Enzyme histochemical characteristics of spontaneous and induced hepatocellular neoplasms in mice

Hepatocellular neoplasms are known to differ in enzyme activity from the surrounding non-neoplastic liver. We have compared histochemically the enzyme activity of spontaneous hepatocellular tumors in mice with tumors induced by diethylnitrosamine and dieldrin. Some neoplasms had increased activity, others had decreased enzyme activity, yet other had the same activity as the surrounding liver. Alkaline phosphatase, glucose-6-phosphatase, succinic dehydrogenase and adenosine triphosphatase, as well as glycogen levels were studied. Carcinomas differed from adenomas in having elevated enzyme activity significantly more often than adenomas. However, the carcinomas showed elevated glycogen levels less frequently than adenomas. Histochemically, pulmonary metastases resembled the primary hepatocellular carcinomas from which they were derived. Tumors of dieldrin animals were notable in having increased activity of all the enzymes which we studied more frequently than tumors of diethylnitrosamine animals or of controls. Differences in enzyme activity between the three mouse strains were slight.