title: Molecular therapy targeting Sonic hedgehog and hepatocyte growth factor signaling in a mouse model of medulloblastoma.
abstract: The use of genetically engineered mice has provided insights into the molecular pathogenesis of the pediatric brain tumor medulloblastoma and revealed promising therapeutic targets. Ectopic expression of Sonic hedgehog (Shh) in cerebellar neural progenitor cells induces medulloblastomas in mice, and coexpression of hepatocyte growth factor (HGF) enhances Shh-induced tumor formation. To determine whether Shh + HGF-driven medulloblastomas were responsive to Shh signaling blockade and whether treatment response could be enhanced by combination therapy targeting both HGF and Shh signaling pathways, we carried out a survival study in mice. We induced medulloblastomas by retrovirus-mediated expression of Shh and HGF, after which we treated the mice systemically with (a) HGF-neutralizing monoclonal antibody L2G7, (b) Shh signaling inhibitor cyclopamine, (c) Shh-neutralizing monoclonal antibody 5E1, (d) L2G7 + cyclopamine, or (e) L2G7 + 5E1. We report that monotherapy targeting either HGF signaling or Shh signaling prolonged survival and that anti-HGF therapy had a more durable response than Shh-targeted therapy. The effect of L2G7 + 5E1 combination therapy on cumulative survival was equivalent to that of L2G7 monotherapy and that of L2G7 + cyclopamine therapy was worse. The principal mechanism by which Shh- and HGF-targeted therapies inhibited tumor growth was a potent apoptotic death response in tumor cells, supplemented by a weaker suppressive effect on proliferation. Our observation that combination therapy either failed to improve or even reduced survival in mice bearing Shh + HGF-induced medulloblastomas compared with monotherapy underscores the importance of preclinical testing of molecular-targeted therapies in animal models of tumors in which the targeted pathways are known to be active.
authors.affiliation: Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah 84132, USA.
authors.forename: Valerie
authors.initials: V
authors.lastname: Coon
authors.forename: Tamara
authors.initials: T
authors.lastname: Laukert
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Pedone
authors.forename: John
authors.initials: J
authors.lastname: Laterra
authors.forename: K Jin
authors.initials: KJ
authors.lastname: Kim
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Fults
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D048708:Cell Growth Processes / Q000187:drug effects; D004195:Disease Models, Animal; D053823:Hedgehog Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D017228:Hepatocyte Growth Factor / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008527:Medulloblastoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D058990:Molecular Targeted Therapy / Q000379:methods; D015398:Signal Transduction / Q000187:drug effects; D014704:Veratrum Alkaloids / Q000494:pharmacology
chemical_list: D053823:Hedgehog Proteins; D014704:Veratrum Alkaloids; D017228:Hepatocyte Growth Factor; C000541:cyclopamine
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