Potentiation by hydroxyurea in G2-prophase of thiotepa- and bleomycin-induced chromosomal aberrations in Chinese hamster cells.

Abstract

The potentiating effect of 5times10-3M hydroxyurea in G2-prophase on chemically induced chromosomal aberrations has been studied in Chinese hamster cells. Hydroxyurea, when given during the last 2 h before fixation, enhanced the frequency of aberrations induced by both S-dependent (thiotepa) and S-independent (bleomycin) agents. The most striking effect was seen on the frequencies of gaps and chromatid breaks but an increase was also found in the number of iso-chromatid breaks of the non-union type. The frequencies of exchanges and iso-chromatid breaks of the sister-union type were comparatively little affected. The results indicate that hydroxyurea inhibits a repair system in G2-prophase involved in the formation of chromosomal aberrations in mammalian cells.