The Role And Mechanism Of LncRNA TUG1 In The Biological Behavior Of Endometrial Carcinoma

Background:Endometrial Carcinoma(EC)is characterized as a type of epithelial malignancy that originates in the endometrium.Long non-coding RNA(LncRNA)can regulatemany types cancer including the endometrial cancer,whichisinvolved with comlex signaling pathways.Studies have shown that IncRNA TUG1 participates in the development and progression of various cancers by regulating miRNA and its target cell genes,but the IncRNA TUG1 effect on endometrial cancer have not been reported.Objective:To investigate the level of IncRNA TUG1 in the endometrial carcinoma tissues and corresponding normal tissues,and to confirm the effect of IncRNA TUG1 on the proliferation of endometrial cancer cells at the level of cells and animals.Finally,the underlying mechanism oflncRNA TUG1 on endometrial cancer is well discovered.Methods:The expression of IncRNATUG1 was detected by qPCR in 104 pairs of endometrial carcinoma tissues and their corresponding adjacent normal tissues.Theexpression of VEGFAand LncRNATUG1 in 30 endometrial cancerpatienttumor tissues were detected by qPCR assay,and their correlation between VEGFA and LncRNA TUG1 was analyzed.The expression of VEGFA,miR-299 and miR-34a-5p was detected by qPCR in tumor tissues of 30 patients with endometrial cancer,and the correlations were analyzed.In the endometrial cancer cells(HEC-1-A cells and ishikawa cells)and HEK293 cells,the expression of lncRNA-TUG1 was detected by qPCR assay.The luciferase reporter system of IncRNA TUG 1-3’ UTR and VEGFA-3’ UTR was constructed.In endometrial cancer cells(including HEC-1-A cells and ishikawa cells),the miR-299 and miR-34a effects on lncRNA TUG 1-3’ UTR and VEGFA-3’ UTR were determined by the luciferase reporter assayand qPCR assay.The IncRNA TUG1 knockdown plasmid and VEGFA luciferase reporter plasmid were co-transfection into the endometrial cancer cells(including HEC-1-A cells and ishikawa cells),and then the lncRNA TUG 1 effect on VEGFA-3’UTRwas determined by the luciferase reporter assay.CCK8 assay were carried out to investigate the lncRNA TUG1 effecton endometrial cancer cells(including HEC-1-A cells and ishikawa cells)proliferation.Subcutaneousxenografts of endometrial cancer cells(HEC-1-A cells and ishikawa cells)or lnccRNA-TUG1knockdown endometrial cancer cells(HEC-1-A cells and ishikawa cells)were performed in Nude/nude mice,and then were tumor growth wereexamined.Results:The expression of IncRNATUG1 in tumor tissues of 71 endometrial cancer patients in 104 endometrial cancer patients was significantly higher than that in the corresponding normal tissues(71/104,68.27%,P<0.05).The expression level of VEGFA was also up-regulated in the case of high expression of lncRNA-TUG1 in tumor tissues of 30 patients with endometrial cancer,and the expression levels of VEGFA and lncRNA-TUG1 were highly positive correlated(R2=0.33,P<0.05).In the 20 endometrial cancerpatienttumor tissues,there was a high negative correlation between miR-299 and VEGFA(R2=0.43,P<0.05),and there was a high negative correlation betweenmiR-34a-5p and VEGFA(R2=0.48,P<0.05).The expression level of lIncRNATUG1 is significantly higher than that in normal human HEK-293 cells.In endometrial cancer cells(HEC-1-A cells and ishikawa cells),miR-299 or miR-34a-5p can down-regulate the the miRNA level of VEGFA or lncRNA-TUG1 through acting with the 3’ UTR region of their target gene VEGFA or IncRNA-TUG1.In endometrial cancer cells(HEC-1-A cells and ishikawa cells),down-regulated lncRNA-TUG1 can significantly inhibit VEFGA Expression.LncRNA-TUG1 specifically interactwith miR-299 or miR-34a-5p,thereby playing a competitive inhibition.The viability of EC cells wassignificantly lower in lncRNA-TUG1 down-regulated cells(HEC-1-A was 21%decrease and ishikawa was 21.3%decrease,P<0.05).Finally,the growth of tumors from lncRNA-TUG1-do wnregulated xenografts were significantly inhibited compared with that of the control xenografts(330±21.6mm3 versus 466.7±38.6mm3 for HEC-1-A cells(P<0.05);and 326.7±24.9 mm3 versus 453.3±44.9 mm3 for ishikawa cells(P<0.05))Conclusion:LncRNA-TUG1 can promote VEGFA expression through the competitive inhibition of miR-299 and miR-34a-5p.In conclusion,our present study firstly revealed that lncRNA-TUG1 was upregulated in EC tissues and cell lines.LncRNA-TUG1 may improve VEGFA expression by competing for miR-299 and miR-34a-5p,subsequently mediating cell proliferation in EC.The lncRNA-TUG 1/miRNA/VEGFA network may become a candidate target for EC therapy...