Irene L. Andrulis

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.

BRCA1 and BRCA2 mutation carriers in the Breast Cancer Family Registry: an open resource for collaborative research

The Breast Cancer Family Registry is a resource for interdisciplinary and translational studies of the genetic epidemiology of breast cancer. This resource is available to researchers worldwide for collaborative studies. Herein, we report the results of testing for germline mutations in BRCA1 and BRCA2. We have tested 4,531 probands for mutations in BRCA1 and 4,084 in BRCA2. Deleterious mutations in BRCA1 and BRCA2 were identified for 9.8% of probands tested [233/4,531 (5.1%) for BRCA1 and 193/4,084 (4.7%) for BRCA2]. Of 1,385 Ashkenazi Jewish women tested for only the three founder mutations, 17.4% carried a deleterious mutation. In total, from the proband and subsequent family testing, 1,360 female mutation carriers (788 in BRCA1, 566 in BRCA2, 6 in both BRCA1 and BRCA2) have been identified. The value of the resource has been greatly enhanced by determining the germline BRCA1 and BRCA2 mutation statuses of nearly 6,000 probands.

Modification of BRCA1-associated breast and ovarian cancer risk by BRCA1-interacting genes

Inherited BRCA1 mutations confer elevated cancer risk. Recent studies have identified genes that encode proteins that interact with BRCA1 as modifiers of BRCA1-associated breast cancer. We evaluated a comprehensive set of genes that encode most known BRCA1 interactors to evaluate the role of these genes as modifiers of cancer risk. A cohort of 2,825 BRCA1 mutation carriers was used to evaluate the association of haplotypes at ATM, BRCC36, BRCC45 (BRE), BRIP1 (BACH1/FANCJ), CTIP, ABRA1 (FAM175A), MERIT40, MRE11A, NBS1, PALB2 (FANCN), RAD50, RAD51, RAP80, and TOPBP1, and was associated with time to breast and ovarian cancer diagnosis. Statistically significant false discovery rate (FDR) adjusted P values for overall association of haplotypes (P(FDR)) with breast cancer were identified at ATM (P(FDR) = 0.029), BRCC45 (P(FDR) = 0.019), BRIP1 (P(FDR) = 0.008), CTIP (P(FDR) = 0.017), MERIT40 (P(FDR) = 0.019), NBS1 (P(FDR) = 0.003), RAD50 (P(FDR) = 0.014), and TOPBP1 (P(FDR) = 0.011). Haplotypes at ABRA1 (P(FDR) = 0.007), BRCC45 (P(FDR) = 0.016 and P(FDR) = 0.005 in two haplotype blocks), and RAP80 (P(FDR) < 0.001) were associated with ovarian cancer risk. Overall, the data suggest that genomic variation at multiple loci that encode proteins that interact biologically with BRCA1 are associated with modified breast cancer and ovarian cancer risk in women who carry BRCA1 mutations.

Heteroduplex and protein truncation analysis of the BRCA1 185delAG mutation

Abstract We describe a heteroduplex analysis for the detection of the 185delAG mutation in the BRCA1 gene. The protein truncation test (PTT) has previously been used to identify many of the mutations in BRCA1 that result in premature termination of the protein. However, we were not able to detect the 185delAG mutation by PTT and suggest that heteroduplex analysis may complement PTT for analysis of BRCA1 mutations. This simple technique may be useful for studies on the prevalence and the penetrance of the 185delAG mutation.

Breast Cancer Risk for Noncarriers of Family-Specific BRCA1 and BRCA2 Mutations: Findings From the Breast Cancer Family Registry

PURPOSE Women with germline BRCA1 and BRCA2 mutations have five- to 20-fold increased risks of developing breast and ovarian cancer. A recent study claimed that women testing negative for their family-specific BRCA1 or BRCA2 mutation (noncarriers) have a five-fold increased risk of breast cancer. We estimated breast cancer risks for noncarriers by using a population-based sample of patients with breast cancer and their female first-degree relatives (FDRs). PATIENTS AND METHODS Patients were women with breast cancer and their FDRs enrolled in the population-based component of the Breast Cancer Family Registry; patients with breast cancer were tested for BRCA1 and BRCA2 mutations, as were FDRs of identified mutation carriers. We used segregation analysis to fit a model that accommodates familial correlation in breast cancer risk due to unobserved shared risk factors. RESULTS We studied 3,047 families; 160 had BRCA1 and 132 had BRCA2 mutations. There was no evidence of increased breast cancer risk for noncarriers of identified mutations compared with FDRs from families without BRCA1 or BRCA2 mutations: relative risk was 0.39 (95% CI, 0.04 to 3.81). Residual breast cancer correlation within families was strong, suggesting substantial risk heterogeneity in women without BRCA1 or BRCA2 mutations, with some 3.4% of them accounting for roughly one third of breast cancer cases. CONCLUSION These results support the practice of advising noncarriers that they do not have any increase in breast cancer risk attributable to the family-specific BRCA1 or BRCA2 mutation.

Molecular and genetic characterization of human cell lines resistant tol-asparaginase and albizziin

Human cell lines resistant tol-asparaginase or albizziin were isolated by multistep selection of HT1080 fibrosarcoma and MIA PaCa-2 pancreatic carcinoma cells. Mutants were cross-resistant to both drugs, but more resistant to the drug used for selection. The drug-resistant cell lines expressed elevated levels of asparagine synthetase activity and protein, up to 17-fold over that of the parental cells. Enzyme overproduction was due to gene amplification in the albizziin-resistant cells, whereas increased expression without amplification was observed inl-asparaginase-resistant cells.

No association of TGFB1 L10P genotypes and breast cancer risk in BRCA1 and BRCA2 mutation carriers: a multi-center cohort study

Background The transforming growth factor β-1 gene (TGFB1) is a plausible candidate for breast cancer susceptibility. The L10P variant of TGFB1 is associated with higher circulating levels and secretion of TGF-β, and recent large-scale studies suggest strongly that this variant is associated with breast cancer risk in the general population. Methods To evaluate whether TGFB1 L10P also modifies the risk of breast cancer in BRCA1 or BRCA2 mutation carriers, we undertook a multi-center study of 3,442 BRCA1 and 2,095 BRCA2 mutation carriers. Results We found no evidence of association between TGFB1 L10P and breast cancer risk in either BRCA1 or BRCA2 mutation carriers. The per-allele HR for the L10P variant was 1.01 (95%CI: 0.92–1.11) in BRCA1 carriers and 0.92 (95%CI: 0.81–1.04) in BRCA2 mutation carriers. Conclusions These results do not support the hypothesis that TGFB1 L10P genotypes modify the risk of breast cancer in BRCA1 or BRCA2 mutation carriers.

Integrative analyses reveal signaling pathways underlying familial breast cancer susceptibility

The signaling events that drive familial breast cancer (FBC) risk remain poorly understood. While the majority of genomic studies have focused on genetic risk variants, known risk variants account for at most 30% of FBC cases. Considering that multiple genes may influence FBC risk, we hypothesized that a pathway‐based strategy examining different data types from multiple tissues could elucidate the biological basis for FBC. In this study, we performed integrated analyses of gene expression and exome‐sequencing data from peripheral blood mononuclear cells and showed that cell adhesion pathways are significantly and consistently dysregulated in women who develop FBC. The dysregulation of cell adhesion pathways in high‐risk women was also identified by pathway‐based profiling applied to normal breast tissue data from two independent cohorts. The results of our genomic analyses were validated in normal primary mammary epithelial cells from high‐risk and control women, using cell‐based functional assays, drug‐response assays, fluorescence microscopy, and Western blotting assays. Both genomic and cell‐based experiments indicate that cell–cell and cell–extracellular matrix adhesion processes seem to be disrupted in non‐malignant cells of women at high risk for FBC and suggest a potential role for these processes in FBC development.

Characterisation of differential gene expression of soft tissue sarcomas by microarray technology

Characterisation of differential gene expression of soft tissue sarcomas by microarray technology

Analysis of gene expression patterns in breast cancer by microarray technology

Although alterations in several specific genes have been implicated in breast cancer progression, greater understanding of the molecular basis of the disease may result from the evaluation of global gene expression patterns using microarray technology. To identify patterns of gene expression of prognostic importance in axillary node−negative breast cancer, we are studying a large cohort of patients with this type of cancer. Before using the limited amount of RNA from these specimens, we performed pilot studies designed to evaluate the feasibility of applying the technology on a larger scale. We studied gene expression in four different breast cancer cell lines (T47D, MDA231, SKBR3 and BT474) using complementary DNA microarrays containing 1,700 and 19,000 sequence-verified human cDNAs produced by the microarray facility at the Ontario Cancer Institute, Toronto (http://www.oci.utoronto.ca/services/microarray). Each hybridization compared Cy5-labeled complementary DNA from one of the cell lines with Cy3-labeled cDNA from a reference sample (MCF12A, a normal breast cell line). We also performed reciprocal labeling with subsequent hybridization to demonstrate the consistency and reproducibilty of the technology. In addition, different amounts of RNA (50 g, 25 g and 10 g) from the same cell lines were labeled to determine the sensitivity of the system. We have been able to devise a system that can now be applied to primary breast tumors. After expression analysis, we will use biostatistical modeling to detect clusters of genes that are coordinately expressed, repressed or both. These clusters are likely to represent common pathways of genes involved in breast carcinogenesis.