We demonstrated that exogenous pyruvate promotes survival under glucose depletion in aerobic mutant p53 (R175H) human melanoma cells. Others subsequently indicated that mutant p53 tumor cells undergo p53 degradation and cell death under aerobic glucose-free conditions. Since glucose starvation occurs in hypoxic gradients of poorly vascularized tumors, we investigated the role of p53 siRNA under hypoxia in wt p53 C8161 melanoma using glucose starvation or 5 mM physiological glucose. p53 Silencing decreased survival of glucose-starved C8161 melanoma with pyruvate supplementation under hypoxia (<= 1% oxygen), but increased resistance to glycolytic inhibitors oxamate and 2-deoxyglucose in 5 mM glucose, preferentially under normoxia. Aiming to counteract hypoxic tumor cell survival irrespective of p53 status, genetically-matched human C8161 melanoma harboring wt p53 or mutant p53 (R175H) were used combining true hypoxia (<= 1% oxygen) and hypoxia mimetic CoCl2. No significant decrease in metabolic activity was evidenced in C8161 melanoma irrespective of p53 status in 2.5 mM glucose after 48 h of physical hypoxia. However, combining the latter with 100 mu M CoCl2 was preferentially toxic for mutant p53 C8161 melanoma, and was enhanced by catalase in wt p53 C8161 cells. Downregulation of MnSOD and LDHA accompanied the toxicity induced by hypoxia and CoCl2 in 5 mM glucose, and these changes were enhanced by oxamate or 2-deoxyglucose. Our results show for the first time that survival of malignant cells in a hypoxic microenvironment can be counteracted by hypoxia mimetic co-treatment in a p53 dependent manner. (C) 2013 The Authors. Published by Elsevier Inc. All rights reserved.