[Transformation of rat hepatocytes in an in vitro primary culture by aflatoxin B1].
Aflatoxin B1 (AFB1) is one of the major causative factors of hepatocellular carcinoma. In this study, the combined effects of AFB1 activated by human cytochrome p450 IA2 and c-myc in transformation of rat hepatocytes were investigated in an in vitro primary culture system. The expression vectors, Xm-6/c-myc was first constructed and their expression possibilities were examined in Alexander cells by immunocytochemistry. Then both c-myc and human cytochrome p450 IA2 expression vectors were sequentially transfected into newborn rat liver cells in serum-free primary culture. Results showed that p450 IA2 could activate AFB1 at concentrations as low as 5 ng/ml, and the activated AFB1 coupled with exogenous c-myc could induce rat hepatocytes to survive and grow beyond two-month limit in primary culture. During long-term in vitro culturing including four-month in crisis, one of the randomly selected transformed hepatocytes with the growth advantage became immortalized. Immunocytochemical assays for CK-18 and rat albumin plus observed electron microscopic features clearly confirmed these cells derived from epithelial hepatocytes. Further characterization showed that the process of immortalization was associated with chromosomal abnormalities and elevated expression of TGF alpha.
Yuan
B
B
Cancer Institute, CAMS and PUMC, Beijing.
Sun
Z
Z
D016604:Aflatoxin B1 / Q000633:toxicity*; D000818:Animals; D000831:Animals, Newborn; D002273:Carcinogens / Q000633:toxicity*; D002471:Cell Transformation, Neoplastic / Q000187:drug effects*; D002478:Cells, Cultured; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics; D004847:Epithelial Cells / Q000166:cytology; D016259:Genes, myc; D006801:Humans; D008099:Liver / Q000166:cytology*; D051381:Rats; D017208:Rats, Wistar; D014162:Transfection
D002273:Carcinogens; D016604:Aflatoxin B1; D019388:Cytochrome P-450 CYP1A2