Abstract
Ultracytochemical localizations and biochemical activities of alkaline phosphatase (ALPase) and 5′-nucleotidase (5′-Nase) in carcinogen-induced adenocarcinomas of the rat stomach were investigated. Immunoprecipitations and isozyme patterns of ALPase revealed a significant increase of liver/bone type ALPase in well-differentiated adenocarcinomas. Ultracytochemically, the reaction product of ALPase activity appeared on the basal plasma membrane of glandular carcinoma cells, whereas 5′-Nase was on the apical plasma membrane; poorly-differentiated carcinoma cells were devoid of these enzyme activities. Both activities of ALPase and 5′-Nase were conspicuous in the extracellular matrix (ECM), and especially on the fibroblasts adjacent to carcinoma cells. The pronounced activities of these enzymes may possibly be involved in the interaction between neoplastic cells and their ECM. For ultrastructural demonstration of 5′-Nase, the cerium-based method appeared to provide little nonspecific deposits of the reaction product, being superior to the conventional lead-based method.
