974 research outputs found
Reply: Reduced DNA repair in BRCA1 mutation carriers undetectable before onset of breast cancer?
DNA repair capacity as a possible biomarker of breast cancer risk in female BRCA1 mutation carriers
The BRCA1 gene product helps to maintain genomic integrity through its participation in the cellular response to DNA damage: specifically, the repair of double-stranded DNA breaks. An impaired cellular response to DNA damage is a plausible mechanism whereby BRCA1 mutation carriers are at increased risk of breast cancer. Hence, an individual's capacity to repair DNA may serve as a useful biomarker of breast cancer risk. The overall aim of the current study was to identify a biomarker of DNA repair capacity that could distinguish between BRCA1 mutation carriers and non-carriers. DNA repair capacity was assessed using three validated assays: the single-cell alkaline gel electrophoresis (comet) assay, the micronucleus test, and the enumeration of Ī³-H2AX nuclear foci. DNA repair capacity of peripheral blood lymphocytes from 25 cancer-free female heterozygous BRCA1 mutation carriers and 25 non-carrier controls was assessed at baseline and following cell exposure to Ī³ ā irradiation (2āGy). We found no significant differences in the mean tail moment, in the number of micronuclei or in the number of Ī³-H2AX nuclear foci between the carriers and non-carriers at baseline, and following Ī³-irradiation. These data suggest that these assays are not likely to be useful in the identification of women at a high risk for breast cancer
Oral contraceptive use and ovarian cancer risk among carriers of BRCA1 or BRCA2 mutations
Women with mutations of the genes BRCA1 or BRCA2 are at increased risk of ovarian cancer. Oral contraceptives protect against ovarian cancer in general, but it is not known whether they protect against the disease in carriers of these mutations. We obtained self-reported lifetime histories of oral contraceptive use from 451 women who carried mutations of BRCA1 or BRCA2. We used conditional logistic regression to estimate the odds ratios associated with oral contraceptive use, comparing the histories of 147 women with ovarian cancer (cases) to those of 304 women without ovarian cancer (controls) who were matched to cases on year of birth, country of residence and gene (BRCA1 vs BRCA2). Reference ages for controls had to exceed the ages at diagnosis of their matched cases. After adjusting for parity, the odds-ratio for ovarian cancer associated with use of oral contraceptives for at least 1 year was 0.85 (95 percent confidence interval, 0.53-1.36). The risk decreased by 5% (1-9%) with each year of use (P for trend=0.01). Use for 6 or more years was associated with an odds-ratio of 0.62 (0.35-1.09). These data support the hypothesis that long-term oral contraceptive use reduces the risk of ovarian cancer among women who carry mutations of BRCA1 or BRCA2
Prevalence of BRCA1 and BRCA2 mutations in unselected breast cancer patients from Greece
<p>Abstract</p> <p>Background</p> <p>Inheritance of a mutation in either <it>BRCA1 </it>or <it>BRCA2 </it>accounts for approximately 5% of all breast cancer cases, but varies by country. Investigations into the contribution of <it>BRCA </it>mutations to breast cancer incidence in Greece have been, for the most part, limited by small sample sizes and by the use of cases selected for their family history of cancer. The aim of the current study was to estimate <it>BRCA </it>mutation frequencies in breast cancer patients unselected for family history.</p> <p>Methods</p> <p>To do so, we enrolled 127 unselected women with breast cancer from the Alexandra Hospital in Athens, Greece, a large public hospital in the city. Mutations in <it>BRCA1 </it>and <it>BRCA2 </it>were detected using a combination of techniques and were confirmed by direct sequencing. Two large genomic deletions were sought using mutation-specific assays. A detailed family history of cancer was obtained from each patient.</p> <p>Results</p> <p>We were able to successfully complete testing on samples from 127 women. Among these, six mutations were identified (four in <it>BRCA1 </it>and two in <it>BRCA2</it>) representing 4.7% of the total or 9.5% of cases diagnosed before age forty. None of the mutation carriers had a family history of breast or ovarian cancer. Three of the four <it>BRCA1 </it>mutations were in exon 20: two were a G5331A mutation and the third was a 3.2 kb deletion. The fourth <it>BRCA1 </it>mutation was the 3819delGTAAA in exon 11. The two <it>BRCA2 </it>mutations were in exon 11 (3782del10 and 4512insT).</p> <p>Conclusions</p> <p>The G5331A mutation in <it>BRCA1 </it>appears to be a founder mutation in the Greek population.</p
Familial risks of esophageal cancer among the Turkmen population of the Caspian littoral of Iran
In northeastern Iran, there is an area of high incidence of esophageal cancer, which is populated by residents of Turkmen ancestry. Several environmental risk factors for esophageal cancer have been proposed, but the roles of familial and genetic factors have not been studied extensively in the Turkmen population. We evaluated the importance of familial risk factors for esophageal cancer by performing a case-control study of 167 cases of esophageal squamous cell carcinoma and 200 controls of Turkmen ethnicity. Detailed family pedigrees of the cases and controls were constructed, which documented all cancers in first- and second-degree relatives. The actuarial risk of cancer was then estimated in 2,097 first-degree relatives of cases and 2,783 first-degree relatives of the controls. A hazard ratio was constructed, based on a comparison of the 2 cumulative incidence curves. The risk to age 75 of esophageal cancer in the first-degree relatives of Turkmen patients with esophageal cancer was 34% versus 14% for the first-degree relatives of the controls (hazard ratio = 2.3; p = 3 Ć 10ā»āø). Cases (9.6%) reported that their parents were related, versus 2.5% of the controls who reported this, (odds ratio = 4.1; p value = 0.006). Familial factors are important in the etiology of esophageal cancer among the Turkmen residents of Iran. The hazard ratio of 2.3 for cancer among first-degree relatives is consistent with an important contribution of heritable factors. It will be of interest to perform marker studies to establish which genes are responsible. Ā© 2006 Wiley-Liss, Inc
An ELISA-based high throughput protein truncation test for inherited breast cancer
Abstract
Introduction
Breast cancer is the most diagnosed and second leading cause of cancer deaths in the U.S. female population. An estimated 5 to 10 percent of all breast cancers are inherited, caused by mutations in the breast cancer susceptibility genes (BRCA1/2). As many as 90% of all mutations are nonsense mutations, causing a truncated polypeptide product. A popular and low cost method of mutation detection has been the protein truncation test (PTT), where target regions of BRCA1/2 are PCR amplified, transcribed/translated in a cell-free protein synthesis system and analyzed for truncated polypeptides by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and autoradiography. We previously reported a novel High Throughput Solid-Phase PTT (HTS-PTT) based on an enzyme-linked immunosorbent assay (ELISA) format that eliminates the need for radioactivity, SDS-PAGE and subjective interpretation of the results. Here, we report the next generation HTS-PTT using triple-epitope-tagged proteins and demonstrate, for the first time, its efficacy on clinical genomic DNA samples for BRCA1/2 analysis.
Methods
Segments of exons 11 of BRCA1/2 open reading frames were PCR amplified from either blood derived genomic DNA or cell line mRNA. PCR primers incorporate elements for cell-free transcription/translation and epitope tagging. Cell-free expressed nascent proteins are then antibody-captured onto the wells of a microtiter plate and the relative amount of truncated polypeptide measured using antibodies against the N- and C-terminal epitope tags in an ELISA format.
Results
100% diagnostic sensitivity and 96% specificity for truncating mutations in exons 11 of BRCA1/2 were achieved on one hundred blood-derived clinical genomic DNA samples which were previously assayed using the conventional gel based PTT. Feasibility of full gene coverage for BRCA1/2 using mRNA source material is also demonstrated.
Conclusions
Overall, the HTS-PTT provides a simple, quantitative, objective, low cost and high throughput method for analysis of truncating mutations as an alternative to gel based PTT for BRCA analysis. The technology is readily accessible to virtually any laboratory, with the only major instrumentation required being a PCR thermocycler and a basic micro-well plate reader. When compared to conventional gel based PTT, the HTS-PTT provides excellent concordance
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Rapid progression of prostate cancer in men with a BRCA2 mutation.
Men with BRCA2 mutations have been found to be at increased risk of developing prostate cancer. There is a recent report that BRCA2 carriers with prostate cancer have poorer survival than noncarrier prostate cancer patients. In this study, we compared survival of men with a BRCA2 mutation and prostate cancer with that of men with a BRCA1 mutation and prostate cancer. We obtained the age at diagnosis, age at death or current age from 182 men with prostate cancer from families with a BRCA2 mutation and from 119 men with prostate cancer from families with a BRCA1 mutation. The median survival from diagnosis was 4.0 years for men with a BRCA2 mutation vs 8.0 years for men with a BRCA1 mutation, and the difference was highly significant (P<0.01). It may be important to develop targeted chemotherapies to treat prostate cancer in men with a BRCA2 mutation
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