CROCIDOLITE ASBESTOS CAUSES AN INDUCTION OF P53 AND APOPTOSIS IN CULTURED A-549 LUNG-CARCINOMA CELLS

A number of genotoxic chemicals and agents, such as benzo(a)pyrene and ultraviolet light, are able to induce nuclear accumulation of p53 pro tein, Usually, this response is transient and a consequence of stabili zation of the wild-type p53 protein. After withdrawal of the exposure, the amount of p53 protein returns to a normal level within hours or a few days. We have studied the p53 response to the exposure of crocido lite asbestos in A-549 lung carcinoma cells using three different meth ods, i.e., p53 immunohistochemistry, Western blotting and metabolic la belling followed by p53 immunoprecipitation, With these techniques we demonstrate a dose-dependent p53 nuclear response to crocidolite expos ure. The half-life of p53 protein in A-549 lung carcinoma cells cultur ed in serum-free media increased from 30 up to 80 min, and the protein reacted with a wild-type specific antibody suggesting that it was in a wild-type conformation. In situ 3'-end labelling of A-549 cells demo nstrated a dose-dependent increase in apoptotic activity, Our data sup port the idea that increased apoptotic activity, induced by crocidolit e, is mediated by p53.