title: The treatment of glioblastoma multiforme through activation of microglia and TRAIL induced by rAAV2-mediated IL-12 in a syngeneic rat model.
abstract: BACKGROUND
  Microglial cells are the predominant immune cells in malignant brain tumors, but tumors may release some factors to reduce their defensive functions. Restoration of the anti-cancer function of microglia has been proposed as a treatment modality for glioblastoma. We examined the effect of intra-cranially administered recombinant adeno-associated virus encoding interleukin-12 (rAAV2/IL12) on transfection efficiency, local immune activity and survival in a rat model of glioblastoma multiforme.
  
  
  METHODS
  F344 rats were injected with rAAV2/IL12 and implanted with syngeneic RG2 cells (glioblastoma cell line). Intracerebral interleukin-12 and interferon-γ concentrations were determined by ELISA. Activation of microglia was determined by expressions of ED1 and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) which were evaluated by Western blotting and immunohistochemistry. The proliferation of cancer cells was evaluated with Ki67 immunohistochemistry and apoptosis of cancer cells with TUNEL.
  
  
  RESULTS
  The brains treated with rAAV2/IL-12 maintained high expression of interleukin-12 and interferon-γ for at least two months. In syngeneic tumor model, brains treated with rAAV2/IL12 exhibited more infiltration of activated microglia cells as examined by ED1 and TRAIL stains in the tumor. In addition, the volume of tumor was markedly smaller in AAV2/IL12-treated group and the survival time was significantly longer in this group too.
  
  
  CONCLUSIONS
  The intra-cerebrally administered rAAV2/IL-12 efficiently induces long lasting expression of IL-12, the greater infiltration of activated microglia cells in the tumor associated improved immune reactions, resulting in the inhibited growth of implanted glioblastoma and the increased survival time of these rats.
authors.affiliation: Tzu-Chi University, Hualien, Taiwan. 2Division of Neuro-Oncology, Neuro-Medical Scientific Center, Buddhist Tzu-Chi General Hospital, Hualien, Taiwan.
authors.forename: Tsung-Lang
authors.initials: TL
authors.lastname: Chiu
authors.forename: Mei-Jan
authors.initials: MJ
authors.lastname: Wang
authors.forename: Chin-Cheng
authors.initials: CC
authors.lastname: Su
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D000229:Dependovirus; D004195:Disease Models, Animal; D015972:Gene Expression Regulation, Neoplastic; D015316:Genetic Therapy; D005909:Glioblastoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D006801:Humans; D018664:Interleukin-12 / Q000096:biosynthesis* / Q000235:genetics; D008297:Male; D017628:Microglia / Q000378:metabolism / Q000473:pathology*; D009368:Neoplasm Transplantation; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D011916:Rats, Inbred F344; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000096:biosynthesis* / Q000235:genetics; D014161:Transduction, Genetic; D014185:Transplantation, Isogeneic
chemical_list: D009419:Nerve Tissue Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505655:Tnfsf10 protein, rat; D018664:Interleukin-12