Interaction Between 2N-methyl-9-hydroxyellipticinium and Ionizing Radiation in CHO Cells

Abstract

Incubation with 2N-methyl-9-hydroxyellipticinium (NMHE) increases the killing of γ-irradiated CHO cells. The main effect is observed in the case of exponentially growing cells which are also more sensitive to the drug alone than plateau phase cells. Radiosenstitivity increases with drug concentration and incubation time in the presence of the drug until a plateau value. However, the presence of NMHE in the culture medium inhibits neither the repair of sublethal nor potentially lethal damage. The influence of different ellipticine derivatives on the cell radiosensitivity was measured. The results show that only the hydroxylated derivatives (NMHE and 9—hydroxyellipticinium), which covalently bind to nucleic acids, increase the cellular sensitivity to ionizing radiations, whereas the non-hydroxylated derivative, 2N-methylellipticinium, has no influence on cell radiosensitivity.