title: On-target JAK2/STAT3 inhibition slows disease progression in orthotopic xenografts of human glioblastoma brain tumor stem cells.
abstract: BACKGROUND
  Glioblastoma multiforme (GBM) is characterized by an aggressive clinical course, therapeutic resistance, and striking molecular heterogeneity. GBM-derived brain tumor stem cells (BTSCs) closely model this molecular heterogeneity and likely have a key role in tumor recurrence and therapeutic resistance. Emerging evidence indicates that Janus kinase (JAK)2/signal transducer and activator of transcription (STAT)3 is an important mediator of tumor cell survival, growth, and invasion in a large group of GBM. Here, we used a large set of molecularly heterogeneous BTSCs to evaluate the translational potential of JAK2/STAT3 therapeutics.
  
  
  METHODS
  BTSCs were cultured from GBM patients and MGMT promoter methylation, and the mutation statuses of EGFR, PTEN, and TP53 were determined. Endogenous JAK2/STAT3 activity was assessed in human GBM tissue, BTSCs, and orthotopic xenografts by immunohistochemistry and Western blotting. STAT3 short hairpin (sh)RNA, cucurbitacin-I, and WP1066 were used to inhibit JAK2/STAT3 activity in vitro and in vivo.
  
  
  RESULTS
  The JAK2/STAT3 pathway was demonstrated to be highly activated in human GBM, molecularly heterogeneous BTSCs derived from these tumors, and BTSC xenografts. STAT3 shRNA knockdown or cucurbitacin-I and WP1066 administration resulted in on-target JAK2/STAT3 inhibition and dramatically reduced BTSC survival regardless of endogenous MGMT promoter methylation or EGFR, PTEN, and TP53 mutational status. BTSC orthotopic xenografts maintained the high levels of activated JAK2/STAT3 seen in their parent human tumors. Intraperitoneal WP1066 reduced intratumoral JAK2/STAT3 activity and prolonged animal survival.
  
  
  CONCLUSIONS
  Our study demonstrates the in vitro and in vivo efficacy of on-target JAK2/STAT3 inhibition in heterogeneous BTSC lines that closely emulate the genomic and tumorigenic characteristics of human GBM.
authors.affiliation: Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Owen D
authors.initials: OD
authors.lastname: Stechishin
authors.forename: H Artee
authors.initials: HA
authors.lastname: Luchman
authors.forename: Yibing
authors.initials: Y
authors.lastname: Ruan
authors.forename: Michael D
authors.initials: MD
authors.lastname: Blough
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Nguyen
authors.forename: John J
authors.initials: JJ
authors.lastname: Kelly
authors.forename: J Gregory
authors.initials: JG
authors.lastname: Cairncross
authors.forename: Samuel
authors.initials: S
authors.lastname: Weiss
mesh_terms: D000368:Aged; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D049109:Cell Proliferation; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000235:genetics; D045643:DNA Repair Enzymes / Q000235:genetics; D018450:Disease Progression; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D005909:Glioblastoma / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D006801:Humans; D007124:Immunoenzyme Techniques; D053614:Janus Kinase 2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008875:Middle Aged; D014411:Neoplastic Stem Cells / Q000378:metabolism / Q000473:pathology*; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011725:Pyridines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014315:Triterpenes / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics; D020032:Tyrphostins / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
chemical_list: D011725:Pyridines; D034741:RNA, Small Interfering; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C495901:TP53 protein, human; D014315:Triterpenes; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D020032:Tyrphostins; C519885:WP1066; D015254:DNA Modification Methylases; C515491:MGMT protein, human; C512478:EGFR protein, human; D066246:ErbB Receptors; C507924:JAK2 protein, human; D053614:Janus Kinase 2; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D045643:DNA Repair Enzymes; C038106:cucurbitacin I