Berberine protects immortalized line of human melanocytes from H2O2-induced oxidative stress via activation of Nrf2 and Mitf signaling pathway

Background: Oxidative stress plays important roles in the pathogenesis of vitiligo. The removal of hydrogen peroxided (H2O2) has been established to be beneficial to vitiligo patients. Berberine (BBR), a natural isoquinoline alkaloid, has antioxidant activity, however, whether BBR can defend human melanocytes against oxidative injury remains to be elucidated. Objective: In the present study, we investigated the potential protective effect of BBR against oxidative stress on an immortalized normal human melanocyte cell line PIG1. Methods: Generally, PIG1 cells were pretreated with various concentrations of BBR for 1 h followed by exposure to 1.0 mM H2O2 for 24 h. Cell apoptosis, intracellular reactive oxygen species (ROS) levels were assessed through flow cytometry. Cell apoptosis, melanogenesis and the activation of Nrf2-ARE and Mitf signaling pathway were assayed. Results: Our results showed that cell viability rose and intracellular ROS generation, cell apoptosis of melanocytes decreased significantly in response to H2O2 through pretreatment with BBR. Furthermore, We found that BBR can dramatically induce Nrf2 nuclear translocation, increase total Nrf2 levels and enhance ARE activity. Besides, Nrf2-siRNA transfection can abrogate the protection of BBR in melanocytes against oxidative injury. At last, we verified that BBR could facilitate melanogenesis function via modulation of Mitf and its target proteins. Conclusion: The results above suggest that BBR can protect melanocytes against oxidative stress via its anti-oxidative activity. Also, we found H2O2-induced activation of NF kappa B was inhibited by BBR. Therefore, it is worthy of investigation BBR as a potential drug for treatment of vitiligo. (C) 2019 Published by Elsevier B.V. on behalf of Japanese Society for Investigative Dermatology.