Pyrene acts as a cocarcinogen with the carcinogens benzo[a]pyrene, beta-propiolactone and radiation in the induction of malignant transformation in cultured mouse fibroblasts; soybean extract containing the Bowman-Birk inhibitor acts as an anticarcinogen.

Pyrene was found to act as a cocarcinogen in the induction of transformation of cultured Balb/c3T3 cells by three different types of carcinogens: a direct acting chemical carcinogen, beta-propiolactone, a chemical carcinogen requiring metabolic activation, benzo[a]pyrene, and a physical carcinogen (60Co) gamma radiation. Since pyrene enhanced transformation in vitro by approximately the same amount for all the carcinogens tested, these results suggest that the carcinogenic action of pyrene is not related to carcinogen metabolism or uptake in vitro. An extract of soybeans containing the Bowman-Birk protease inhibitor was shown to reduce transformation induced by beta-propiolactone, benzo[a]pyrene and gamma-rays, both with and without the cocarcinogenic effect of pyrene, to background levels; the magnitude of the reduction in transformation by the protease inhibitor preparation was unrelated to the concentration of carcinogen. Neither the mechanism for the cocarcinogenic action of pyrene not the anticarcinogenic effect of the soybean extract is known, but several hypotheses are discussed.