NUCLEOTIDE EXCISION-REPAIR CAPACITY IS ATTENUATED IN HUMAN PROMYELOCYTIC HL60 CELLS THAT OVEREXPRESS BCL2

We investigated the effect of the BCL2 overexpression on nucleotide ex cision repair (NER) and DNA replication in UV-irradiated HL60 cells. F orty-eight h after 10 J/m(2) irradiation, only 4% of the cyclobutane p yrimidine dimers were removed in the BCL2-overexpressing cells, in con trast to 38% removal in control cells. However, the repair of 6-4 pyri midine pyrimidone photoproducts was not affected by BCL2 overexpressio n. Eight h after irradiation, DNA replication recovered to 60% of norm al in the BCL2-overexpressing cells, whereas little DNA replication re covered in control cells. The antioxidant N-acetyl cysteine also atten uated cyclobutane pyrimidine dimer removal but did not enhance the rec overy of DNA replication. Both BCL2-overexpressing and NAC-treated cel ls were more resistant to UV. Our data suggest that Bcl2 may promote m utagenesis and genomic instability in surviving cells.