Histochemical studies of enzymatic patterns during experimental carcinogenesis in the mouse parotid gland

Abstract

Histochemical studies of the distribution patterns of the following enzymes during experimental carcinogenesis induced by 9,10-dimethyl-l,2-benzanthracene in the mouse parotid gland were made; alkaline phosphatase, acid phosphatase, esterase, β-glucuronidase, aminopeptidase, aconitase, aldolase, monoamine oxidase and succinate-, lactate-, malate-, glutamate-, α-glycerophosphate-, β-hydroxybutyrate-, isocitrate-, and glucose-6-phosphate dehydrogenases. The carcinogen produced a relatively constant sequence of histological changes consisting of degenerative, proliferative, squamous metaplastic and malignant neoplastic changes. Most of the neoplasms induced were epidermoid carcinomata and fibrosarcomata, and occasionally cystadenomata and adenocarcinomata. There was one malignant pleomorphic adenoma. The carcinomata were considered from the histological and histochemical appearances to originate from duct cells and not from acinar or myoepithelial cells. Enzymatic behaviour in the epithelial cells during carcinogenesis showed a marked decrease in alkaline phosphatase, esterase and succinate dehydrogenase, but a marked increase in lactate, and glucose-6-phosphate dehydrogenase. The distribution patterns of the enzymes in induced carcinomata were similar to those in naturally-occurring epidermoid carcinomata. Mesodermal tumours showed no clear-cut patterns of enzyme reactivity. The study suggests that the pentose cycle may play a role in the metabolism of carcinogenesis.