title: Down-regulation of AMP-activated protein kinase sensitizes DU145 carcinoma to Fas-induced apoptosis via c-FLIP degradation.
abstract: The death receptor Fas (APO-1/CD95) induces apoptosis in many tissues upon cross-linking by its ligand (FasL), but a number of cancer cells exhibit resistance to such apoptosis. Indeed, resistance to apoptosis seems to be one of the hallmarks of cancer, and therefore, it is clinically important to understand the underlying mechanisms by which cancer cells acquire such resistance. In the present study, we demonstrate that Fas signaling in DU145 human prostate cancer cells leads to rapid activation of AMP-activated protein kinase (AMPK), which plays a major role in adaptive responses to ATP-depleting conditions; prostate cancer is resistant to Fas-mediated apoptosis despite high levels of Fas surface expression and no mutation in the Fas gene. We further demonstrate that inhibition of AMPK sensitizes DU145 cells to Fas-induced apoptosis via enhancement of ubiquitination and consequent proteasome degradation of the apoptosis inhibitory protein c-FLIP. These findings thus reveal a novel anticancer property of AMPK inhibition and support the synergistic application of AMPK inhibition in cancer therapy to overcome Fas resistance.
authors.affiliation: Department of Biochemistry and Molecular Biology, Medical Research Center and Biomedical Science Institute, Kyung Hee University School of Medicine, 1 Hoegi-dong, Tongdaemun-gu, Seoul 130-701, Republic of Korea.
authors.forename: Seung-Nam
authors.initials: SN
authors.lastname: Jung
authors.forename: In-Ja
authors.initials: IJ
authors.lastname: Park
authors.forename: Min-Jung
authors.initials: MJ
authors.lastname: Kim
authors.forename: Insug
authors.initials: I
authors.lastname: Kang
authors.forename: Wonchae
authors.initials: W
authors.lastname: Choe
authors.forename: Sung-Soo
authors.initials: SS
authors.lastname: Kim
authors.forename: Joohun
authors.initials: J
authors.lastname: Ha
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017209:Apoptosis / Q000502:physiology*; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000378:metabolism*; D002277:Carcinoma / Q000201:enzymology*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D019014:fas Receptor / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D019014:fas Receptor; D055372:AMP-Activated Protein Kinases; D020169:Caspases