| Objective: To study the role and mechanism of Let-7d in the progression of gastric cancer,and to provide experimental basis for whether Let-7d can be used as a new molecular marker of gastric cancer and discover a new pathogenesis of gastric cancer.Methods:1.We searched the qualified mi RNA chip from the GEO database,then used the online analysis tool GEO2 R to analyze the differentially expressed mi RNA,and got the candidate mi RNA.The target genes of mi RNA were predicted by Target Scan,mir DB and mir DIP databases,and the Venn map was used to get the intersection.Then the final target genes were obtained by consulting the literature,and the binding sites of mi RNA and target genes were predicted by Starbase database.2.q RT-PCR was used to detect the expression of Let-7d and HMGA2 in BGC-803 cells and GES-1 cells.3.Let-7d mimic was transfected into BGC-803 cells to overexpress Let-7d,and then the expression of HMGA2 in overexpressed group and control group was detected.4.The proliferation,migration and invasion of BGC-803 cells were detected by CCK-8 experiment,Wound healing experiment and Transwell assays.Results:1.GEO database analysis showed that there were 7 differentially expressed mi RNAs: hsa-Let-7d,hsa-mi R-196a-5p,hsa-mi R-199a-5p,hsa-mi R-4636,hsa-mi R-27b-3p,hsa-mi R-125b-5p,hsa-mi R-23b-3p.After consulting the literature,hsa-Let-7d was selected as the candidate gene,and 60 target genes were obtained after Venn diagram after predicting target genes through three databases.After consulting the literature,we knew that HMGA2 plays an important role in the occurrence and development of gastric cancer.The binding sites of Let-7d and HMGA2 were analyzed by Starbase database.2.The expressions of Let-7d and HMGA2 in BGC-803 cells and GES-1cells were detected by q RT-PCR: the expression of Let-7d in BGC-803 cells was significantly lower than that in GES-1 cells(P< 0.01).The expression of HMGA2 in BGC-803 cells was significantly higher than that in GES-1 cells(P<0.05).3.Compared with the control group,the expression of HMGA2 in BGC-803 cells transfected with Let-7d mimic was significantly decreased(P< 0.01).4.The results of CCK-8 experiment showed that the OD value of control group at 48 h was 1.430±0.063,and that of overexpression group at 48 h was0.995±0.109.The proliferative activity of overexpressed group was significantly lower than that of control group at 48h(P < 0.01).5.The results of wound healing experiment showed that the scratch widths in the control group were 1.955±0.041 and 0.390±0.088 at 0h and 48 h,while those in the overexpression group were 1.992±0.058 and 1.447±0.168 at0 h and 48 h.The migration ability at 48 h in the overexpression group was significantly lower than that in the control group(P< 0.01).6.The results of Transwell assays showed that the number of cell invasion was 55.00±3.00 in the control group and 33.1±7.75 in the overexpression group at 48 h.The number of invasive cells in the overexpression group was significantly less than that in the control group at48h(P< 0.01).Conclusion:1.The expression of Let-7d was down-regulated in BGC-803 cells,while the expression of HMGA2 was up-regulated in BGC-803 cells.2.Let-7d inhibits the proliferation,migration and invasion of BGC-803 cells by down-regulating HMGA2. |
