Downregulation of CEMIP enhances radiosensitivity by promoting DNA damage and apoptosis in colorectal cancer.

Colorectal cancer (CRC) is the third leading malignancy worldwide in both new cases and deaths. Neoadjuvant radiotherapy is the standard preoperative regimens for locally advanced patients. However, approximately 50% of patients develop recurrence and metastasis after radiotherapy, which is largely due to the radiation resistance properties of the tumor, and the internal mechanism has not been elucidated. Here we found that CEMIP expression is up-regulated in a variety of tumor types, particularly in CRC. Public databases and clinical samples revealed that CEMIP expression is significantly higher in tumor tissues than in adjacent normal tissues in patients with locally advanced CRC who received neoadjuvant chemoradiotherapy, and it is closely related to the poor prognosis. Functional characterization uncovered that downregulation of CEMIP expression can enhance the radiosensitivity of CRC cells, which is confirmed to be achieved by promoting DNA damage and apoptosis. In vivo studies further verified that CEMIP knockdown can significantly improve the radiosensitivity of subcutaneously implanted colorectal tumors in mice, suggesting that CEMIP may be a radiation-resistant gene in CRC. Mechanistically, EGFR/PI3K/Akt signaling pathway is hypothesized to play a key role in CEMIP mediating radiation resistance. These results provide a potential new strategy targeting CEMIP gene for the comprehensive treatment of locally advanced CRC patients.