AMP-Activated Protein Kinase Couples 3-Bromopyruvate-Induced Energy Depletion to Apoptosis via Activation of FoxO3a and Upregulation of Proapoptotic Bcl-2 Proteins


Bodur C., Karakas B., Timucin A. C. , Tezil T., Basaga H.

MOLECULAR CARCINOGENESIS, vol.55, no.11, pp.1584-1597, 2016 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 55 Issue: 11
  • Publication Date: 2016
  • Doi Number: 10.1002/mc.22411
  • Title of Journal : MOLECULAR CARCINOGENESIS
  • Page Numbers: pp.1584-1597
  • Keywords: 3-bromopyruvate, AMPK, bcl-2, bim, apoptosis, foxO3a, warburg, N-TERMINAL KINASE, FORKHEAD TRANSCRIPTION FACTOR, CANCER-CELL DEATH, DEPENDENT APOPTOSIS, HEXOKINASE-II, SIGNALING PATHWAYS, OXIDATIVE STRESS, SURVIVAL SIGNALS, HEPATOMA-CELLS, LIVER-CANCER

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. (C) 2015 Wiley Periodicals, Inc.