Deletion of Serine Dehydrase and Cystathionine Synthetase Activities During Azo-Dye Carcinogenesis

Summary

Serine dehydrase and cystathionine synthetase activities were determined in rat liver, precancerous livers, primary hepatomas induced with 3′-methyl-4-dimethylaminoazobenzene (3′-Me-DAB) and transplanted hepatomas induced with azo dyes. Both enzyme activities were absent in all malignant tissues assayed. After 4 weeks on diets containing 3′-Me-DAB both enzyme activities were reduced more than 50% but returned to normal values at 8 and 12 weeks. Precancerous alterations in these enzyme activities did not appear to be correlated with the carcinogenic activity of azo dyes employed. Deletion or alteration patterns in all tissues assayed supported the contention that both enzyme activities were manifested by a single apoenzyme.