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Open Access Highly Accessed Primary research

Localization of BRCA1 protein in breast cancer tissue and cell lines with mutations

Natalie Tulchin1*, Leonard Ornstein1, Steven Dikman1, James Strauchen1, Shabnam Jaffer1, Chandandeep Nagi1, Ira Bleiweiss1, Ruth Kornreich2, Lisa Edelmann2, Karen Brown2, Carol Bodian3, Venugopalan D Nair4, Monique Chambon5, Nicholas T Woods67 and Alvaro NA Monteiro6

Author Affiliations

1 Department of Pathology, Mount Sinai School of Medicine, 1 Gustave L. Levy Place, New York, NY 10029, USA

2 Department of Genetics, Mount Sinai School of Medicine, New York, NY, USA

3 Department of Anesthesiology, Mount Sinai School of Medicine, New York, NY, USA

4 Department of Neurology, Mount Sinai School of Medicine, New York, NY, USA

5 Faculté de Pharmacie, IBMM, Montpellier, France

6 Cancer Epidemiology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA

7 Department of Oncological Sciences, Morsani College of Medicine, University of South Florida, Tampa, FL, USA

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Cancer Cell International 2013, 13:70  doi:10.1186/1475-2867-13-70

Published: 15 July 2013

Abstract

Background

The 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.

Methods

In 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).

Results

In 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.

Conclusions

The 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.

Keywords:
Breast cancer; BRCA1 mutations; Frozen section immunohistology; Nucleolar localization