Localization of hepatitis B virus DNA in hepatocellular carcinoma by polymerase chain reaction in situ hybridization.

The polymerase chain reaction in situ hybridization (PCR-ISH) is a new technique that combines the sensitivity of PCR with the localizing ability of ISH. To investigate the expression pattern of hepatitis B virus (HBV) in the tissue of hepatocellular carcinoma (HCC), we detected HBV-DNA with PCR-ISH in paraffin-embedded tumor and corresponding non-tumor tissues from 11 HCC patients. HBV-DNA was detected in 4 of 11 tumor tissues and in 7 of 10 non-tumor tissues. In tumor tissues, positive signals were scattered in the tissue with occasional clustering, and were found mainly in the cytoplasm of HCC cells rather than in the nucleus. In non-tumor tissues, the number of positive signals was higher than in tumor tissues and they were found in regenerating nodules with differing patterns and intensities. When we compared the detection rate of PCR-ISH with nested PCR among 10 tissue samples, HBV-DNA was detected in 5 tissue samples by PCR-ISH, but the S gene was detected in 10, precore gene in 9 and X gene in 8 by nested PCR. The findings suggest that PCR-ISH is a sensitive technique for localizing HBV in tissue sections and that the low level of HBV replication persists in HCC cells.