Cytoplasmic expression of BAP1 as an independent prognostic biomarker for patients with gliomas

BRCA1-associated protein-1 (BAP1) has been investigated the prognostic value for some carcinomas, including mammary carcinoma, pulmonary carcinoma and mesothelioma and so on. However, the status of BAP1 expression and the relationship of that with overall survival were not still estimated in patients with gliomas. Therefore, it was necessary to investigate the effect of BAP1 expression for the survival of patients with gliomas in this study.

Clinicopathological information of 229 patients with gliomas was used to perform the further analysis. We defined the nucleus expression of BAP1 score of median 0 and cytoplasmic expression of BAP1 score of median 100 as the rational cutoff value for survival analysis, respectively. These patients were categorized into the low cytoplasmic expression of BAP1 and the high expression of BAP1 group, presence of nucleus expression and absence of nucleus expression according to the corresponding cutoff point, respectively. The associations of clinicopathological characteristics with overall survival (OS) were investigated by univariate analysis in patients with gliomas. Multivariate analysis was further performed to find the independent prognostic indicator of OS by Cox regression model.

Thirty-nine of 229 patients (17.0%) with gliomas had the nucleus expression of BAP1, 213 of 229 patients (93.0%) had the cytoplasmic expression of BAP1, and 28 patients (12.2%) with both cytoplasmic and nucleus expression, 5 cases (2.2%) without neither cytoplasmic nor nucleus expression. Univariate analysis demonstrated that high cytoplasmic expression of BAP1, tumor location, tumor relapse, advanced clinical stage were significant linkage with worse OS (P<0.05). Multivariate analysis revealed that high cytoplasmic expression of BAP1 was a significantly independent biomarker for adverse OS (hazard ratio: 1.516, 95% CI: 1.029-2.234, P=0.035). In stratified analysis, we found that the patients with high cytoplasmic expression of BAP1 had the shorter overall survival than these with low cytoplasmic expression of BAP1 in the 190 patients without nucleus expression of BAP1 (P=0.001). ROC curve analysis showed that cytoplasmic expression of BAP1 was superior to nucleus expression of BAP1 as a predictive factor in patients with gliomas (AUC=0.583, P=0.030 vs. AUC=0.516, P=0.679).

This study suggested that cytoplasmic expression of BAP1 might be served as a valuable predictive biomarker of the prognosis in gliomas. High cytoplasmic expression of BAP1 might be benefit to identify patients who need to carry out further therapy.