Chrysotile-induced cell transformation and transcriptional changes of c-myc oncogene in human embryo lung cells.

It has been verified that asbestos induce neoplastic transformation of several rodent cell lines in vitro. Very little information is available, however, on asbestos-induced human cell line transformation and oncogene activation in the development of asbestos-induced cell transformation. This study was designed to investigate the induction of cell transformation and transcriptional changes of the c-myc oncogene by chrysotile asbestos fibers (CAF) in human embryo lung (HEL) cells. Surface-modified CAF soaked in aluminium citrate (AC), rare earth compounds (REC) or sodium selenite (SS) solutions were used to observe the effects of surface modification on chrysotile-induced cell transformation and transcriptional changes in the c-myc oncogene. The results showed that the natural CAF caused dose-dependent increases in transformed foci, along with increased transcription of the c-myc oncogene in HEL cells, while the pretreated CAF induced fewer transformed foci and less c-myc oncogene transcription than the natural CAF. The percent inhibition of equivalent AC, REC and SS were 38.9%, 50.0%, 33.3% (for transformation focus), 81.6%, 69.5%, 89.9% (for c-myc oncogene transcription), respectively. These results indicated that CAF may induce cell transformation and transcriptional changes and that the carcinogenicity of CAF might be reduced by pretreatment of CAF with the above-mentioned compounds.