Transient Receptor Potential-Melastatin Channel Family Member 2: Friend or Foe.

Transient receptor potential melastatin 2 (Trpm2) channels are nonvoltage-activated channels permeable to monovalent and divalent cations, and are expressed in heart, brain, kidney, vasculature, and hematopoietic cells. Trpm2 is overexpressed in bladder, lung, breast, liver, head, and neck cancers. Classically, Trpm2 activation induces cell injury and death by Ca2+ overload or enhanced inflammatory response. Recent studies show that Trpm2 protects lungs from endotoxin-induced injury by reducing reactive oxygen species production in phagocytes; and improves cardiac function after ischemia-reperfusion injury by preserving mitochondrial respiration and cellular adenosine triphosphate levels while decreasing reactive oxygen species levels. In neuroblastoma xenografts, Trpm2 overexpression promotes tumor growth through modulation of hypoxia-inducible transcription factor expression and cellular bioenergetics; whereas Trpm2 inhibition results in enhanced sensitivity to doxorubicin. The robust expression in cancer cells and its pro-survival and proliferative properties make Trpm2 a rational target for cancer therapy. Indiscriminate Trpm2 inhibition, however, may engender serious untoward side effects in other vital organs.