Identification of 27 5 ' CpG islands aberrantly methylated and 13 genes silenced in human pancreatic cancers
ONCOGENE
Authors: Hagihara, A; Miyamoto, K; Furuta, J; Hiraoka, N; Wakazono, K; Seki, S; Fukushima, S; Tsao, MS; Sugimura, T; Ushijima, T
Abstract
Aberrantly methylated DNA fragments were searched for in human pancreatic cancers, using the genome scanning technique: methylation-sensitive-representational difference analysis (MS-RDA). MS-RDA isolated 111 DNA fragments derived from CpG islands (CGIs), and 35 of them were from CGIs in the 5' regions of known genes. Methylation-specific PCR (MSP) of the CGIs in seven pancreatic cancer cell lines and two pancreatic ductal epithelial cell lines showed that 27 CGIs in the 5' regions were aberrantly methylated in at least one of the cancer cell lines. Quantitative reverse-transcription-PCR analysis showed that downstream genes of all the CGIs were either not expressed or only very weakly expressed in cancer cell lines with the aberrant methylation. In the pancreatic ductal epithelial cell lines, 18 genes were expressed at various levels, and nine genes were not expressed at all. Treatment of a cancer cell line with a demethylating agent, 5-aza-2'-deoxycytidine, restored the expression of 13 genes, RASGRF2, ADAM23, NEF3, NKX2-8, HAND1, EGR4, PRG2, FBN2, CDH2, TLL1, NPTX1, NTSR1 and THBD, showing their silencing by methylation of their 5' CGIs. MSP of 24 primary pancreatic cancers showed that all these genes, except for THBD, were methylated in at least one cancer. Some of those were suggested to be potentially involved in pancreatic cancer development and progression.
A Genome-Wide Scan of Ashkenazi Jewish Crohn's Disease Suggests Novel Susceptibility Loci
PLOS GENETICS
Authors: Kenny, Eimear E.; Pe'er, Itsik; Karban, Amir; Ozelius, Laurie; Mitchell, Adele A.; Ng, Sok Meng; Erazo, Monica; Ostrer, Harry; Abraham, Clara; Abreu, Maria T.; Atzmon, Gil; Barzilai, Nir; Brant, Steven R.; Bressman, Susan; Burns, Edward R.; Chowers, Yehuda; Clark, Lorraine N.; Darvasi, Ariel; Doheny, Dana; Duerr, Richard H.; Eliakim, Rami; Giladi, Nir; Gregersen, Peter K.; Hakonarson, Hakon; Jones, Michelle R.; Marder, Karen; McGovern, Dermot P. B.; Mulle, Jennifer; Orr-Urtreger, Avi; Proctor, Deborah D.; Pulver, Ann; Rotter, Jerome I.; Silverberg, Mark S.; Ullman, Thomas; Warren, Stephen T.; Waterman, Matti; Zhang, Wei; Bergman, Aviv; Mayer, Lloyd; Katz, Seymour; Desnick, Robert J.; Cho, Judy H.; Peter, Inga
Abstract
Crohn's disease (CD) is a complex disorder resulting from the interaction of intestinal microbiota with the host immune system in genetically susceptible individuals. The largest meta-analysis of genome-wide association to date identified 71 CD-susceptibility loci in individuals of European ancestry. An important epidemiological feature of CD is that it is 2-4 times more prevalent among individuals of Ashkenazi Jewish (AJ) descent compared to non-Jewish Europeans (NJ). To explore genetic variation associated with CD in AJs, we conducted a genome-wide association study (GWAS) by combining raw genotype data across 10 AJ cohorts consisting of 907 cases and 2,345 controls in the discovery stage, followed up by a replication study in 971 cases and 2,124 controls. We confirmed genome-wide significant associations of 9 known CD loci in AJs and replicated 3 additional loci with strong signal (p < 5 x 10(-6)). Novel signals detected among AJs were mapped to chromosomes 5q21.1 (rs7705924, combined p = 2 x 10(-8); combined odds ratio OR = 1.48), 2p15 (rs6545946, p = 7 x 10(-9); OR = 1.16), 8q21.11 (rs12677663, p = 2 x 10(-8); OR = 1.15), 10q26.3 (rs10734105, p = 3 x 10(-8); OR = 1.27), and 11q12.1 (rs11229030, p = 8 x 10(-9); OR = 1.15), implicating biologically plausible candidate genes, including RPL7, CPAMD8, PRG2, and PRG3. In all, the 16 replicated and newly discovered loci, in addition to the three coding NOD2 variants, accounted for 11.2% of the total genetic variance for CD risk in the AJ population. This study demonstrates the complementary value of genetic studies in the Ashkenazim.