An in Vitro Study Elucidating the Effect of Oxidative Stress on Melanocytes

Oxidative stress plays a major role in melanocyte destruction in vitiligo, however the exact mechanism responsible for melanocyte death remains uncertain. We aimed to examine the effect of oxidative stress on melanocyte viability by MTT assay and expression of antioxidant genes (CAT, GPX1, G6PD and PRDX3), stress related genes (HSP60, HSP70, SERP1, SIRT1 and POLH) and melanocyte specific genes (MITF, TYR, TYRP1, TRPM1, EDN1, EZR and LAMP1) by real-time PCR upon exposing the normal human melanocytes (NHM), immortalized melanocytes derived from healthy human (PIG1) and from vitiligo patient (PIG3V) to cumene hydroperoxide (CHP). The transcript levels of selected genes were estimated by using real-time PCR. The NHM, PIG1 and PIG3V melanocytes showed significant decrease in viability under CHP (10-100μM) induced oxidative stress. PIG3V displayed significantly increased expression of PRDX3, HSP70, SERP1, POLH as well as decreased expression of CAT, MITF, TYR, TYRP1, TRPM1, EDN1 and LAMP1 under CHP (10 & 20μM) treatment, as compared to NHM and/or PIG1 melanocytes. These results suggest that vitiligo melanocytes are more sensitive to CHP induced oxidative stress, as compared to normal melanocytes. The present study demonstrates that vitiligo may result from an insufficient response of melanocytes to oxidative stress induced by high H2O2 levels.