A pilot systematic genomic comparison of recurrence risks of hepatitis B virus-associated hepatocellular carcinoma with low- and high-degree liver fibrosis

Cellular Genomic Sites of Hepatitis B Virus DNA Integration

Infection with the Hepatitis B Virus (HBV) is one of the strongest risk-factors for liver cancer (hepatocellular carcinoma, HCC). One of the reported drivers of HCC is the integration of HBV DNA into the host cell genome, which may induce pro-carcinogenic pathways. These reported pathways include: induction of chromosomal instability; generation of insertional mutagenesis in key cancer-associated genes; transcription of downstream cancer-associated cellular genes; and/or formation of a persistent source of viral protein expression (particularly HBV surface and X proteins). The contribution of each of these specific mechanisms towards carcinogenesis is currently unclear. Here, we review the current knowledge of specific sites of HBV DNA integration into the host genome, which sheds light on these mechanisms. We give an overview of previously-used methods to detect HBV DNA integration and the enrichment of integration events in specific functional and structural cellular genomic sites. Finally, we posit a theoretical model of HBV DNA integration during disease progression and highlight open questions in the field.

Integration of hepatitis B virus DNA in chronically infected patients assessed by Alu-PCR

Hepatitis B virus (HBV) infection is the main risk factor for hepatocellular carcinoma (HCC) worldwide. Integration of HBV DNA into the human genome has been found in >80% of HBV-related HCC cases. Some studies have, however, found similar integration patterns in tumorous and nontumorous tissues. Thus, the role of integrations for the development of HCC as well as the rate of integration in different stages of infection remain unclear. The aim of this study was to investigate integrations in patients without HCC, representing different stages of chronic HBV (CHB) infection. Extracted DNA in liver biopsies from 74 patients (one with 2 available biopsies) with CHB infection was analyzed by Alu-PCR. Amplicons were further analyzed by Sanger sequencing. Integration was detected in 39 biopsies (52%) as an amplicon containing both human and HBV sequences by Alu-PCR with one primer targeting a region in the HBV genome. Integrations were found in patients representing the different stages of CHB infection. A majority of the HBV sequences were located upstream or downstream of nucleotide position 1820, which previously has been identified as a common breakpoint in the HBV genome in integrated sequences. Approximately 60% of the HBV integrations were found in noncoding regions of the human genome. Integrations of HBV DNA into the human genome is an event frequently found in mild phases of chronic hepatitis.

Progress in non-invasive detection of liver fibrosis

Liver fibrosis is an important pathological precondition for hepatocellular carcinoma. The degree of hepatic fibrosis is positively correlated with liver cancer. Liver fibrosis is a series of pathological and physiological process related to liver cell necrosis and degeneration after chronic liver injury, which finally leads to extracellular matrix and collagen deposition. The early detection and precise staging of fibrosis and cirrhosis are very important for early diagnosis and timely initiation of appropriate therapeutic regimens. The risk of severe liver fibrosis finally progressing to liver carcinoma is >50%. It is known that biopsy is the gold standard for the diagnosis and staging of liver fibrosis. However, this method has some limitations, such as the potential for pain, sampling variability, and low patient acceptance. Furthermore, the necessity of obtaining a tissue diagnosis of liver fibrosis still remains controversial. An increasing number of reliable non-invasive approaches are now available that are widely applied in clinical practice, mostly in cases of viral hepatitis, resulting in a significantly decreased need for liver biopsy. In fact, the non-invasive detection and evaluation of liver cirrhosis now has good accuracy due to current serum markers, ultrasound imaging, and magnetic resonance imaging quantification techniques. A prominent advantage of the non-invasive detection and assessment of liver fibrosis is that liver fibrosis can be monitored repeatedly and easily in the same patient. Serum biomarkers have the advantages of high applicability (>95%) and good reproducibility. However, their results can be influenced by different patient conditions because none of these markers are liver-specific. The most promising techniques appear to be transient elastography and magnetic resonance elastography because they provide reliable results for the detection of fibrosis in the advanced stages, and future developments promise to increase the reliability and accuracy of the staging of hepatic fibrosis. This article aims to describe the recent progress in the development of non-invasive assessment methods for the staging of liver fibrosis, with a special emphasize on computer-aided quantitative and deep learning methods.