Binding of the azocarcinogen 3'-methyl-p-dimethylaminoazobenzene to cellular components of normal rat liver and azocarcinogen-induced hepatomas.

The location of binding sites for 3'-methyl-p-dimethylaminoazobenzene (3'-Me-DAB) or metabolites on components of rat liver cells and hepatoma cells in tumors induced by this carcinogen was determined at 2 stages during the induction of tumors in rats: (a) in normal liver immediately following the application of a massive dose of the azocarcinogen by intragastric feeding, and (b) in liver and tumor after hepatomas had developed following repeated exposures to the carcinogen by s.c. injections. Bound 3'-Me-DAB or metabolites were detected by the use of rabbit antisera directed against either p-azoazobenzene or p'-azo-p-dimethylaminoazobenzene in an indirect fluorescent antibody technique. Soon after massive intragastric doses of 3'-Me-DAB, the staining observed when the anti-p-azoazobenzene antiserum was used was principally on cytoplasmic components of liver cells with some staining of the intranuclear components. When the second antiserum, anti-p'-azo-p-dimethylaminoazobenzene antiserum, was used, the most intense fluorescent staining was on the nuclear membranes, although there was some cytoplasmic and intranuclear staining as well.