title: Detection of irradiation-induced, membrane heat shock protein 70 (Hsp70) in mouse tumors using Hsp70 Fab fragment.
abstract: OBJECTIVE
  The major stress-inducible heat shock protein 70 (Hsp70) is frequently overexpressed in highly aggressive tumors, and elevated intracellular Hsp70 levels mediate protection against apoptosis. Following therapeutic intervention, such as ionizing irradiation, translocation of cytosolic Hsp70 to the plasma membrane is selectively increased in tumor cells and therefore, membrane Hsp70 might serve as a therapy-inducible, tumor-specific target structure.
  
  
  METHODS
  Based on the IgG1 mouse monoclonal antibody (mAb) cmHsp70.1, we produced the Hsp70-specific recombinant Fab fragment (Hsp70 Fab), as an imaging tool for the detection of membrane Hsp70 positive tumor cells in vitro and in vivo.
  
  
  RESULTS
  The binding characteristics of Hsp70 Fab towards mouse colon (CT26) and pancreatic (1048) carcinoma cells at 4 °C were comparable to that of cmHsp70.1 mAb, as determined by flow cytometry. Following a temperature shift to 37 °C, Hsp70 Fab rapidly translocates into subcellular vesicles of mouse tumor cells. Furthermore, in tumor-bearing mice Cy5.5-conjugated Hsp70 Fab, but not unrelated IN-1 control Fab fragment (IN-1 ctrl Fab), gradually accumulates in CT26 tumors between 12 and 55 h after i.v. injection.
  
  
  CONCLUSIONS
  In summary, the Hsp70 Fab provides an innovative, low immunogenic tool for imaging of membrane Hsp70 positive tumors, in vivo.
authors.affiliation: Dept. of Radiation Oncology, TU München and Helmholtz Zentrum München (HMGU), CCG-Innate Immunity in Tumor Biology, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Stangl
authors.forename: George
authors.initials: G
authors.lastname: Themelis
authors.forename: Lars
authors.initials: L
authors.lastname: Friedrich
authors.forename: Vasilis
authors.initials: V
authors.lastname: Ntziachristos
authors.forename: Athanasios
authors.initials: A
authors.lastname: Sarantopoulos
authors.forename: Michael
authors.initials: M
authors.lastname: Molls
authors.forename: Arne
authors.initials: A
authors.lastname: Skerra
authors.forename: Gabriele
authors.initials: G
authors.lastname: Multhoff
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D002453:Cell Cycle / Q000528:radiation effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000532:radiotherapy; D003602:Cytotoxicity, Immunologic / Q000276:immunology / Q000528:radiation effects; D004195:Disease Models, Animal; D005260:Female; D005434:Flow Cytometry; D018840:HSP70 Heat-Shock Proteins / Q000276:immunology / Q000378:metabolism*; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D010190:Pancreatic Neoplasms / Q000378:metabolism* / Q000532:radiotherapy
chemical_list: D018840:HSP70 Heat-Shock Proteins; D007140:Immunoglobulin Fab Fragments