Prolyl hydroxylase 2: a promising target to inhibit hypoxia-induced cellular metabolism in cancer cells.

Hypoxia-inducible factor-1α (HIF-1α) shifts the metabolism of glucose from highly efficient oxidative phosphorylation to less efficient glycolysis. Pyruvic acid thus accumulated is oxidized to lactic acid which is pumped out in the tumor microenvironment. Protons generated from the pentose phosphate pathway (PPP) and upon hydrolysis of ATP further enhance the acidity in the tumor microenvironment. The resultant pH in the tumor microenvironment activates an endoplasmic reticulum protein: sterol regulatory element binding protein-1c (SREBP-1c), which once activated enhances proliferation of the tumor cell. Prolyl hydroxylase 2 (PHD2) is a negative regulator of HIF-1α and causes degradation of HIF-1α in the presence of oxygen. Chemical activation of PHD2 can downregulate HIF-1α and thus restore all its effects. The present review is an attempt to describe PHD2 as the target to combat cancer hypoxia and consequential cellular and metabolic alterations.