ABSTRACT
In this paper, Scully et al. describe the nuclear localization of BRCA1 in breast and ovarian cancer cell lines. Immuno-staining with BRCA1-specific antibodies showed that endogenous BRCA1 migrates as a doublet of approximately 220 kDa and that BRCA1 localizes to discrete foci (dots) in the nucleus of all the cell lines tested, including breast cancer and ovarian cancer cell lines. This finding was in contrast to other studies, which suggested that BRCA1 was localized in the cytoplasm or secreted into the extracellular space (see related references 1-3). However, Scully et al. showed that the technique with which the cells were treated prior to staining with antibody greatly influenced the ability to accurately detect the location of BRCA1. Cytoplasmic staining of BRCA1 was only detected in alcoholic formalin-fixed cells, whereas nuclear BRCA1 signal was only apparent in cells that had been fixed in neutral-buffered formalin and exposed to microwave heating before staining. In a related publication, Wilson et al. further demonstrated that several antibodies were not BRCA1-specific and cross-reacted with p185HER2/neu, explaining the spurious finding of secreted protein.
