Comparison of arsenic-induced cell transformation, cytotoxicity, mutation and cytogenetic effects in Syrian hamster embryo cells in culture.

Sodium arsenite and sodium arsenate were observed to induce morphological transformation of Syrian hamster embryo cells in a dose-dependent manner. A linear dose-dependence with a slope of approximately 1 was observed with both compounds when the data were plotted on a log-log graph. The trivalent sodium arsenite was greater than 10-fold more potent than the pentavalent sodium arsenate. The compounds also exhibited toxicity; however, transformation was observed at non-toxic as well as toxic doses. At low doses, enhanced colony-forming efficiency of the cells was observed. To understand the mechanism of arsenic-induced transformation, the genetic effects of the two arsenicals were examined over the same doses that induced transformation. No arsenic-induced gene mutations were detected at two genetic loci. However, cell transformation and cytogenetic effects, including endoreduplication, chromosome aberrations, and sister chromatid exchanges were induced by the arsenicals with similar dose-responses. These results support a possible role for chromosomal changes in arsenic-induced transformation.