title: Altered proliferation and differentiation properties of primary mammary epithelial cells from BRCA1 mutation carriers.
abstract: Female BRCA1 mutation carriers have a nearly 80% probability of developing breast cancer during their life-time. We hypothesized that the breast epithelium at risk in BRCA1 mutation carriers harbors mammary epithelial cells (MEC) with altered proliferation and differentiation properties. Using a three-dimensional culture technique to grow MECs ex vivo, we found that the ability to form colonies, an indication of clonality, was restricted to the aldehyde dehydrogenase 1-positive fraction in MECs but not in HCC1937 BRCA1-mutant cancer cells. Primary MECs from BRCA1 mutation carriers (n = 9) had a 28% greater ability for clonal growth compared with normal controls (n = 6; P = 0.006), and their colonies were significantly larger. Colonies in controls and BRCA1 mutation carriers stained positive for BRCA1 by immunohistochemistry, and 79% of the examined single colonies from BRCA1 carriers retained heterozygosity for BRCA1 (ROH). Colonies from BRCA1 mutation carriers frequently showed high epidermal growth factor receptor (EGFR) expression (71% EGFR positive versus 44% in controls) and were negative for estrogen receptor (ERalpha; 32% ER negative, 44% mixed, 24% ER positive versus 90% ER positive in controls). Expression of CK14 and p63 were not significantly different. Microarray studies revealed that colonies from BRCA1-mutant PMECs anticipate expression profiles found in BRCA1-related tumors, and that the EGFR pathway is up-regulated. We conclude that BRCA1 haploinsufficiency leads to an increased ability for clonal growth and proliferation in the PMECs of BRCA1 mutation carriers, possibly as a result of EGFR pathway activation. These altered growth and differentiation properties may render BRCA1-mutant PMECs vulnerable to transformation and predispose to the development of ER-negative, EGFR-positive breast cancers.
authors.affiliation: Department of Surgery, Division of Hematology/Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Laura N
authors.initials: LN
authors.lastname: Burga
authors.forename: Nadine M
authors.initials: NM
authors.lastname: Tung
authors.forename: Susan L
authors.initials: SL
authors.lastname: Troyan
authors.forename: Mihnea
authors.initials: M
authors.lastname: Bostina
authors.forename: Panagiotis A
authors.initials: PA
authors.lastname: Konstantinopoulos
authors.forename: Helena
authors.initials: H
authors.lastname: Fountzilas
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Spentzos
authors.forename: Alexander
authors.initials: A
authors.lastname: Miron
authors.forename: Yosuf A
authors.initials: YA
authors.lastname: Yassin
authors.forename: Bernard T
authors.initials: BT
authors.lastname: Lee
authors.forename: Gerburg M
authors.initials: GM
authors.lastname: Wulf
mesh_terms: D000328:Adult; D000368:Aged; D000444:Aldehyde Dehydrogenase / Q000235:genetics; D000080924:Aldehyde Dehydrogenase 1 Family; D019313:BRCA1 Protein / Q000235:genetics*; D001943:Breast Neoplasms / Q000201:enzymology / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology; D002454:Cell Differentiation / Q000235:genetics*; D002455:Cell Division / Q000235:genetics*; D066246:ErbB Receptors / Q000235:genetics; D005260:Female; D006580:Genetic Carrier Screening; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000235:genetics; D008875:Middle Aged; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D012334:RNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D012016:Reference Values; D050697:Retinal Dehydrogenase; D012307:Risk Factors; D014407:Tumor Cells, Cultured
chemical_list: D019313:BRCA1 Protein; D007527:Isoenzymes; D012334:RNA, Neoplasm; D000080924:Aldehyde Dehydrogenase 1 Family; D000444:Aldehyde Dehydrogenase; C510223:ALDH1A1 protein, human; D050697:Retinal Dehydrogenase; D066246:ErbB Receptors