High expression of Jun activation domain-binding protein 1 (Jab1) is a strong prognostic marker in oral squamous cell carcinoma patients treated by UFT in combination with radiation.

Low expression of p27Kip1 is associated with disease progression and an unfavorable outcome in several malignancies, including oral squamous cell carcinoma (OSCC). In addition, the p27Kip1 protein is thought to be degraded by the Jun activation domain-binding protein 1 (Jab1). The purpose of this study was to examine whether Jab1 expression can be a useful prognostic factor in OSCC patients treated by 1 M Tegafur and 4 M uracil (UFT) in combination with radiation. Jab1 expression was investigated by immunohistochemistry in biopsy samples from 102 OSCC patients who were treated by UFT in combination with radiation. The associations of each expression with the clinicopathological characteristics and patient survival were also analyzed. A significant association was found between Jab1 expression and cervical lymph node metastasis (p=0.0004), stage of disease (p=0.0011), therapeutic effect (p=0.0133) and patient outcome (p=0.0095). The 5-year survival rates of Jab1 high- and low-expression tumors were 53.0% and 80.6%, respectively and this difference was significant (p=0.0053) by the log-rank test. Multivariate analysis revealed that reduced term survival was related to high levels of Jab1 expression (p=0.0082). These results suggest that Jab1 may be a useful prognostic factor in OSCC patients treated by UFT in combination with radiation.