Persistent binding of 3-methylcholanthrene to mouse lung DNA and its correlation with susceptibility to pulmonary neoplasia.

A/J, C3H/HeJ, DBA/2J, and C57BL/6J mice have different susceptibilities to polycyclic aromatic hydrocarbon-induced pulmonary neoplasia, whereas the livers from these animals are uniformly resistant to the carcinogenic actions of these substances. After i.v. injection of [3H]-3-methylcholanthrene, radiolabel was detected in the DNA of both lung and liver of all these strains. The DNA was digested to deoxyribonucleosides and chromatographed on Sephadex LH-20. The amounts of nucleoside-bound adducts detected varied markedly with the different tissues and strains. These adducts were undetectable in liver DNA by 28 days. Although all lung preparations showed some reduction in adducts by 28 days, the amounts in A/J lung were always highest; this correlated with its high susceptibility to neoplastic transformation. In all preparations, radioactivity eluted from Sephadex LH-20 with the column void volume or with underivatized nucleosides. Tissue, but not strain differences were observed in these chromatographic profiles. The predominance of these early-eluting peaks in liver, rather than lung, suggests that they may represent noncarcinogenic lesions. This radiolabeled material remains uncharacterized, but some possibilities are discussed.