Citations

Abstract Both genetic and epigenetic factors influence the development and progression of epithelial ovarian cancer (EOC). However, there is an incomplete understanding of the interrelationship between these factors and whether they interact to impact disease risk. Given that the development of ovarian cancer is complex, we aimed to identify DNA methylation marks that are candidates for mediating ovarian cancer genetic risk. We used 214 cases and 214 age-matched controls from the Mayo Clinic Ovarian Cancer Study. Pretreatment, blood-derived DNA was profiled for genome-wide methylation (Illumina Infinium HumanMethylation27 BeadArray) and single nucleotide polymorphisms (SNPs, Illumina Infinium HD Human610-Quad BeadArray). We employed a three-step filtering procedure, followed by the Causal Inference Test (CIT), to distinguish CpG sites that mediate genetic risk, from those that are consequential or independently acted on by genotype. Controlling for the estimated distribution of immune cells and other key covariates, we identified 1,993 out of 25,926 (7.7%) CpGs that were significantly differentially methylated between cases and controls (FDR, q < 0.05). The relationship between methylation and case-control status among these 1,993 CpGs was found to be highly consistent with the results of an independent study. Implementation of the CIT test revealed 13 CpG/SNP pairs, comprising 13 unique CpGs and 17 unique SNPs, which represent potential methylation-mediated relationships between genotype and EOC risk. These findings provide additional insight into EOC etiology and may serve as novel biomarkers for EOC susceptibility. Citation Format: Devin C. Koestler, Prabhakar Chalise, Mine S. Cicek, Julie M. Cunningham, Sebastian Armasu, Melissa C. Larson, Jeremy Chien, Matthew Block, Kimberly R. Kalli, Thomas A. Sellers, Ellen L. Goode, Brooke L. Fridley. Integrative genomic analysis identifies epigenetic marks that mediate genetic risk for epithelial ovarian cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 260. doi:10.1158/1538-7445.AM2014-260

Abstract An ovarian cancer Genome Wide Association Study (GWAS) identified 9p22.2 as a novel susceptibility locus with the most statistically significant single nucleotide polymorphisms (SNPs) located in an intergenic region near the Basonuclin 2 (BNC2) gene, which codes for a putative transcription regulator containing three pairs of zinc finger (ZF) domains. The minor alleles are protective in terms of ovarian cancer susceptibility. However, the molecular mechanisms by which these SNPs modify susceptibility remain largely unknown. The significant SNPs in the 9p22.2 locus lie in non-coding regions and therefore are hypothesized to affect the activity of regulatory elements and modify the expression of a target gene(s). In order to test this hypothesis we conducted fine mapping for the locus which delimited a ∼74kb region containing SNPs with a p-value less than 10-8. FAIRE-Seq and ChIP-Seq experiments for histone markers conducted in immortalized ovarian surface epithelial cells (IOSE) and fallopian tube epithelial cells (IFTE) were used to prioritize functional SNP candidates which overlap with regulatory elements. Luciferase assays tested the ability of these regulatory elements to activate transcription. Chromosome conformation capture (3C) experiments demonstrate a physical interaction between the BNC2 promoter and candidate regulatory elements containing risk-associated SNPs. Methylation Quantification at Trait Loci (mQTL) revealed an association between decreased methylation at the BNC2 promoter and the protective minor alleles. Expression analysis shows decreased expression of BNC2 in cancer versus normal tissue implicating tumor suppressor function of BNC2. Therefore the protective minor allele likely increases expression of BNC2 which in turn contains tumor suppressing properties that decrease ovarian cancer risk. BNC2 protein is in complex with transcriptional regulatory proteins, in particular the NURD complex components. Moreover, BNC2 acts as a transcriptional repressor in in vitro transfection assays indicating that it functions in transcriptional repression. We then used protein binding microarrays and CHIP-Seq experiments to identify its putative DNA binding motifs and its downstream target genes. Analysis of this data suggests that BNC2 functions in a regulatory transcription network that impacts on genes implicated in ovarian cancer with enrichment for genes in the TGF-beta response pathway. Citation Format: Melissa A. Buckley, Howard C. Shen, Gustavo A. Mendoza-Fandino, Nicholas T. Woods, Anxhela Gjyshi, Juliet French, Kate Lawrenson, Honglin Song, Jonathan Tyrer, Renato S. Carvalho, Alexandra Valle, Ann Chen, Sean Yoder, Gregory Bloom, Ya-Yu Tsai, Ally Yang, Timothy R. Hughes, Xiaotao Qu, Mine Cicek, Melissa Larson, Ellen Goode, Brooke Fridley, Susan Ramus, Georgia Chenevix-Trench, Paul Pharoah, Thomas A. Sellers, Simon Gayther, Alvaro N.A. Monteiro, Ovarian Cancer Association Consortium. Functional analysis of the 9p22 locus implicates the transcriptional regulation of BNC2 as a mechanism in ovarian cancer predisposition. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3285. doi:10.1158/1538-7445.AM2014-3285

Abstract Background: To better understand colorectal cancer etiology and prognosis, archived surgical tissues were collected from Cancer Prevention Study II (CPS-II) Nutrition Cohort participants who were diagnosed with colorectal cancer. Herein, the methodology for this collection is described to help inform other efforts to collect tissues. Methods: The main components to accruing tissue were: (i) obtaining consent from participants or next-of-kin; (ii) contacting hospitals to request materials; and (iii) pathology review and laboratory processing. Results: In CPS-II, we identified 3,643 participants diagnosed with colorectal cancer between 1992/1993 and 2009. Of these, tissue could not be sought from cases verified through state cancer registry linkage (N = 1,622), because of insufficient information on tissue location. We sought tissue from the 2,021 cases verified using medical records, and received tissue from 882. When hospitals were contacted within 10 years of diagnosis, we received 87% of tissue materials; beyond that 10-year mark, we received 32%. Compared with the 2,761 colorectal cancer cases without tissue, the 882 cases with tissue were more likely to be alive, diagnosed more recently during follow-up, and had less-advanced staged disease. Cases with and without tissues were similar with respect to age at diagnosis, smoking, body mass index, physical activity, and other epidemiologic factors. Conclusions: Some of the most important elements in forming a tissue repository included having the cases' hospital contact and surgical accession information as well as contacting patients/next-of-kin and hospitals within 10 years of surgery. Impact: This tissue repository will serve as an important resource for colorectal cancer studies. See all the articles in this CEBP Focus section, “Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology.” Cancer Epidemiol Biomarkers Prev; 23(12); 2694–702. ©2014 AACR.

Abstract To reveal biologic mechanisms underlying clinical outcome of high-grade serous (HGS) epithelial ovarian carcinomas (EOC), we evaluated the association between tumor epigenetic changes and time to recurrence (TTR). We assessed methylation at approximately 450,000 genome-wide CpGs in tumors of 337 Mayo Clinic (Rochester, MN) patients. Semi-supervised clustering of discovery (n = 168) and validation (n = 169) sets was used to determine clinically relevant methylation classes. Clustering identified two methylation classes based on 60 informative CpGs, which differed in TTR in the validation set [R vs. L class, P = 2.9 × 10−3, HR = 0.52; 95% confidence interval (CI), 0.34–0.80]. Follow-up analyses considered genome-wide tumor mRNA expression (n = 104) and CD8 T-cell infiltration (n = 89) in patient subsets. Hypomethylation of CpGs located in 6p21.3 in the R class associated with cis upregulation of genes enriched in immune response processes (TAP1, PSMB8, PSMB9, HLA-DQB1, HLA-DQB2, HLA-DMA, and HLA-DOA), increased CD8 T-cell tumor infiltration (P = 7.6 × 10−5), and trans-regulation of genes in immune-related pathways (P = 1.6 × 10−32). This is the most comprehensive assessment of clinical outcomes with regard to epithelial ovarian carcinoma tumor methylation to date. Collectively, these results suggest that an epigenetically mediated immune response is a predictor of recurrence and, possibly, treatment response for HGS EOC. Cancer Res; 74(11); 3084–91. ©2014 AACR.

Abstract Background: Colorectal cancer (CRC) in densely affected families without Lynch Syndrome may be due to mutations in undiscovered genetic loci. Familial linkage analyses have yielded disparate results; the use of exome sequencing in coding regions may identify novel segregating variants. Methods: We completed exome sequencing on 40 affected cases from 16 multicase pedigrees to identify novel loci. Variants shared among all sequenced cases within each family were identified and filtered to exclude common variants and single-nucleotide variants (SNV) predicted to be benign. Results: We identified 32 nonsense or splice-site SNVs, 375 missense SNVs, 1,394 synonymous or noncoding SNVs, and 50 indels in the 16 families. Of particular interest are two validated and replicated missense variants in CENPE and KIF23, which are both located within previously reported CRC linkage regions, on chromosomes 1 and 15, respectively. Conclusions: Whole-exome sequencing identified DNA variants in multiple genes. Additional sequencing of these genes in additional samples will further elucidate the role of variants in these regions in CRC susceptibility. Impact: Exome sequencing of familial CRC cases can identify novel rare variants that may influence disease risk. Cancer Epidemiol Biomarkers Prev; 22(7); 1239–51. ©2013 AACR.

Abstract Background Ovarian cancer is the fifth most common cause of cancer death in women in the US; approximately 15,000 women will die from this disease in 2011 (ACS, 2011). The 5 year survival rate for stage IV disease is only 18%. Only a handful of independent significant prognostic factors are known, including tumor stage at surgery, size of residual tumor at the end of primary surgery, and age at diagnosis. Understanding how the variation of cytosine methylation in the context of cytosine-guanine dinucleotides (CpGs) affects complex disease etiology and survival is the current focus of many ongoing research studies. We conducted an epigenome-wide study of methylation in ovarian cancer cases to evaluate whether variation in methylation of CpG sites in genomic DNA may be associated with ovarian cancer survival. Methods Subjects included cases from an ongoing case-control study. The Mayo Clinic Ovarian Cancer Study is a clinic-based study that recruits ovarian cancer cases within 12 months of diagnosis. Pre-treatment, germline DNA from lymphocytes from 137 cases was bisulfite-modified, amplified and genotyped on the Illumina 450K methylation chip and included in these analyses. Quality control (QC) analyses include the elimination of all methylation probes with a single nucleotide polymorphism (SNP) or insertion/deletion (in/del) at the same location; removal of non-specific probes; and estimation of bisulfite conversion rates using embedded control probes. Planned analyses include assessment of clinical covariates (age, stage, extent of surgical debulking, grade, presence of ascites) to determine which are associated with overall survival in our data. Additional analyses will assess the age- and multi-variate-adjusted association of each methylation probe with overall survival using Cox proportional hazards regression models with each methylation probe modeled as a continuous variable. Data will be summarized using Manhattan plots. These analyses will be repeated using ‘time to recurrence’ as the outcome variable, with recurrence defined as time to ovarian cancer recurrence/progression or death. Results Bioinformatics analyses suggest that 36,659 probes were located at the site of a SNP or in/del and should be removed from future analyses. Another 448 probes had a detection rate of p< 0.01 and 6630 probes had signals for the negative control samples; all were removed from analyses. A total of 43,802 probes were removed. In addition, ten cases were excluded due to either poor bisulfite conversion (N=9) or extremely low raw methylation values across all probes (N=1). This leaves a total of 127 cases for analyses. Results from planned analyses will be presented, including estimation of the association of methylation probes with both overall survival and time to recurrence. Conclusions Data to be presented will describe whether there is any evidence that methylation of genomic DNA in ovarian cancer cases is associated with outcome of ovarian cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5008. doi:1538-7445.AM2012-5008

Abstract A substantial proportion of familial colorectal cancer (CRC) is not a consequence of known susceptibility loci, such as mismatch repair (MMR) genes, supporting the existence of additional loci. To identify novel CRC loci, we conducted a genome-wide linkage scan in 356 white families with no evidence of defective MMR (i.e., no tumors with loss of expression of MMR proteins; no microsatellite instability (MSI)-high tumors, and no evidence of linkage to MMR genes). This represents the largest linkage analysis of proficient MMR (pMMR) familial CRC to date. Families were ascertained via the NCI-supported Colon Cancer Family Registry multi-site (Colon CFR) consortium, the City of Hope, and Memorial University of Newfoundland. A total of 1,612 individuals (average 5.0 per family, range 2-10 with an average of 2.2 affected and 2.8 unaffected individuals) were genotyped using genome-wide single nucleotide polymorphism linkage arrays; parametric and non-parametric linkage analysis used MERLIN in a priori-defined family groups. Five lod scores greater than 3.0 were observed, accounting for heterogeneity, in four chromosomal regions. The greatest lod scores were at 4q21.1 among families with mean age of diagnosis less than 50 years (dominant HLOD=4.51, α=0.84, 145.40 cM, rs10518142) and at 12q24.32 among all families (dominant HLOD=3.60, α=0.48, 285.15 cM, rs952093). Among families with four or more affected individuals and among clinic-based families, a common peak was observed at 15q22.31 (101.40 cM, rs1477798; dominant HLOD=3.07, α=0.29; dominant HLOD=3.03, α=0.32, respectively). Analysis of families with only two affected individuals yielded a peak at 8q13.2 (recessive HLOD=3.02, α=0.51, 132.52 cM, rs1319036). These linkage regions comprise previously unreported loci, supporting the hypothesis that novel loci contribute to CRC in familial pMMR cases. These loci are also largely distinct from those identified in case-control GWAS. To follow up on these findings, a custom Agilent Sure Select Target Enrichment panel has been designed for genes in three of these regions, in order to sequence probands using an Illumina HiSeq 2000. This study demonstrates the utility of family-based data and provides evidence for additional alleles for familial CRC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2930. doi:1538-7445.AM2012-2930

Abstract Ovarian cancer is the leading cause of death in gynecologic malignancies in the United States with most patients presenting with late stage disease; patients receive the same treatment regardless of histology or tumor characteristics. The mismatch repair (MMR) molecular pathway is well-defined and known to be involved in up to 20% of ovarian cancers; however, association of deficient v proficient MMR status (dMMR v pMMR status) with risk factors and outcome is not well understood. We are conducting extensive molecular testing of the MMR genes MLH1, MSH2, MSH3, MSH6, and PMS2 on Mayo Clinic invasive epithelial ovarian cancer cases. First, the prevalence of dMMR tumors will be estimated in ovarian cancer cases (n=496) based on loss of expression of MLH1, MSH2, MSH3, MSH6, and PMS2 determined by immunohistochemistry staining of primary antibodies using negative and positive controls. Staining of tissue microarrays (TMAs) is complete; triplicate cores will be scored independently for presence or loss of protein expression by a board-certified pathologist. Second, for those dMMR cases, the possible cause of MMR deficiency will be evaluated considering germline and somatic mutations. The loss of expression of each protein will be characterized as germline if a deleterious mutation is present in peripheral blood or somatic if the pathogenic mutation is only present in tumor tissue. In cases with MLH1 loss somatic hypermethylation will also be considered. Analysis of germline mutation data will include all 496 cases and somatic mutations data will include a subset of cases tested with frozen tumor DNA (n=292) using Fluidigm access array targeted resequencing. Third, the clinical features of dMMR disease will be compared to those of pMMR; in particular, age at diagnosis, histopathology, and disease outcome. Among cases in this analysis, the majority have high-grade serous disease with a mean age at diagnosis of 61 years, about half had recurrence or progression (n=243) of which two-thirds (n=167) are deceased. Finally, known and suspected ovarian cancer risk factors (family history, smoking, body mass index, parity, use of hormone therapy, and genetic variation in susceptibility loci at 2q31, 3q25, 8q24, 9p22, 17q21, and 19p13) will be analyzed by MMR phenotype. Risk factor questionnaire data is available on 462 cases (93%), as well as 737 population controls with germline genome-wide genotype data. About half of the cases (n=231) report a 1st or 2nd degree family member with breast or ovarian cancer. Given the limited knowledge about ovarian cancer etiology and the poor prognosis of advanced disease, it is very important to study risk factors with this molecular subtype. The ovarian cancer dMMR phenotype may have distinct clinicopathological features that could guide risk stratification and be useful in diagnostics and therapeutics. This is the largest study characterizing MMR in an ovarian cancer population to date. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2619. doi:1538-7445.AM2012-2619