Stress protein synthesis in human keratinocytes treated with sodium arsenite, phenyldichloroarsine, and nitrogen mustard

Cells from bacteria to man respond to sublethal thermal and certain chemical stresses by synthesis of heat shock, or stress, proteins. The human epidermal keratinocyte is a target for a variety of cytotoxic substances. One response of cells exposed to such agents may be the synthesis of stress proteins. Human epidermal keratinocytes were treated thermally (43 degrees C) or chemically with sodium arsenite and the skin irritants phenyldichloroarsine and mechlorethamine. Proteins synthesized by keratinocytes were radiolabeled with [35S]methionine, separated on polyacrylamide gels under denaturing conditions, and visualized by fluorography. Quantitation by computer-assisted densitometry of fluorograms revealed different patterns of synthesis of two heat shock proteins (hsp's) with apparent molecular weights of 70 and 90 kDa after treatment with heat, sodium arsenite, phenyl-dichloroarsine, or mechlorethamine. Sodium arsenite induced the highest levels of synthesis of these two proteins, approximately 10-fold and 3-fold increases in hsp-70 and hsp-90, respectively. Phenyldichloroarsine at 0.5 microM produced a 2-fold increase in hsp-70 but no significant increase in hsp-90. Mechlorethamine, in contrast, had an apparent inhibitory effect on hsp-70 synthesis. These results suggest that some but not all skin irritants induce the synthesis of heat shock proteins in human keratinocytes.