FN1 Promotes Thyroid Carcinoma Cell Proliferation and Metastasis by Activating the NF-b Pathway

Background: Thyroid cancer (THCA) is a common endocrine tumor. This study aims to identify the THCA-related key gene Fibronectin 1 (FN1) by bioinformatics methods and explore its function and regulatory mechanism. Methods: Gene Expression Omnibus database (GSE3678, GSE33630, and GSE53157 datasets) was searched for the analysis of differentially expressed genes (DEGs) in THCA tissues v.s. (normal tissues). The enrichment of DEGs was investigated by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways using the DAVID database. Screening the hub gene was performed with the STRING database and Cytoscape software. The expression and survival analyses of these hub genes in THCA were studied with the Gene Expression Profiling Interactive Analysis database. LinkedOmics database was searched for the related signaling pathways regulated by FN1 in THCA. Real-time quantitative reverse transcriptase polymerase chain reaction was adopted to detect the mRNA expression of Fibromodulin, microfibril-associated protein 4, Osteoglycin, and FN1. The cell viability, growth, migration and aggressiveness were examined by Cell counting kit-8, 5-Ethynyl-2 ′- deoxyuridine assay, scratch assay, and Transwell assay. The expression levels of NF-ΚB signaling pathway-related proteins (p-IΚB-α, p-IKK-β, NF-ΚB p65) were detected by Western blot. Results: FN1 mRNA was up-regulated in THCA tissues and cell lines (MDA-T85 and MDA-T41). The high expression of FN1 is relevant to larger tumor diameters and lymph node metastasis in sufferers with THCA. Functional experiments showed that overexpression of FN1 in the MDA-T85 cell line promoted growth, migration and aggressiveness; knockdown of FN1 in MDA-T41 cells inhibited these malignant behaviors. In mechanism, FN1 promoted the expression levels of proteins related with NF-ΚB signaling pathway and activated NF-ΚB signaling pathway. Conclusion: FN1 is up-regulated in THCA and facilitates cell growth, migration and invasion by activating the NF-ΚB signaling pathway. FN1 will be a promising biomarker of THCA and may become a molecular target for THCA treatment.