Properties and malignant transformation of established rat liver parenchymal cells in culture

Epithelioid cells from the livers of normal and genetically impaired (Gunn) rats were established in long-term cultures in vitro. These cells grew as flat, epithelioid cobble-stone-type monolayers and showed a diploid karyotype. They secreted rat serum albumin and proteins into their growth media and contained aryl hydrocarbon hydroxylase. Such cells were transformed by treatment with methylazoxymethanol acetate; they then exhibited an irregular, piling growth pattern, acquired the ability to grow in soft agar, and thereafter grew as tumors in hamsters given cortisone and in nude mice. These malignant spindle-cell tumors were reestablished in culture and still secreted serum albumin. The transformed cells became highly multinucleate when exposed to cytochalasin B and thus behaved like tumor cells. This behavior was not shown by the original cells. Cells transformed by benzo[a]pyrene failed to grow in soft agar culture or as tumor in animals. Cells were not affected by diethylnitrosamine.