Effect of heat shock on protein synthesis by normal and malignant human lung cells in tissue culture.

Heat shock proteins were found in cultured human lung cells by sodium dodecyl sulfate:gel electrophoresis and autoradiography using [35S]methionine. The synthesis of a M.W. 70,000 protein was markedly stimulated in normal, malignant, and SV40-transformed cells, and that of M.W. 90,000 and M.W. 100,000 proteins was stimulated only in malignant and SV40-transformed cells after heat shock treatment. In contrast, the synthesis of M.W. 200,000 and M.W. 250,000 proteins observed in the unheated normal cells was diminished after the same procedure. The heat shock proteins were induced within a given range of temperature and duration of treatment, the conditions for normal and malignant cells being clearly different, i.e., optima of 43 degrees for 1 hr in the normal cells and 41 degrees for 1 hr in the malignant cells. The results suggest that the analysis of heat shock protein is very useful for identifying the differential heat susceptibilities of normal and malignant cells and for elucidating their bases and mechanisms.