EFFECT OF SPECIFIC ENZYME-INHIBITORS ON REPLICATION, TOTAL GENOME DNA-REPAIR AND ON GENE-SPECIFIC DNA-REPAIR AFTER UV IRRADIATION IN CHO CELLS

We have studied the effect of some specific enzyme inhibitors on DNA repair and replication after UV damage in Chinese hamster ovary cells. The DNA repair was studied at the level of the average, overall genome and also in the active dihydrofolate reductase gene. Replication was measured in the overall genome. We tested inhibitors of DNA polymerase alpha and delta (aphidicolin), of poly(ADPr) polymerase (3-aminobenzamide), of ribonucleotide reductase (hydroxyurea), of topoisomerase I (camptothecin), and of topoisomerase II (merbarone, VP-16). In addition, we tested the effect of the potential topoisomerase I activator, beta-lapachone. All of these compounds inhibited genome replication and all topoisomerase inhibitors affected the overall genome repair; beta-lapachone stimulated it. None of these compounds had any effect on the gene-specific repair.