The relationship between chromosomal aberrations, survival and DNA repair in tumour cell lines of differential sensitivity to X-rays and sulphur mustard.

Abstract

Abstract A pair of cultured rat lymphosarcoma cell lines (Yoshida) with a pronounced differential sensitivity to killing with sulphur mustard (SM), but with the same sensitivity to X-rays, was examined for chromosome damage and DNA repair replication after treatment with these agents. A pair of mouse lymphoma cell lines (L5178Y) with a differential sensitivity to X-rays was similarly investigated. SM-resistant Yoshida cells suffered much less chromosome damage than sensitive cells in spite of equal alkylation of DNA, RNA and protein in sensitive and resistant cells. The pair of Yoshida cell lines sustained the same amount of chromosome damage after X-irradiation. Much less chromosome damage was observed in the radiation-resistant lymphoma cell line than in the sensitive line after X-irradiation. No differences was found between the pairs of cell lines in their capacities for repair replication after SM or X-ray treatment. Thus, the drug and radiation resistance is accompanied by, and perhaps mediated through, a reduced amount of induced chromosome damage but is not quantitatively related to the capacity for DNA repair replication. Apart from small differences in modal chromosome numbers there are no obvious karyotype differences between the sulphur mustard-sensitive and -resistant Yoshida cells or between the radiation-sensitive and -resistant lymphoma cells.