ABSTRACT
OBJECTIVE: To investigate the role of USP33 as an independent prognostic marker in the regulation of SLIT2/ROBO1 signaling pathway to inhibit lung adenocarcinoma invasion and metastasis. METHODS: The expression of USP33 in 20 lung adenocarcinoma specimens was detected by qPCR and immunohistochemistry. A549 and SPC-A-1 cells with small interfering RNA (siRNA)-mediated USP33 silencing were examined for changes in invasion and metastasis abilities using scratch assay and Matrigel assay. Western blotting was used to detect the expression of SLIT2 and ROBO1 in the cells after USP33 silencing and the expression of USP33 after interleukin-6 (IL-6) stimulation. RESULTS: qPCR and immunohistochemistry showed that USP33 was significantly decreased in lung adenocarcinoma tissues as compared with the adjacent tissues. USP33 silencing in A549 and SPC-A-1 cells significantly promoted the cell migration, invasion and metastasis and obviously down-regulated the expressions of SLIT2 and ROBO1. IL-6 stimulation of the cells obviously enhanced the expression of USP33. CONCLUSIONS: USP33 silencing can promote the migration, invasion and metastasis of lung adenocarcinoma cells in vitro, and the mechanism may involve IL-6 and SLIT2/ROBO1 signaling pathways.
Subject(s)
Adenocarcinoma of Lung/metabolism , Intercellular Signaling Peptides and Proteins/metabolism , Lung Neoplasms/metabolism , Neoplasm Proteins/metabolism , Nerve Tissue Proteins/metabolism , Receptors, Immunologic/metabolism , Ubiquitin Thiolesterase/metabolism , Adenocarcinoma of Lung/pathology , Cell Line, Tumor , Cell Movement , Down-Regulation , Humans , Interleukin-6/metabolism , Interleukin-6/pharmacology , Lung Neoplasms/pathology , Neoplasm Invasiveness , Roundabout ProteinsABSTRACT
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.
