Localization of gamma-glutamyl transpeptidase in hamster buccal pouch epithelium treated with 7,12-dimethylbenz[a]anthracene.

The utility of gamma-glutamyl transpeptidase (GGT) was explored as a histochemical marker for chemical carcinogenesis in hamster buccal pouch mucosa. One or both buccal pouches of 18 noninbred male Syrian golden hamsters were treated topically with 0.5% 7,12-dimethylbenz[a]anthracene (DMBA) in mineral oil over 16 weeks to produce numerous epithelial lesions at various stages of neoplastic development. Both buccal pouches of 4 control animals were similarly treated with mineral oil alone. At the completion of the DMBA treatment, patchy GGT histochemical activity was detected in areas of dysplasia and in 35 of 106 papillomas and well-differentiated squamous cell carcinomas. GGT activity was not detectable in untreated pouches or pouches treated with mineral oil alone. In a separate experiment, Wholemounts of buccal pouch epithelium were used to detect and quantitate minute populations of GGT-stained cells induced in the epithelium by eight topical applications of DMBA over 4 weeks. With this technique, multiple discrete GGT-stained areas were visible in wholemounts prepared at 1 and 6 weeks after the final application of DMBA. The experimental results were consistent with the hypothesis that the early GGT-stained cell populations are preneoplastic in nature.