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

Highly Sensitive Detection of HBV RNA in Liver Tissue by In Situ Hybridization

As soon as HBV was identified, HBV localization at the cellular level became instrumental in studying HBV infection. Multiple methodologies for detection of viral antigens and nucleic acids at the cellular level, not only in patient derived liver biopsy samples, but also in many other experimental systems, have been developed over the years. Recently, the development of highly sensitive and specific in situ hybridization systems enabled detection of cellular mRNAs at the single copy level. Adaptation of such a system (ViewRNA ISH Tissue Assay; Affymetrix, Santa Clara, CA, USA) for the detection of viral RNAs allowed us to reliably identify hepatitis C virus RNA positive cells in the liver of HCV infected patients. Similarly, this protocol enabled detection of very rare HBV positive cells in liver biopsy tissue. Here, we now describe the specifics of the protocol for detection of HBV RNA using the ViewRNA ISH system. The protocol focuses on probe set design, sample preparation and data interpretation for accurate HBV RNA detection in liver tissue samples. The methodology is straightforward and will be very useful in the study of basic HBV virology as well as in clinical applications.

Detection of hepatitis B and C viruses in almost all hepatocytes by modified PCR-based in situ hybridization

Although PCR-based in situ hybridization (PCR-ISH) can be used to determine the distribution and localization of pathogens in tissues, this approach is hampered by its low specificity. Therefore, we used a highly specific and sensitive PCR-ISH method to reveal the lobular distribution and intracellular localization of hepatitis B virus (HBV) and HCV in chronic liver disease and to clarify the state of persistent HBV and HCV infection in the liver. HBV genomic DNA was detected in almost all hepatocytes, whereas HBV RNA or protein was differentially distributed only in a subset of the HBV DNA-positive region. Further, HCV genomic RNA was detected in almost all hepatocytes and was localized to the cytoplasm. HCV RNA was also detected in the epithelium of the large bile duct but not in endothelial cells, portal tracts, or sinusoidal lymphocytes. In patients with HBV and HCV coinfection, HCV RNA was localized to the noncancerous tissue, whereas HBV DNA was found only in the cancerous tissue. Using this novel PCR-ISH method, we could visualize the staining pattern of HBV and HCV in liver sections, and we obtained results consistent with those of real-time detection (RTD)-PCR analysis. In conclusion, almost all hepatocytes are infected with HBV or HCV in chronic liver disease; this finding implies that the viruses spreads throughout the liver in the chronic stage.

Detection of human papillomavirus type 16 DNA in formalin-fixed, paraffin-embedded tissue specimens of gastric carcinoma

OBJECTIVES

Human papillomavirus type 16 (HPV16) is regarded as one of the important tumor-related viruses, which are known to have a role in cervical carcinoma; however, there are few reports on HPV16 in gastric carcinoma (GC). Our study aimed to investigate the relationship between HPV16 and the occurrence of GC.

METHODS

Liquid PCR (LPCR) and in-situ PCR (ISPCR) methods were carried out to detect the HPV16 oncogene E6 cell-type-specific enhancer in the long control region of HPV16 in 40 GCs and corresponding gastric adjacent normal mucosa (GANM). The patients were from Shaanxi Province in China; Helicobacter pylori (Hp) was detected by immunohistochemistry and by hematoxylin and eosin staining in their gastric tissues.

RESULTS

The HPV16 E6 gene was detected in 37.5% (15/40) of the GCs and 5% (2/40) of the GANMs with LPCR, as was the cell-type-specific enhancer; however, the positive rate of E6 was 27.5% (11/40) in GCs and 0% (0/40) in GANMs, respectively, with ISPCR. HPV16 DNA was mainly located in the nucleus of gastric glandular epithelium cells. The infection rate of HPV16 DNA in GCs was higher than that in GANMs (P=0.0004), and the HPV16 had no statistical correlations with sex, age, invasion, grading or lymph node metastasis (P>0.05). The infection rate of HPV16 in cardiac GCs was significantly higher than that in noncardiac ones (P=0.0136), and HPV16 had no correlation with Hp in GCs (P=0.0829). Receiver operator characteristic curve analysis indicated that there was no statistical difference between the LPCR and ISPCR methods in our study through optimizing parameters in ISPCR procedures (P=0.768).

CONCLUSIONS

These findings suggested that HPV16 can infect gastric glandular epithelium cells and that viral infection might play a role in the occurrence of GCs independent of or without the cooperation of an Hp infection.

Significance of HBV DNA in the hepatic parenchyma from patients with non-B, non-C hepatocellular carcinoma

INTRODUCTION

The etiologic and prognostic factors for non-B, non-C hepatocellular carcinoma (HCC), which is defined by its seronegativity for both hepatitis B surface antigen and hepatitis C virus (HCV) antibody, remain unclear.

METHODS

Nonneoplastic liver tissue from 46 patients with non-B, non-C HCC were examined for hepatitis B virus (HBV) DNA and HCV RNA using in situ hybridization. Recurrence-free survival rates were compared between patients showing high or low HBV DNA expression. Other potential prognostic factors were examined as well.

RESULTS

HBV DNA was detected in nonneoplastic liver specimens from 35 patents (76.1%), whereas HCV RNA was not detected in any case. In patents with high HBV DNA group expression, recurrence-free survival rates at 1 and 5 years after onset were 68.8% and 13.8%, respectively; those with low expression had higher rates of 89.2% and 59.2%, respectively. Multivariate analysis identified high tumor stage (P=0.042) and high HBV DNA expression (p=0.014) as independent negative prognostic factors.

CONCLUSIONS

In many patients with non-B, non-C HCC, HBV DNA in the liver appears to be involved in the carcinogenesis, with intense HBV DNA expression predicting poor outcome for patients with these cancers.

Surface, core, and X genes of hepatitis B virus in hepatocellular carcinoma: an in situ hybridization study

BACKGROUND

The incidence of hepatocellular carcinoma (HCC) and the seroprevalence of hepatitis B virus (HBV) in this disease state are significantly higher in South India than in North India. Because data on serologic studies do not project the actual association between the two parameters, this study was undertaken.

METHODS

The prevalence of HBV genes in HCC patients was studied using nonisotopic in situ hybridization. Fifty patients from South India were diagnosed with HCC after performing ultrasound-guided fine-needle aspiration biopsies of liver lesions. The diagnosis was confirmed by cell block studies. Sections cut from paraffin-embedded cell blocks made out of the aspirates were probed with digoxigenin-labeled surface, core, and X regions of the viral genome.

RESULTS

Nuclear integration of the surface gene was observed in 100% (50 of 50), the core gene was positive in 94% (47 of 50), and the X gene was present in 98% (49 of 50) of the cases. An episomal form of the virus was not found. Serum hepatitis B surface antigen was positive only in 48% (12 of 25) of the patients screened.

CONCLUSIONS

We found molecular evidence that HBV is an important contributing factor in the etiology of HCC in South India. In HCC, the S gene of the virus was the most prevalent followed by the X and C genes. Only integrated forms of the viral DNA were observed. Nonisotopic in situ hybridization using multiple regions of the viral genome is a good technique for studying this association. It has an added advantage over polymerase chain reaction, of localization of signals in a tumor cell. Cell blocks made from fine-needle aspirates are ideal for in situ hybridization.