title: Persistence of gamma-glutamyl transpeptidase-positive foci during hamster buccal pouch carcinogenesis.
abstract: This study describes the kinetics of induction and growth as well as the property of persistence of gamma-glutamyl transpeptidase (GGT)-stained cell populations (GGT-positive foci) induced in hamster buccal pouch epithelium by a 5-week regimen of biweekly topical applications of 7, 12-dimethylbenz(a)anthracene (DMBA). During such treatment, and at various times thereafter, GGT-positive foci were detected and quantitated in whole mounts of pouch epithelium stained histochemically for GGT activity. A comparison of GGT-positive foci at the completion of the DMBA regimen and at 10 weeks thereafter revealed no significant decrease in either the number or the size of the foci. During the same 10-week posttreatment period, several dysplastic and occasional neoplastic lesions, some of which displayed patchy GGT activity, developed in the pouch epithelium of DMBA-treated animals. Twenty-two hamsters were sacrificed between the 15th and 34th weeks of the experiment for histological and histochemical study. Fifteen of these animals had grossly visible epithelial neoplasms, and the 11 which could be evaluated using the whole-mount technique had a few residual GGT-positive foci. None of the 33 control animals evaluated at various times during the experiment developed any gross, microscopic, or GGT-positive lesions. These data indicate that, following a 5-week regimen of DMBA applications, an appreciable number of GGT-positive foci persist throughout the latent period, during which dysplastic and neoplastic buccal pouch lesions develop. The expression of GGT activity in early hyperplastic and dysplastic lesions and its persistence in several animals provide additional support for the hypothesis that GGT-positive foci may represent sites of subsequent neoplastic development.
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D002610:Cheek; D006224:Cricetinae; D006651:Histocytochemistry; D007700:Kinetics; D008297:Male; D008647:Mesocricetus; D009062:Mouth Neoplasms / Q000139:chemically induced / Q000201:enzymology* / Q000473:pathology; D011230:Precancerous Conditions / Q000201:enzymology* / Q000473:pathology; D005723:gamma-Glutamyltransferase / Q000378:metabolism*
chemical_list: D015127:9,10-Dimethyl-1,2-benzanthracene; D005723:gamma-Glutamyltransferase