Exosome-Derived hsa_circ_0005741 Promotes Malignant Progression of Non-Small Cell Lung Cancer by Mediating the MiR-1251-5p/YAP1 Pathway

Abstract

Background: Abnormal levels of circular RNAs (circRNAs) induce tumorigenesis and metastasis in non-small cell lung cancer (NSCLC). Cancer cells-derived exosomes (exo), acting as carriers for intercellular communication, were involved in tumor progression by transporting specific circRNAs. Here, this study selected specific circRNA (hsa_circ_0005741) molecules by bioinformatics and was designed to clarify and explore the effect and mechanism of exosomal circ_0005741 on malignant behaviors of NSCLC cells. Methods: NSCLC (A549 and PG49) cells-derived exosomes (A549-exo, PG49-exo) purified from cell supernatants were characterized using western blot analysis, transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). The impact of exosomes on cell proliferation, metastasis was demonstrated by colony formation, wound healing, and transwell assays, respectively. Western blot analysis was also constructed to evidence the expression of Neural cadherin (N-cadherin), Epithelial cadherin (E-cadherin), and Yes-associated protein 1 (YAP1) after exosome treatment. Moreover, we carried out quantitative real-time PCR (RT-qPCR) to identify circ_0005741 expression in NSCLC and normal samples. Circ_0005741, miR-1251-5p, and YAP1 levels in exo-stimulated or unstimulated NSCLC cells were also measured by RT-qPCR. Binding relationships between miR-1251-5p and circ_0005741 or YAP1 were analyzed or pooled by online software, and then confirmed via dual luciferase reporter assay. Results: NSCLC cell-derived exosomes accelerated growth and metastasis of normal NSCLC cells. Importantly, exosome treatment induced cellular epithelial mesenchymal transition (EMT), as evidenced by down-regulated E-cadherin level (p < 0.001) and up-regulated N-cadherin level (p < 0.001). Circ_0005741 expression was elevated in NSCLC cell-derived exosomes (p < 0.001), tumor cells (p < 0.001) and cancer tissues (p < 0.001). Silencing of circ_0005741 demonstrated inhibitory effects on NSCLC cell biological behaviors. Mechanistically, circ_0005741 promoted YAP1-mediated cellular malignant evolution through sponging miR-1251-5p. Moreover, rescue experiments evidenced that miR-1251-5p and YAP1 were two essential participants in NSCLC, and co-culture of exosomes with NSCLC cells reversed the effects of circ_0005741 depletion. Conclusions: Our study indicated a previously unknown regulatory pathway, exosomes-delivered circ_0005741 accelerated the malignant evolution of NSCLC by miR-1251-5p/YAP1 axis.