Troxerutin induces protective effects against ultraviolet B radiation through the alteration of microRNA expression in human HaCaT keratinocyte cells

Ultraviolet light B (UVB), contained in sunlight, induces damaging effects on skin by impairing cells in the epidermis and dermis. In particular, keratinocytes in the epidermis are those cells which are mainly affected by UVB light. UVB radiation induces cell death, growth arrest, DNA damage and restricts cell migration. Various phytochemicals have been shown to alleviate UVB-induced cellular damage. Troxerutin is a natural flavonoid rutin mainly found in extracts of Sophora japonica, and is a well-known antioxidant and anti-inflammatory compound used in experimental mouse models. In this study, we examined the effects of troxerutin on UVB-induced damage in HaCaT cells. HaCaT cells were pre-treated with troxerutin (0-10 mu M) and then exposed to UVB radiation (50 mJ/cm(2)). Cell viability, cell cycle and migration assays were performed to determine the protective effects of troxerutin on the cells. DNA repair activity was also measured. Troxerutin protected the cells against UVB-induced damage, such as cell death, growth arrest, restriction of cell migration and decreased DNA repair activity in HaCaT cells. Analyses of microRNA (miRNA) expression demonstrated that the protective effects of troxerutin correlated with alterations in miRNA expression, as indicated by Gene Ontology analyses of putative target genes. Overall, our data demonstrate that troxerutin exerts protective effects against UVB-induced damage by regulating miRNA expression.