Effects of bleomycins on synchronized cells by centrifugal elutriation

Chinese hamster ovary (CHO) cells and human oat cell lung carcinoma (ME-MAR) cells were synchronized by centrifugal elutriation. The study of bleomycins (BLM) cytotoxicity to CHO cells showed that G2M phase was sensitive to BLM, S phase intermediate, and G1 phase resistant. In synchronized MEMAR cells the late S phase was sensitive, G2M phase intermediate, and G1 phase resistant to BLM toxicity. DNA distribution patterns measured by flow cytometry showed that a significant G2 block was obtained in CHO cells exposed to BLM 4-15 vg/ml. BLM also prevented cell passage from S to G2 phase. A similar G2 block was found in MEMAR cells. However, no S phase accumulation was found up to BLM 15 vg/ml.