Expression of microRNA-220 in human glioma tissues and its effects on the human glioma cell line U87

Objective To investigate the expression of microRNA (miRNA, miR)-220 in human glioma tissues and its effects on proliferation, invasion and apoptosis of the human glioma cell line U87. Methods The tumor tissues of 102 patents with glioma were selected. Forty-three cases of normal brain tissues from patients with traumatic injury undergoing intracranial decompression were selected as the control group. The human glioma cell line U87 cells were cultured. According to the differences of transfections, the cells were divided into groups of miR-220 inhibitors, miR-220 normal control (NC) and miR-220 mimics. The expression levels of miR-220 in glioma and control groups were detected by real-time quantitative reverse transcription polymerase chain reaction (RT-PCR). The cell invasion abilities were tested by Transwell assay. The apoptosis rate of different transfected groups was measured by flow cytometry. Results The relative expression levels of miR-220 in glioma tissues were 2.45±0.22, significantly higher than 1.31±0.17 in the healthy brain tissues with the difference being statistically significant (P=0.008). The results of cell counting kit-8 (CCK-8) assay showed that the cell proliferation speed in miR-220 mimics group (2.62±0.26) was increased as compared with the miR-220 NC group (2.06±0.17, P=0.037), meanwhile the cell proliferation speed in miR-220 inhibitors group (1.63±0.24) was reduced as compared with the the miR-220 NC (P=0.006). The results of Transwell assay revealed that the cell invasion abilities in miR-220 mimics group (163.8±16.5) were stronger than in the miR-220 NC group (131.5±14.3, P=0.008), and those in miR-220 inhibitors group (108.3±9.9) were weaker than in miR-220 NC group (P=0.041). The results of flow cytometry demonstrated that the cell apoptosis rate in miR-220 mimics group [(10.24±1.73)%] was lower than in miR-220 NC group [(13.92±1.89)%] (P=0.039), and that in miR-220 inhibitors group [(20.08±3.29)%] was higher than in miR-220 NC group (P=0.007). Conclusion MiR-220 was highly expressed in glioma tissues. Down-regulation expression of miR-220 could inhibit the proliferation and invasion of glioma cells, and could accelerate the apoptosis of glioma cells. Key words: Glioma; MicroRNA-220; Proliferation; Invasion; Apoptosis