QUALITATIVE AND QUANTITATIVE-ANALYSIS OF AGNOR PROTEINS IN CHEMICALLY-INDUCED RAT-LIVER CARCINOGENESIS

A qualitative and quantitative analysis of silver-stained nuclear orga nizer regions (AgNOR) proteins was performed during hepatocarcinogenes is induced in rats initiated by diethylnitrosamine (DENA) using the re sistant-hepatocyte model Nuclear proteins from control hepatocytes, hy perplastic nodules, and hepatocellular carcinomas (HCC) separated by s odium dodecyl sulfate-polyacrylamide gel electrophoresis were transfer red to nitrocellulose membranes and specifically silver-stained for Ag NOR proteins, No difference was observed in the distribution pattern o f the silver-stained bands among control, hyperplastic, or cancer cell s, The same was true if human cirrhosis and HCC were compared. The eva luation of individual AgNOR protein amounts by computerized densitomet ric analysis showed that 1) the integrated optical density value of th e total AgNOR proteins was greatest in cancer cells, lesser in hyperpl astic hepatocytes, and lowest in control hepatocytes, and 2) the amoun t of the two major silver-stained proteins, nucleolin (105 kd) and pro tein B23 (39 Sd), was always a constant percentage of total AgNOR prot eins, An experiment using bromodeoxyuridine incorporation showed that, during hepatocarcinogenesis, AgNOR protein quantity progressively inc reased and was significantly related to the increased hepatocyte label ing index, These results show that AgNOR protein distribution changes during hepatocarcinogenesis are caused neither by the synthesis of new AgNOR proteins nor by an unbalanced synthesis of individual AgNOR pro teins, but to an increased synthesis of nucleolin and protein B23, whi ch is associated with a progressive increased hepatocyte proliferation rate.