[Effect of DNA polymerase beta on repair of DNA damage induced by benzo(a) pyrene]

To clarify the relationship between the expression of pol beta and DNA damage /repair induced by Benzo(a)pyrene (BaP).

pol beta wild-type cells (pol beta +/+), pol beta null cells (pol beta -/-) and wild-type pol beta overexpressed cells (pol beta oe) which had the same genetic background were studied. Firstly, RT-PCR and Western blot targeting to pol beta were carried out to measure the expression of pol beta mRNA and protein in above three kinds of cells, then MTT test and single cell gel electrophoresis (comet assay) were used to compare cell viability and DNA damage/repair of the three kinds of cells when exposed to BaP.

There was pol beta deletion in pol beta -/- cells and the level of pol beta mRNA and protein in pol beta oe cells was twice higher than that in pol beta +/+ cells. BaP could induce DNA damage and reduce cell viability, when compared with pol beta +/+ cells, IC50 of pol beta -/- cells was remarkably lower, DNA was prone to damage and more difficult to be repaired, on the other hand, IC50 of pol beta oe cells was obviously higher and the damage effect on DNA was weaker and prone to be repaired.

Pol beta played an important role in the repair of DNA damage induced by BaP, deficiency of pol beta could decrease the DNA repair capability of cells, and overexpression of pol beta could help cells response to DNA damage and protect cells from death in a certain degree.