Comparison of Activity and Isozyme Patterns of Four Enzymes From Hepatomas of Different Growth Rates

Summary

The activity and relative isozyme distribution of 4 enzymes—glutamic-oxalacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), malate dehydrogenase (MDH), and lactic dehydrogenase (LDH)—from chemically induced, transplantable rat hepatomas of different growth rates were compared. The hepatomas were 3924A, 5123tc, 7793, and R₇. Of the 4 enzymes from these tumors compared for specific activity, 2 showed a correlation between growth rate and activity. GOT had a roughly inverse relationship with growth rate, and LDH, a direct relationship. LDH levels of tumors were lower than those of normal liver, except for the LDH level of Hepatoma 3924A, which was higher. The MDH level seemed to be unrelated to growth rate. GPT was low or undetectable in Hepatomas 3924A and 5123tc. The relative distribution of the isozymes of the different enzymes varied considerably among the tumors, but none resembled the distribution profile of the enzymes and isozymes of normal liver; i.e., the enzyme patterns of the tumor tissues differed from the pattern of normal liver in the activity of at least 1 enzyme or isozyme. The enzyme patterns of Hepatoma 3924A, a fast-growing, poorly differentiated tumor, had the greatest deviation from those of the normal liver, in that 5 of the 6 components of the enzyme profile were abnormal.