The cytotoxicity of Bleomycin A 2 on adult rat liver epithelial cell lines at different stages of spontaneous cell transformation

Abstract

Cytotoxic effects of Bleomycin A 2 on adult rat liver epithelial cell lines were evaluated by three methods: the incorporation rate of ( 3H)thymidine for DNA biosynthesis, the incorporation rate of L-( 3H)leucine for protein biosynthesis and Giemsa dye staining of surviving cells. Chromosome investigations at successive passages of cell lines have shown that spontaneous chromosome abnormalities in distribution and structure after 15–20 passages, i.e. 50 to 60 cell generations, were the earliest morphological sign of spontaneous transformation. In this study a highly spontaneously transformed cell line was very sensitive to the drug. Another cell line at the beginning of spontaneous transformation appeared to be insensitive although on further passage it became more sensitive. The use of microtitration plates made it easier for us to undertake a comparative study of the different parameters. Following Bleomycin A 2 exposure, Giemsa staining gave the best evaluation of cell killing whereas thymidine incorporation allowed the estimation of cell recovery. The antineoplastic effect of Bleomycin A 2 can probably be used to evaluate the malignant potential of different rat liver epithelial cell lines.