CHANGES IN CANCER-RELATED GENE EXPRESSION IN AN IN VITRO HUMAN SKIN MODEL FOLLOWING UVB-IRRADIATION.

UV-irradiation causes initiation and promotion of skin cancers, photoaging and immunosuppression. To further our understanding of these processes at the molecular level, we utilized cDNA array technology to examine changes in gene expression in the EpiDerm™ in vitro human skin model following irradiation with UVB (175 ml per cm2). Viability of irradiated EpiDerm tissue, as determined by formazan dye reduction, was reduced by only 20% at 24 h postirradiation. At 1,6 and 24 h postirradiation, total RNA was isolated from irradiated or control EpiDerm tissues. Radio-labeled cDNA probes were prepared and hybridized with an Atlas™ Human Canter cDNA Expression Array of 588 cancer-related cDNAs. Resultant autoradiographs were analyzed by AtlasImage™ software. A variety of cytokeratins, caspases, transcription factors, and GSH transferase homolog were upregulated within 1 h postirradiation. At 6 h, p21, ERKs1 JNKs, p38, caspases, DAP kinase, p53-induced protein, GADD, DNA repair proteins, VEGF, TIMP-1 and others were also increased. IL-6, IFN-γ-inducible peptide, pre-B cell stimulating factor and 23 kDa highly basic protein were downregulated at 6 h. At 24 h. MMP-1, caspase 10, cytokeratin 6B were still upregulated while endothelin ET2, transcription factor ETR 103, IL-6, IL-13, IFN-γ-inducible peptide and TGF-β were all down-regulated. The data reveal a cascade of gene expression changes, many of which have not previously been reported, occurring within 24 h following exposure of human skin cells to a relatively nonlethal dose of UVB. These results may help to identify new targets for intervention of UVB-mediated pathologies.

CDNA, Complementary DNA (cDNA), EpiDerm, Gene expression, Messenger RNA (mRNA), Microarray, Phototoxicity, Sun screens, UVA, UVB