BRCA1 protein expression and subcellular localization in primary breast cancer: Automated digital microscopy analysis of tissue microarrays

• Published in: PloS one Vol. 12; no. 9; p. e0184385
• Main Authors: Mahmoud, Abeer M, Macias, Virgilia, Al-Alem, Umaima, Deaton, Ryan J, Kadjaksy-Balla, Andre, Gann, Peter H, Rauscher, Garth H
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.09.2017; Public Library of Science (PLoS)
• Subjects: Aged; Androgen receptors; Animals; Biology and Life Sciences; BRCA1 protein; BRCA1 Protein - genetics; BRCA1 Protein - metabolism; Breast cancer; Breast Neoplasms - genetics; Breast Neoplasms - metabolism; Cancer; Care and treatment; Cell Nucleus - metabolism; Compartments; Correlation; Cross-Sectional Studies; Cytokeratin; Cytoplasm - metabolism; Dosage and administration; Electronic Data Processing; Epidermal growth factor receptors; Epithelial cells; ErbB-2 protein; Estrogens; Female; Gene mutation; Genetics; Humans; Image analysis; Image processing; Immunohistochemistry; Invasiveness; Localization; Mammary gland; Mammography; Medicine and Health Sciences; Mice; Microscopy; Microscopy - methods; Microscopy, Fluorescence; Middle Aged; Monoclonal antibodies; Mutation; Progesterone; Prognosis; Quality; Receptors; Research and Analysis Methods; Signal Processing, Computer-Assisted; Software; Staining; Tissue analysis; Tissue Array Analysis; Tissue microarrays; Tissues; Tumors; United States > US; Illinois; Chicago Illinois
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0184385

Mutations in BRCA1 are associated with familial as well as sporadic aggressive subtypes of breast cancer, but less is known about whether BRCA1 expression or subcellular localization contributes to progression in population-based settings. We examined BRCA1 expression and subcellular localization in invasive breast cancer tissues from an ethnically diverse sample of 286 patients and 36 normal breast tissue controls. Two different methods were used to label breast cancer tissues for BRCA1: (1) Dual immunofluoresent staining with BRCA1 and cytokeratin 8/18 and (2) immunohistochemical staining using the previously validated MS110 mouse monoclonal antibody. Slides were visualized and quantified using the VECTRA Automated Multispectral Image Analysis System and InForm software. BRCA1 staining was more intense in normal than in invasive breast tissue for both cytoplasmic (p<0.0001) and nuclear (p<0.01) compartments. BRCA1 nuclear to cytoplasmic ratio was higher in breast cancer cells than in normal mammary epithelial cells. Reduced BRCA1 expression was associated with high tumor grade and negative hormone receptors (estrogen receptor, progesterone receptor and Her2). On the other hand, high BRCA1 expression correlated with basal-like tumors (high CK5/6 and EGFR), and high nuclear androgen receptor staining. Lower nuclear to cytoplasmic ratio of BRCA1 correlated significantly with high Ki67 labeling index (p< 0.05) and family history of breast cancer (p = 0.001). Findings of this study indicate that alterations in BRCA1 protein expression and subcellular localization in breast cancer correlate with poor prognostic markers and aggressive tumor features. Further large-scale studies are required to assess the potential relevance of BRCA1 protein expression and localization in routine classification of breast cancer.