Monoclonal Antibodies Against BAP1 (BRCA1-Associated Proteins)
Wistar researchers have identified a novel protein, BAP1, which is a nuclear-localized, ubiquitin carboxyl-terminal hydrolase that binds to the wild-type RING finger domain of the Breast/Ovarian Cancer Susceptibility Gene product, BRCA1. Murine Bap1 and Brca1 are temporally and spatially co-expressed during murine breast development and remodeling, and show overlapping patterns of subnuclear distribution. BAP1 resides on human chromosome 3p21.3 and rearrangements, deletions and missense mutations of BAP1 have been found in lung carcinoma cell lines and in primary breast tumor samples. BAP1 enhances BRCA1-mediated inhibition of breast cancer cell growth and is the first nuclear-localized ubiquitin carboxy-terminal hydrolase to be identified.
Monoclonal Antibody BR64 for the Identification of BRCA1
Analysis of the underlying genetic component of breast cancer localized the heritable component of this disease to a gene, the breast cancer susceptibility gene (BRCA1), located on chromosome 17 (at q21). As expected, the BRCA1 gene is mutated in the majority of heritable breast cancers and the mutations within the coding region occur throughout the gene with little apparent clustering. The majority of these mutations lead to shortened BRCA1 gene products, thus describing the need for a marker of the amino-terminus of the protein. Wistar scientists have isolated antibodies secreted by hybridomas derived from the immunization of mice with purified polypeptide representing a 100-amino acid segment of the amino terminus of the BRCA1 gene product. Hybridomas with restricted reactivities were selected, subcloned and the secreted antibodies have been tested for anti-BRCA1 reactivity in a variety of assays. The antibody demonstrates an extreme specificity to the BRCA1 gene product by immunoprecipitation analysis. The Wistar-developed antibody described herein provides an excellent tool for the identification of both the full-length and mutated (shortened) forms of BRCA1.
Monoclonal Antibodies Against Wilms' tumor (WT1)
Scientists at The Wistar Institute have created monoclonal antibodies that react with the Wilms' tumor (WT1) protein. These antibodies can be used diagnostically in a variety of malignancies that over-express the WT1 protein. In particular, they can be used for distinguishing mesotheliomas from other tumors or nonmalignant conditions that affect the pleura. In addition, the antibodies may be used to monitor disease activity in acute leukemias.
The wt1 gene was originally identified as a candidate tumor suppressor gene by researchers investigating the causes of Wilms' tumor, a childhood kidney tumor. The gene codes for the WT1 protein, which has the structural features of a DNA-binding transcription factor. The WT1 protein has been shown to be over-expressed in a variety of tumors.
Three monoclonal antibodies have been developed, designated 6F-H2, 6F-H7, 6F-H17, and the isotype for each is IgG1.
The hybridomas producing these antibodies resulted from the fusion of spleen cells from mice immunized with a peptide comprising the N-terminal 173 amino acids of the WT1 protein and cells of the myeloma fusion partner P3x63AG8/653. This N-terminal region of the WT1 protein has little sequence homology to any other known protein. The resulting antibodies do not cross react with other transcription factors containing the zinc finger motif. Consequently, these monoclonal antibodies are more specific than either polyclonal or monoclonal antibodies to WT1 that have been produced by other researchers.