Altered Gene Expression in Morphologically Normal Epithelial Cells from Heterozygous Carriers of BRCA1 or BRCA2 Mutations

Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
Cancer Prevention Research (Impact Factor: 4.44). 01/2010; 3(1):48-61. DOI: 10.1158/1940-6207.CAPR-09-0078
Source: PubMed


We hypothesized that cells bearing a single inherited "hit" in a tumor suppressor gene express an altered mRNA repertoire that may identify targets for measures that could delay or even prevent progression to carcinoma. We report here on the transcriptomes of primary breast and ovarian epithelial cells cultured from BRCA1 and BRCA2 mutation carriers and controls. Our comparison analyses identified multiple changes in gene expression, in both tissues for both mutations, which were validated independently by real-time reverse transcription-PCR analysis. Several of the differentially expressed genes had been previously proposed as cancer markers, including mammaglobin in breast cancer and serum amyloid in ovarian cancer. These findings show that heterozygosity for a mutant tumor suppressor gene can alter the expression profiles of phenotypically normal epithelial cells in a gene-specific manner; these detectable effects of "one hit" represent early molecular changes in tumorigenesis that may serve as novel biomarkers of cancer risk and as targets for chemoprevention.

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    • "Evidence lending support to the idea of carrier-phenotype expression profiling comes from several studies, including small-scale studies on BRCA1 carrier fibroblasts following exposure to ionizing radiation (IR) [38], [39]. Bellacosa et al. 2010 [40], showed that BRCA1 carriers had altered gene expression profiles in cultured primary breast and ovarian epithelial cells compared to non-carriers. Another recent study [41] showed that lymphocytes from BRCA1 mutation carriers demonstrated altered gene expression profiles following exposure to IR, which could be used as a prediction tool to identify BRCA1 mutation carriers. "
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    ABSTRACT: The assessment of BRCA1 and BRCA2 coding sequences to identify pathogenic mutations associated with inherited breast/ovarian cancer syndrome has provided a method to identify high-risk individuals, allowing them to seek preventative treatments and strategies. However, the current test is expensive, and cannot differentiate between pathogenic variants and those that may be benign. Focusing only on one of the two BRCA partners, we have developed a biological assay for haploinsufficiency of BRCA1. Using a series of EBV-transformed cell lines, we explored gene expression patterns in cells that were BRCA1 wildtype compared to those that carried (heterozygous) BRCA1 pathogenic mutations. We identified a subset of 43 genes whose combined expression pattern is a sensitive predictor of BRCA1 status. The gene set was disproportionately made up of genes involved in cellular differentiation, lending credence to the hypothesis that single copy loss of BRCA1 function may impact differentiation, rendering cells more susceptible to undergoing malignant processes.
    PLoS ONE 06/2014; 9(6):e100068. DOI:10.1371/journal.pone.0100068 · 3.23 Impact Factor
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    • "SUM149 and SUM190 cells were cultured in Ham’s F-12 media supplemented with 10% fetal bovine serum (FBS), 1 μg/ml hydrocortisone, 5 μg/ml insulin and antibiotic-antimycotic. Primary human mammary epithelial cells (HMEC) were isolated and cultured as previously described [30]. The protocol was approved by institutional review board (IRB) of Fox Chase Cancer Center (FCCC). "
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    • "As an important regulator of both DNA repair and apoptosis, the expression of this gene is critical in the development of breast cancer - demonstrated by its frequent mutation in familial breast cancers [111,112] and its downregulation in many sporadic breast tumors [113]. The loss of 50% of BRCA1 function in BRCA1 mutation carriers leads to an altered profile of gene expression, which resembles the genetic profile of BRCA1-associated hereditary carcinomas [114]. The approximately 50% decrease in BRCA1 levels we observed in response to elevated cortisol levels is therefore biologically significant. "
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