ACTIVITIES OF KEY GLUCONEOGENIC ENZYMES AND GLYCOGEN SYNTHASE IN RAT AND HUMAN LIVERS, HEPATOMAS, AND HEPATOMA CELL-CULTURES

  • 1 January 1978
    • journal article
    • research article
    • Vol. 38  (5) , 1317-1322
Abstract
The activities of pyruvate carboxylase (PC) [EC 6.4.1.1], phosphoenolpyruvate carboxykinase (PEPCK) [EC 4.1.1.32], glucose-6-phosphatase (G6Pase) [EC 3.1.3.9], and glycogen synthetase (GS) [EC 2.4.1.11] were determined in cancerous and apparently uninvolved (host) regions of livers from primary hepatoma patients as well as in normal adult human livers and human fetal livers. The activities of these enzymes were also assayed in a fairly fast-growing, 3''-methyl-4-dimethylaminoazobenzene-induced transplantable rat hepatoma and hepatoma cell lines derived from rat and human tumors. In the human hepatoma, as in the rat hepatoma, the activities of PC, PEPCK and G6Pase were reduced, compared to those in host liver. The activities of the a (glucose-6-phosphate-independent) and b (glucose-6-phosphate-dependent) forms of GS were also lower in human and rat hepatomas than in the respective host livers. Activities of PC, PEPCK and G6Pase in the human hepatomas were often comparable with those of fetal livers. In rat and human hepatoma cells, the activities of PC, PEPCK and G6Pase were similar to or lower than the activities in the respective hepatomas. The activites of GS a were also similar to those in the hepatoma, whereas the activities of GS b were somewhat higher.