Oridonin protects HaCaT keratinocytes against hydrogen peroxide-induced oxidative stress by altering microRNA expression.

microRNAs (miRNAs) have been shown to function as primary regulators of a variety of biological processes, including proliferation, differentiation and apoptosis in human keratinocytes. However, the biological significance of miRNAs in the defense against oxidative stress in keratinocytes remains to be elucidated. In this study, we demonstrate that oridonin, a diterpenoid compound isolated from Rabdosia rubescens with established antioxidant properties, protects HaCaT human keratinocytes from oxidative stress induced by exposure to hydrogen peroxide (H2O2). Our data demonstrate that low doses of oridonin (1-5 µM) protect keratinocytes against H2O2-induced apoptosis in a concentration- and time-dependent manner. Moreover, as shown by our results, oridonin markedly decreased H2O2-induced reactive oxygen species production in HaCaT cells. Oridonin mediated these effects by altering miRNA expression. Bioinformatics analysis identified several putative target genes of the differentially expressed miRNAs. Assessment of their gene ontology annotation revealed that these target genes are likely involved in cell growth and inhibition of apoptosis. Thus, the data from this study establish a role for miRNAs in mediating oridonin-induced protective effects against oxidative stress in human keratinocytes.