title: [Preclinical studies on thymidine kinase gene (TK) and gancyclovir system for treatment of malignant astrocytoma].
abstract: OBJECTIVE
  To study preclinically TK gene mediated GCV system for treatment of human malignant astrocytoma.
  
  
  METHODS
  The TK gene (TKc) was isolated from a Chinese strain of HSV-1 (17) and sequenced. A retroviral vector with TKc (pLTKcSN) and its package cell line (pLTKcSN/VPC) were constructed. The in vitro assay for its activity was performed by mixed cultures of TK producer cells and rat glioma C6 cells after treatment with GCV. The in vivo efficacy was examined by in situ inoculation of virus-producer cells after intracerebral implantation of C6 cells. Safety tests were analyzed by inoculation of pLTKcSN/VPC and injection of GCV, in mouse, rat, and Rhesus monkey, evaluated by histopathological examination and in situ hybridization with TK probe.
  
  
  RESULTS
  TKc gene contained 5 nucleotide difference covering 2 amino acid variation. The retroviral vector pLTKcSN and its producer cell pLTKcSN/VPC (with a titer at 0.5-1.0 x 10(6) CFU/ml) can efficiently mediate cytotoxicity of GCV to C6 cells, both in vitro and in vivo. The above system had no serious adverse effect and remarkable or irreversible pathological changes in 48 mice, 24 rats and 6 Rhesus monkeys.
  
  
  CONCLUSIONS
  The preclinical studies indicated that it would be effective and safe for clinical trial after approval.
authors.affiliation: National Laboratory for Oncogenes and Related Genes, Shanghai Cancer Institute.
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: Z
authors.initials: Z
authors.lastname: Guo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001254:Astrocytoma / Q000628:therapy*; D001932:Brain Neoplasms / Q000628:therapy*; D003602:Cytotoxicity, Immunologic; D004353:Drug Evaluation, Preclinical; D015774:Ganciclovir / Q000627:therapeutic use*; D015316:Genetic Therapy; D018259:Herpesvirus 1, Human / Q000235:genetics*; D008253:Macaca mulatta; D051379:Mice; D008969:Molecular Sequence Data; D051381:Rats; D013937:Thymidine Kinase / Q000737:chemistry / Q000235:genetics*
chemical_list: D013937:Thymidine Kinase; D015774:Ganciclovir