circDENND4C serves as a sponge for miR-200b to drive non-small cell lung cancer advancement by regulating MMP-9 expression

Yaming Lv ^1,2* Lan Wang ^1,2* Yunhui Zhang ^1,2 Dong Wei ^3* Yajie Hu ^1,2*

• ¹ School of Medicine, Kunming University of Science and Technology, Kunming, China
• ² The First People’s Hospital of Yunnan Province, Kunming, Yunnan Province, China
• ³ The Second Affiliated Hospital of Kunming Medical University, Kunming, Yunnan Province, China

Introduction: Lung cancer has a higher incidence and mortality rate than other cancers, especially non-small-cell lung cancer (NSCLC) accounting for 85% of the cases. The role of circDENND4C/miR-200b/MMP-9 regulatory axis in NSCLC remains largely unknown.: NSCLC cell lines were used to examined the expression of circDENND4C, miR-200b, MMP-9 via qRT-PCR or western blot. And the target relationship of circDENND4C, miR-200b, MMP-9 was examined by RNA-FISH, IF, dual-luciferase reporter system, qRT-PCR and western blot. Then, CCK8 experiment, flow cytometry, and migration/invasion assays were performed to assess the biological function of circDENND4C, miR-200b and MMP-9 by transfecting with their overexpression or knockout plasmids in A549 cells. Finally, the proteins related to cell adhesion and tight junction were further tested by western blot and IF. Results: It was found that circDENND4C and MMP-9 were highly expressed in NSCLC cell lines, while miR-200b were lowly expressed in NSCLC cell lines. Moreover, circDENND4C could sponge miR-200b to target MMP-9. Subsequently, it was observed that knockdown of circDENND4C and MMP-9, or up-regulation of miR-200b repressed cell proliferation and cell cycle progression, increased cell apoptosis, and hindered cell migration and invasion. Finally, it also found that circDENND4C/miR-200b/MMP-9 regulatory axis might be involved in cooperating cell adhesion and tight junction to influence tumor metastasis. Conclusions: Altogether, our study reveals a novel regulatory loop that circDENND4C/miR-200b/MMP-9 axis may modulate NSCLC progression, indicating potential biomarkers for the diagnosis or treatment of NSCLC.