Involvement of microRNAs in epigallocatechin gallate-mediated UVB protection in human dermal fibroblasts

The green tea polyphenol epigallocatechin-3-gallate (EGCG) is a potent anti-oxidant and anticancer compound. Recently, EGCG-mediated UVB photoprotection was reported in normal human dermal fibroblasts (NHDFs); however, the molecular mechanism underlying this process remains unknown. Thus, we investigated the EGCG-specific microRNAs (miRNAs) involved in the UVB protective response in NHDFs. WST-1 assays confirmed that low doses (<50 mu M) of EGCG were non-cytotoxic and capable of recovering NHDF cell viability following UVB irradiation up to 83.7% compared to the control cells. Microarray analysis identified several miRNAs that were upregulated and downregulated significantly in this UVB protective response, with downregulated miRNAs outnumbering the upregulated ones. Bioinformatic studies, including miRNA target gene prediction and gene ontology analysis, revealed that the EGCG-specific miRNAs may control genes involved in transcription regulation and inhibition of apoptosis, but not MAPK activation, in NHDFs. Therefore, these results suggest that EGCG may serve as a potential natural photoprotective agent against UVB-mediated damage in NHDFs by altering specific miRNA expression.