G648C variant of DNA polymerase ß sensitizes esophageal cancer to chemotherapy.

Human DNA polymerase ß (polß) 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. We have previously identified a G to C point mutation at nucleotide 648 (G648C) of polß in esophageal cancer (EC). In this study, we evaluated the mutation of polß in a larger cohort of EC patients by RT-PCR and sequencing analysis. The function of the mutation was evaluated by MTT, in vivo tumor growth, and flow cytometry assays. The G648C mutation occurred in 15 (3.45 %) of 435 EC patients. In addition, patients with this mutation had significantly longer survival time than those without, following postoperative chemotherapy. Cell lines with G648C mutation in polß gene were more sensitive to treatment with 5-fluorouracil and cisplatin than those with wild-type polß. These results suggest that polß gene with G648C mutation in surgically resected esophagus may be clinically useful for predicting responsiveness to chemotherapy in patients with EC. The polß gene alteration may serve as a prognostic biomarker for EC.