title: Functional isogenic modeling of BRCA1 alleles reveals distinct carrier phenotypes.
abstract: Clinical genetic testing of BRCA1 and BRCA2 is commonly performed to identify specific individuals at risk for breast and ovarian cancers who may benefit from prophylactic therapeutic interventions. Unfortunately, it is evident that deleterious BRCA1 alleles demonstrate variable penetrance and that many BRCA1 variants of unknown significance (VUS) exist. In order to further refine hereditary risks that may be associated with specific BRCA1 alleles, we performed gene targeting to establish an isogenic panel of immortalized human breast epithelial cells harboring eight clinically relevant BRCA1 alleles. Interestingly, BRCA1 mutations and VUS had distinct, quantifiable phenotypes relative to isogenic parental BRCA1 wild type cells and controls. Heterozygous cells with known deleterious BRCA1 mutations (185delAG, C61G and R71G) demonstrated consistent phenotypes in radiation sensitivity and genomic instability assays, but showed variability in other assays. Heterozygous BRCA1 VUS cells also demonstrated assay variability, with some VUS demonstrating phenotypes more consistent with deleterious alleles. Taken together, our data suggest that BRCA1 deleterious mutations and VUS can differ in their range of tested phenotypes, suggesting they might impart varying degrees of risk. These results demonstrate that functional isogenic modeling of BRCA1 alleles could aid in classifying BRCA1 mutations and VUS, and determining BRCA allele cancer risk.
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Rory L
authors.initials: RL
authors.lastname: Cochran
authors.affiliation: Oncology iMED, AstraZeneca, Waltham, MA, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Cidado
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Minsoo
authors.initials: M
authors.lastname: Kim
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Zabransky
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Croessmann
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: David
authors.initials: D
authors.lastname: Chu
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Hong Yuen
authors.initials: HY
authors.lastname: Wong
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Julia A
authors.initials: JA
authors.lastname: Beaver
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Cravero
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Bracha
authors.initials: B
authors.lastname: Erlanger
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Heather
authors.initials: H
authors.lastname: Parsons
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Heaphy
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Alan K
authors.initials: AK
authors.lastname: Meeker
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Josh
authors.initials: J
authors.lastname: Lauring
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.|The Whiting School of Engineering, Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Ben Ho
authors.initials: BH
authors.lastname: Park
mesh_terms: D019313:BRCA1 Protein / Q000235:genetics*; D014408:Biomarkers, Tumor / Q000235:genetics*; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle / Q000528:radiation effects; D002461:Cell Line, Transformed; D049109:Cell Proliferation / Q000528:radiation effects; D018385:Centrosome / Q000378:metabolism / Q000528:radiation effects; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020022:Genetic Predisposition to Disease; D042822:Genomic Instability; D040941:Heredity; D006579:Heterozygote; D006801:Humans; D008957:Models, Genetic; D009154:Mutation; D010641:Phenotype; D011836:Radiation Tolerance; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D014162:Transfection
chemical_list: D019313:BRCA1 Protein; C492913:BRCA1 protein, human; D014408:Biomarkers, Tumor
keywords: BRCA1; VUS; breast cancer; centrosome amplification; haploinsufficiency