Prognostic significance of BRCA1-associated protein 1 in colorectal cancer

Mutations of BRCA1-associated protein 1 (BAP1), a nuclear-localized deubiquitinating enzyme, had been documented in multiple human cancers. However, its role and clinical relevance in colorectal cancer is unknown. The purpose of this study was to reveal the prognostic significance of BAP1 in colorectal cancer. We performed quantitative PCR and Western blotting analyses to examine BAP1 expression in 8 cases of CRC tissues and matched adjacent non-cancerous tissues. And immunohistochemistry was used to evaluate BAP1 expression in archived 252 paraffin-embedded CRC specimens. We found that the mRNA and protein levels of BAP1 were down-regulated in 6 out of 8 cases of CRC tissues compared with their adjacent non-cancerous tissues. The BAP1 expression was closely correlated with age (p = 0.037), clinical stage (p = 0.001), T classification (p < 0.001), N classification (p < 0.001), and pathologic differentiation (p = 0.008) and histological type (p = 0.047) in CRC. The CRC patients with lower BAP1 expression survived shorter than those with higher BAP1 expression. Importantly, multi-variate analysis demonstrated that BAP1 expression was an independent prognostic factor for CRC (p = 0.037). Collectively, we provide the first evidence that reduced BAP1 expression is associated with poor prognosis of CRC and BAP1 may serve as a novel prognostic biomarker for CRC.