Immunohistochemical demonstration of 3,2'-dimethyl-4-aminobiphenyl DNA adduct formation in various organs of Syrian golden hamsters.

3,2'-Dimethyl-4-aminobiphenyl (DMAB), known to be a wide-spectrum genotoxic carcinogen in rats, is also tumorigenic to hamster organs such as the forestomach, small and large intestines, gallbladder and urinary bladder. Using a specific antibody against DMAB-DNA adducts, adduct formation in various organs of Syrian golden hamsters after single s.c., i.g. or i.p. injections of DMAB was immunohistochemically examined in relation to its carcinogenic specificity. The nuclei of basal cells of forestomach, epithelia of small intestine, large intestine, gallbladder and urinary bladder of hamsters were stained to various degrees. However, no differences in the formation of DMAB-DNA adducts were observed between these and non-target organs regarding carcinogenicity. The staining intensity after i.g. or i.p. injections was slightly stronger than after s.c. injection. In line with previous findings for rats, the present results indicate that adduct formation is necessary but not itself sufficient for tumor induction in the Syrian golden hamster.