Abstract 3137: Functional analysis of the chr13q22.1 pancreatic cancer risk locus suggests allele-specific effects on DIS3 expression.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Pancreatic cancer is the 10th most common cancer and 4th most common cause of cancer mortality in the United States. A genome wide association study has revealed pancreatic cancer susceptibility loci on chromosomes 13q22.1, 1q32.1 and 5p15.33. The chr13q22.1 region contains the most significant of all risk SNPs, rs9543325, (P= 3.27 x 10−11) which is located in a gene desert. The nearest genes are KLF5, KLF12, PIBF1, DIS3 and BORA, which range in distance from 265kb to 586kb, respectively, from the most significant variants. Given the high linkage disequilibrium across this risk locus, there are many candidate functional variants to consider. Imputation in the region did not improve the signal but gave a set of highly correlated SNPs which likely includes the functional variant(s). In an effort to identify the functional variant(s) we performed eQTL analyses to test the association between the genotypes of these candidate SNPs and expression of nearby genes. Among 100 normal pancreatic tissue samples, DIS3 showed the strongest association with SNPs in our risk locus (P-values as low as 0.0004). Mutations in DIS3 have been identified in acute myeloid leukemia and multiple myeloma, and its expression has been correlated with metastatic potential in colorectal cancer, suggesting this gene could be important in pancreatic cancer biology. Chromosome Conformation Capture (3C) was performed to test for physical interactions between the risk locus and nearby genes. This assay confirmed the three dimensional proximity of the risk locus and DIS3 promoter. Sub-regions of the risk locus were then cloned upstream of a minimal promoter controlling luciferase expression to assay for potential allele specific enhancer/silencer activity. This assay revealed a sub-region downstream of rs9543325 that causes allele-specific silencing. These results suggest that a sub-region of the chr13q22.1 risk locus has allele-specific effects on DIS3 expression, which may have implications in the susceptibility to pancreatic cancer. Citation Format: Jason Hoskins, Abdisamad Ibrahim, Jinping Jia, Irene Collins, Hemang Parikh, Gloria M. Petersen, Laufey Amundadottir. Functional analysis of the chr13q22.1 pancreatic cancer risk locus suggests allele-specific effects on DIS3 expression. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3137. doi:10.1158/1538-7445.AM2013-3137