BRCA1 protein products: Antibody specificity

The recent publication of Chen et al. and Jensen et al. have generated conflicting views of BRCA1 protein kinesis that must be resolved before the functional analysis of this unique protein can proceed. Jensen et al. have suggested that BRCA1 contains a granin motif and that the protein functions as...

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Bibliographic Details
Published in:	Nature genetics Vol. 13; no. 3; pp. 264 - 265
Main Authors:	Wilson, Cindy A, Payton, Marc N, Pekar, Susan K, Zhang, Ke, Pacifici, Robert E, Gudas, Jean L, Thukral, Sushil, Calzone, Frank J, Reese, David M, Slamon, Dennis I
Format:	Journal Article
Language:	English
Published:	United States 01-07-1996
Subjects:	Amino Acid Sequence Animals Antibodies Antibody Specificity BRCA1 Protein Cell Nucleus - chemistry Cross Reactions - physiology Epitopes Humans Immunoblotting Mice Molecular Sequence Data Neoplasm Proteins - analysis Neoplasm Proteins - chemistry Neoplasm Proteins - immunology Peptide Fragments - immunology Receptor, Epidermal Growth Factor - immunology Receptor, ErbB-2 - immunology Sequence Homology, Amino Acid Subcellular Fractions Transcription Factors - analysis Transcription Factors - chemistry Transcription Factors - immunology Tumor Cells, Cultured
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Summary:	The recent publication of Chen et al. and Jensen et al. have generated conflicting views of BRCA1 protein kinesis that must be resolved before the functional analysis of this unique protein can proceed. Jensen et al. have suggested that BRCA1 contains a granin motif and that the protein functions as a secreted growth inhibitor. Chen et al. have published data demonstrating that BRCA1 is a nuclear protein in normal cells whereas the protein is aberrantly localized to the cytoplasm in breast and ovarian tumour cells. This latter observation has been challenged by Scully et al. who have stated that BRCA1 is exclusively nuclear regardless of cell type. Scientists have analysed BRCA1 subcellular localization using a variety of different BRCA1 antibodies. Careful examination of the specificity of these reagents is crucial to resolving the current controversy. We examined the specificity of peptide antibodies raised against the BRCA1 C terminus and find that the commercially available C-20 antibody (Santa Cruz) raised against residues 1843-1862 cross-reacts with the human epidermal growth factor receptor (EGFR) and HER2. Given the frequency of overexpression of type I tyrosine kinase receptors in human breast and ovarian cancers the C-20 antibody should be used with great caution in the analysis of BRCA1. While investigating the expression of BRCA1 in various human malignant epithelial cell lines using the C-20 antibody, we consistently noted overexpression of a similar to 190 kD species in cells with substantial quantities of the EGFR, whereas other BRCA1 antibodies did not detect this species. This observation raised the possibility that the C-20 antibody might recognize EGFR as well as BRCA1. To evaluate this potential cross-reactivity, the C-20 specificity was examined with human EGFR overexpressed in two murine cell lines that normally produce little or no EGFR.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 SourceType-Other Sources-1 content type line 63 ObjectType-Correspondence-1 ObjectType-Commentary-2
ISSN:	1061-4036 1546-1718
DOI:	10.1038/ng0796-264