Carcinogenesis Advance Access originally published online on February 6, 2008
Carcinogenesis 2008 29(4):713-721; doi:10.1093/carcin/bgn032
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Reactive oxygen species stabilize hypoxia-inducible factor-1 alpha protein and stimulate transcriptional activity via AMP-activated protein kinase in DU145 human prostate cancer cells
Department of Biochemistry and Molecular Biology, Kyung Hee University School of Medicine, Seoul 130-701, Korea
1 Department of Life Science, University of Seoul, Seoul 130-743, Korea
* To whom correspondence should be addressed. Tel: +82 2 961 0922; Fax: +82 2 965 6349; Email: iskang{at}khu.ac.kr Correspondence may also be addressed to Joohun Ha. Tel: +82 2 961 0921; Fax: +82 2 959 8168; Email: hajh{at}khu.ac.kr
Hypoxia-inducible factor (HIF-1) plays a central role in the cellular adaptive response to hypoxic conditions, which are closely related to pathophysiological conditions, such as cancer. Although reactive oxygen species (ROS) have been implicated in the regulation of hypoxic and non-hypoxic induction of HIF-1 under various conditions, the role of ROS is quite controversial, and the mechanism underlying the HIF-1 regulation by ROS is not completely understood yet. Here, we investigated the biochemical mechanism for the ROS-induced HIF-1 by revealing a novel role of adenosine monophosphate-activated protein kinase (AMPK) and the upstream signal components. AMPK plays an essential role as energy-sensor under adenosine triphosphate-deprived conditions. Here we report that ROS induced by a direct application of H2O2 and menadione to DU145 human prostate carcinoma resulted in accumulation of HIF-1
protein by attenuation of its degradation and activation of its transcriptional activity in an AMPK-dependent manner. By way of contrast, AMPK was required only for the transcriptional activity of HIF-1 under hypoxic condition, revealing a differential role of AMPK in these two stimuli. Furthermore, our data show that inhibition of AMPK enhances HIF-1 ubiquitination under ROS condition. Finally, we show that the regulation of HIF-1 by AMPK in response to ROS is under the control of c-Jun N-terminal kinase and Janus kinase 2 pathways. Collectively, our findings identify AMPK as a key determinant of HIF-1 functions in response to ROS and its possible role in the sophisticated HIF-1 regulatory mechanisms.
Abbreviations: ACC, Acetyl-CoA Carboxylase; Ad-AMPK-DN, AMPK dominant negative form; AMPK, adenosine monophosphate-activated protein kinase; ATP, adenosine triphosphate; ERK, extracellular signal-regulated kinase; GSK-3, glycogen synthase kinase-3; HIF-1, hypoxia-inducible factor-1; JAK2, Janus kinase 2; JNK, c-Jun N-terminal kinase; NAC, N-acetyl-cysteine; PHD, prolyl hydroxylase; pVHL, von Hippel-Lindau protein; ROS, reactive oxygen species; STAT, signal transducers and activators of transcription; VEGF, vascular endothelial growth factor
Received September 10, 2007; revised January 24, 2008; accepted January 26, 2008.