title: Loss of BRCA1-associated protein 1 (BAP1) expression is rare in non-small cell lung cancer.
abstract: BRCA1-associated protein 1 (BAP1) is a tumor suppressor gene involved in regulation of the cell cycle, cellular differentiation, repair of DNA damage, and apoptosis. In the distinction of malignant mesothelioma from benign mesothelial proliferations, immunohistochemical loss of BAP1, the protein expressed by the BAP1 gene, has proven highly specific for malignant mesothelioma. However, few studies have investigated the rate of BAP1 loss in tumors that commonly metastasize to the pleura. Our objective is to determine the rate of BAP1 loss in non-small cell lung cancer (NSCLC). Immunohistochemistry for BAP1 was performed using tissue microarrays containing 133 confirmed cases of NSCLC (80 of lung adenocarcinoma and 53 of squamous cell carcinoma). Cases were interpreted as showing BAP1 loss if nuclear staining was completely absent in all tumor cells and present in stromal and inflammatory cells that served as internal controls. Cases showing no BAP1 staining in the internal controls were excluded. After exclusion of 32 cases for technical reasons, only 1 case of pulmonary adenocarcinoma of 101 cases of NSCLC (69 adenocarcinoma and 32 squamous cell carcinoma; 1.0% of cases) showed BAP1 loss. We conclude that loss of BAP1 expression is a rare event in NSCLC. Therefore, BAP1 is a potentially useful addition to the immunohistochemical markers used to distinguish mesothelioma from pleural metastasis of NSCLC.
authors.affiliation: Department of Pathology, Vancouver General Hospital, Vancouver, British Columbia, Canada V5Z 1M9. Electronic address: daniel.owen@alumni.ubc.ca.
authors.forename: Daniel
authors.initials: D
authors.lastname: Owen
authors.affiliation: Department of Pathology, Abbotsford Regional Hospital and Cancer Center, Abbotsford, British Columbia, Canada V2S 0C2. Electronic address: brandon.s.sheffield@gmail.com.
authors.forename: Brandon S
authors.initials: BS
authors.lastname: Sheffield
authors.affiliation: Department of Pathology, British Columbia Cancer Agency, Vancouver, British Columbia, Canada V5Z 4E6. Electronic address: DIonescu@bccancer.bc.ca.
authors.forename: Diana
authors.initials: D
authors.lastname: Ionescu
authors.affiliation: Department of Pathology, Vancouver General Hospital, Vancouver, British Columbia, Canada V5Z 1M9. Electronic address: achurg@mail.ubc.ca.
authors.forename: Andrew
authors.initials: A
authors.lastname: Churg
mesh_terms: D000230:Adenocarcinoma / Q000737:chemistry* / Q000473:pathology / Q000601:surgery; D000077192:Adenocarcinoma of Lung; D014408:Biomarkers, Tumor / Q000032:analysis*; D001706:Biopsy; D001955:British Columbia; D002289:Carcinoma, Non-Small-Cell Lung / Q000737:chemistry* / Q000473:pathology / Q000601:surgery; D002294:Carcinoma, Squamous Cell / Q000737:chemistry* / Q000473:pathology / Q000601:surgery; D003937:Diagnosis, Differential; D015536:Down-Regulation; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000737:chemistry* / Q000473:pathology / Q000601:surgery; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D046888:Tissue Array Analysis; D025521:Tumor Suppressor Proteins / Q000032:analysis*; D043222:Ubiquitin Thiolesterase / Q000032:analysis*
chemical_list: C400134:BAP1 protein, human; D014408:Biomarkers, Tumor; D025521:Tumor Suppressor Proteins; D043222:Ubiquitin Thiolesterase
keywords: BAP1; Lung adenocarcinoma; Mesothelial hyperplasia; Mesothelioma; Non–small cell lung cancer; Pleural metastasis