Genomic landscape of HBV-related hepatocellular carcinoma in south China patients with high mutational frequency of TP53 and TERT promoter.

Abstract

e15670 Background: Development of hepatocellular carcinoma (HCC) is a complex process with accumulations of polygene abnormalities and multi-pathway misregulation. Hepatitis B virus (HBV) exposure can cause liver damage and promote hepatocarcinogenesis via various biological effects. We aimed to investigate the molecular mechanisms underlying the etiology of HBV-related HCC development, and provide new insights into novel molecular targets. Methods: 84 HBV-positive HCC patients from Guangxi Province, South China, who underwent hepatic resection, were enrolled in this study. Genomic alterations were analyzed in pair-matched tumor and adjacent normal tissue using a hybridization capture-based next-generation sequencing (NGS) assay targeting 422 cancer-relevant genes. Results: In total, 691 somatic mutations, 166 copy number variations and 10 gene fusions were detected in 81 (96.4%) of 84 tumor samples. The most commonly mutated gene is TP53 in this cohort (84% of the patients), which is much higher than its frequency in the reported overall HCC patients. TERT promoter has somatic mutations in 32% of the patients, reactivation of which has been implicated in multiple cancer types. Dysfunction in the cell cycle control pathway (TP53, RB1, CCND1, CDKN2A and CCNE1) was dominant, followed by PI3K/AKT cascade (PIK3CA, AKT3, MTOR, TSC1 and TSC2), while genes of WNT signaling pathway (CTNNB1, APC and AXIN2) were mutated at a lower frequency. In addition, 69 variants in 25 DNA damage repair (DDR) genes were identified in 37 (45.7%) patients. Patients with DDR mutations had a higher tumor mutation burden (TMB) than those without DDR mutations. Conclusions: This study revealed a unique genomic landscape of HBV-related HCC. Besides TP53 being the highest mutated gene, a significant fraction of patients was identified with TERT promoter mutations, suggesting that TERT may play a role in HBV-related hepatocarcinogenesis as a novel molecular marker. Furthermore, the most common biological processes affected by HBV status in HCC were cell cycle control, PI3K/AKT and WNT signaling pathways. The possible synergistic effects of HBV in hepatocarcinogenesis warrant further investigations.