Quantification of hepatitis B virus covalently closed circular DNA in patients with hepatocellular carcinoma

Background/Aims: This study aimed to measure the intrahepatic total hepatitis B virus (HBV) DNA and covalently closed circular DNA (cccDNA) levels in tumor and non-tumor tissues in hepatocellular carcinoma (HCC) patients. Methods: Intrahepatic total HBV DNA and cccDNA were measured in 25 HCC patients (21 hepatitis B surface antigen [HBsAg]-positive and 4 HBsAg-negative) by the Invader (R) assay. Results: A low level of intrahepatic HBV DNA was detectable in all HBsAg-negative patients. For HBsAg-positive patients, the intrahepatic total HBV DNA levels in the tumor and non-tumor tissues were comparable (P = 0.903). However, the tumor tissues had significantly higher levels of cccDNA (0.35 vs. 0.16 copies/cell, P = 0.030) and higher proportion of intrahepatic HBV DNA in the form of cccDNA (100% vs. 84%, P = 0.004) than the non-tumor tissues. Seventeen out of 21 (81%) tumor tissues had intrahepatic HBV DNA solely in cccDNA form. Analysis of HBV mRNA expression indicated that HBV replication appeared to be lower in the tumor tissues than the non-tumor tissues. Conclusions: Compared to the non-tumor tissues, the levels of HBV replication in the tumor tissues appeared to be lower, and cccDNA was the predominant form of HBV DNA in the tumor tissues. (c) 2006 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.