Imunoexpressão de BAP1 em ameloblastomas

Abstract

Ameloblastoma is an odontogenic tumor of epithelial origin of great clinical relevance due to its aggressive, locally invasive nature and high rate of relapse. The treatment of choice, in most cases, involves radical methods that cause morbidity and facial deformity to the patient. Its pathogenesis is still controversial, but recent studies have described the frequent presence of the BRAF V600E mutation, already described in cutaneous melanoma, uveal melanoma, oral melanoma and benign melanocytic lesions. The tumour suppressor gene BAP1 encodes the nuclear protein BRCA-1 associated protein 1 (BAP1). Loss of BAP1 nuclear expression has been reported in several human tumours. A possible combination between the BRAFV600E mutation and loss of BAP1 expression has been reported in melanocytic proliferations. Considering the high frequency of BRAFV600E in ameloblastomas, we aimed to investigate the immunoexpression of BAP1 in ameloblastomas. And, because loss of BAP1 strongly associates with poor prognosis of the tumors, the immunoexpression were associated with clinicopathological parameters of the ameloblastomas. For this a convenience sample of 33 solid and unicystic ameloblastomas were selected and submitted to immunohistochemistry for detection of BAP1. Clinicopathological data were also collected. Most tumour cases (60.6%; 20/33) exhibited a high loss of BAP1 expression, i.e. > 70% of tumour nuclei with loss of BAP1 expression. No significant association between BAP1 expression with clinical variables evaluated could be established. We detected loss of BAP1 nuclear expression in a high proportion of ameloblastoma cases, independently of the clinicopathological parameters investigated. Additional studies are warranted to better characterize if BAP1 plays a role in ameloblastomas tumorigenesis.