Effect of recombinant interferon-alpha on streptonigrin-induced chromosome aberrations and sister-chromatid exchanges...

The effect of recombinant interferon-alpha-2a (rIFN-alpha-2a) on the induction of chromosomal aberrations (CAs) and sister-chromatid exchanges (SCEs) by the radiomimetic antibiotic streptonigrin (SN, 250 ng/ml, 20 min, 37 degrees C) in Chinese hamster ovary (CHO) cells was investigated. Recombinant IFN-alpha-2a (4500-45,000 IU/ml) was added to the cell cultures 30 min before SN and left in the culture medium until the end of SN treatment or until cell harvesting. A statistically significant increase in the frequency of CAs and SCEs was observed following treatment with SN (P < 0.05), whereas treatments with rIFN-alpha-2a alone did not produce any significant increase of CAs and SCEs over control values. Low rIFN-alpha-2a doses produced a reduction in the frequency of CAs and an increase in the yield of SCEs induced by SN, while high doses of the cytokine caused an increase in the yield of CAs and a reduction in the frequency of SCEs induced by the antibiotic. In addition, rIFN-alpha-2a caused a marked inhibition (around 50%) on the yield of SN-induced chromatid-type aberrations in the G(2) phase of the cell cycle. It is suggested that the inhibitory effect of rIFN-alpha-2a on the SN-induced chromosome damage is due to the stimulation of DNA synthesis and repair by the cytokine. On the other hand, our results give further support to our previous hypothesis that the induction of CAs and SCEs by SN is based on different mechanisms.