GGT reduction in beta carotene-inhibition of hamster buccal pouch carcinogenesis

Abstract

Levels of activity for gamma glutamyl transpeptidase (GGT) were studied in hamster buccal pouches developing DMBA-induced epidermoid carcinomas and in pouches in which carcinogenesis was inhibited by topical application of beta carotene. The beta carotene acted to inhibit tumor development when applied topically on days alternate to the application of 0.25% DMBA in heavy mineral oil thrice weekly for 22 weeks. Forty male young adult Syrian hamsters were divided into four equal groups. Group 1 had DMBA applied to left buccal pouches thrice weekly. Group 2 had DMBA applied as in Group 1 but also beta carotene thrice weekly on days alternate to the DMBA application. Group 3 animals were painted with only beta carotene and Group 4 animals were untreated controls. The left buccal pouches were dissected at autopsy and divided in half. One half was fixed in formalin, sectioned in paraffin and stained with hematoxylin-eosin for histologic study. The other half was prepared for the histochemical demonstration of GGT activity using epithelial whole mount preparations. GGT activity was found to be reduced in the left buccal pouches of those animals treated with both beta carotene and DMBA when compared to those animals treated with DMBA alone.