Molecular and cellular mechanisms of transformation of C3H/10T1/2 Cl 8 and diploid human fibroblasts by unique carcinogenic, nonmutagenic metal compounds

Abstract

Work from our laboratory showed that carcinogenic metal salts of arsenic, nickel, and chromium induced morphological transformation of cultured C3H/10T1/2 Cl 8 (10T1/2) mouse embryo cells, and that many of the transformants grow in soft agarose and form tumors in nude mice. Concentrations of arsenic, nickel, and chromium compounds that induced morphological transformation did not induce mutation to ouabain resistance in 10T1/2 cells. This indicated that the mechanism of metal induced morphological transformation was likely not caused by induction of base substitution mutations, and in the case of lead chromate, likely not caused by frameshift or deletion mutations. In addition, we showed that carcinogenic arsenic, nickel, and chromium compounds, and MNNG, induced anchorage independence in diploid human fibroblasts. Anchorage-independent cell strains derived from anchorage-independent colonies were stable but did not form foci and eventually senesced, therefore, arsenic and nickel compounds and lead chromate induced stable anchorage independence as an isolated phenotype. Nickel compounds and lead chromate induced anchorage independence but not mutation to ouabain resistance or to 6-thioguanine resistance. Hence, the mechanism of induction of anchorage independence by these metal salts in human fibroblasts was likely not via induction of base substitution, frameshift, or deletion mutations that would be measured in these mutation assays.(ABSTRACT TRUNCATED AT 250 WORDS)