title: Modeling pharmacological inhibition of mast cell degranulation as a therapy for insulinoma.
abstract: Myc, a pleiotropic transcription factor that is deregulated and/or overexpressed in most human cancers, instructs multiple extracellular programs that are required to sustain the complex microenvironment needed for tumor maintenance, including remodeling of tumor stroma, angiogenesis, and inflammation. We previously showed in a model of pancreatic β-cell tumorigenesis that acute Myc activation in vivo triggers rapid recruitment of mast cells to the tumor site and that this is absolutely required for angiogenesis and macroscopic tumor expansion. Moreover, systemic inhibition of mast cell degranulation with sodium cromoglycate induced death of tumor and endothelial cells in established tumors. Hence, mast cells are required both to establish and to maintain the tumors. Whereas this intimates that selective inhibition of mast cell function could be therapeutically efficacious, cromoglycate is not a practical drug for systemic delivery in humans, and no other systemic inhibitor of mast cell degranulation has hitherto been available. PCI-32765 is a novel inhibitor of Bruton tyrosine kinase (Btk) that blocks mast cell degranulation and is currently in clinical trial as a therapy for B-cell non-Hodgkin lymphoma. Here, we show that systemic treatment of insulinoma-bearing mice with PCI-32765 efficiently inhibits Btk, blocks mast cell degranulation, and triggers collapse of tumor vasculature and tumor regression. These data reinforce the notion that mast cell function is required for maintenance of certain tumor types and indicate that the Btk inhibitor PCI-32765 may be useful in treating such diseases.
authors: Department of Pathology, University of California San Francisco, San Francisco, CA, USA.
authors: Laura
authors: L
authors: Soucek
authors: Joseph J
authors: JJ
authors: Buggy
authors: Roderik
authors: R
authors: Kortlever
authors: Shanthi
authors: S
authors: Adimoolam
authors: Helena Allende
authors: HA
authors: Monclús
authors: Maria Teresa Salcedo
authors: MT
authors: Allende
authors: Lamorna Brown
authors: LB
authors: Swigart
authors: Gerard I
authors: GI
authors: Evan
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives; D000077329:Agammaglobulinaemia Tyrosine Kinase; D000818:Animals; D015550:Cell Degranulation / Q000187:drug effects* / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000473:pathology; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000187:drug effects; D016259:Genes, myc; D007340:Insulinoma / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D008407:Mast Cells / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D008962:Models, Theoretical; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D010880:Piperidines; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology* / Q000627:therapeutic use*; D011743:Pyrimidines / Q000494:pharmacology* / Q000627:therapeutic use*; D014407:Tumor Cells, Cultured
chemical_list: D010880:Piperidines; D011720:Pyrazoles; D011743:Pyrimidines; C551803:ibrutinib; D011505:Protein-Tyrosine Kinases; D000077329:Agammaglobulinaemia Tyrosine Kinase; C000625949:BTK protein, human; C000625951:Btk protein, mouse; D000225:Adenine