We also observed that metformin treatment dramatically reduced epidermal growth factor receptor(EGFR) and phosphorylated mitogen activated protein kinase(P-MAPK) in both a time-and dose-dependent manner in all cell lines tested.CONCLUSION:Metformin significantly inhibits cell proliferation and apoptosis in all pancreatic cell lines.And the metformin-induced apoptosis is associated with PARP cleavage,activation of caspase-3,-8,and-9 in a time-and dose-dependent manner.Hence,both caspase-8 and-9-initiated apoptotic signaling pathways contribute to metformin-induced apoptosis in pancreatic cell lines.
AIM：To assess the role and mechanism of metformin in inducing apoptosis of pancreatic cancer cells.METHODS：The human pancreatic cancer cell lines ASPC-1,BxPc-3,PANC-1 and SW1990 were exposed to metformin.The inhibition of cell proliferation and colony formation via apoptosis induction and S phase arrest in pancreatic cancer cell lines of metformin was tested.RESULTS：In each pancreatic cancer cell line tested,metformin inhibited cell proliferation in a dose dependent manner in MTS（3-（4,5-dimethylthiazol-2-yl）-5-（3-carboxymethoxyphenyl）-2-（4-sulfophenyl）-2H-tetrazolium assays）.Flow cytometric analysis showed that metformin reduced the number of cells in G1 and increased the percentage of cells in S phase as well as the apoptotic fraction.Enzymelinked immunosorbent assay（ELISA） showed that metformin induced apoptosis in all pancreatic cancer cell lines.In Western blot studies,metformin induced poly-ADP-ribose polymerase（PARP） cleavage（an indicator of caspase activation） in all pancreatic cancer cell lines.The general caspase inhibitor（VAD-fmk） completely abolished metformin-induced PARP cleavage and apoptosis in ASPC-1 BxPc-3 and PANC-1,the caspase-8 specific inhibitor（IETD-fmk） and the caspase-9 specific inhibitor（LEHD-fmk） only partially abrogated metformin-induced apoptosis and PARP cleavage in BxPc-3 and PANC-1 cells.We also observed that metformin treatment dramatically reduced epidermal growth factor receptor（EGFR） and phosphorylated mitogen activated protein kinase（P-MAPK） in both a time-and dose-dependent manner in all cell lines tested.CONCLUSION：Metformin significantly inhibits cell proliferation and apoptosis in all pancreatic cell lines.And the metformin-induced apoptosis is associated with PARP cleavage,activation of caspase-3,-8,and-9 in a time-and dose-dependent manner.Hence,both caspase-8 and-9-initiated apoptotic signaling pathways contribute to metformin-induced apoptosis in pancreatic cell lines.
基金
Supported by The National Natural Science Foundation of China,No.30700360
