Effects of long non-coding RNA MALAT1 on the proliferation，migration，and invasion of gastric cancer through regulating the miR-22/snail axis

Abstract:

Objective：To investigate the effects of long non-coding RNA MALAT1 on the proliferation，migration，and invasion of gas－tric cancer through regulating the miR-22/snail axis. Methods：The expression of MALAT1 was inhibited by siRNA technology，and miR-22 and snail were overexpressed；real-time PCR was used to determine the expression levels of MALAT1，miR-22，and snail in gastric cancer cell lines（n=3）；Western blot was used to determine the expression level of snail protein in NC group and si-MALAT1 group（n=3）；CCK8 assay was used to determine the cell absorbance values in NC group，si-MALAT1 group，miR-22 group，miR-22+snail group，and si-MALAT1+miR-22 group at 12 h，24 h，48 h，and 72 h（n=3）；wound healing assay was used to determine the mi－gration rate in NC group，si-MALAT1 group，and miR-22 group（n= 3）；transwell assay was used to determine the number of trans－membrane cells in NC group，si-MALAT1 group，miR-22 group，miR-22+snail group，and si-MALAT1+miR-22 group（n=3）；dual luciferase assay was used to determine the fluorescence activity in NC+pMIR-MALAT1-WT group，NC+pMIR-MALAT1-MUT group，miR-22+pMIR-MALAT1-WT group，miR-22+pMIR-MALAT1-MUT group，NC+pMIR-Snail-WT group，NC+pMIR-Snail-MUT group，miR-22+pMIR-Snail-WT group，and miR-22+pMIR-Snail-MUT group（n=3）. The t-test was used for comparison between two independent samples；one-way analysis of variance was used for comparison between multiple sets of data，and repeated measures analysis of variance was used for time-associated fac－tors. Results：The expression level of MALAT1 in gastric cancer cell lines was significantly higher than that in normal gastric mucosal epithelial cells（all P=0.000）；after underexpression of MALAT1，AGS and SGC-7901 had significantly decreased prolifer－ative ability，migration ability，and invasion ability（P1=0.001，0.018，and 0.024，respectively；P2=0.005，0.007，and 0.015，respectively）；meanwhile，the dual luciferase assay results showed that MALAT1 could targetedly bind to miR-22，and miR-22 could targetedly bind to snail（both P=0.001）. The expression level of miR-22 in gastric cancer cells was significantly lower than that in normal gastric mucosal epithelial cells（P<0.05）；after overexpression of miR-22，AGS and SGC-7901 had significantly decreased proliferative ability，migration ability，and invasive ability（P1=0.004，0.034，and 0.037，respectively；P2=0.009，0.005，and 0.011，respectively）. Concomi－tant underexpression of MALAT1 and overexpression of miR-22 could further enhance the inhibitory effect on the proliferation and invasion of AGS and SGC-7901 after underexpression of MALAT1（P1=0.022 and 0.024，respectively；P2=0.006 and 0.015，respectively）；concomitant overexpression of miR-22 and snail could reverse the inhibitory effect of miR-22 on the proliferation and invasion of AGS and SGC-7901（P1=0.003，and 0.015，respectively；P2=0.004 and 0.01，respectively）. Conclusion：There is significantly overex－pressed MALAT1 in gastric cancer cells，which can facilitate the proliferation，migration，and invasion of gastric cancer by regulating the miR-22/snail axis.