The effect of 3'-methy 1-4-dimethylaminoazobenzene (3'-Me-DAB) in the presence or absence of liver microsomes (S15 mixture) on cloned liver cell line derived from a rat fed 4-dimethylaminoazobenzene Part 1 Some biological properties of 3'-Me-DAB treated cells.

A cloned strain, CL20, which was derived from the liver of rats fed 4-dimethylaminoazobenzene had low tumor-producing capacity, but had high tumor producing capacity after treatment of the cells with 3'-Me-DAB in the presence or absence of S15 mixture. The size of tumors produced at 60 days after back-transplantation of the cells treated with 3'-Me-DAB in the presence or absence of S15 mixture was larger than that of the non-treated control cells. Similar results were obtained for the weight of tumors produced at 90 days after back-transplantation. Treatment of the cells with 3'-Me-DAB in the presence or absence of S15 mixture produced morphological changes of cells in vitro. The plating efficiency and the size of aggregates formed by rotation culture were higher in treated cells than in control cells. A few differences in growth patterns and in the resistances to the toxic effects of 3'-Me-DAB in the presence or absence of S15 mixture were found between treated and control cells. These findings suggested that cell malignancy was promoted by the treatment of 3'-Me-DAB in the presence or absence of S15 mixture.