FOXH1 Promotes Tumor Growth and Metastasis via Regulation of Wnt/β-catenin Signaling Pathway in Lung Cancer 

Abstract

Background: Forkhead box protein H1 (FOXH1) is upregulated in a variety of cancer types but its expression patterns and specific functions in lung cancer are unclear at present. The main objective of the present study was to establish whether FOXH1 plays a role in regulation of lung cancer progression. Methods: The TCGA and Kaplan-Meier plotter dataset was analyzed for possible association between FOXH1 expressions in lung cancer tissues and patient prognosis. A549 and PC9 cells were transfected with shRNA targeting FOXH1 mRNA. The Cell Counting Kit-8 (CCK8), plate clone formation, soft agar, wound healing, transwell invasion and flow cytometry assay were performed to detect the cell proliferation, migration and invasion in lung cancer cells. Tumorigenicity was examined in mouse model system. Western blot analysis was used to detect FOXH1, Matrix metalloproteinase 2 (MMP2), Vimentin, N-cadherin, E-cadherin, Snail, Slug, p-GSK-3β, β-catenin and Cyclin D1. The β-catenin activity was measured by luciferase reporter system assay. Results: FOXH1 expression in the lung cancer was determined using the TCGA and Kaplan-Meier plotter databases. Higher expression of FOXH1 was observed in tumor tissue relative to normal tissue, which was associated with reduced overall survival. FOXH1 knockdown resulted in significant inhibition of the proliferation, the cell cycle, the migration as well as the invasion of lung cancer cells. Then, we confirmed that FOXH1 knockdown can significantly slow down tumor growth and tumor cell proliferation in vivo using the mouse model. It also significantly reduced the migration and invasion capabilities of lung cancer cells. Using Western blot analyses, we found that FOXH1 depletion inhibited the epithelial-mesenchymal transition of lung cancer cells through downregulation of the mesenchymal cell markers Snail, Slug, MMP2, N-cadherin, and Vimentin, and upregulation of the epithelial marker E-cadherin. Moreover, FOXH1 knockdown significantly downregulated β-catenin and its downstream targets, such as p-GSK-3β and cyclin D1, and also led to direct suppression of β-catenin activity, as determined by the luciferase reporter system assay. Conclusion: In conclusion, FOXH1 promotes proliferation, migration, and invasion of lung cancer cells via regulation of Wnt/β-catenin signaling. FOXH1 is a prognostic marker and a potential therapeutic target for lung cancer treatment.