A method for the comparative study of replicative DNA synthesis in GGT-positive and GGT-negative hepatocytes in primary culture isolated from carcinogen-treated rats.
The presence of gamma-glutamyl transpeptidase (GGT) in focal nodules of hepatocytes is a commonly used marker for the identification of preneoplastic cell populations. Female Fischer 344 rats were initiated with a single intragastric administration of 200 mg diethylnitrosamine/kg, altered cells were selected after 0.02% 2-acetylaminofluorene was given in the diet; this was followed by a partial hepatectomy and promotion with dietary sodium phenobarbital for 4 wk. A mixed-cell population of GGT-positive and GGT-negative hepatocytes was obtained after collagenase perfusion and Percoll purification. An enriched population of GGT-positive hepatocytes was obtained by a modified "panning" technique. With quantitative scintillation spectrometry and autoradiography of [3H]thymidine incorporation, replicative DNA synthesis of GGT-positive and GGT-negative rat hepatocytes was observed in both the mixed-cell population and the enriched GGT-positive and GGT-negative cell populations. Under the culture conditions used, GGT-positive cells showed a higher level of replicative DNA synthesis than did GGT-negative cells; this indicates that such altered hepatocytes in the stage of promotion possess an inherently greater capacity for all replication, as previously suggested from studies in vivo.
D000818:Animals; D002273:Carcinogens / Q000494:pharmacology; D002469:Cell Separation; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis*; D005260:Female; D008099:Liver / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D011230:Precancerous Conditions / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D005723:gamma-Glutamyltransferase / Q000378:metabolism*
D002273:Carcinogens; D004247:DNA; D005723:gamma-Glutamyltransferase