Characterization of the miRNA profile in UVB-irradiated normal human keratinocytes.

The aim of this study was to assess the effects of ultraviolet B (UVB) irradiation on microRNA (miRNA) expression in normal human keratinocytes. Global miRNA expression profiles of primary cultures of normal human keratinocytes 4 and 24 h postirradiation were studied using miRNA microarray with further confirmation by real-time PCR. We found that upon 30 or 60 mJ/cm(2) of UVB radiation, the expression of 44 miRNAs was up- or downregulated more than twofold compared with non-irradiated keratinocytes. MiRNAs were either up- or downregulated after 4 h and then either returned to normal levels or remained affected after 24 h, resulting in four distinct patterns of miRNA expression change. It appears that acute exposure of keratinocytes to UVB radiation results in several specific patterns of miRNA response.