Vanadate enhances transformation of bovine papillomavirus DNA-transfected C3H/10T1/2 cells

Bovine papillomavirus (BPV) DNA-transfected C3H/10T1/2 cells respond to tumor promoters by enhanced production of transformed foci. Vanadate, a suspected carcinogen, is a mitogen, generates active oxygen species and alters phosphorylation of proteins. We investigated whether vanadate would enhance transformation of BPV DNA-transfected C3H/10T1/2 cells. Transformed foci in BPV DNA transfected C3H/10T1/2 cells exposed continuously to vanadate for 21 days increased in a dose-dependent manner to 50-fold at 4 microM vanadate. This increase was not due to enhanced uptake of BPV DNA post transfection. Neither catalase nor superoxide dismutase inhibited the vanadate-mediated increase in transformed foci but this does not necessarily rule out the involvement of intracellular active oxygen species. At vanadate concentrations greater than 6 microM, cells lost adherence to the Petri plates. We conclude that vanadate is capable of enhancing BPV DNA-mediated cell transformation. Possible mechanisms may involve active oxygen species or altered patterns of protein phosphorylation.