ras transformation of simian virus 40-immortalized rat hepatocytes: an in vitro model of hepatocarcinogenesis.
Primary rat hepatocytes were transfected with simian virus 40 DNA and cultured in a chemically defined medium. Proliferating colonies developed after 2-3 weeks. Three cell lines were established by cloning albumin-secreting colonies, as identified by an immunooverlay assay. Two of the cell lines, ALB-6 and ALB-8, expressed all five liver-specific mRNAs studied, albumin, alpha-1-antitrypsin, fibrinogen, alpha-1-acid glycoprotein, and histidase. ALB-6 cells were nontumorigenic in nude mice while ALB-8 cells were weakly tumorigenic with only one of four injected nude mice developing a slowly growing tumor. Further transfection of ALB-6 and ALB-8 cells with an activated c-Ha-ras or N-ras oncogene resulted in strongly tumorigenic cells. The tumors induced by ras-transformed ALB-6 cells were moderately differentiated hepatocellular carcinomas. The tumors derived from ras-transformed ALB-8 cells were poorly differentiated, while the slowly growing tumors induced by untransfected or control DNA-transfected ALB-8 cells were well-differentiated trabecular hepatocellular carcinomas, suggesting histological dedifferentiation of cells following ras transformation. However, the synthetic capabilities of the cells were not lost in that the ras-transfected cultures and the tumors induced by ras-transformed cells retained the ability to synthesize the five liver-specific mRNAs. Thus we have developed an in vitro model of carcinogenesis in which, by sequential exposure to SV40 DNA and a ras oncogene, primary rat hepatocytes are transformed.
Fang
X J
XJ
Department of Medicine, Toronto Hospital, University of Toronto, Ontario, Canada.
Flowers
M
M
Keating
A
A
Cameron
R
R
Sherman
M
M
D000818:Animals; D014408:Biomarkers, Tumor / Q000032:analysis; D002454:Cell Differentiation; D002461:Cell Line, Transformed; D011905:Genes, ras; D008114:Liver Neoplasms, Experimental / Q000737:chemistry / Q000235:genetics* / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D010641:Phenotype; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D013539:Simian virus 40 / Q000235:genetics*; D014162:Transfection / Q000235:genetics*
D014408:Biomarkers, Tumor; D012333:RNA, Messenger