Loss of nuclear BAP1 expression is associated with poor prognosis in oral mucosal melanoma.

Oral mucosal melanoma (OMM) is an aggressive neoplasm with an extremely poor prognosis. BAP1 is a tumor suppressor that has been associated with the outcome of melanomas and other malignancies. In this study, we investigated the genetic alterations in BAP1 and the prognostic potential of BAP1 protein expression in oral mucosal melanoma. DNA sequence analysis of BAP1 from 12 OMM patient samples revealed missense mutations in the tissues from four patients. Based on immunohistochemical staining, loss of nuclear BAP1 expression was associated with poor overall survival (P < 0.001, Log-rank = 21.308) and distant metastasis (P = 0.034, OR = 0.320). Multivariate analysis showed BAP1 to be an independent prognostic factor (P = 0.027, HR = 0.479). It thus appears that loss of nuclear BAP1 expression is an independent prognostic factor of poor overall survival and associated with distant metastasis in OMM.