Long noncoding RNA Linc00460 promotes breast cancer progression by regulating the miR-489-5p/FGF7/AKT axis

Purpose: Evidence indicates that long noncoding RNAs (lncRNA) possess important roles in various cellular processes and that dysregulation of lncRNAs promotes tumor progression. However, the expression patterns and biological functions of many specific lncRNAs in breast cancer remain to be determined. Methods: Quantitative real-time polymerase chain reaction was performed to detect Linc00460, miR-489-5p and FGF7 expression. Protein levels were determined using Western blot. MTT and colony formation assay were used to measure cell proliferation. Transwell assays were conducted to determine cell migration and invasion. Luciferase reporter assays were carried out to assess the interaction between miR-489-5p and Linc00460 or FGF7. Biotin pull-down assay was used to detect the direct interaction between miR-489-5p and Linc00460. In vivo experiments were performed to measure tumor formation and lung metastasis. Results: We demonstrated that lncRNA Linc00460 was upregulated in breast cancer, and its expression level was positively associated with lymphatic metastasis and poor overall survival. Forced expression of Linc00460 increased, whereas Linc00460 silencing decreased, breast cancer cell viability, migration and invasion both in vitro and in vivo. Linc00460 was identified as a direct target of miR-489-5p, which further targeted FGF7 and exerted oncogenic functions in breast cancer. Mechanistically, Linc00460 served as a competing endogenous RNA of FGF-7 mRNA by sponging miR-489-5p, resulting in upregulated FGF7 expression and AKT activity. Notably, forced expression of miR-489-5p abrogated Linc00460-mediated oncogenic behavior and activation of the FGF7-AKT pathway in breast cancer cells. Conclusion: We have demonstrated that Linc00460 promotes breast cancer progression partly through the miR-489-5p/FGF7/AKT axis.