Objective:To investigate the role of Linc00339 in the development of triple-negative breast cancer and its related molecular mechanisms.Methods:The expression levels of Linc00339 in human normal breast epithelial cells and breast cancer cells were detected by real time fluorescent quantitative polymerase chain reaction (qRT-PCR). The Linc00339 was overexpressed in MDA-MB-231 cells by plasmid transfection test; the activity of MDA-MB-231 cells was detected by methyl thiazolyl tetrazolium (MTT) method; the adhesion, invasion and migration ability of MDA-MB-231 cells were detected by adhesion test and transwell test respectively; Western blot was used to detect the expression of APC and Wnt/β-catenin signaling pathway-related proteins in MDA-MB-231 cells. qRT-PCR was used to detect the expression of miRNA-135a, miRNA-135b and miRNA-138 in MDA-MB-231 cells. MDA-MB-231 cells were successfully transfected into nude mice to establish tumor-bearing nude mice model. The volume and weight of tumor were observed and measured. The expression levels of APC, Wnt/β - catenin signaling pathway related proteins were detected by Western blot, and the expression levels of miRNA-135a, miRNA-135b and miRNA-138 were detected by qRT-PCR.Results:Compared with the normal breast epithelial cell group (Hs578Bst), the expression level of Linc00339 in breast cancer cell lines (MCF-7, MDA-MB-468, MDA-MB-231) was significantly up-regulated, especially MDA-MB-231. The results of transfection experiments showed that the expression level of Linc00339 and cell viability were significantly up-regulated in the Linc00339 group compared with the pcDNA3.1 group. The overexpression of Linc00339 significantly increased the proliferation, adhesion and migration and invasion ability of MDA-MB-231 cells, as well as increased the volume and weight of tumor mass in tumor-bearing nude mice. Western blot results showed that Linc00339 overexpression can down-regulate APC protein expression and up-regulate Wnt/β-catenin signaling protein expression. Meanwhile, qRT-PCR results indicated Linc00339 overexpression can up-regulate miRNA-135b expression levels without affecting miRNA-135a and miRNA-138.Conclusions:This study demonstrated that Linc00339 may promote the development and progression of triple-negative breast cancer via the miR-135b/APC-mediated Wnt/β-catenin signaling pathway.

Objective: To explore the mechanism of llinc00052 regulating Wnt pathway affecting invasion and metastasis of gastric cancer. Methods: SGC-7901 cells were selected from gastric cancer cell lines, and siRNAs related to INC0005 and had invasion and metastasis effects in gastric cancer cells were screened by binding of IncRNA expression profiles to qRT-PCR.Ilinc00052 and miRNA expression changes were studied by in vitro cell transfection experiments.Through molecular experiments, the expression of llinc00052 and the effect on Wnt/β-catenin expression were investigated to explore whether llinc00052 could affect the invasion and metastasis of gastric cancer cells by regulating miRNAs affecting Wnt/β-catenin signaling pathway. Results: Transwell chamber test showed that the number of transmembrane cells in the untransfected plasmid group was (134.10±4.29), and the number of transmembrane cells in the overexpressed llinc000522 plasmid group was (169.24±6.99)(t=8.956, P=0.001). The scratch test showed that the migration distance in the llinc000522 overexpression transfection plasmid group was significantly higher than that in the no-load plasmid transfection group(r=0.907, P<0.01). The clone formation rate of llinc000522 overexpressed transfected plasmid group was significantly higher than that of the empty plasmid group[(92.75±6.32)% vs.(73.34±9.14)%](t=5.998, P<0.05). Compared with the transfection of blank plasmid, the expressions of Wnt1, Wnt3a, Wnt2 and β-catenin mRNA in the llinc000522 overexpression transfection group were significantly up-regulated(P<0.05), while the miRNA transfection group had no significant effect on the expression.The expressions of Wnt1, Wnt3a, Wnt2, and β-catenin mRNA were significantly increased [(1.82±0.11), (1.52±0.15), (1.42±0.21), (1.71±0.19)](P<0.05), but their expressions were still lower than those of the genes transfected with llinc000522 alone.Compared with the blank plasmid transfection, the expressions of Wnt1, Wnt3a, Wnt2 and β-catenin protein in the llinc000522 overexpression transfection group were significantly up-regulated(all P<0.05), while the miRNA transfection group had no significant effect on its expression.The protein expressions of Wnt1, Wnt3a, Wnt2 and β-catenin were also significantly increased[(1.53±0.09), (1.4±0.21), (1.33±0.07), (1.47±0.19)](P<0.05), but their expressions were still lower than those of the gene transfected with llinc000522 alone. Conclusion In gastric cancer cells, llinc00052 can affect the invasion and metastasis of gastric cancer by regulating the level of miRNA and affecting the Wnt/β-catenin pathway.