Downregulation of hsa-miR-30b-3p Inhibits the Oncogenicity of Lung Adenocarcinoma by Targeting the METTL7B Gene

OBJECTIVE: Lung adenocarcinoma (LUAD) is one of the malignant tumors with the highest morbidity and mortality rates worldwide. Although surgery-based combination therapy can greatly improve the prognosis of LUAD patients, the overall outcome is still poor, and there is an urgent need to develop new and effective treatment alternatives for LUAD. The microRNA (miRNA) miR-30b-3p is a typical multifunctional miRNA that has been reported to promote the development of various malignancies. In this study, we investigated the effects of miR-30b-3p on the biological properties of LUAD and the possible mechanisms involved to provide new ideas for the development of more effective treatment options for LUAD. METHODS: Fluorescence quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure the expression of miR-30b-3p and its target METTL7B gene in tumor tissues and adjacent noncancerous lung tissues of LUAD patients and to determine their correlation. The effect of miR-30b-3p on the biological properties of LUAD was investigated, after transfection of miR-30b-3p mimics or scramble miRNA (negative control) in LUAD cells, using various approaches, including by measuring cell proliferation using CCK-8 and Edu assays, cell invasion by Transwell assay, and apoptosis and cell cycle distribution by flow cytometry. Additionally, rescue assays were performed to verify the effect of METTL7B on miR-30b-3p function. RESULTS: In LUAD patients, low expression of miR-30b-3p and high expression of METTL7B in tumor tissues were significantly and negatively correlated with those in adjacent noncancerous lung tissues of the LUAD patients. It was also found that miR-30b-3p inhibits the proliferation and invasion of LUAD cells, promotes apoptosis, and changes the cell cycle distribution. METTL7B is a target gene of miR-30b-3p. METTL7B overexpression significantly reversed the biological effects of miR-30b-3p overexpression, including inhibition of cell proliferation and invasion, promotion of apoptosis, and alteration of the cell cycle distribution. CONCLUSIONS: The miR-30b-3p alters the biology of LUAD by negatively regulating METTL7B expression, indicating the importance of the miR-30b-3p/METTL7B pathway in the development of LUAD.