HBV-human DNA integration in non-hepatic tumors.

Abstract

e13544 Background: Hepatitis B virus (HBV) infection in hepatocytes may induce chronic liver damage, which further leads to hepatocellular carcinoma. HBV infection was also reported in other cell types including peripheral blood mononuclear cells (PBMCs). Moreover, epidemiological evidence suggested that HBV infection was associated with various types of cancers. In this study, we investigated whether HBV DNA integration was observed in extrahepatic tumor cells. Methods: The study enrolled thousands of Chinese patients with different types of cancers. Peripheral blood and tumor tissue samples were collected, plasma cfDNA, PBMC gDNA and tumor tissue DNA were extracted. By targeted capture and next-generation sequencing, we sequenced the cancer-related genes and identified HBV DNA integration events in these samples. Moreover, the subtype of HBV captured in the host genome was verified, and the ratio of reads mapped to the HBV genome was calculated. Results: Samples with more than 0.1% of the sequencing reads mapped to the HBV genome were identified as HBV positive cases. Thirty-two liver cancer patients were subtype-b HBV positive, among which 8 tumor samples exhibited HBV genome integration. Three colorectal cancer patients were infected by subtype-c HBV, only one tumor sample carried HBV DNA integration. Two lung cancer patients were shown to be HBV positive; one was infected by subtype-b HBV and the other carried subtype-c HBV. Subtype-b and-c HBV genome was observed in the tumor sample of two cholangiocarcinoma patients, whereas subtype-b HBV DNA was identified in the PBMC of one gastrointestinal stromal cancer patient. Conclusions: HBV genome integration was identified in the tumor cells of lung, colorectal, biliary ducts, and gastrointestinal stromal cancer. The mechanisms by which the HBV genome integrates into these tissues requires further investigation.