Abstract
BACKGROUND: Abnormal microRNA expression is closely related to cancer occurrence and development. miR-365a-3p plays an oncogenic role in skin cancer, but its role in lung cancer remains unclear. In this study, we aimed to investigate its role and underlying molecular mechanisms in lung cancer. METHODS: Western blot and real-time quantitative PCR (qPCR) were used to detect the expression of miR-365a-3p in lung adenocarcinoma and lung cancer cell lines. The effects of miR-365a-3p on lung cancer cell proliferation, migration, and invasion were also explored in vitro. The potential miR-365a-3p that targets USP33 was determined by dual luciferase reporter assay and verified by qPCR and western blot analysis. miR-365a-3p acts as an oncogene by promoting lung carcinogenesis via the downregulation of the miR-365a/USP33/SLIT2/ROBO1 axis based on western blot analysis. Subcutaneous tumourigenesis further demonstrated that miR-365a-3p promotes tumour formation in vivo. RESULTS: miR-365a-3p was upregulated in lung adenocarcinoma and lung cancer cell lines. Overexpression of miR-365a-3p promoted and inhibition of miR-365a-3p suppressed the proliferation, migration, and invasion of lung cancer cells. We identified USP33 as the downstream target of miR-365a-3p and observed a negative correlation between miR-365a-3p and USP33 expression in lung adenocarcinoma patients. The miR-365/USP33/SLIT2/ROBO1 axis, a new mechanism, was reported to inhibit the invasion and metastasis of lung cancer. A nude mouse model of lung cancer further verified these findings. CONCLUSIONS: In summary, miR-365a-3p acts as an oncogene by promoting lung carcinogenesis via the downregulation of the USP33/SLIT2/ROBO1 signalling pathway, making the miR-365/USP33/SLIT2/ROBO1 axis a new mechanism of lung cancer promotion and a novel therapeutic target for predicting prognosis and response to gene therapy.