LncRNA MIR9-3HG Enhances LIMK1 MRNA and Protein Levels to Contribute to the Carcinogenesis of Lung Squamous Cell Carcinoma Via Sponging MiR-138-5p and Recruiting TAF15

The aberrantly expressed long non-coding RNAs (lncRNAs) are closely correlated with the malignant progression of cancer cells. In our study, we identified lncRNA MIR9-3 host gene (MIR9-3HG) as the research target and explored its roles in lung squamous cell carcinoma (LUSC). RT-qPCR was conducted to reveal that MIR9-3HG was observably overexpressed in LUSC cells. Functional assays encompassing colony formation, 5-ethynyl-2'-deoxyuridine (EdU) staining, transwell and flow cytometry assays and western blot detecting related proteins demonstrated that MIR9-3HG depletion hampered cell proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) while accelerating cell apoptosis in LUSC. Subcellular fractionation assay were performed to demonstrate that MIR9-3HG was prominently distributed in the cytoplasm of LUSC cells. Luciferase reporter, RNA-binding protein immunoprecipitation (RIP), immunofluorescence (IF), fluorescent in situ hybridization (FISH) and RNA pull down assays were implemented to confirm that MIR9-3HG modulates LIM domain kinase 1 (LIMK1) mRNA and protein levels by sequestering microRNA-138-5p (miR-138-5p) and recruiting TATA-box binding protein associated factor 15 (TAF15) protein. Taken together, our research determined that MIR9-3HG up-regulated LIMK1 mRNA and protein levels to promote LUSC carcinogenesis, which offers a novel insight into mechanisms of LUSC.