Overexpression of TEAD4 correlates with poor prognosis of glioma and promotes cell invasion

Abstract

This study aimed to reveal the correlation of increased TEA domain transcription factor 4 (TEAD4) expression and disease prognosis in glioma. The expression data of TEAD4 mRNA in glioma were collected from GEO database (GSE4290), and the expression of TEAD4 protein in glioma was confirmed using western blot and Immunohistochemistry. Kaplan-Meier analysis with the log-rank test was used to reveal the correlation of TEAD4 expression level and patients' survival. The effects of TEAD4 on migration and invasion were separately examined by Transwell assay and Boyden assay. Gene set enrichment analysis (GSEA) was performed to predict the possible biological function of TEAD4 in glioma. The results showed that TEAD4 mRNA and protein expression were upregulated in glioma tissues compared to normal brain tissues. Furthermore, overexpression of TEAD4 correlated with poor prognosis in glioma patients. Knockdown of TEAD4 markedly inhibited glioma cells migration and invasion in vitro. Consistent with the result that TEAD4 was associated with epithelial-mesenchymal transition (EMT) closely by GESA, knockdown of TEAD4 resulted in N-cadherin, vimentin and Slug downregulated but E-cadherin upregulated. Our study indicated that overexpression of TEAD4 may represent as a potential unfavorable marker for poor survival and prognosis in glioma. Knockdown of TEAD4 led to suppressed glioma migration and invasion.

Keywords: EMT; TEAD4; glioma; invasion; migration; prognosis.

Figure 1

TEAD4 mRNA expression in glioma and normal brain tissues. Scatter plots showed that expression of TEAD4 mRNA was significantly increased in high-grade gliomas (WHO grade III+IV, grade IV, n=76; grade III, n=32) compared with normal brain (NB) tissues (n=23) (P<0.0001), but the expression in low-grade gliomas (WHO grade I+II, n=45) compared with NB tissues was not increased (P=0.1496).

Figure 2

TEAD4 protein expression in glioma and normal brain tissues. A. The expression of TEAD4 was evaluated in 20 glioma tissues compared with 6 normal brain tissues by western blot. The unpaired t test was used for this assay (P=0.002). B. The expression and location of TEAD4 were examined by immunohistochemical staining. a. Weak staining of TEAD4 in normal tissues. b. Strong staining of TEAD4 in normal tissues. c. Weak staining of TEAD4 in glioma tissues. d. Strong staining of TEAD4 in glioma tissues. Original magnification 400×.

Figure 3

Overall survival and progression-free survival analysis for glioma patients according to TEAD4 expression levels (low and high). A. Comparison of progression free survival (PFS) of glioma patients with higher (n=169) and lower (n=103) expression of TEAD4 in TCGA databases (P<0.0001). B. Comparison of overall survival (OS) of glioma patients with higher (n=326) and lower (n=319) expression of TEAD4 in TCGA databases (P<0.0001). C. Comparison of overall survival (OS) of glioma patients with higher (n=156) and lower (n=154) expression of TEAD4 in CCGA databases. D. Comparison of overall survival (OS) of glioma patients with higher (n=50) and lower (n=38) expression of TEAD4 with collected samples from Nanfang Hospital (P=0.0002).

Figure 4

Knockdown of TEAD4 reduces cell migration and invasion in vitro. A. Western blot showed protein expression levels in NC and siTEAD4 treated U87 and U251; GAPDH served as a loading control. Bar graph shows the relative expression of protein among the groups. Data were presented as mean ± SD for three independent experiments. B. Downregulation of TEAD4 reduced U87 and U251 cell migration in vitro. Data are presented as mean ± SD for three independent experiments. C. Less expression of TEAD4 reduced U87 and U251 cell invasion in vitro. Data are presented as mean ± SD for three independent experiments. *P<0.05, significant difference. Scale bars.

Figure 5

TEAD4 is involved in glioma epithelial-mesenchymal transition. A. Gene set enrichment analysis (GSEA) showed that there was a clear correlation between TEAD4 mRNA expression and the epithelial-mesenchymal transition (EMT) signature. B. Knockdown of TEAD4 enhanced the expression of E-cadherin and weakened the expression level of N-cadherin, vimentin and Slug in U87 and U251 cells. GAPDH was used as a loading control.