In an analysis of 31,717 cancer cases and 26,136 cancer-free controls drawn from 13 genome-wide association studies (GWAS), we observed large chromosomal abnormalities in a subset of clones from DNA obtained from blood or buccal samples. Mosaic chromosomal abnormalities, either aneuploidy or copy-neutral loss of heterozygosity, of size >2 Mb were observed in autosomes of 517 individuals (0.89%) with abnormal cell proportions between 7% and 95%. In cancer-free individuals, the frequency increased with age; 0.23% under 50 and 1.91% between 75 and 79 (p=4.8×10−8). Mosaic abnormalities were more frequent in individuals with solid-tumors (0.97% versus 0.74% in cancer-free individuals, OR=1.25, p=0.016), with a stronger association for cases who had DNA collected prior to diagnosis or treatment (OR=1.45, p=0.0005). Detectable clonal mosaicism was common in individuals for whom DNA was collected at least one year prior to diagnosis of leukemia compared to cancer-free individuals (OR=35.4, p=3.8×10−11). These findings underscore the importance of the role and time-dependent nature of somatic events in the etiology of cancer and other late-onset diseases.

Purpose: To provide a comprehensive, thorough analysis of somatic mutation and promoter hypermethylation of the von Hippel-Lindau (VHL) gene in the cancer genome, unique to clear cell renal cancer (ccRCC). Identify relationships between the prevalence of VHL gene alterations and alteration subtypes with patient and tumor characteristics. Experimental Design: As part of a large kidney cancer case-control study conducted in Central Europe, we analyzed VHL mutations and promoter methylation in 205 well-characterized, histologically confirmed patient tumor biopsies using a combination of sensitive, high-throughput methods (endonuclease scanning and Sanger sequencing) and analysis of 11 CpG sites in the VHL promoter. Results: We identified mutations in 82.4% of cases, the highest VHL gene mutation prevalence reported to date. Analysis of 11 VHL promoter CpG sites revealed that 8.3% of tumors were hypermethylated and all were mutation negative. In total, 91% of ccRCCs exhibited alteration of the gene through genetic or epigenetic mechanisms. Analysis of patient and tumor characteristics revealed that certain mutation subtypes were significantly associated with Fuhrman nuclear grade, metastasis, node positivity, and self-reported family history of RCC. Conclusion: Detection of VHL gene alterations using these accurate, sensitive, and practical methods provides evidence that the vast majority of histologically confirmed ccRCC tumors possess genetic or epigenetic alteration of the VHL gene and support the hypothesis that VHL alteration is an early event in ccRCC carcinogenesis. These findings also indicate that VHL molecular subtypes can provide a sensitive marker of tumor heterogeneity among histologically similar ccRCC cases for etiologic, prognostic, and translational studies.Considerable progress has been made in understanding the genetic basis of kidney cancer (1, 2). The susceptibility genes associated with several forms of inherited renal cell cancer (RCC) have been identified by rigorous analysis of families using genetic linkage analysis and positional cloning (3 -7). The most common subtype of RCC is the conventional clear cell type (ccRCC), which accounts for f75% of cases. In both familial and sporadic ccRCC, allelic inactivation of the von

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BackgroundPersistent organic pollutants (POPs) may influence epigenetic mechanisms; therefore, they could affect chromosomal stability and gene expression. DNA methylation, an epigenetic mechanism, has been associated with cancer initiation and progression. Greenlandic Inuit have some of the highest reported POP levels worldwide.ObjectiveOur aim in this study was to evaluate the relationship between plasma POPs concentrations and global DNA methylation (percent 5-methylcytosine) in DNA extracted from blood samples from 70 Greenlandic Inuit. Blood samples were collected under the Arctic Monitoring and Assessment Program and previously analyzed for a battery of POPs.MethodsWe used pyrosequencing to estimate global DNA methylation via Alu and LINE-1 assays of bisulfite-treated DNA. We investigated correlations between plasma POP concentrations and global DNA methylation via correlation coefficients and linear regression analyses.ResultsWe found inverse correlations between percents methylcytosine and many of the POP concentrations measured. Linear regressions, adjusting for age and cigarette smoking, showed statistically significant inverse linear relationships mainly for the Alu assay for p,p′-DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane; β = −0.26), p,p′-DDE [1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene; β = −0.38], β-hexachlorocyclohexane (β = −0.48), oxychlordane (β = −0.32), α-chlordane (β = −0.75), mirex (β = −0.27), sum of polychlorinated biphenyls (β = −0.56), and sum of all POPs (β = −0.48). Linear regressions for the LINE-1 assay showed β estimates of similar magnitudes to those using the Alu assay, however, none was statistically significant.ConclusionsThis is the first study to investigate environmental exposure to POPs and DNA methylation levels in a human population. Global methylation levels were inversely associated with blood plasma levels for several POPs and merit further investigation.

There are concerns about the health effects of formaldehyde exposure, including carcinogenicity, in light of elevated indoor air levels in new homes and occupational exposures experienced by workers in health care, embalming, manufacturing, and other industries. Epidemiologic studies suggest that formaldehyde exposure is associated with an increased risk of leukemia. However, the biological plausibility of these findings has been questioned because limited information is available on the ability of formaldehyde to disrupt hematopoietic function. Our objective was to determine if formaldehyde exposure disrupts hematopoietic function and produces leukemia-related chromosome changes in exposed humans. We examined the ability of formaldehyde to disrupt hematopoiesis in a study of 94 workers in China (43 exposed to formaldehyde and 51 frequency-matched controls) by measuring complete blood counts and peripheral stem/progenitor cell colony formation. Further, myeloid progenitor cells, the target for leukemogenesis, were cultured from the workers to quantify the level of leukemia-specific chromosome changes, including monosomy 7 and trisomy 8, in metaphase spreads of these cells. Among exposed workers, peripheral blood cell counts were significantly lowered in a manner consistent with toxic effects on the bone marrow and leukemia-specific chromosome changes were significantly elevated in myeloid blood progenitor cells. These findings suggest that formaldehyde exposure can have an adverse effect on the hematopoietic system and that leukemia induction by formaldehyde is biologically plausible, which heightens concerns about its leukemogenic potential from occupational and environmental exposures.

Background-DNA hypomethylation has been suggested to cause genomic instability and increase cancer risk. In this study we aimed to test the hypothesis that DNA hypomethylation was associated with bladder cancer risk.

contributed to the design and execution of the overall study. M.P.P., M.J., J.R.T., G.S., L.E.M., L.A.K., X.W., V.G., K.B.J., J.D.M., N.R., S.J.C., and P Brennan contributed to the statistical analysis. M.P.P., M.J., S.J.C. and P. Brennan wrote the first draft of the manuscript. D. Zeleniak, E.P., L.A.K., X.W., K.B.J., S.H.V., S.L.M., Y.Y., A.M.M., E.S.B., N.N.C., M.F., D.L., I.G., S.H., H. Blanche, A.H., G.T., Z.W., M.Y., K.G.S., S.J.C., and M.L. supervised or conducted the genotyping. The remaining authors conducted the epidemiologic studies and contributed samples to the GWAS and/or replication. All authors contributed to the writing of the manuscript. NIH Public Access Author ManuscriptNat Genet. Author manuscript; available in PMC 2012 January 1. AbstractWe conducted a two-stage genome-wide association study of renal cell carcinoma (RCC) in 3,772 cases and 8,505 controls of European background from 11 studies, and followed up 6 SNPs in three replication studies of 2,198 cases and 4,918 controls. Two loci on the regions of 2p21 and 11q13.3 were associated with RCC susceptibility below genome-wide significance. Two correlated variants (r 2 = 0.99 in controls), rs11894252 (P = 1.8×10 −8 ) and rs7579899 (P = 2.3×10 −9 ), map to EPAS1 on 2p21, which encodes hypoxia-inducible-factor-2 alpha, a transcription factor previously implicated in RCC. The second locus, rs7105934, at 11q13, contains no characterized genes (P = 7.8×10 −14 ). In addition, we observed a promising association on 12q24.31 for rs4765623 which maps to the scavenger receptor class B, member 1 (SCARB1) gene (P = 2.6×10 −8 ). Our study reports novel genomic regions associated with RCC risk that may lead to new etiological insights. Table 1, Online Methods and Supplementary note). All subjects from the IARC/CNG study were genotyped at the CNG with the exception of 305 cases and 323 controls from Russia that were genotyped at the Center "Bioengineering" and at the "Kurchatov Institute" in Moscow. All subjects from the NCI study were scanned at the NCI Core Genotyping Facility. In addition, 1,438 controls from the Wellcome Trust Case-Control Consortium were genotyped at the Sanger Institute, UK 10 . All RCC cases were defined on the basis of the International Classification of Diseases for Oncology, Second Edition (ICD-O-2), and included all cancers that were coded as C64.Comparable quality control metrics were applied to the two scanned data sets and following sample and SNP exclusions, genotype data for up to 577,547 SNPs were available for 2,461 cases and 5,081 controls in the IARC/CNG scan, while data for 585,576 SNPs were available for 1,311 cases and 3,424 controls in the NCI scan (Online Methods). Primary analyses were conducted using unconditional logistic regression models for genotype trend effects (1 degree of freedom) and adjusted for sex, country, eigenvectors, and study for the USA (Online Methods). In order to compute summary findings across both scans, a metaanalysis was performed using a fixed effects model with inverse variance wei...

Ingestion ofarsenic, both from water supplies and medicinal preparations, is known tocause skin cancer. The evidence assessed here indicates that arsenic can also cause liver, lung, kidney, and bladder cancer and that the population cancer risks due to arsenic in U.S. water supplies may be comparable to those from environmental tobacco smoke and radon in homes. Large population studies in an area ofTaiwan with high arsenic levels in well water (170-800 jAg/L) were used to establish dose-response relationships between cancer risks and the concentration of inorganic arsenic naturally present in water supplies. It was estimated that at the current EPA standard of50 ug/L, the lifetime risk ofdying from cancer of the liver, lung, kidney, or bladder from drinking 1 L/day of water could be as high as 13 per 1000 persons. It has been estimated that more than 350,000 people in the United States may be supplied with water containing more than 50 yg/L arsenic, and more than 2.5 million people may be supplied with water with levels above 25 Ag/L. For average arsenic levels and waterconsumption patterns in the United States, the risk estimate was around 1/1000. Although further researh is needed to validate these findings, measures to reduce arsenic levels in water supplies should be considered.