Background & objective: Abnormal expression of p15 and p16 were commonly found in many kinds of primary tumors, but the possible correlation between p15 and p16 abnormalities and tongue neoplasms is still unknown. This study was designed to investigate the expression of p15 and p16 proteins and their possible correlation with clinicopathology and prognosis of tongue squamous cell carcinoma (TSCC).
Methods: The expression of p15 and p16 were detected by immunohistochemistry (ultra-sensitive SP method) and the results were analyzed quantitatively by imagine cytometry in 45 cases of TSCC and 10 cases of normal tongue tissues, thereafter, the results were analyzed with clinicopathological parameters and survival time.
Results: Both p15 and p16 proteins were expressed in squamous epithelia of the normal tongue tissues. The negative expression rates of p15 and p16 protein in TSCC were 46.7%(21/45) and 66.7%(30/45), respectively. 80%(12/15) of the p16 positive cases accompanied with p15 positive staining. However, 85.7%(18/21) of the cases with p15 deletion exhibited p16 negative expression. Most of the cases with both p15 and p16 co-deletion were found in stage III and IV (16/18). The expression rates of p15 and/or p16 in stage I, II were significantly higher than those in stage III, IV (P< 0.05), while p15 and/or p16 expression rates in node-positive groups were much lower than those in node-negative groups (P< 0.01). p15 deletion, or both p15 and p16 co-deletion group, also had a decreased 3-year survival rate (P< 0.05).
Conclusion: The expression of p15 and p16 protein are closely associated with clinical stages and cervical lymph node metastasis of TSCC. p15 deletion, or both p15 and p16 co-deletion in TSCC can also predict a poor prognosis. p15 and p16 expression can be used as parameters for evaluating clinical stages and metastatic potential as well as prognosis of TSCC.