Influence of sodium butyrate on the induction of radiation-induced chromosomal aberrations and sister chromatid exchanges in Chinese hamster ovary (CHO) cells

CHO cells were pre-treated with sodium butyrate (SB) for 24 h and then X-ir radiated in G1, Metaphases were scored for the induction of chromosomal abe rrations and sister chromatid exchanges (SCEs). The data were compared with those obtained after irradiation of cells not pre-treated with SB and show ed that SB has different effects on the endpoints examined. The frequencies of dicentric chromosomes were elevated and of small acentric rings (double minutes, DMs) reduced. These results are discussed to be a consequence of conformational changes in hyperacetylated chromatin which could lead to mor e interchromosomal and to less intrachromosomal exchanges. SB itself induce s a few SCEs but suppresses the induction of SCEs by X-rays. We assume that a minor part of radiation induced SCEs are 'false' resulting from structur al chromosomal aberrations, such as inversions, induced in G1. Inversions a re the symmetrical counterparts of DMs. If inversions are suppressed by SB treatment to a similar extent as DMs a small reduction of SCEs by SB can be expected. (C) 1999 Elsevier Science B.V. All rights reserved.