Chloroethylnitrosourea-induced cell death and genotoxicity: cell cycle dependence and the role of DNA double-strand breaks, HR and NHEJ.

Chloroethylnitrosureas (CNUs) are powerful DNA-reactive alkylating agents used in cancer therapy. Here, we analyzed cyto- and genotoxicity of nimustine (ACNU), a representative of CNUs, in synchronized cells and in cells deficient in repair proteins involved in homologous recombination (HR) or nonhomologous end-joining (NHEJ). We show that HR mutants are extremely sensitive to ACNU, as measured by colony formation, induction of apoptosis and chromosomal aberrations.