The value of placental glutathione S-transferase and {gamma}-glutamyl transpetidase as markers of altered foci during hamster pouch carcinogenesis

This study investigated the value of an immunohistochemicaldemonstration of placental glutathione S-transferase (GST P)and a histochemical demonstration of -glutamyl trans peptidase(GGT) for the detection of putative preneoplastic lesions andsquamous cell carcinomas in the Syrian golden hamster buccalpouches treated with 7,12-dimethylbenz[a]anthracene (DMBA).The results showed that GST-P foci appeared earlier than GGTfoci, that the GST-P foci were much more numerous than GGT fociand that most of the GGT positive foci were GST-P positive.All tumors stained strongly positive for GST-P. Only 62.5% oftumors stained for GGT and the staining was usually weak andinvolved only the superficial layer of the epithelium or keratin,suggesting that the enzyme activity in the basal cells had decreasedwith formation of neoplasms. The length percentage of basalcells that were GST-P positive increased rapidly during theexperiment and by week 12,25% of the basal cells exhibited GST-Pstaining. Such rapid expansion of the putative initiated cellsmay explain the early development of chemically induced invasivesquamous cell carcinoma (weeks 10–12) in 100% of hamsters.