Initiation of C3H/10T1/2 cell transformation by formaldehyde.

The effects of formaldehyde were evaluated in the C3H/10T1/2 Cl 8 cell transformation system. Treatment of the cells with 0.1-2.5 micrograms/ml for formaldehyde alone did not result in significant rates of transformation. If formaldehyde treatment was followed by continuous treatment with 0.1 microgram/ml of the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA), transformed foci were produced. Methanol and formic acid lacked significant transforming activity under either treatment regimen. The results suggest that formaldehyde is an initiating agent for C3H/10T1/2 Cl 8 transformation. The fact that some compounds may act solely as initiators should be considered when this transformation system is used to study chemicals which may interact with cells by mechanisms similar to that of formaldehyde.