Decreased expression of BRCA1-associated protein 1 predicts unfavorable survival in gastric adenocarcinoma.

BRCA1-associated protein 1 (BAP1) has been reported as a novel tumor suppressor, while in gastric adenocarcinoma, the function of this protein was still await to be uncovered. Based on a large group of patients with gastric adenocarcinoma, our study aimed to have a further understanding about the correlation of BAP1 expression and patients' clinical outcomes. We performed quantitative PCR and Western blot to examine BAP1 expression in 38 cases of gastric adenocarcinoma samples and adjacent non-cancerous tissues. Immunochemistry was used to evaluate BAP1 expression in a large cohort of 474 paraffin-embedded specimens. The clinical and prognostic significance of BAP1 expression was statistically analyzed. Postoperative survival between groups was using Kaplan-Meier analysis. BAP1 was overexpressed in paracancerous normal mucosa compared with gastric cancer. Decreased BAP1 expression was associated with higher histologic grade (P = 0.044), tumor infiltration (P < 0.001), metastasis status (P = 0.023), and TNM stage (P < 0.001). Patients with low expression of BAP1 had shorter overall survival compared with those with high expression (P < 0.001). Patients' survival in stage N0 could be stratified by the expression of BAP1. Multivariate analysis showed that in gastric adenocarcinoma, BAP1 expressing level was an independent prognostic factor (RR = 0.575, P < 0.001). Decreased expression of BAP1 suggests pessimistic prognosis for gastric adenocarcinoma patients. Further studies are warranted.