MicroRNA-215 Regulates the Apoptosis of HCT116 Colon Cancer Cells by Inhibiting X-Linked Inhibitor of Apoptosis Protein.

X-linked inhibitor of apoptosis protein (XIAP) is the strongest member of the family of inhibitor of apoptosis protein. Studies found that the expression of XIAP in colon cancer tissue was significantly higher than that in adjacent tissues. Studies have shown that the expression of microRNA-215 (miR-215) was significantly lower than that of the adjacent tissues. This study investigated whether dysregulated miR-215 and XIAP play important roles in colon cancer cell apoptosis and the incidence of colon cancer. Forty-two patients with colorectal cancer (CRC) diagnosed and treated in the authors' hospital were selected. Human CRC cell line HCT116 and normal colonic mucosal epithelial cells (CMECs) were used. Luciferase reporter gene vector was constructed and dual-luciferase reporter gene assay was performed. HCT116 cells were cultured and divided into five groups: mimic normal control (NC) group, miR-215 mimic group, si-NC group, si-XIAP group, and miR-215 mimic + si-XIAP group. Western blot and polymerase chain reaction were conducted to examine XIAP and caspase-3. Apoptosis was detected by flow cytometry and cell proliferation was detected by cell counting kit-8 assay. Compared with the adjacent tissues, the expression of miR-215 in colon cancer tissue was significantly lower, whereas the expression of XIAP in colon cancer tissue was significantly higher. The apoptosis rate and miR-215 expression level of HCT116 cells were lower than that of normal CMECs, whereas XIAP expression was significantly higher than that in normal colon mucosa epithelial cells. MiR-215 targeted the 3'-untranslated regions of XIAP and inhibited its expression. Overexpressing miR-215 and (or) silencing XIAP expression could significantly enhance the activity of caspase-9 and caspase-3, and promote the apoptosis of HCT116 cells. MiR-215 inhibited the expression of XIAP and promoted the apoptosis of HCT116 cells.