To investigate the effect of miR-9 expression on the invasion of human gastric cancer cell line SGC-7901 and the possible mechanism involved.

Human SGC-7901 cells were cultured and transfected with miR-NC, miR-9 mimic, or miR-9 inhibitor for up-regulation or down-regulation of miR-9 expression. Transwell assay was used to evaluate the change of invasive ability. SYBR Green fluorescence quantitative PCR and Western blot were performed to examine the expression of MMP-2.

Compared with the blank control group, the expression of miR-9 in SGC-7901 cells in the miR-9 mimic group was significantly increased [(1.002±0.083) vs (15.375±3.097), P=0.012 ], and the expression of miR-9 in the miR-9 inhibitor group was significantly decreased [(1.002±0.083) vs (0.279±0.039), P=0.022]. Compared with the blank control group, the number of invasive cells in the miR-9 mimic group was significantly reduced [(72.0±2.2) vs (23.6±4.2), P=0.026], and the number of invasive cells in the miR-9 inhibitor group was significantly increased [(72.0±2.2) vs (102.4±7.6), P=0.037]. In comparison with the blank control group, the mRNA and protein expression of MMP-2 was significantly decreased [(1.006±0.133) vs (0.371±0.132), P=0.011; (0.573±0.063) vs (0.261±0.159), P=0.024] in SGC-7901 cells in the miR-9 mimic group, and the mRNA and protein expression of MMP-2 was significantly increased [(1.006±0.133) vs (2.995±0.701), P=0.015; (0.573±0.063) vs (0.708±0.079), P=0.016] in the miR-9 inhibitor group.

In human gastric cancer cell line SGC-7901, miR-9 can down-regulate the expression of MMP-2 and inhibit the invasive ability of the cells.