Characterization of gamma-glutamyltransferase from neoplastic and non-neoplastic liver tissues in man and during rat liver hepatocarcinogenesis.
The activity and the affinity for concanavalin A-Sepharose (Con A) of liver gamma-glutamyltransferase (gamma GT) were investigated in man, under various clinical conditions and in rats during experimental hepatocarcinogenesis. In man, gamma GT activity was higher than normal in hepatomas and (except for 1 case of hemochromatosis) also higher in the surrounding cirrhotic liver. The proportion of gamma GT which did not bind to Con A (Con A- form) was also increased in the tumors and in the surrounding liver, yet (with the same exception as above) to a greater extent in the hepatomas. In rat, gamma GT activity was higher in fetal liver (15-fold) and in hepatocarcinomas (10-fold) than in normal adult liver; total liver gamma GT activity gradually increased during progression from foci of altered cells to neoplastic nodules and tumors. The proportion of the Con A- form of gamma GT in the early or late stage of the carcinogenic process did not significantly differ from that in normal adult or regenerating rat liver, i.e. about 20% of the total activity. By contrast, nearly all the gamma GT from fetal rat liver bound to Con A. This suggests that gamma GT expression in rat liver carcinoma does not correspond to so-called retrodifferentiation process.
D000293:Adolescent; D000328:Adult; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000201:enzymology*; D002846:Chromatography, Affinity; D003208:Concanavalin A; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000032:analysis*; D008099:Liver / Q000196:embryology / Q000201:enzymology*; D008113:Liver Neoplasms / Q000201:enzymology*; D008114:Liver Neoplasms, Experimental / Q000201:enzymology; D008115:Liver Regeneration; D008297:Male; D008875:Middle Aged; D051381:Rats; D011919:Rats, Inbred Strains; D005723:gamma-Glutamyltransferase / Q000032:analysis*
D007527:Isoenzymes; D003208:Concanavalin A; D005723:gamma-Glutamyltransferase