Differential clinical significance of COL5A1 and COL5A2 in tongue squamous cell carcinoma.

BACKGROUND: Type V collagen (COL5), in the functional heterotrimer [α1(V)2 α2(V)] isoform, participates in the malignancies of various cancers. However, its role in tongue squamous cell carcinoma (TSCC) remains unclear. MATERIALS AND METHODS: The expression levels of COL5A1 and COL5A2 polypeptide chains were examined using the tissue microarray from 245 TSCC patients with immunohistochemistry. Paired t test and Wilcoxon signed-rank test were performed for comparisons among the groups. Survival rates were estimated by using the Kaplan-Meier method and compared with log-rank tests. A Cox proportional hazards model was used to evaluate the impact of protein expression level on survival rate. RESULTS: Expression level of COL5A1 was significantly increased in tumor tissues (P < 0.001) compared to that in corresponding adjacent normal tissues. High expression level of COL5A1 was associated with advanced pathological stage (III, IV, P = 0.015) and lymph node metastasis (P = 0.005) of TSCC patients. High expression level of COL5A1 was also correlated with poor disease-specific survival (DSS, P = 0.001) and disease-free survival (DFS, P = 0.003) in TSCC patients. However, high expression level of COL5A2 was correlated with better DFS in TSCC patients (P = 0.043). Moreover, co-expression level of high (COL5A1)2 /low (COL5A2) heterotrimer was correlated with worse DSS (P = 0.004) and DFS (P = 0.004). CONCLUSION: COL5A1 is an unfavorable factor for tumorigenesis, clinicopathological outcomes, and prognosis, whereas COL5A2 is only a favorable factor for prognosis in TSCC. The co-expression of high (COL5A1)2/low (COL5A2) heterotrimer is a more potential unfavorable factor for prognosis in TSCC.

Global DNA hypomethylation is associated with the development and poor prognosis of tongue squamous cell carcinoma.

BACKGROUNDS: Oral cancer is the 4th leading cause of cancer death for males and the top cancer in young adult males in Taiwan. Tongue squamous cell carcinoma (TSCC) is a common oral cancer and generally associated with poor prognosis. Global DNA hypomethylation at the 5 position of cytosine (5mC) is a well-known epigenetic feature of cancer. Therefore, the purpose of this study was to investigate the relationship of the global 5mC content with the tumorigenesis and prognosis of patients with TSCC. METHODS: The levels of global 5mC were evaluated by immunohistochemistry using tissue microarray slides of 248 surgically resected TSCC and 202 corresponding tumor adjacent normal (TAN) tissues. RESULTS: We found that the level of 5mC in TSCC (P < 0.001) was significantly decreased as compared to TAN. Among TSCC tissues, decreased levels of 5mC were associated with female gender (P = 0.036). In addition, the global hypomethylation was associated with the poor disease-specific survival in TSCC patients (adjusted hazard ratio: 1.55, P = 0.043), especially for patients in older age group (> 50 years, P = 0.013), with moderate or poor cell differentiation (P = 0.044), early stage of disease (I-II, P = 0.046), small tumor size (T1-T2, P = 0.005), without lymph node involvement (P = 0.041), and ever received postoperative radiotherapy (P = 0.009). CONCLUSIONS: Global hypomethylation was an independent biomarker for the development and poor prognosis of TSCC.