JC virus and its possible role in oncogenesis

JC virus existence in Chinese gastrointestinal carcinomas

The John Cunningham virus (JCV) infects a large proportion of the population worldwide and may cause progressive multifocal leukoencephalopathy upon immunodeficiency. Recent reports provided evidence of its oncogenetic role in malignancies. In this study, JCV was examined by targeting T antigen, viral protein and agnoprotein in paraffin-embedded or frozen gastrointestinal carcinomas and paired non-neoplastic mucosa (NNM) samples by nested-PCR followed by Southern blot analysis. In addition, the expression of JCV T antigen, ki-67, caspase-3, p53, Rb and β-catenin was studied by immunohistochemistry on tissue microarrays. The positive rate of JCV T antigen was higher in paraffin-embedded gastrointestinal carcinomas compared to adjacent NNM by nested-PCR followed by Southern blot analysis (36.9 vs. 16.9%, P<0.05), while there was no difference in other viral oncogenes regardless of whether they were paraffin-embedded or frozen samples. Immunohistochemically, T antigen was detectable in 9.6% (13/135) of carcinoma cases, which was higher than its positive rate in NNM (0.8%, 1/126, P<0.01). However, the genomic JCV DNA existence or its T antigen expression was not correlated with age, gender, tumor size, histological types, lymph node metastasis, expression of ki-67, caspase-3, p53, Rb and β-catenin of gastric carcinomas (P>0.05). In conlusion, JCV T antigen may be involved in gastrointestinal carcinogenesis as an oncogene in China.

Mapping the history and current situation of research on John Cunningham virus - a bibliometric analysis

Background

John Cunningham virus (JCV) constitutes a family of polyoma viruses, which plays important roles in the progressive multifocal leukoencephalopathy (PML) and tumorigenesis. However, no bibliometric investigation has been reported to guide the researchers and potential readers.

Methods

Papers were collected from database Sci-expanded and Pubmed until May 22, 2008. The highly-productive authors, institutes and countries, highly-cited authors and journals were ranked. The highly-cited articles were subjected to co-citation and chronological analysis with highly-frequent MeSH words for co-occurrence analysis.

Results

Until now, 1785 articles about JCV were indexed in Sci-expanded and 1506 in Pubmed. The main document type was original article. USA, Japan and Italy were the largest three producers about JCV. Temple University published 128 papers and ranked the top, followed by University of Tokyo. Khalili K and Yogo Y became the core authors due to more than 20 documents produced. Journal of Neurovirology published more than 15 papers and ranked the top. Padgett BL and Berger JR were the first two highly-cited authors. Journal of Virology and Journal of Neurovirology respectively ranked to the first two highly-cited journals. These top highly-cited articles were divided into 5 aspects: (1) The correlation between JC virus and tumors; (2) Causal correlation of JCV with PML; (3) Polyoma virus infection and its related diseases in renal-allograft recipients; (4) Detection of JCV antibody, oncogene and its encoding protein; (5) Genetics and molecular biology of JCV. The MeSH/subheadings were classified into five groups: (1) JCV and virus infectious diseases; (2) JCV pathogenicity and pathological appearance of PML; (3) JCV isolation and detection; (4) Immunology of JCV and PML; (5) JCV genetics and tumors.

Conclusion

JCV investigation mainly focused on its isolation and detection, as well as its correlation with PML and tumors. Establishment of transgenic animal model using JCV T antigen would be a hopeful and useful project in the further study.

High JC virus load in gastric cancer and adjacent non-cancerous mucosa

The JC virus (JCV) infects a large proportion of the worldwide population and approximately 90% of adults are seropositive. Recent reports have described the possibility of its oncogenetic role in several malignancies. The aim of the present study was to assess the oncogenetic significance of JCV for gastric cancer. Twenty-two sample pairs of fresh tumor and adjacent non-cancerous tissue (ANCT) as well as 10 normal gastric mucosa specimens were investigated on the basis of nested polymerase chain reaction (PCR) followed by Southern blotting, DNA direct sequencing, real-time PCR, in situ PCR and immunohistochemistry. The T antigen sequence was detected in 86.4% of gastric cancers and ANCT, and in 100% of the normal mucosa samples, as for virus capsid protein, 54.1%, 68.1% and 70%, respectively. A generally low incidence was noted for agnoprotein. The JCV DNA load was approximately 10-fold higher in both gastric cancers and paired ANCT (4784 +/- 759 and 5394 +/- 1466 copies/microg DNA, respectively) than in normal gastric tissue (542.4 +/- 476.0 copies/microg DNA, P < 0.0001). In situ PCR revealed sporadic JCV genome-positive cancer cells and foveolar epithelial cells. T antigen protein expression assessed by immunohistochemistry was detected only in one case (1/22; 4.5%), probably because the half life of T antigen might be short. It was concluded that the gastric epithelium in most Japanese people is infected with JCV at a low rate but levels of infection are increased markedly in both cancer cells and ANCT, indicating that multiplication of JCV copies might be a risk factor and a background for gastric carcinogenesis.

Oncogenic role of JC virus in lung cancer

The JC virus (JCV) infects a large proportion of the population world wide and can cause progressive multifocal leucoencephalopathy in the context of immunodeficiency. Recent reports provide evidence that it may also be oncogenic. Here, JCV was examined by targeting its T-antigen in lung carcinomas (n=103) and normal lung tissues (n=18) by nested-PCR followed by Southern blot, real-time PCR, immunohistochemistry, in situ hybridization and in situ PCR. Additionally, expression of Ki-67, caspase-3, beta-catenin, p53, and Rb was analysed by immunohistochemistry on tissue microarrays of lung carcinomas. Copy numbers of JCV were compared with clinicopathological features. Normal lung tissue was positive significantly less frequently, and contained a lower copy number of JCV than lung carcinomas (p<0.05), and copies were lower in lung adenocarcinomas than in squamous, small or large cell carcinomas (p<0.05). In situ PCR and immunolabelling revealed JCV positivity in the nuclei of lung carcinoma cells. The JCV copy number correlated closely with sex, and expression of Ki-67 and membrane beta-catenin (p<0.05), but not with age, tumour size, pleural invasion, lymph node metastasis, expression of caspase-3, cytoplasmic beta-catenin, p53 or Rb, prognosis, smoking or cancer family history (p>0.05). Age and UICC staging were independent prognostic factors for lung carcinoma patients. These data suggest that JCV may be involved in lung carcinogenesis, especially in tumour types other than adenocarcinoma. Lung carcinomas with higher JCV copy numbers display high proliferation and down-regulation of cell adhesion mediated by membrane beta-catenin.