title: Upregulation of the antiapoptotic factor Livin contributes to cisplatin resistance in colon cancer cells.
abstract: The antiapoptotic factor Livin has been considered critical for tumor progression and poor prognosis for variant types of tumors. However, there are only limited reports regarding its expression and biological functions in colon cancer. Here, we examined Livin expression in four colon cancer cell lines (HCT116, RKO, KM12C, and SW620) in the presence or absence of cisplatin that was used as a model reagent. We found the different response to cisplatin was related to endogenous Livin expression level. From among a panel of apoptosis-related factors (p53, Bcl-2, Bcl-XL, BAX, and survivin), the expression of Livin was upregulated after cisplatin treatment in a dose-dependent manner. Both immunocytochemistry and nuclear cytoplasmic fractionation indicated Livin remained in the cytoplasm after treatment with cisplatin. In an attempt to explore the mechanism, we found the elevated expression of Livin was not due to the decreased degradation by proteosome but was enhanced at the mRNA level. Besides, cisplatin treatment activated the mammalian target of rapamycin (mTOR) pathway as shown by increased phosphorylation of Akt1, mTOR, S6K, and 4E-BP1, together with the elevated Livin. The PI3K inhibitor LY294002 inhibited both the phosphorylation of mTOR and upregulation of Livin. The stable overexpression of Livin inhibited the activation of caspase-3 and led to resistance to cisplatin, while the knockdown of Livin by siRNA rendered colon cancer cells more sensitive to cisplatin. Our study, along with others, highlighted the potential of Livin for cancer therapy in colon cancer.
authors.affiliation: Division of Oncology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Country Council of Östergötland, University of Linköping, S-581 85, Linköping, Sweden.
authors.forename: Zhen-Yu
authors.initials: ZY
authors.lastname: Ding
authors.forename: Gui-Hong
authors.initials: GH
authors.lastname: Liu
authors.forename: Birgit
authors.initials: B
authors.lastname: Olsson
authors.forename: Xiao-Feng
authors.initials: XF
authors.lastname: Sun
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D019008:Drug Resistance, Neoplasm; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000970:Antineoplastic Agents; C419866:BIRC7 protein, human; D051034:Inhibitor of Apoptosis Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D002945:Cisplatin