Reduced activity of DNA polymerase prepared from bleomycin-treated cancer cells.

Rat-ascites-hepatoma AH 130 cells were incubated at 37°C for 1 hour with bleomycin at the concentration of l~30 #g/ml. Then, DNA polymerase was prepared from the cells. The enzymatic activity was about half of the control value. Thymidine kinase similarly prepared from bleomycin-treated cells, did not show such a marked inhibition in their activities. In vitro addition of bleomycin to the DNA polymerase assay system did not produce any appreciable inhibition. Moreover, the antibiotic stimulated the enzymatic activity when native DNA was used as template.