Impact of Brachyury on epithelial-mesenchymal transitions and chemosensitivity in non-small cell lung cancer

Abstract

The objective of the current study was to investigate the impact of Brachyury on epithelial-mesenchymal transitions and chemosensitivity in non-small cell lung cancer (NSCLC). In 115 archived NSCLC tissue samples, the expression of Brachyury was observed to be significantly higher than that in adjacent normal lung tissues. In addition, the current study demonstrated that the expression of Brachyury is closely associated with TNM staging, lymph node metastasis and the prognosis of NSCLC, although not with patient age, gender or tumor differentiation. Brachyury expression is also accompanied by the downregulation of E-cadherin and the upregulation of N-cadherin. Brachyury may promote lung cancer through induction of epithelial-mesenchymal transition, which leads to metastasis and consequent poor prognosis in patients with lung cancer. Furthermore, the present study observed that interfering with Brachyury increases the sensitivity of cells to chemotherapeutic treatment with cisplatin. These results, in combination with those of additional studies, suggest that Brachyury may be used as a novel target for the prevention and treatment of lung cancer.

Figure 1

Immunostaining demonstrating the expression of Brachyury in non-small cell lung cancer tissues and matched adjacent non-cancerous lung tissues. Brachyury was negatively or weakly expressed in the cytoplasm of the matched adjacent non-cancerous normal lung tissue (A) and (B). In the lung cancer cells (C) and (D), Brachyury was predominantly located in the nucleus, with only a low level of cytoplasmic expression (magnification, ×200; red bar, 50 μm).

Figure 2

Association between Brachyury expression and survival time of patients with NSCLC. Kaplan-Meier curves for overall survival of 115 patients with NSCLC, stratified by Brachyury expression. A correlation between positive expression of Brachyury and poor overall survival was observed (P<0.001). NSCLC, non-small cell lung cancer.

Figure 3

Immunohistochemical analysis of the impact of Brachyury expression on E-cadherin and N-cadherin expression in lung cancer. In Brachyury-negative (A), (B) and (C) and Brachyury-positive (D), (E) and (F) lung tissues, serial sections were stained with anti-Brachyury (A) and (D), anti-E-cadherin (B) and (E) and anti-N-cadherin (C) and (F) antibodies for immunohistochemical analysis. Magnification, ×200; red bar, 50 μm.

Figure 4

Impact of Brachyury expression on cell proliferation and invasion. (A) Expression of Brachyury following knockdown with siRNA in A549 cells. (B) Cell proliferation capacity of A549 cells was reduced following Brachyury knockdown (^*P<0.05; n=3). (C) Invasive capacity of A549 cells was inhibited following transfection of Brachyury-specify siRNA. (D) At 48 h after Brachyury silencing, the average number of invasive cells was 19.17±2.89, which was significantly lower than that of the control group (63.47±2.93; P<0.05). Values are presented as the mean ± standard error of the mean. siRNA, small interfering RNA.

Figure 5

Knockdown of Brachyury increased cell sensitivity to DDP. (A) When treated with 1, 3 or 5 μg/ml DDP, the cytotoxicity of the combination treatment group was higher than that of the group treated with DDP alone (^**P<0.01). (B) Cell growth inhibition rates of the combination treatment group were significantly higher than those of the group treated with DDP alone (^**P<0.01). DDP, cisplatin; combination treatment, DDP with brachyury-specific small interfering RNA.