title: Expression of a human polyomavirus oncoprotein and tumour suppressor proteins in medulloblastomas.
abstract: OBJECTIVE
  Although the aetiology of medulloblastoma remains elusive, several lines of evidence suggest an association with the human neurotropic polyomavirus JC and its oncoprotein T antigen. The tumour forming properties of JC virus T antigen are the result, at least in part, of its ability to bind and inactivate tumour suppressor/cell cycle regulatory proteins, such as p53 and the retinoblastoma family of proteins.
  
  
  METHODS
  To examine potential relations between these factors, immunohistochemistry was used to determine associations between the T antigen and the expression of p53 and the retinoblastoma proteins pRb, p107, and Rb2/p130 in eight medulloblastomas.
  
  
  RESULTS
  Only the three medulloblastomas with T antigen expression also showed nuclear positivity with antibodies to p53. Although immunohistochemistry detected nuclear labelling for pRb in five of the cases, the three that were positive for T antigen showed the highest pRb labelling. The retinoblastoma related proteins p107 and Rb2/p130 were also immunopositive in most T antigen positive medulloblastomas. Double label immunohistochemistry also demonstrated p53 and pRb positivity in the same cells that were T antigen positive.
  
  
  CONCLUSIONS
  These correlations suggest that associations between T antigen and p53 and/or T antigen and pRb occur in some of these tumours. These data provide indirect evidence that JC virus, acting through T antigen, might be involved in the formation and progression of medulloblastoma.
authors.affiliation: The Center for NeuroVirology and Cancer Biology, Temple University, Philadelphia, PA 19122, USA.
authors.forename: L
authors.initials: L
authors.lastname: Del Valle
authors.forename: J
authors.initials: J
authors.lastname: Baehring
authors.forename: C
authors.initials: C
authors.lastname: Lorenzana
authors.forename: A
authors.initials: A
authors.lastname: Giordano
authors.forename: K
authors.initials: K
authors.lastname: Khalili
authors.forename: S
authors.initials: S
authors.lastname: Croul
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism*; D016022:Case-Control Studies; D002528:Cerebellar Neoplasms / Q000378:metabolism* / Q000821:virology; D002648:Child; D002675:Child, Preschool; D005260:Female; D005656:Fungal Proteins; D016147:Genes, Tumor Suppressor / Q000502:physiology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007577:JC Virus / Q000276:immunology; D008297:Male; D008527:Medulloblastoma / Q000378:metabolism* / Q000821:virology; D008875:Middle Aged; D009687:Nuclear Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011506:Proteins; D050720:Retinoblastoma-Like Protein p107; D050717:Retinoblastoma-Like Protein p130; D012697:Serine Endopeptidases / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D000952:Antigens, Polyomavirus Transforming; D005656:Fungal Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011506:Proteins; C493844:RBL1 protein, human; C493837:RBL2 protein, human; D050720:Retinoblastoma-Like Protein p107; D050717:Retinoblastoma-Like Protein p130; D016159:Tumor Suppressor Protein p53; D012697:Serine Endopeptidases