The inhibition effect of expressions of miR-221 and miR-222 on glioma and corresponding mechanism.

PURPOSE: This study was designed to investigate the expressions of genes miR-221 and miR-222 in glioma cells and elucidate the mechanism of the inhibition of expressions of miR-221 and miR-222 in glioma. METHODS: After being cultured, in vitro cells of U251 malignant glioma were divided into five groups, namely, blank control group, nonsense sequence ODN transfection group, AS-miR-221-ODN transfection group, AS-miR-222-ODN transfection group, AS-miR-221 ODN and AS-miR-222 0DN co-transfection group. RESULTS: The growth of the cells in AS-miR-221/222 group was significantly inhibited after transfection of 24 hours. Moreover, this inhibition degree became more apparent with prolonged time. The cell percentage in AS-miR-221/222 transfection group was 57.2 % in G0/G1 phase, 35.1 % in S phase, and 38.2 % in G2/M phase. The cell percentage in S phase was decreased. Cell cycle arrest was found in G0/G1 phase. Animal experiments showed that the glioma volume of AS-miR-221/222 treatment group was significantly different to that of the control group (p < 0.05). Furthermore, this difference gradually increased with time. It reached the maximum at the end of the observation period. In the U251 glioma specimens in AS-miR-221/222 treatment group, local glioma tissue developed necrosis foci. In addition, the nuclear size, color, heteromorphism, and new vessel number of these glioma tissues were decreased. CONCLUSION: There are a series of abnormal miRNA expressions in glioma. Among them, miR-221 and miR -222 are clustered miR s with elevated expressions. The over-expressions of miR-221 and miR-222 can be considered as new molecular tags for human glioma (Tab. 5, Fig. 4, Ref. 30).