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Tu T, Mason WS, Clouston AD, Shackel NA, McCaughan GW, Yeh MM, Schiff ER, Ruszkiewicz AR, Chen JW, Harley HAJ, Stroeher UH, Jilbert AR. Clonal expansion of hepatocytes with a selective advantage occurs during all stages of chronic hepatitis B virus infection. J Viral Hepat 2015; 22:737-53. [PMID: 25619231 DOI: 10.1111/jvh.12380] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 11/15/2014] [Indexed: 12/23/2022]
Abstract
Hepatocyte clone size was measured in liver samples of 21 patients in various stages of chronic hepatitis B virus (HBV) infection and from 21 to 76 years of age. Hepatocyte clones containing unique virus-cell DNA junctions formed by the integration of HBV DNA were detected using inverse nested PCR. The maximum hepatocyte clone size tended to increase with age, although there was considerable patient-to-patient variation in each age group. There was an upward trend in maximum clone size with increasing fibrosis, inflammatory activity and with seroconversion from HBV e-antigen (HBeAg)-positive to HBeAg-negative, but these differences did not reach statistical significance. Maximum hepatocyte clone size did not differ between patients with and without a coexisting hepatocellular carcinoma. Thus, large hepatocyte clones containing integrated HBV DNA were detected during all stages of chronic HBV infection. Using laser microdissection, no significant difference in clone size was observed between foci of HBV surface antigen (HBsAg)-positive and HBsAg-negative hepatocytes, suggesting that expression of HBsAg is not a significant factor in clonal expansion. Laser microdissection also revealed that hepatocytes with normal-appearing histology make up a major fraction of the cells undergoing clonal expansion. Thus, preneoplasia does not appear to be a factor in the clonal expansion detected in our assays. Computer simulations suggest that the large hepatocyte clones are not produced by random hepatocyte turnover but have an as-yet-unknown selective advantage that drives increased clonal expansion in the HBV-infected liver.
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Affiliation(s)
- T Tu
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia.,Centenary Institute, Sydney, NSW, Australia.,Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - W S Mason
- Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - A D Clouston
- Centre for Liver Disease Research, School of Medicine, Faculty of Health Sciences, University of Queensland, Brisbane, QLD, Australia
| | - N A Shackel
- Centenary Institute, Sydney, NSW, Australia.,Sydney Medical School, University of Sydney, Sydney, NSW, Australia.,A. W. Morrow Gastroenterology and Liver Centre, Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - G W McCaughan
- Centenary Institute, Sydney, NSW, Australia.,Sydney Medical School, University of Sydney, Sydney, NSW, Australia.,A. W. Morrow Gastroenterology and Liver Centre, Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - M M Yeh
- Department of Pathology, University of Washington School of Medicine, Seattle, WA, USA
| | - E R Schiff
- Schiff Liver Institute and Center for Liver Diseases, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - A R Ruszkiewicz
- Department of Anatomical Pathology and Centre for Cancer Biology, SA Pathology, Adelaide, SA, Australia
| | - J W Chen
- South Australian Liver Transplant Unit, Flinders Medical Centre, Adelaide, SA, Australia
| | - H A J Harley
- Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, Adelaide, SA, Australia
| | - U H Stroeher
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | - A R Jilbert
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
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Tu T, Budzinska MA, Shackel NA, Jilbert AR. Conceptual models for the initiation of hepatitis B virus-associated hepatocellular carcinoma. Liver Int 2015; 35:1786-800. [PMID: 25640596 DOI: 10.1111/liv.12773] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 12/18/2014] [Indexed: 12/18/2022]
Abstract
Although chronic hepatitis B virus (HBV) infection is a known risk factor for the development of hepatocellular carcinoma (HCC), the steps involved in the progression from normal liver to HCC are poorly understood. In this review, we apply five conceptual models, previously proposed by Vineis et al. to explain carcinogenesis in general, to explore the possible steps involved in the initiation and evolution of HBV-associated HCC. Available data suggest that the most suitable and inclusive model is based on evolution of hepatocyte subpopulations. In this evolutionary model, HCC-associated changes are driven by selection and subsequent clonal expansion of phenotypically altered hepatocyte subpopulations in the microenvironment of the HBV-infected liver. This model can incorporate the wide range of mechanisms proposed to play a role in the initiation of HCC including oncogenic HBV proteins, integration of HBV DNA and chronic inflammation of the liver. The model may assist in the early prevention, detection and treatment of HCC and may guide future studies of the initiation of HBV-associated HCC.
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Affiliation(s)
- Thomas Tu
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia.,Liver Cell Biology, Centenary Institute, Sydney, NSW, Australia.,Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Magdalena A Budzinska
- Liver Cell Biology, Centenary Institute, Sydney, NSW, Australia.,Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Nicholas A Shackel
- Liver Cell Biology, Centenary Institute, Sydney, NSW, Australia.,Sydney Medical School, University of Sydney, Sydney, NSW, Australia.,A.W. Morrow Gastroenterology and Liver Centre, Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - Allison R Jilbert
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
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