BACKGROUND/AIM: Neoadjuvant concurrent chemoradiotherapy (CCRT) is the standard therapeutic strategy for rectal cancer. However, 15-20% of patients undergoing neoadjuvant CCRT progress to recurrence or distant metastases. Therefore, identifying a predictive biomarker is necessary for treating CCRT. MATERIALS AND METHODS: We investigated the relationship between the levels of histone ubiquitination enzyme and clinicopathological outcomes in patients with rectal cancer who were administered CCRT and confirm the role of histone ubiquitination enzyme in regulating the cell response to ionizing radiation (IR). RESULTS: Clinical data indicated that UBE2B expression was significantly correlated with tumor regression grade. Inhibition of UBE2B elevated the genotoxicity of IR to radioresistant cell lines. In contrast, UBE2B over-expression reduced cell sensitivity to IR. Importantly, the recruitment of 53BP1 and Rad51 was remarkably prolonged in cells after pre-treatment with UBE2B inhibitor, TZ9, suggesting a defective DNA repair pathway in UBE2B-deficient cells. CONCLUSION: These results indicate that over-expression of UBE2B correlates with poor response and low survival rate in patients who are administered preoperative CCRT.
