Correlation between mitochondrial TRAP-1 expression and lymph node metastasis in colorectal cancer

Abstract

Aim: To evaluate the effect of mitochondrial tumor necrosis factor receptor-associated protein-1 (TRAP-1) on the lymph node metastasis (LNM) in Chinese colorectal cancer (CRC) patients, and develop potential LNM-associated biomarkers for CRC using quantitative real-time polymerase chain reaction (RT-PCR) analysis.

Methods: Differences in mitochondrial TRAP-1 gene expression between primary CRC with LNM (LNM CRC) and without LNM (non-LNM CRC) were assessed in 96 Chinese colorectal carcinoma samples using quantitative RT-PCR analysis, Western blotting, and confirmed with immunohistochemical assay. The relationship between clinicopathological parameters and potential diagnostic biomarkers was also examined.

Results: TRAP-1 was significantly upregulated in LNM CRC compared with non-LNM CRC, which was confirmed by RT-PCR, Western blotting and immunohistochemical assay. The expression of TRAP-1 in two different metastatic potential human colorectal cancer cell lines, LoVo and HT29, was analyzed with Western blotting. The expression level of TRAP-1 was dramatically higher in LoVo than in HT29. Overexpression of TRAP-1 was significantly associated with LNM (90.2% in LNM group vs 22% in non-LNM group, P < 0.001), the advanced tumor node metastasis stage (89.1% in LNM group vs 26.9% in non-LNM group, P < 0.001), the increased 5-year recurrence rate (82.7% in LNM group vs 22.6% in non-LNM group, P < 0.001) and the decreased 5-year overall survival rate (48.4% in LNM vs 83.2% in non-LNM group, P < 0.001). Univariate and multivariate analyses indicated that TRAP-1 expression was an independent prognostic factor for recurrence and survival of CRC patients (Hazard ratio of 2.445 in recurrence, P = 0.017; 2.867 in survival, P = 0.028).

Conclusion: Mitochondria TRAP-1 affects the lymph node metastasis in CRC, and may be a potential biomarker for LNM and a prognostic factor in CRC. Over-expression of TRAP-1 is a predictive factor for the poor outcome of colorectal cancer patients.

Keywords: Colorectal cancer; Hsp90 family; Lymph node metastasis; Mitochondria tumor necrosis factor receptor-associated protein-1; Prognosis; Quantitative real-time polymerase chain reaction analysis.

Figure 1

Confirmation of the overexpression of tumor necrosis factor receptor-associated protein-1 in colorectal cancer. A: Western blotting analysis for tumor necrosis factor receptor-associated protein-1 (TRAP-1) expression in different metastatic potential LoVo cell and HT29 cell. β-actin was used as the internal loading control. The histogram shows the relative expression levels of TRAP-1 in LoVo and HT29 cell; B: Western blotting analysis for TRAP-1 expression in non-lymph node metastasis (LNM) and LNM groups. Data represent the mean ± SE (P < 0.001, Student t test); C, D: mRNA level of TRAP-1 via quantitative real-time polymerase chain reaction. TRAP-1 was consistently increased in the LNM group compared with non-LNM group. The mRNA level was normalized to that of β-actin. Data represent the mean ± SE (P < 0.001, Student t test); E: Immunohistochemical labeling for the TRAP-1 in the CRC sample. TRAP-1 was identified in non-LNM cancer tissues (weak in middle) and strong staining in LNM cancer group (right), but was rare in normal mucosa (left).

Figure 2

Overexpression of tumor necrosis factor receptor-associated protein-1 correlated with poor prognosis in 96 colorectal cancer patients. A: Cumulative recurrence; B: Cumulative survival. The tumor necrosis factor receptor-associated protein-1 (TRAP-1)-positive vs TRAP-1-negative groups (P < 0.001, log-rank test).