Effects and mechanism of stress induced phosphoprotein 1 regulates ID3 expression on invasion, migration and epithelial-mesenchymal transition in gastric cancer cells

Objective To investigate the effects and mechanism of stress induced phosphoprotein 1 (STIP1) on invasion, migration and Epithelial-mesenchymal transition through regulating the expression of ID3 in gastric cancer cells. Methods The expression levels of STIP1 and ID3 were detected by Western blotting and real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) in two cells (BGC803 and GES-1). To detect the change of expression of STIP1 and ID3, the STIP1 over-expression vector and small interfering RNA (siRNA) were transfected into gastric cancer cells. Cell proliferation was detected by cell counting kit-8 (CCK-8) assay, invasion and migration were detected by Transwell, E-cadherin and Vimentin were detected by Western blotting. Results The expression of STIP1 mRNA and protein in BGC803 cells were significantly higher than those in GES-1 (1.851±0.058 vs. 1.000±0.034, t=21.924, P=0.000; 2.033±0.107 vs. 1.000±0.031, t=16.061, P=0.004). The expression of ID3 mRNA and protein in BGC803 cells were significantly higher than those in GES-1 (1.629±0.063 vs. 1.000±0.025, t=16.074, P=0.004; 2.374±0.096 vs. 1.000±0.029, t=23.731, P=0.002). The results showed that ID3 mRNA expression was significantly higher (2.018±0.124 vs. 1.331±0.036, t=9.216, P=0.012), cell proliferation after transfected for 48 h and 72 h (t=10.062, P=0.002; t=6.466, P=0.008) were significantly increased, the number of invasion and migration cells were significantly increased (t=5.669, P=0.011; t=5.265, P=0.013), Vimentin expression was higher (t=7.410, P=0.005) and E-cadherin was lower (t=-5.821, P=0.010) by over-expression of STIP1. Knockdown of STIP1 decreased ID3 mRNA expression (0.732±0.037 vs. 1.252±0.051, t=-14.295, P=0.001), cell proliferation after transfected for 48 h and 72 h (t=-19.851, P=0.000; t=-19.222, P=0.008), the number of invasion and migration cells (t=-5.822, P=0.010; t=-4.859, P=0.017), Vimentin expression (t=-6.244, P=0.008) and increased E-cadherin expression (t=7.697, P=0.005). Conclusion STIP1 can increase cell proliferation, invasion, migration and Epithelial-mesenchymal transition through regulating the expression of ID3 in gastric cancer cells. Key words: Gastric cancer; Stress induced phosphoprotein 1; Inhibitor of DNA binding/differentiation 3; Epithelial-mesenchymal transition