title: Immunotherapeutic targeting of membrane Hsp70-expressing tumors using recombinant human granzyme B.
abstract: BACKGROUND
  We have previously reported that human recombinant granzyme B (grB) mediates apoptosis in membrane heat shock protein 70 (Hsp70)-positive tumor cells in a perforin-independent manner.
  
  
  RESULTS
  Optical imaging of uptake kinetics revealed co-localization of grB with recycling endosomes (Rab9/11) as early as 5 min after internalization, with late endosomes (Rab7) after 30 min, and the lysosomal compartment (LAMP1/2) after 60 to 120 min. Active caspase-3-mediated apoptosis was induced in mouse CT26 monolayer cells and 3D tumor spheroids, but not in normal mouse endothelial cells. Granzyme B selectively reduced the proportion of membrane Hsp70-positive cells in CT26 tumor spheroids. Consecutive i.v. injections of recombinant human grB into mice bearing membrane Hsp70-positive CT26 tumors resulted in significant tumor suppression, and a detailed inspection of normal mouse organs revealed that the administration of anti-tumoral concentrations of grB elicited no clinicopathological changes.
  
  
  CONCLUSIONS
  These findings support the future clinical evaluation of human grB as a potential adjuvant therapeutic agent, especially for treating immunosuppressed patients that bear membrane Hsp70-positive tumors.
authors: Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, and Clinical Cooperation Group (CCG) "Innate Immunity in Tumor Biology", Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt, Munich, Germany.
authors: Mathias
authors: M
authors: Gehrmann
authors: Stefan
authors: S
authors: Stangl
authors: Andreas
authors: A
authors: Kirschner
authors: Gemma A
authors: GA
authors: Foulds
authors: Wolfgang
authors: W
authors: Sievert
authors: Brigitte T
authors: BT
authors: Doss
authors: Axel
authors: A
authors: Walch
authors: Alan G
authors: AG
authors: Pockley
authors: Gabriele
authors: G
authors: Multhoff
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002166:Camptothecin / Q000378:metabolism; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects; D005434:Flow Cytometry; D053804:Granzymes / Q000494:pharmacology / Q000627:therapeutic use*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008807:Mice, Inbred BALB C; D018613:Microscopy, Confocal; D011994:Recombinant Proteins / Q000494:pharmacology / Q000627:therapeutic use; D023041:Xenograft Model Antitumor Assays
chemical_list: D018840:HSP70 Heat-Shock Proteins; D011994:Recombinant Proteins; D053804:Granzymes; D002166:Camptothecin