Arsenic and chromium enhance transformation of bovine papillomavirus DNA-transfected C3H/10T1/2 cells

Tumor promoters such as phorbol esters, teleocidin and okadaic acid increase the numbers of multilayered, transformed foci produced by BPV DNA-transfected C3H/10T1/2 cells. We questioned whether arsenic and chromium, which are known human carcinogens also enhance transformation of BPV DNA-transfected C3H/10T1/2 cells. Cr(III) potassium sulfate at 100 μM enhanced transformation by 1.4-fold, but Cr(VI) as potassium chromate did not enhance transformation, although toxicity of potassium chromate may have prevented enhancement of transformation. Sodium arsenite (As(III)) at 5 μM and sodium arsenate (As(V)) at 25 μM both enhanced neoplastic transformation by 6-fold. By comparison, in previous studies, sodium orthovanadate (V(V)) or vanadyl sulfate (V(IV)) at 4μM enhanced numbers of transformed foci by 25–50-fold. The comparatively strong enhancement of transformation by vanadium and phorbol esters suggests that neoplastic transformation may occur by mechanisms that are common to these compounds including alteration of tyrosine phosphorylation.