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Epigenetic mechanisms such as aberrant DNA methylation (DNAme) are known to drive esophageal squamous cell carcinoma (ESCC), yet they remain poorly understood. Here, we studied tumor-specific DNAme in ESCC cases from nine high-incidence countries of Africa, Asia, and South America. Infinium MethylationEPIC array was performed on 108 tumors and 51 normal tissues adjacent to the tumors (NAT) in the discovery phase, and targeted pyrosequencing was performed on 132 tumors and 36 NAT in the replication phase. Top genes for replication were prioritized by weighting methylation results using RNA-sequencing data from The Cancer Genome Atlas and GTEx and validated by qPCR. Methylome analysis comparing tumor and NAT identified 6,796 differentially methylated positions (DMP) and 866 differential methylated regions (DMR), with a 30% methylation (Δβ) difference. The majority of identified DMPs and DMRs were hypermethylated in tumors, particularly in promoters and gene-body regions of genes involved in transcription activation. The top three prioritized genes for replication, PAX9, SIM2, and THSD4, had similar methylation differences in the discovery and replication sets. These genes were exclusively expressed in normal esophageal tissues in GTEx and downregulated in tumors. The specificity and sensitivity of these DNAme events in discriminating tumors from NAT were assessed. Our study identified novel, robust, and crucial tumor-specific DNAme events in ESCC tumors across several high-incidence populations of the world. Methylome changes identified in this study may serve as potential targets for biomarker discovery and warrant further functional characterization.Significance:This largest genome-wide DNA methylation study on ESCC from high-incidence populations of the world identifies functionally relevant and robust DNAme events that could serve as potential tumor-specific markers.

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PDF file - 67KB, Antibodies to type-specific HPV proteins and the risk of lung cancer.

Human papillomavirus (HPV) infections have been implicated in lung carcinogenesis, but causal associations remain uncertain. We evaluated a potential causal role for HPV infections in lung cancer through an analysis involving serology, tumor DNA, RNA, and p16 protein expression. Association between type-specific HPV antibodies and risk of lung cancer was examined among 3,083 cases and 4,328 controls in two case–control studies (retrospective) and one nested case–control study (prospective design). Three hundred and thirty-four available tumors were subjected to pathologic evaluation and subsequent HPV genotyping following stringent conditions to detect all high-risk and two low-risk HPV types. All HPV DNA-positive tumors were further tested for the expression of p16 protein and type-specific HPV mRNA. On the basis of the consistency of the results, although HPV11 and HPV31 E6 antibodies were associated with lung cancer risk in the retrospective study, no association was observed in the prospective design. Presence of type-specific antibodies correlated poorly with the presence of the corresponding HPV DNA in the tumor. Although nearly 10% of the lung tumors were positive for any HPV DNA (7% for HPV16 DNA), none expressed the viral oncogenes. No association was observed between HPV antibodies or DNA and lung cancer survival. In conclusion, we found no supportive evidence for the hypothesized causal association between HPV infections and lung cancer. Cancer Res; 74(13); 3525–34. ©2014 AACR.

PDF file - 55KB, Association between type-specific HPV antibodies and risk of lung cancer by seropositivity threshold.

PDF file - 52KB, Comparison of HPV16 DNA positivity by sex, smoking status and lung histology.

Exposure to aristolochic acid (AA, IARC Group 1 carcinogen) present in some traditional herbal medicines leads to aristolochic acid nephropathy (AAN), often complicated by development of multiple urothelial carcinomas of sequential onset. We used genome-scale mutational signature analysis of multiple urinary tract tumors of AAN cases from a unique patient group to determine the relationships of the patients’ late-onset second cancers to the AA exposure as well as to the first cancers. Aristolactam-DNA adduct-positive AAN patients (n=4) who developed cancer within 8 years following the initial exposure to AA were chosen for analysis of their first cancers (upper tract urothelial carcinomas, UTUC) and second cancers of delayed onset (1-9 years after first-cancer diagnosis, involving the bladder or ureteral meatus). All patients had received a kidney transplant before developing the second cancers and had a functional renal graft prior to prophylactic nephroureterectomy. Genomic DNAs were isolated from FFPE sections of the renal cortex and from the upper and lower tract tumors of each patient using laser capture micro-dissection or macro-dissection of the tumor areas. Low-coverage (~15x) exome 100-bp paired-end sequencing was performed using Illumina HiSeq2500. Customized variant calling identified somatic variants absent in non-tumor tissues. Non-negative matrix factorization was applied to extract mutational signatures in the tumor tissues. In all cases, we established the mutational signature of AA (the COSMIC signature 22) in the first UTUC as well as second cancers involving the bladder or lower ureter (meatus). Additionally, the first and second cancers harbored considerable overlaps in exposure-specific (A>T) somatic mutations. This finding provides evidence that the delayed onset of bladder urothelial carcinomas in AAN patients is likely due to distal seeding of cancer cells originating from the primary UTUC tumors. Our first-of-its-kind study addresses the risk as well as mechanistic factors leading to the second, late-onset bladder urothelial carcinomas following kidney transplantation and primary UTUC development. Our results underline the importance of long-term bladder follow-up in high-risk populations with established or suspected AA exposure. Funding: IARC; NYU Genome Technology Center is partially supported by the NIH/NCI (P30CA016087) grant. Citation Format: Xavier Castells, Maude Ardin, Sandrine Rorive, Nilufer Broeders, Yan Song, Stephanie Villar, Christine Carreira, Pierre-Paul Bringuier, Adriana Heguy, Thierry Quackels, Thierry Roumeguere, Joelle Nortier, Jiri Zavadil. Tracking the genetic relationship between first and late-onset second urothelial cancers by mutational signature analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5738. doi:10.1158/1538-7445.AM2017-5738

Renal cell carcinoma (RCC) is a poorly documented cancer, although time trends and geographical variations in incidence are intriguing. In addition to the frequent VHL mutation, recent studies have identified novel somatic alterations involved in RCC pathogenesis. Microarray and next generation sequencing efforts have been mostly performed on North American and Western European populations, while the highest incidence rates are found in Central/Eastern Europe. Our project has focused on the delineation of gene expression patterns specific to the Czech Republic population, where the incidence rates are the highest in the world. As a feasibility study, we performed whole genome expression profiling on 12 pairs of fresh frozen conventional clear cell RCC (ccRCC) tumors and adjacent non-tumor renal tissue using the Illumina HumanHT-12 v4 Expression BeadChips. To identify genes differentially expressed in ccRCC tumor versus normal tissue samples, the Significance Analysis of Microarrays (SAM) was used. Gene set enrichment analysis (GSEA) software was used for analysis of differentially expressed BioCarta categories and pathways associated with ccRCC pathogenesis. Following initial analyses a signature composed of 994 downregulated and 872 upregulated genes was found in ccRCC compared with normal tissue (FDR 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 5103. doi:1538-7445.AM2012-5103