title: AMP-activated protein kinase couples 3-bromopyruvate-induced energy depletion to apoptosis via activation of FoxO3a and upregulation of proapoptotic Bcl-2 proteins.
abstract: Most tumors primarily rely on glycolysis rather than mitochondrial respiration for ATP production. This phenomenon, also known as Warburg effect, renders tumors more sensitive to glycolytic disturbances compared to normal cells. 3-bromopyruvate is a potent inhibitor of glycolysis that shows promise as an anticancer drug candidate. Although investigations revealed that 3-BP triggers apoptosis through ATP depletion and subsequent AMPK activation, the underlying molecular mechanisms coupling AMPK to apoptosis are poorly understood. We showed that 3-BP leads to a rapid ATP depletion which was followed by growth inhibition and Bax-dependent apoptosis in HCT116 cells. Apoptosis was accompanied with activation of caspase-9 and -3 while pretreatment with a general caspase inhibitor attenuated cell death. AMPK, p38, JNK, and Akt were phosphorylated immediately upon treatment. Pharmacological inhibition and silencing of AMPK largely inhibited 3-BP-induced apoptosis and reversed phosphorylation of JNK. Transcriptional activity of FoxO3a was dramatically increased subsequent to AMPK-mediated phosphorylation of FoxO3a at Ser413. Cell death analysis of cells transiently transfected with wt or AMPK-phosphorylation-deficient FoxO3 expression plasmids verified the contributory role of AMPK-FoxO3a axis in 3-BP-induced apoptosis. In addition, expression of proapoptotic Bcl-2 proteins Bim and Bax were upregulated in an AMPK-dependent manner. Bim was transcriptionally activated in association with FoxO3a activity, while Bax upregulation was abolished in p53-null cells. Together, these data suggest that AMPK couples 3-BP-induced metabolic disruption to intrinsic apoptosis via modulation of FoxO3a-Bim axis and Bax expression. © 2015 Wiley Periodicals, Inc.
authors.affiliation: Molecular Biology, Genetics, and Bioengineering Program, Sabanci University, Tuzla, Istanbul, Turkey. cagribodur@gmail.com.
authors.forename: Cagri
authors.initials: C
authors.lastname: Bodur
authors.affiliation: Molecular Biology, Genetics, and Bioengineering Program, Sabanci University, Tuzla, Istanbul, Turkey.
authors.forename: Bahriye
authors.initials: B
authors.lastname: Karakas
authors.affiliation: Molecular Biology, Genetics, and Bioengineering Program, Sabanci University, Tuzla, Istanbul, Turkey.
authors.forename: Ahmet Can
authors.initials: AC
authors.lastname: Timucin
authors.affiliation: Molecular Biology, Genetics, and Bioengineering Program, Sabanci University, Tuzla, Istanbul, Turkey.
authors.forename: Tugsan
authors.initials: T
authors.lastname: Tezil
authors.affiliation: Molecular Biology, Genetics, and Bioengineering Program, Sabanci University, Tuzla, Istanbul, Turkey.
authors.forename: Huveyda
authors.initials: H
authors.lastname: Basaga
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D017209:Apoptosis; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D000071316:Forkhead Box Protein O3 / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006019:Glycolysis / Q000187:drug effects; D045325:HCT116 Cells; D006367:HeLa Cells; D006801:Humans; D009369:Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D011773:Pyruvates / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects; D015854:Up-Regulation
chemical_list: C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D019253:Proto-Oncogene Proteins c-bcl-2; D011773:Pyruvates; C017092:bromopyruvate; D000255:Adenosine Triphosphate; D055372:AMP-Activated Protein Kinases
keywords: 3-bromopyruvate; AMPK; apoptosis; bcl-2; bim; foxO3a; warburg