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OBJECTIVE The aim of this study was to explore the regulatory effects of micro ribonucleic acid (miR)-376b-3p on proliferation and apoptosis of non-small cell lung cancer (NSCLC) cells by targeting Kruppel-like factor 15 (KLF15) and its mechanism of action. PATIENTS AND METHODS The expression of miR-376b-3p in NSCLC and para-carcinoma normal tissues, as well as NSCLC cell lines, was detected via quantitative Polymerase Chain Reaction (qPCR). The effects of miR-548-3p on the proliferation, cycle distribution, and apoptosis of NSCLC cells were detected via colony formation assay, flow cytometry, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay, respectively. The interaction between miR-376b-3p and KLF15 was determined using Dual-Luciferase reporter gene assay. In vivo tumorigenic ability of NSCLC cells was studied using nude mouse tumorigenicity assay. Furthermore, the expression of Ki67 in tumor in nude mice was detected via immunohistochemistry. RESULTS The expression of miR-376b-3p was significantly downregulated in NSCLC tissues when compared with para-carcinoma normal tissues (p<0.05). MiR-376b-3p was lowly expressed in NSCLC cells as well (p<0.05). After overexpression of miR-376b-3p, the proliferation ability of NSCLC cells remarkably declined (p<0.05). The apoptosis rate rose, and cell cycle was arrested in the G1/G0 phase. Dual-Luciferase reporter gene assay confirmed that miR-376b-3p could specifically bind to KLF15 3'UTR to regulate the expression activity of KLF15. After overexpression of miR-376b-3p, tumor volume and weight were significantly reduced in tumor-bearing mice (p<0.05). CONCLUSIONS MiR-376b-3p plays an important role in the occurrence and development of NSCLC, which affects the proliferation and apoptosis of NSCLC cells by targeting KLF15.