Radioprotective Effects of Combined Melatonin and Famotidine Treatment on Radiation Induced Apoptosis in Peripheral Blood Leukocytes of Breast Cancer Patients and Normal Individuals

There is growing evidence showing that circular RNAs (circRNAs) are crucial regulators in modulating the biological behavior of tumors. This work is aimed to probe the role of circ_0000517 in non-small cell lung cancer (NSCLC) and to elucidate its mechanism of action.

In this experimental study, the differentially expressed circRNAs in NSCLC were screened using the GEO database (GSE158695). Circ_0000517, miR-326, miR-330-5p, and MMP2 expression levels were determined by quantitative real-time polymerase chain reaction (qRT-PCR) analysis and Western blot. The proliferation, apoptosis, migration, and invasion of NSCLC cells were detected by CCK-8, flow cytometry, and transwell assays. RNA immunoprecipitation (RIP), RNA pull-down, and dual-luciferase reporter gene assays were performed to clarify the association between the circ_0000517 and miR-326/miR-330-5p.

Circ_0000517 was shown to be up-regulated in NSCLC tissues and cell lines. The up-regulation of circ_0000517 is closely associated with advanced clinical stage of cancer, lymph node metastasis, and poor prognosis in NSCLC patients. Circ_0000517 knockdown impeded the proliferation, migration, and invasion of NSCLC cells and enhanced their apoptosis. Mechanistically, circ_0000517 was demonstrated to up-regulate MMP2 expression via decoying miR-326 and miR-330-5p to facilitate the malignant biological behaviors of NSCLC cells.

This work reveals that circ_0000517 is implicated in NSCLC cell growth and metastasis through the modulation of miR-326/miR-330-5p/MMP2, providing novel insights into the role of circRNAs in NSCLC progression.