title: Overexpression of Smac promotes Cisplatin-induced apoptosis by activating caspase-3 and caspase-9 in lung cancer A549 cells.
abstract: Second mitochondrial-derived activator of caspase (Smac) plays crucial roles in mitochondrial apoptosis pathways and promotes chemotherapy-induced apoptosis. In this study, Smac levels were examined in various lung cancer cell lines, and the effects of overexpressed Smac in the nonsmall-cell lung cancer cell line A549 were assayed by stable transfection of Smac. Subsequently, MTT assays, cell counting, and flow cytometry were applied to show that overexpression of Smac inhibits cell viability and cell growth and enhances apoptosis after cisplatin treatment. Western blotting was performed before and after cisplatin treatment to demonstrate that drug treatment could release Smac from mitochondria into the cytosol and promote apoptosis by activating caspase-3 and caspase-9. Promotion of apoptosis by cytosolic Smac could be blocked by pretreating cells with the caspase-9 inhibitor z-LEHD-FMK. Our findings indicate that overexpressed Smac significantly inhibited A549 cell growth and promoted apoptosis following cisplatin treatment due to the release of Smac from mitochondria into the cytosol, which increased the activities of caspase-3 and caspase-9.
authors.affiliation: Department of Thoracic Surgery, First Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, P.R. China.
authors.forename: Sida
authors.initials: S
authors.lastname: Qin
authors.forename: Chengcheng
authors.initials: C
authors.lastname: Yang
authors.forename: Xifang
authors.initials: X
authors.lastname: Wang
authors.forename: Chongwen
authors.initials: C
authors.lastname: Xu
authors.forename: Shuo
authors.initials: S
authors.lastname: Li
authors.forename: Boxiang
authors.initials: B
authors.lastname: Zhang
authors.forename: Hong
authors.initials: H
authors.lastname: Ren
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D053181:Caspase 8 / Q000378:metabolism*; D053453:Caspase 9 / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005434:Flow Cytometry; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; C412403:DIABLO protein, human; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D053181:Caspase 8; D053453:Caspase 9; D002945:Cisplatin