Oval cell proliferation in early stages of hepatocarcinogenesis in simian virus 40 large T transgenic mice.

In transgenic mice bearing the Simian Virus 40 large T antigen under the control of the human antithrombin III regulatory sequences, a stepwise progression toward hepatocellular carcinoma is observed. We have used two monoclonal antibodies (A6 and G7) developed against a surface antigen expressed in oval cells from dipin-treated mice, to analyze the emergence of such preneoplastic populations in the livers of antithrombin III Simian Virus 40 T transgenic mice. We show that a unique population of small heterogeneous epithelial cells, which probably corresponds to oval and/or transitional cells according to their morphological features, consistently appears at approximately the 10th week after birth and proliferates thereafter.

Retroviral infection of primary hepatocytes from normal mice and mice transgenic for SV40 large T antigen.

Cultured adult rodent hepatocytes are extensively used as a model system for gene transfer in vitro. In the present study, we examined the influence differentiation status and growth capacity of the hepatocytes on their infectivity in vitro by a retroviral vector. These parameters were initially studied in primary cultures of rat hepatocytes transduced with an ecotropic retroviral vector containing Escherichia coli beta-galactosidase.

Retroviral-mediated transfer and expression of human beta-globin genes in cultured murine and human erythroid cells.

We have cloned human beta-globin DNA sequences from a genomic library prepared from DNA isolated from the human leukemia cell line K562 and have used the retroviral vector pZip-NeoSV(X)1 to introduce a 3.0-kilobase segment encompassing the globin gene into mouse erythroleukemia cells. Whereas the endogenous K562 beta-globin gene is repressed in K562 cells, when introduced into mouse erythroleukemia cells by retroviral-mediated gene transfer, the beta-globin gene from K562 cells was transcribed and induced 5-20-fold after treatment of the cells with dimethyl sulfoxide.

Regulated expression of a complete human beta-globin gene encoded by a transmissible retrovirus vector.

We introduced a human beta-globin gene into murine erythroleukemia (MEL) cells by infection with recombinant retroviruses containing the complete genomic globin sequence. The beta-globin gene was correctly regulated during differentiation, steady-state mRNA levels being induced 5- to 30-fold after treatment of the cells with the chemical inducer dimethyl sulfoxide. Studies using vectors which yield integrated proviruses lacking transcriptional enhancer sequences indicated that neither retroviral transcription nor the retroviral enhancer sequences themselves had any obvious effect on expression of the globin gene.