Effect of over-expressed DNA polymerase β on malignant degree of esophageal cancer EC9706 cells

AIM: To observe the effect of over-expressed DNA polymerase β on the malignant degree of EC9706 cells of esophageal cancer. METHODS: The wild and mutant type DNA polβ gene were amplified by polymerase chain reaction (PCR) and cloned into pEGFP-C3 vector to obtain wild and mutant pEGFP-C3-polβ. Then pEGFP-C3-polβ was transfected into EC9706 cells using lipofectamine method. The location of DNA polβ gene-encoded protein was observed under fluorescent microscope. The growth of the cells was detected by MTT assay and the cycle of the cells was examined by flow cytometry. RESULTS: The sequences of the two recombinants were confirmed and they were transfected into the EC9706 cells successfully. The wild DNA polβ protein was mostly located inside the nuclear, but the mutant DNA Polβ protein was distributed in the whole cell. The proliferation of EC9706-wtPolβ cells was significantly slower than that of control cells (P<0.05). Furthermore, the S-period frequency (SPF) was significantly decreased in EC9706-wtPolβ cells (22.11 ± 0.12 vs 44.86 ± 0.03, P<0.05), but not in EC9706-mtpolβ ones (P>0.05). CONCLUSION: Over-expression of wild type DNA polymerase β can decrease the malignant degree of esophageal cancer.