MODULATORS OF CARCINOGENESIS

For decades, it has been known that a number of different factors (e.g ., species, metabolism, age, animal husbandry, diet) may exhibit a sig nificant modulating effect on the process of carcinogenesis. Often, ho wever, these modulators have been largely uncontrolled and thus have m ade uncertain the results of many carcinogenicity bioassays. Fortunate ly, current research into molecular carcinogenesis is beginning to pro vide methods, not only to understand the molecular basis of known modu lators of carcinogenesis, previously described only in empirical terms , but also to allow genetic modulation of carcinogenesis in experiment al systems. An expanding body of knowledge regarding the role of oncog enes and tumor suppressor genes in neoplastic events is leading to a b etter understanding of carcinogenic mechanisms and points to the use o f transgenic animal species in carcinogenicity bioassays. The transgen ic animal provides methods to examine the molecular basis of carcinoge nesis in experimental systems in addition to enhancing the sensitivity of carcinogen identification and the biological specificity of chemic al risk extrapolation. (C) 1995 Academic Press, Inc.