Induction of the 72-kD heat shock protein in human skin melanoma and squamous cell carcinoma cell lines.

Heat shock proteins (HSPs) or stress proteins comprise a characteristic group of proteins synthesized in cells exposed to heat or other environmental stimuli. Of the many HSPs, the 72-kD heat shock protein (HSP72) is the most stress-inducible one. In the present study, we examined the effects of heat, chemicals (azetidine and sodium arsenite), ultraviolet (UV) light, and gamma-ray irradiation on the induction of HSP72 in cultured human skin melanoma cell lines (P-39 and G-361), a human skin squamous cell carcinoma cell line (HSC-1), and an SV40-transformed human lung fibroblast cell line (WI38VA13) as a control. In these cell lines, heat treatment induced HSP72 more rapidly and intensely than did chemical exposure. Compared with the SCC cell line, the two melanoma cell lines produced less HSP72 with heat treatment. UVC irradiation (20 J/m2) induced HSP72 only in the WI38VA13 cells. After gamma-ray irradiation, no HSP72 induction was detected in any of the cell lines examined. These observations suggest that, in cultured cells, inducibility of HSP72 depends not only on the inducer but also on the origin of each cell line.