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Objective: To explore the effects of exosomes loaded with circular RNA PARD3 on EBV-miR-BART4-induced stemness and resistance of cisplatin in nasopharyngeal carcinoma side population (NPC-SP) cells through the miR-579-3p/SIRT1/SSRP1 axis. Methods: Sixty-five cancer tissues and 65 noncancerous tissues were collected from NPC patients or patients with rhinitis. The expressions of circPARD3, miR-579-3p, SIRT1, and SSRP1 were detected by qRT-PCR, western blot, or immunohistochemistry. In vivo tumor formation assay was performed in nude mice. Immunofluorescence and qRT-PCR were conducted for the determination of CD44 and CD133 expressions, and flow cytometry combined with Hoechst 33,342 dye efflux for identifying SP cells, CCK-8 and EdU assays for cell proliferation, and Transwell assay for migration and invasion. Results: CircPARD3, SIRT1, and SSRP1 were upregulated while miR-579-3p was downregulated in NPC tissues and cells. CircPARD3 was positively correlated with the expressions of SIRT1 and SSRP1, and miR-579-3p was negatively correlated with circPARD3, SIRT1, and SSRP1. Exosomes loaded with circPARD3 promoted EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells, while miR-579-3p reversed the effect of exosomal circPARD3 on EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells. Additionally, miR-579-3p suppressed EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells by regulating SIRT1. SIRT1 upregulated SSRP1 expression by catalyzing H3K4 methylation and down-regulation of SSRP1 reversed the effect of SIRT1 on EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells. Conclusion: Exosomes loaded with circPARD3 promoted EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells through the miR-579-3p/SIRT1/SSRP1 axis. [ABSTRACT FROM AUTHOR]

Background: Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignant tumor worldwide with high morbidity and mortality. However, the diagnosis and molecular mechanisms of HNSCC remains poor. Methods: Robust rank aggregation method was performed to excavate the differentially expressed genes (DEGs) in five datasets (GSE6631, GSE13601, GSE23036, GSE30784, GSE107591) from the Gene Expression Omnibus. Search Tool for the Retrieval of Interacting Genes (STRING) database extracted hub genes from the protein‐protein interaction network. The expression of the hub genes was validated using expression profile from The Cancer Genome Atlas and Oncomine database. The module analysis and disease‐free survival analysis of the hub genes were analyzed by Cytoscape and the Kaplan‐Meier curve, respectively. The expression of hub genes was verified in clinical specimens. The functions of MMP1 which is most important in hub genes were explored in vitro and in vivo. Results: Totally, 235 DEGs were identified in the present study which consists of 103 up‐regulated and 132 down‐regulated genes which were significantly enriched in the molecular function of calcium ion binding followed in the biological process of skin development. The mainly enriched pathways were ECM (extracellular matrix)‐receptor interaction (hsa04512) and protein digestion and absorption (hsa04974). Six hub genes were screened out which showed dramatically increased expression in HNSCC samples compared with normal samples, including COL4A1, MMP1, PLAU, RBP1, SEMA3C, and COL4A2. These hub genes all showed worse disease‐free survival with higher expression and were up‐regulated in HNSCC clinical samples. MMP1 was proved to promote cell growth, migration, and phosphorylation of AKT in vitro and to promote liver metastasis in vivo. Conclusion: Bioinformatics analysis identified six key genes in HNSCC. Of these, MMP1 is the most likely biomarker. It activates the AKT pathway and promotes tumor progression. [ABSTRACT FROM AUTHOR]

Examines the anisotropic structure and properties of interphase in carbon fiber reinforced polyetheretherketone composites. Relationship between the interfacial interaction and macroscopic mechanical properties; Role of interphasial microstructure in stress transfer; Effect of carbon fiber on matrix crystallization.