Abstract 4897: Genome-wide structural variation analysis and characterization of Hepatitis B Virus integration sites in hepatocellular carcinomas using Bionano Genomics whole genome imaging

Abstract

Abstract Large genomic rearrangements are known contributors to cancer formation. Hepatitis B virus (HBV) integration is a frequent driver of hepatocellular carcinoma, frequently associated with genomic rearrangements. Next generation sequencing (NGS) is commonly used to study these integration sites and rearrangements; however, due to short read lengths, NGS is often unable to characterize large and complicated genomic rearrangements. To solve this problem, whole genome imaging was used to perform genome-wide detection of large structural variants (SVs) in DNA extracted from liver tumors, including characterization of HBV viral integration sites and nearby rearrangements. Ultra-high molecular weight DNA was extracted from liver tissue of four patients diagnosed with hepatocellular carcinoma. The DNA was fluorescently labeled at the motif CTTAAG, linearized, and imaged in nanochannel arrays using a Bionano Genomics Saphyr platform. Images of molecules were converted into digital single-molecule reads. 400X coverage of DNA molecules at least 150 kbp in length was collected for each sample. For three of the patients, somatic structural variants (SV) were identified by comparing SV calls and single molecule DNA reads of liver tumor resections against those of matching physiologically normal liver tissue. For the fourth patient, putative somatic SVs were identified by comparing SV calls against a database of 59,490 known variants from 57 physiologically normal individuals. Among the matched-pair samples, 511 large tumor-unique structural variants were identified. For the fourth sample, 619 putative somatic events were identified. HBV viral integration sites, which had previously been identified via NGS, and nearby SVs were characterized. Complex SVs were resolved, including translocation events with several loci. These findings demonstrate the utility of whole genome imaging for studying the relationship between viral integration and cancer. Citation Format: Karl Hong, Camille Péneau, Quentin Bayard, Sandrine Imbeaud, Andy Pang, Alex Hastie, Eric Letouzé, Jessica Zucman-Rossi. Genome-wide structural variation analysis and characterization of Hepatitis B Virus integration sites in hepatocellular carcinomas using Bionano Genomics whole genome imaging [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4897.