Inhibition of GAS5 promoted invasion, migration and epithelial-mesenchymal transition of colorectal cancer cells via miR-21/PTEN/Akt axis

Abstract

Objective: To explore the effect of growth arrest-specific5 (GAS5) inhibition on the proliferation, colony formation, invasion, migration andepithelial-mesenchymal transition(EMT), cancer cell stem of HCT-116 and its mechanism. Methods: The colorectal carcinoma (CRC) cell HCT116 was divided into blank control, negative control (NC), si-GAS5 and si-GAS5+ miR-21 inhibitor groups. The quantitative real-time polymerase chain reaction (qRT-PCR) was used to test the expressions of miR-21 and GAS5 at 48 h after transfection. The binding site of GAS5 and miR-21 was determined by luciferase reporter array. Cell proliferation ability was detected by CCK-8 assay. Cell colony ability was detected by colony formation assay. Cell invasion and migration abilities were detected by Transwell assay. Cell cycle and apoptosis were examined by flow cytometer (FCM). The protein levels of EMT associated factors including Snail, N-cadherin, vimentin, E-cadherin, stem cell related factors including CD44, SOX2, Oct2, and PTEN/Akt signal pathway associated factors were examined by western blotting. Results: The expression levels of miR-21 in blank, NC, si-GAS5 group were 1.00±0.10, 1.00±0.10, 1.80±0.20, the absorbance values were 0.51±0.02, 0.50±0.01 and 0.65±0.01, the cell clones were 90±4, 91±5, 200±8, the invaded cells were 118±3, 119±3, 150±4, the migrated cells were 110±2, 108±2, 127±2, the cell ratios in G(1) phase were (49.3±2.1)%, (50.1±2.0)% and (42.2±1.1)%, the cell ratios in S phase were (19.2±1.2)%, (20.2±1.1)% and (28.3±2.2)%, the cell apoptotic ratios were (14.4±2.2)%, (14.5±2.1)% and (7.2±1.3)%. These results indicated that inhibition of GAS5 up regulated the expression level of miR-21, promoted cell proliferation, invasion and migration, decreased G(1)-phase cells and increased S-phase cells, and suppressed cell apoptosis (P<0.05). Moreover, inhibition of GAS5 up regulated the expressions of Snail, N-cadherin, vimentin, Sox2, CD44, Oct2 and p-Akt in HCT-116 cells (P<0.05), while down regulated the expressions of E-cadherin and PTEN (P<0.05). Inhibition of miR-21 reversed the impact of GAS5 knockdown on PTEN/Akt signaling pathway (P<0.05). Conclusion: GAS5 can act as a competing endogenous RNA for miR-21, and down regulation of GAS5 can promote the development of CRC by activating the miR-21/PTEN/Akt signaling pathway and promoting the acquisition of EMT and tumor cell stemness.