A genome-wide association study identifies susceptibility loci for ovarian cancer at 2q31 and 8q24

Ovarian cancer accounts for more deaths than all other gynecological cancers combined. To identify common low-penetrance ovarian cancer susceptibility genes, we conducted a genome-wide association study of 507,094 SNPs in 1,768 individuals with ovarian cancer (cases) and 2,354 controls, with follow up of 21,955 SNPs in 4,162 cases and 4,810 controls, leading to the identification of a confirmed susceptibility locus at 9p22 (in BNC2). Here, we report on nine additional candidate loci (defined as having P ≤ 10⁻⁴) identified after stratifying cases by histology, which we genotyped in an additional 4,353 cases and 6,021 controls. We confirmed two new susceptibility loci with P ≤ 5 × 10⁻⁸ (8q24, P = 8.0 × 10⁻¹⁵ and 2q31, P = 3.8 × 10⁻¹⁴) and identified two additional loci that approached genome-wide significance (3q25, P = 7.1 × 10⁻⁸ and 17q21, P = 1.4 × 10⁻⁷). The associations of these loci with serous ovarian cancer were generally stronger than with other cancer subtypes. Analysis of HOXD1, MYC, TIPARP and SKAP1 at these loci and of BNC2 at 9p22 supports a functional role for these genes in ovarian cancer development.

A genome-wide association study identifies a new ovarian cancer susceptibility locus on 9p22.2

Epithelial ovarian cancer has a major heritable component, but the known susceptibility genes explain less than half the excess familial risk. We performed a genome-wide association study (GWAS) to identify common ovarian cancer susceptibility alleles. We evaluated 507,094 SNPs genotyped in 1,817 cases and 2,353 controls from the UK and approximately 2 million imputed SNPs. We genotyped the 22,790 top ranked SNPs in 4,274 cases and 4,809 controls of European ancestry from Europe, USA and Australia. We identified 12 SNPs at 9p22 associated with disease risk (P < 10(-8)). The most significant SNP (rs3814113; P = 2.5 x 10(-17)) was genotyped in a further 2,670 ovarian cancer cases and 4,668 controls, confirming its association (combined data odds ratio (OR) = 0.82, 95% confidence interval (CI) 0.79-0.86, P(trend) = 5.1 x 10(-19)). The association differs by histological subtype, being strongest for serous ovarian cancers (OR 0.77, 95% CI 0.73-0.81, P(trend) = 4.1 x 10(-21)).

Abstract 1660: Cholesterol efflux transporter gene expression predicts clinical outcome in serous ovarian cancer

Ovarian cancer is a devastating disease. More than half the women diagnosed with advanced disease will die within five years. Tumours displaying serous histology are the most common, and although initially responsive to current chemotherapy regimens, the disease is characterised by a frequent rate of relapse, often with disease that is resistant to further treatment. Tumours displaying serous histology are the most common and often have the worst prognosis. The ATP-binding cassette (ABC) transporter superfamily consists of 48 functional transmembrane proteins which are further classified into seven subfamilies according to sequence similarity, designated A through G. Various members of the B, C and G branches are well-known for their abilities to convey drug resistance to cancer cells in vitro, but their precise roles in determining clinical outcome are still unclear. In addition, ABC transporters have important and diverse physiological roles through active transport of a variety of endogenous substrates, which could also contribute to tumour phenotype and treatment response. This is the first study to explore the entire ABC transporter gene family in relation to clinical outcome of ovarian cancer. Using a Taqman low density array format for real-time PCR, we examined expression of all ABC transporter genes in a cohort of 150 serous ovarian cancers. Kaplan-Meier survival analysis revealed that expression of multiple ABCA family transporters was significantly associated with progression-free or overall survival and multivariate modelling identified ABCA1, ABCA5, ABCA6, ABCA8 and ABCA9 as new prognostic markers for serous ovarian cancer that are independent of established clinical indicators. The prognostic significance of ABCA family transporter expression was validated in an independent microarray dataset consisting of 350 serous tumours available through The Cancer Genome Atlas. These ABCA family transporters are not known to transport drugs but instead function in cellular lipid trafficking and cholesterol homeostasis, suggesting that treatment failure may involve mechanisms other than simple efflux of chemotherapeutic drugs. In light of accumulating evidence for the importance of cholesterol and bioactive lipids in several cancers, this study highlights an important area for investigation into the biology and treatment of serous ovarian cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1660. doi:10.1158/1538-7445.AM2011-1660