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The breast and ovarian cancer susceptibility gene BRCA1 encodes a tumor suppressor. BRCA1 protein, which is involved in DNA damage response , has been thought to be found primarily in cell nuclei. In the present investigation , immunohistological studies of BRCA1 protein in frozen breast cancer tissue and MCF7 and HeLa cell lines revealed BRCA1 expression in both nucleoli and nucleoplasmic foci. The majority of known cancer-causing BRCA1 mutations induce protein truncation, highlighting a requirement for the BRCA1 C-terminal domain repeats in mediating BRCA1 tumor suppressor function. However, somatic mutations in BRCA1 have not been found in sporadic breast cancer tumor tissue. 5 Instead it is thought that BRCA1 participates in the tumorigenesis of sporadic breast cancer through reduction in BRCA1 mRNA and protein levels, as compared with normal tissue. -10Functionally, BRCA1 participates in many signaling pathways involved in transcription and checkpoint control, and is recruited for the formation of DNA repair complexes, in association with proteins such as Mre11-Nbs1-Rad50, and BRCA2.11 Cell cycle studies have shown that BRCA1 protein is found in nuclear foci (dots) during S-phase, and after ␥-irradiation BRCA1 colocalizes with BRCA1-associated ring domain and Rad51-containing foci. 12Our immunohistological studies of frozen tissue sections from breast carcinomas and transmission electron microscopic studies of estrogen-stimulated MCF7 cells have shown nuclear, nucleolar, and cytoplasmic BRCA1 protein staining. 13,14 With transmission electron microscopy, we found the BRCA1 nuclear staining on the periphery of dots, around nucleoli, and also in the cytoplasm in

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BackgroundThe breast and ovarian cancer susceptibility gene (BRCA1) encodes a tumor suppressor. The BRCA1 protein is found primarily in cell nuclei and plays an important role in the DNA damage response and transcriptional regulation. Deficiencies in DNA repair capabilities have been associated with higher histopathological grade and worse prognosis in breast cancer.MethodsIn order to investigate the subcellular distribution of BRCA1 in tumor tissue we randomly selected 22 breast carcinomas and tested BRCA1 protein localization in frozen and contiguous formalin-fixed, paraffin embedded (FFPE) tissue, using pressure cooker antigen-retrieval and the MS110 antibody staining. To assess the impact of BRCA1 germline mutations on protein localization, we retrospectively tested 16 of the tumor specimens to determine whether they contained the common Ashkenazi Jewish founder mutations in BRCA1 (185delAG, 5382insC), and BRCA2 (6174delT). We also compared co-localization of BRCA1 and nucleolin in MCF7 cells (wild type) and a mutant BRCA1 cell line, HCC1937 (5382insC).ResultsIn FFPE tissue, with MS110 antibody staining, we frequently found reduced BRCA1 nuclear staining in breast tumor tissue compared to normal tissue, and less BRCA1 staining with higher histological grade in the tumors. However, in the frozen sections, BRCA1 antibody staining showed punctate, intra-nuclear granules in varying numbers of tumor, lactating, and normal cells. Two mutation carriers were identified and were confirmed by gene sequencing. We have also compared co-localization of BRCA1 and nucleolin in MCF7 cells (wild type) and a mutant BRCA1 cell line, HCC1937 (5382insC) and found altered sub-nuclear and nucleolar localization patterns consistent with a functional impact of the mutation on protein localization.ConclusionsThe data presented here support a role for BRCA1 in the pathogenesis of sporadic and inherited breast cancers. The use of well-characterized reagents may lead to further insights into the function of BRCA1 and possibly the further development of targeted therapeutics.

The human parvovirus adeno-associated virus (AAV), type 2, has a number of features that make it an attractive choice as a vector for gene delivery to the kidney. AAV vectors permit long-term gene expression in vivo by integration into the host genome, have potential for site-specific integration on chromosome 19, do not express viral genes or generate a cellular immune response, and demonstrate enhancement of gene expression by chemotherapeutic agents that are approved for use in vivo. These properties confer advantages to AAV over other viral and nonviral methods for gene transfer. Preliminary experiments in our laboratory suggest that AAV is able to transfer genes to both renal cells in culture and the kidney in vivo. Thus, AAV has the potential to be an important gene transfer vector for the kidney in vivo.

Abstract. There has been an increasing interest recently in the possibility of treating renal diseases using gene therapy. The ability to pursue gene therapy for renal diseases has been limited by the availability of an adequate system for gene delivery to the kidney. Adeno-associated virus (AAV) is a defective virus of the parvovirus family that has a number of properties attractive for renal gene delivery: recombinant AAV contains no viral genes; expression of genes delivered by these vectors does not activate cell-mediated immunity; the virus is able to transduce nondividing as well as dividing cells; and both wild-type and recombinant AAV integrate into the host chromosome resulting in long-term gene expression. Studies were performed to determine whether AAV can deliver reporter genes to kidney cells in vitro and in vivo. These studies show that AAV can deliver reporter genes with approximately equal efficiency to human mesangial, proximal tubule, thick ascending limb, collecting tubule, and renal cell carcinoma cells in primary culture. Immortalized mouse mesangial cells are transduced at a much greater efficiency. Transduction can be enhanced by pharmaceutical agents up to sevenfold in primary cells (transducing up to 20% of primary cells per well) and as much as 400-fold in immortalized mesangial cells. AAV delivered in vivo by intraparenchymal injection results in at least 3 mo of reporter gene expression in tubular epithelial, but not glomerular or vascular, cells at the injection site. These data indicate that AAV can deliver genes to renal cells both in vitro and in vivo resulting in prolonged gene expression, and thus AAV can be a useful tool for renal gene delivery.