Overexpression of A613T and G462T variants of DNA polymerase β weakens chemotherapy sensitivity in esophageal cancer cell lines

BACKGROUND: Human DNA polymerase β (polβ) is a small monomeric protein that is essential for short-patch base excision repair. It plays an important role in regulating the sensitivity of tumor cells to chemotherapy. METHODS: We evaluated the mutation of polβ in a larger cohort of esophageal cancer (EC) patients by RT-PCR and sequencing analysis. The function of the mutation was evaluated by CCK-8, in vivo tumor growth, and flow cytometry assays. RESULTS: There are 229 patients with the polβ mutation, 18 patients with A613T mutation, 12 patients with G462T mutation among 538 ECs. Analysis results of survival time showed that EC patients with A613T, G462T mutation had a shorter survival than the others (P < 0.05). CCK-8 and flow cytometry assays results showed the A613T, G462T EC9706 cells were less sensitive than WT cells to 5-FU and cisplatin (P < 0.05). Experiments results in vivo showed that the tumor sizes of A613T and G462T group were larger than WT and polβ(−/−) groups (P < 0.05). CONCLUSIONS: In this study, we discovered A to T point mutation at nucleotide 613 (A613T) and G to T point mutation at nucleotide 462 (G462T) in the polβ gene through 538 EC patients cohort study. A613T and G462T variant of DNA polymerase β weaken chemotherapy sensitivity of esophageal cancer.