title: Proliferative activity and in vitro replication of HSV1716 in human metastatic brain tumours.
abstract: BACKGROUND
  The neurotropic herpes simplex virus mutant HSV1716 lacks the gene encoding the virulence factor ICP34.5 and cannot replicate in non-dividing cells where proliferating cell nuclear antigen (PCNA) is not actively engaged in cellular DNA synthesis. In the brain, tumoral expression of PCNA therefore confers on it oncolytic specificity and may determine its efficacy. Three phase I trials in glioma patients and one in metastatic melanoma patients have established that HSV1716 is safe and replicates selectively in tumour tissue. Here we examine the in situ PCNA profiles of common human metastatic brain tumours and determine their in vitro permissivity for HSV1716 replication to ascertain their suitability for HSV1716 therapy.
  
  
  METHODS
  Histological sections of tumour biopsies obtained from patients undergoing craniotomies were stained for PCNA expression. The replicative ability of HSV wild-type (17(+)) and mutant (1716) viruses was assessed in tissue cultures of the same tumour biopsies and in cancer cell lines by plaque assay.
  
  
  RESULTS
  Biopsies of all 10 metastatic tumours (3 melanoma, 4 carcinoma and 3 adenocarcinoma) as well as 4 glioblastoma multiforme were positive for PCNA immunoexpression and supported the replication of HSV1716. The PCNA-positive cells in the metastatic tumours were distributed comparatively in larger and more contiguous areas than in glioblastoma (1.69 +/- 1.61 mm(2) vs. 0.73 +/- 0.77 mm(2)) and numbered 29.0 +/- 12.4 and 12.6 +/- 4.7%, respectively.
  
  
  CONCLUSIONS
  The results show that human cerebral metastatic tumours have generally larger and more contiguous proliferative areas, support efficient HSV1716 replication, and are thus potential candidates for such oncolytic viral therapy.
authors.affiliation: Department of Neurosurgery, The University of Birmingham, Queen Elizabeth Neuroscience Centre, Edgbaston, Birmingham B15 2TH, UK.
authors.forename: Allah
authors.initials: A
authors.lastname: Detta
authors.forename: June
authors.initials: J
authors.lastname: Harland
authors.forename: Isma
authors.initials: I
authors.lastname: Hanif
authors.forename: S Moira
authors.initials: SM
authors.lastname: Brown
authors.forename: Garth
authors.initials: G
authors.lastname: Cruickshank
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology* / Q000628:therapy; D045744:Cell Line, Tumor; D005260:Female; D015316:Genetic Therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D018139:Simplexvirus / Q000502:physiology*; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism; D014779:Virus Replication / Q000502:physiology*
chemical_list: D018809:Proliferating Cell Nuclear Antigen; D037521:Virulence Factors