USF1 Promotes Lung Adenocarcinoma Progression by Regulating Neurotrophin Signaling Pathway

Abstract Background: We aimed at investigation of the effect and the underlying neurotrophin signaling pathway of the upstream transcription factor 1 (USF1) in lung adenocarcinoma (LUAD).Methods: The Cancer Genome Atlas (TCGA) database was used to analyze USF1 expression data and to extract patients’ clinical records. Immunohistochemical assay and Western blotting (WB) were used to determine the expression levels of USF1 in LUAD. The neurotrophin signaling pathway was analyzed by bioinformatic analysis while the expression of all related proteins was determined by WB. In addition cellular viability, proliferation, migration and invasion potential were investigated by the CCK-8, colony formation, wound healing and transwell. Meanwhile, the effect of USF1 in LUAD progression was investigated in a mouse model. The link between USF1 and UGT1A3 (UDP Glucuronosyltransferase Family 1 Member A3) was studied by the dual-luciferase reporter assay. Results: We have detected a high expression level of USF1 in LUAD, which was associated with advanced tumor stage, nodal metastasis, and poor patient’s survival rate. The knockdown of USF1 inhibited cellular viability, proliferation, migration and invasion. Meanwhile, USF1 knockdown inhibited tumor growth in a mouse model. Besides, USF1 targeted UGT1A3, which was proven by the fact that the USF1 knockdown decreased the expression level of UGT1A3, whereas the upregulated expression of UGT1A3 increased cellular viability and proliferation. We have proved that the neurotrophin signaling pathway in LUAD was activated by USF1 and UGT1A3. The expression of the related proteins was also inhibited by the USF1 knockdown, while the overexpression of IRAK increased cancer cells’ migration and invasion potential.Conclusion: USF1 was highly expressed in LUAD and promoted LUAD progression by regulating the neurotrophin signaling pathway. These findings provide a new theoretical data that could serve as a good foundation for the treatment of LUAD.