MiR-126 inhibits the proliferation and invasion of gastric cancer by downregulation of IGF-1R

Abstract

Objective: To investigate the expression levels and the mechanism of miR-126 and insulin like growth factor 1 receptor (IGF1R) in gastric cancer tissues and cells. Methods: The expression levels of miR-126 and IGF1R in 60 gastric cancer tissues and matched normal gastric tissues were detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and western blot, respectively. The association of miR-126 expression with clinicopathology and prognosis of gastric cancer patients was further analyzed. CCK-8, soft agar assay, transwell assay were used to analyze the proliferation and invasion capacity of gastric cancer cells, respectively, while the dual luciferase reporter assay was used to determine the direct target of miR-126. Results: The expression of miR-126 was obviously correlated with lymphatic metastasis, distant metastasis and TNM stage of gastric cancer (all P<0.05). Cox multivariate analysis revealed that lymphatic metastasis, TNM stage, miR-126 and IGF-1R expression were independent risk factors for prognosis of gastric cancer patients (all P<0.05). The expression level of miR-126 in gastric cancer tissues was 2.01±0.23 significantly lower than 10.12±2.15 of normal gastric tissues (P<0.05). CCK-8 result showed that the absorbance values of MKN28 and BGC823 cells at 72 hours after transfected with miR-126 mimics were 1.06±0.05 and 1.01±0.09, respectively, significantly lower than 1.55±0.12 and 1.36±0.12 of the control group (all P<0.05). The clone numbers of MKN28 and BGC823 cells transfected with miR-126 mimics formed in the soft agar were 33±9 and 29±8, respectively, significantly lower than 76±13 and 71±11 of the control group (all P<0.05). Transwell assay showed that the invasived number of MKN28 and BGC823 cells transfected by miR-126 mimics was 98±12 and 89±8, respectively, significantly lower than 154±18 and 161±17 of the control group (all P<0.05). Double luciferase assay further clarified that miR-126 the 3'-untranslated region (3'-UTR) of IGF-1R, and inhibited its protein expression. CCK-8 results showed that overexpression of IGF-1R partially reversed the miR-126 induced proliferation inhibition in MKN28 (1.65±0.14 v. s. 0.98±0.11, P=0.003) and BGC823 cells (1.44 ±0.15 v. s. 0.89±0.10; P=0.006). Likewise, overexpression of IGF-1R partially reversed the miR-126-inhibited invasion of MKN28 (176±19 v. s. 101±14, P=0.005) and BGC823 cells (186±21 v. s. 92±9, P=0.002). Moreover, the inhibitory effects of miR-126 on proliferation were aggravated by silencing of IGF-1R in MKN28 (0.67±0.09 v. s. 0.99±0.12, P=0.021) and BGC823 cells (0.57±0.07 v. s. 0.92±0.12, P=0.012). Conclusion: miR-126 suppresses the proliferation and invasion of gastric cancer cells through targeting the 3'-UTR of IGF-1R and inhibiting its expression.