Fascin promotes the invasion of pituitary adenoma through partial dependence on epithelial-mesenchymal transition

Abstract

The aim of the present study was to investigate the role and potential regulatory mechanisms of fascin in the invasion and epithelial-to-mesenchymal transition of pituitary adenoma cells. A total of 30 specimens were assessed in the present study. The expression levels of fascin in the invasive pituitary adenoma group and non-invasive pituitary adenoma group were determined by immunochemistry. Fascin was downregulated via small interfering RNA in mouse pituitary AtT-20 cells. The proliferation, cell cycle and apoptosis of AtT-20 cells were assessed using Cell Counting Kit‑8 and flow cytometry. The invasion of AtT-20 cells was detected using a Transwell assay. Transmission electron microscopy was utilized to observe the ultrastructure of AtT-20 cells. Real-time quantitative PCR, Western blotting and immunofluorescence staining were utilized to detect the expression levels of fascin and EMT markers. In the present study, fascin expression and clinical characteristics were not significantly correlated in pituitary adenoma. The protein expression level of fascin in invasive pituitary adenoma was higher than that in non-invasive pituitary adenoma, as assessed by immunochemistry. Downregulation of fascin resulted in significant decreases in cell viability, proliferation and invasion, arrested the cell cycle at the G1 phase and increased apoptosis. In addition, downregulation of fascin significantly decreased the expression levels of N-cadherin, the mesenchymal cell marker vimentin and the transcription factor Twist but significantly increased the expression levels of the epithelial cell marker E-cadherin. Further experiments revealed that overexpression of E-cadherin resulted in significant decreases in cell viability, proliferation, invasion, and the expression of fascin and transcription factor Twist and also arrested the cell cycle at the G2 phase. The results of the present study suggest that suppressing the expression level of fascin could regulate the invasion, proliferation and apoptosis of pituitary tumour cells and alter the expression level of various EMT markers. The present study identified that fascin effectively promotes the invasion, proliferation and apoptosis of pituitary tumour cells partially via the EMT pathway.

Keywords: E-cadherin; Epithelial–mesenchymal transition; Fascin; N-cadherin; Pituitary adenoma; Vimentin.