Expression of gamma-glutamyl transpeptidase during pouch carcinogenesis is not oncofetal

gamma-glutamyl transpeptidase (GGT) is not histochemically detectable in normal adult hamster pouch epithelium but markedly increased during pouch carcinogenesis. The possibility that the increase in GGT activity during pouch carcinogenesis reflects dedifferentiation of cells remains to be answered. The distribution of GGT in fetal and neonatal hamster tissues is unknown. The objective of this study was to determine GGT activity histochemically during hamster pouch development and during development of hamster oral and peri-oral structures, and several extra-oral tissues and organs. High GGT activity was seen mainly in epithelial cells exhibiting marked secretory or absorptive functions. Occasionally, GGT activity was also seen in mesenchymal cells. No GGT activity was noted at any stage of pouch development. The results suggest that the expression of GGT during pouch carcinogenesis represents an acquired phenotype instead of re-expression of a phenotype that is present during normal embryonic development. The results also support the hypothesis that GGT plays an important role in transportation.