MicroRNA-330 inhibited cell proliferation and enhanced chemosensitivity to 5-fluorouracil in colorectal cancer by directly targeting thymidylate synthase.

Colorectal cancer (CRC) is the third most common cancer in males and the second most common in females, worldwide. Currently, 5-fluorouracil (5-FU)-mediated chemotherapy is the adjuvant treatment for patients with CRC following surgical resection. However, a number of patients with CRC develop 5-FU resistance, which is a major challenge for the effective treatment of cancer. Therefore, it is important to investigate the molecular mechanisms underlying chemoresistance and the therapeutic treatments that may improve the treatment of CRC. The present study demonstrated that microRNA (miR)-330 was significantly downregulated in CRC tissues and cell lines. Ectopic miR-330 expression decreased cell proliferation and enhanced cell chemosensitivity to 5-FU via the cell apoptosis pathway in CRC. In addition, thymidylate synthase (TYMS) was revealed to be a direct target gene of miR-330 in CRC. Knockdown of TYMS inhibited CRC cell proliferation, and enhanced cell chemosensitivity to 5-FU by promoting cell apoptosis. In conclusion, the results of the present study indicated that miR-330 targeted TYMS to inhibit the proliferation and enhance the chemosensitivity of CRC cells to 5-FU by promoting cell apoptosis. The present study provided important insight into the molecular mechanism underlying 5-FU-mediated chemoresistance and a novel therapeutic strategy for the enhancement of efficacy in CRC treatment.