Long non-coding RNA TTN-AS1 promotes breast cancer cell migration and invasion via sponging miR-140-5p

Breast cancer (BC) is one of the most common fatal cancers. Recent studies have identified the vital role of long non-coding RNAs (lncRNAs) in the development and progression of BC. In this investigation, lncRNA TTN-AS1 was studied to identify its function in the metastasis of BC. TTN-AS1 expression of tissues was detected by real-time quantitative polymerase chain reaction (RT-qPCR) in 56 BC patients. Wound healing assay and transwell assay were used to observe the biological behavior changes of BC cells through gain or loss of TTN-AS1. In addition, luciferase assays and RNA immunoprecipitation (RIP) assay were performed to discover the potential targets of TTN-AS1 in BC cells. TTN-AS1 expression level in BC samples was higher than that of adjacent tissue. Besides, the ability of cell migration and invasion of BC cells was inhibited after TTN-AS1 was silenced, while cell migration and cell invasion of BC cells were promoted after TTN-AS1 was overexpressed. In addition, miR-140-5p was upregulated after silencing of TTN-AS1 in BC cells, while miR-140-5p was downregulated after overexpression of TTN-AS1 in BC cells. Furthermore, luciferase assays and RIP assay showed that miR-140-5p was a direct target of TTN-AS1 in BC. Our study uncovered a new oncogene in BC and suggests that TTN-AS1 enhances BC cell migration and invasion via sponging miR-140-5p, which provides a novel therapeutic target for BC patients.