Expression of DNA polymerase-β in breast cancer and its effect on proliferation of breast cancer cells

Abstract

Objective To investigate the expression of DNA polymerase-β (DNA pol-β) in breast cancer and its effect on proliferation of breast cancer cells. Methods The mRNA level of DNA pol-β in mammary epithelial cells, breast cancer tissues and paired paracancerous tissues was detected by real-time quantitative polymerase chain reaction (Real-time PCR) and the relationship between DNA pol-β expression and tumor size in patients with breast cancer was analyzed. The effect of DNA pol-β on proliferation of breast cancer cells was investigated. Results The expression of DNA pol-β was up-regulated in breast cancer tissues as compared with adjacent breast tissues (2.37±1.81 vs. 3.15±2.20, P<0.01). The increased expression of DNA pol-β in breast cancer tissues was significantly associated with tumor progression (χ2=7.677, P<0.05). The expression of DNA pol-β increased significantly in human breast cancer cell line MCF-7 in comparison with normal human mammary cell line MCF-10A (0.87±0.26 vs. 2.07±0.56, P<0.05). MCF-7 cells transfected with small interfering RNA (siRNA)-DNA pol-β showed decreased proliferation as compared with control group and negative siRNA group (P<0.05). Conclusion The up-regulation of DNA pol-β in breast cancer tissue is a possible mechanism responsible for the proliferation of breast cancer cells. Key words: Breast cancer; Proliferation; DNA polymerase-β