MicroRNA-874 inhibits growth, induces apoptosis and reverses chemoresistance in colorectal cancer by targeting X-linked inhibitor of apoptosis protein.

MicroRNA-874 (miR-874) is downregulated and acts as a tumor suppressor in several types of cancers, whereas the biological function of miR-874 in colorectal cancer (CRC) remains unclear. The aims of the present study were to investigate the clinical significance, biological effects, and the underlying mechanisms of miR-874 in CRC. Reverse transcription-quantitative PCR (RT-qPCR) was used to detect miR-874 expression in CRC cell lines and tissue samples. MTT and colony formation assays and flow cytometry were performed to analyze the effects of miR-874 expression on growth, apoptosis and the chemoresistance of CRC cells. Regulation of putative miR-874 targets was determined by dual-luciferase reporter assays. RT-qPCR and western blot assays were performed to detected the levels of X-linked inhibitor of apoptosis protein (XIAP) mRNA and protein expression. It was found that expression of miR-874 was downregulated in CRC tissues and cell lines, and its expression was significantly negatively correlated with TNM stage and lymph node metastasis of the CRC patients. Functional assays revealed that restoration of miR-874 inhibited proliferation, reduced colony formation, enhanced apoptosis, as well as decreased the 5-fluorouracil (5-FU) resistance of the CRC cells. Through luciferase activity assay, RT-qPCR and western blot analysis, XIAP was shown to be a direct target of miR-874. In addition, XIAP expression was significantly increased in the CRC tissues and cell lines, and was inversely correlated with miR-874 expression. Importantly, downregulation of XIAP in CRC cells had an effect similar to that of miR-874 overexpression. Taken together, these data showed that miR-874 inhibits growth, increases apoptosis and enhances chemosensitivity in CRC cells by targeting XIAP, suggesting that miR-874 may be a potential molecular target for the treatment of human CRC.