Overexpression of HSP70 prevents ultraviolet B-induced apoptosis of a human melanoma cell line

The heat shock response is a highly conserved reaction common to all cells and organisms, It has been reported that hyperthermic treatment can induce the expression of the heat shock protein (HSP) and can protect cells from u ltraviolet (UV) B radiation. In this study, we evaluated the effects of ind uced HSP70 on resistance to UV radiation, G361 amelanotic human melanoma ce lls were irradiated with increasing doses of UVB, UVB irradiation caused ap optotic cell death in these cells. Following transfection with MFG.hsp70.pu ro plasmid, the expression of HSP70 was determined. Compared to control vec tor-transfected cells, hsp70-transfected cells showed significantly elevate d levels of HSP70 and were highly resistant to UVB irradiation. In order to investigate the effects of HSP70 on the apoptotic pathway, the changes in caspase-3 and PARP were analyzed, Following UVB irradiation, activation of caspase-3 and cleavage of PARP were observed in control vector-transfected cells, and the changes in these molecules were inhibited in the hsp70-trans fected cells. These results suggest that UVB-induced apoptosis of melanoma cells is accompanied by caspase3 activation and PARP cleavage, which can be prevented by an overexpression of HSP70.