[Effects of DNA polymerase beta on certain genotoxicity of mouse fibroblast cell induced by hydroquinone]

Abstract

Objective: To explore the effect of DNA polymerase beta (pol beta) expression level on genotoxicity in mouse fibroblast cell induced by hydroquinone (HQ).

Methods: pol beta wild-type cells (pol beta +/+), pol beta null cells (pol beta -/-) and pol beta overexpressed cells (pol beta oe) were applied as a model cell system. At various concentration of HQ, the cell cytotoxicities were detected by MTT assay. The DCFH-DA fluorescent probe was used to examine the cellular ROS levels. The effects of DNA damage/repair and chromosomal damage were observed by comet assay and micronuleus assay respectively.

Results: MTT assay showed that the doses of HQ increased, the cells viabilities were decreased. The concentrations of HQ that inhibited cell growth by 50% (IC50) in the pol beta -/- cell were more lower than those of other cells (P < 0.05). The cellular ROS level in the three kinds of cells were increased in a concentration dependent way after treated with HQ and it was more stronger in pol beta -/- cell than those in other two kinds of cells (P < 0.05). Comet assay and micronucleus assay showed that HQ induced DNA damage and increased micronucleus formation. DNA and chromosomal damage of pol beta -/- cell were more serious than those of other cells. The DNA damage repair capacities of pol beta oe cell were more stronger than pol beta +/+ and pol beta -/- cells.

Conclusion: Cellular ROS generation could be effectively induced by HQ, leading to DNA and chromosomal damage, pol beta overexpression could help cells response to oxidative damage and protect cells from genotoxicity induced by HQ.