Poly- d-lysine in G 2 potentiates chromosome damage induced by X-rays and mitomycin C in CHO cells

Abstract

A number of reports suggest that the role of radiation-induced G 2 arrest is to allow repair of potentially lethal damage in the cells before it comes to mitosis. Though the exact nature of the damage undergoing repair during the delayed G 2 is not known, the yield of chromosomal aberrations observed in metaphase seems to be a good parameter to predict reproductive death of cells. In a previous paper, we have shown that poly- d-lysine, acting in a fashion reminiscent of that of caffeine in mammalian cells, is able to induce a premature onset of mitosis concomitant with an increase in the frequency of chromosomal aberrations in mutagen-treated plant cells. Cultured CHO cells were pre-exposed to either X-rays or mitomycin C and given different doses of the polycationic compound during G 2 in order to analyze any effect on the frequency of chromatid-type aberrations as well as any modification of cell-cycle kinetics. A potentiation of chromosome damage and a premature arrival at mitosis were observed for both mutagens, though the effect was more evident in X-irradiated cells.