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 the circDENND4C/miR-200b/matrix metalloproteinase-9 (MMP-9) regulatory axis in NSCLC remains largely unknown.Methods: NSCLC cell lines were used to examine the expression of circDENND4C, miR-200b, and MMP-9 via qRT-PCR or Western blot. The target relationship of circDENND4C, miR-200b, and MMP-9 was examined by RNA fluorescence in situ hybridization (RNA-FISH), immunofluorescence (IF), dual-luciferase reporter system, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot. Then, a cell count kit-8 (CCK-8) 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: circDENND4C and MMP-9 were found to be highly expressed in NSCLC cell lines, while miR-200b was 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 the upregulation of miR-200b repressed cell proliferation and cell cycle progression, increased cell apoptosis, and hindered cell migration and invasion. Finally, it was also found that the circDENND4C/miR-200b/MMP-9 regulatory axis might be involved with cell adhesion and tight junction to influence tumor metastasis.Conclusions: Altogether, our study reveals a novel regulatory loop in which the circDENND4C/miR-200b/MMP-9 axis may modulate NSCLC progression, indicating potential biomarkers for the diagnosis or treatment of NSCLC.

We aimed to demonstrate whether coxsackievirus A10 (CV-A10) perturbed the fusion between autophagosomes and lysosomes to cause viral nonlytic spread and inflammatory cytokine release at the blood-brain barrier (BBB), thereby contributing to neuropathological damage. CV-A10-induced autophagic secretory pathway at the cellular level was examined using western blot, immunofluorescence, and flow cytometry methods. Then, the mechanism of autophagic secretory pathway in the neuropathogenesis of CV-A10 infection was demonstrated by constructing a suckling mouse model and combining behavioral, pathological, and molecular biological methods. The expression levels of autophagic secretory pathway-related proteins, extracellular inflammatory cytokines, and viral particles were significantly increased during CV-A10 infection. Moreover, 3-methyladenine significantly impeded the levels of autophagic secretory pathway-related proteins and the release of inflammatory cytokines or viruses; GW4869 and chloroquine partially suppressed these changes, whereas bafilomycin A1 had no obvious effects on these changes, implying that the autophagic secretory pathway without endosome or lysosome involvement might represent a new mode of inflammatory cytokine release and virus spread from intracellular to extracellular environments. Finally, an in vivo suckling mouse model further found that treatment with GW4869 significantly relieved the clinical symptoms and mortality of CV-A16-infected mice and inhibited the spread of the virus and the release of inflammatory cytokines. Our findings provide the first evidence that CV-A10 might trigger the autophagic secretory pathway by limiting autophagosome-lysosome fusion to complete the transmembrane nonlytic transmission of the virus at the BBB and the secretion of inflammatory cytokines, ultimately accelerating neuropathological damage. IMPORTANCE: This study provided the first evidence that coxsackievirus A10 (CV-A10) might use the autophagic secretory pathway for nonlytic intercellular release to complete transmembrane transmission at the blood-brain barrier and inflammatory cytokine secretion to accelerate the formation of neuroinflammation in infected hosts, which not only gave us a new understanding of the neuropathogenesis caused by CV-A10 but also offered a promising target to develop CV-A10 antiviral drugs.

• Please read through all the templates before choosing • Pick the most relevant text template(s) from the following page and delete all others. • Edit the text as necessary, ensuring that the original incorrect text is included for the record, please see the below. • Please do not use any extra formatting when editing the templates, and only modify the red text unless absolutely necessary • Submit to Frontiers following the instructions on this page.When the original text contained incorrect information, to preserve the scientific record, please include that text when editing the below templates. For example:There was a mistake in the Funding statement, an incorrect number was used. The correct number is '2015C03Bd051'. The publisher apologizes for this mistake.The original version of this article has been updated. In the published article, there was an error in [Fig. 5 The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated.Commons CC-BY licence and permission must be obtained for use of copyrighted material from other sources (including re-published/adapted/modified/partial figures and images from the internet). It is the responsibility of the authors to acquire the licenses, to follow any citation instructions requested by third-party rights holders, and cover any supplementary charges.