Dual role of mitochondrial reactive oxygen species in hypoxia signaling: activation of nuclear factor-{kappa}B via c-SRC and oxidant-dependent cell death.
Hypoxia is a prominent feature of solid tumor development and is known to stimulate mitochondrial ROS (mROS), which, in turn, can activate hypoxia-inducible transcription factor-1alpha and nuclear factor-kappaB (NF-kappaB). Because NF-kappaB plays a central role in carcinogenesis, we examined the mechanism of mROS-mediated NF-kappaB activation and the fate of cancer cells during hypoxia after mitochondrial reduced glutathione (mGSH) depletion. Hypoxia generated mROS in hepatoma (HepG2, H35), neuroblastoma (SH-SY5Y), and colon carcinoma (DLD-1) cells, leading to hypoxia-inducible transcription factor-1alpha-dependent gene expression and c-Src activation that was prevented in cells expressing a redox-insensitive c-Src mutant (C487A). c-Src stimulation activated NF-kappaB without IkappaB-alpha degradation due to IkappaB-alpha tyrosine phosphorylation that was inhibited by rotenone/TTFA or c-Src antagonism. The c-Src-NF-kappaB signaling contributed to the survival of cells during hypoxia as c-Src inhibition or p65 down-regulation by small interfering RNA-sensitized HepG2 cells to hypoxia-induced cell death. Moreover, selective mGSH depletion resulted in an accelerated and enhanced mROS generation by hypoxia that killed SH-SY5Y and DLD-1 cells without disabling the c-Src-NF-kappaB pathway. Thus, although mROS promote cell survival by NF-kappaB activation via c-Src, mROS overgeneration may be exploited to sensitize cancer cells to hypoxia.
Liver Unit, Centro de Investigaciones Biomédicas Esther Koplowitz, Instituto de Malalties Digestives, Hospital Clinic I Provincial and CIBEREHD, Instituto Salud Carlos III, University of Barcelona, Barcelona, Spain.
Josep M
JM
Lluis
Francesca
F
Buricchi
Paola
P
Chiarugi
Albert
A
Morales
José C
JC
Fernandez-Checa
D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology; D016923:Cell Death / Q000187:drug effects*; D015687:Cell Hypoxia; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D015151:Immunoblotting; D047468:Immunoprecipitation; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology; D008928:Mitochondria / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009447:Neuroblastoma / Q000378:metabolism / Q000473:pathology; D016877:Oxidants / Q000494:pharmacology*; D010766:Phosphorylation; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014162:Transfection; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism
C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D016328:NF-kappa B; D016877:Oxidants; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D014443:Tyrosine; D016392:Proto-Oncogene Proteins pp60(c-src)