title: Targeting membrane heat-shock protein 70 (Hsp70) on tumors by cmHsp70.1 antibody.
abstract: Immunization of mice with a 14-mer peptide TKDNNLLGRFELSG, termed "TKD," comprising amino acids 450-461 (aa(450-461)) in the C terminus of inducible Hsp70, resulted in the generation of an IgG1 mouse mAb cmHsp70.1. The epitope recognized by cmHsp70.1 mAb, which has been confirmed to be located in the TKD sequence by SPOT analysis, is frequently detectable on the cell surface of human and mouse tumors, but not on isogenic cells and normal tissues, and membrane Hsp70 might thus serve as a tumor-specific target structure. As shown for human tumors, Hsp70 is associated with cholesterol-rich microdomains in the plasma membrane of mouse tumors. Herein, we show that the cmHsp70.1 mAb can selectively induce antibody-dependent cellular cytotoxicity (ADCC) of membrane Hsp70(+) mouse tumor cells by unstimulated mouse spleen cells. Tumor killing could be further enhanced by activating the effector cells with TKD and IL-2. Three consecutive injections of the cmHsp70.1 mAb into mice bearing CT26 tumors significantly inhibited tumor growth and enhanced the overall survival. These effects were associated with infiltrations of NK cells, macrophages, and granulocytes. The Hsp70 specificity of the ADCC response was confirmed by preventing the antitumor response in tumor-bearing mice by coinjecting the cognate TKD peptide with the cmHsp70.1 mAb, and by blocking the binding of cmHsp70.1 mAb to CT26 tumor cells using either TKD peptide or the C-terminal substrate-binding domain of Hsp70.
authors.affiliation: Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, and Clinical Cooperation Group Innate Immunity in Tumor Biology, 81675 Munich, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Stangl
authors.forename: Mathias
authors.initials: M
authors.lastname: Gehrmann
authors.forename: Julia
authors.initials: J
authors.lastname: Riegger
authors.forename: Kristin
authors.initials: K
authors.lastname: Kuhs
authors.forename: Isabelle
authors.initials: I
authors.lastname: Riederer
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Sievert
authors.forename: Kathrin
authors.initials: K
authors.lastname: Hube
authors.forename: Ralph
authors.initials: R
authors.lastname: Mocikat
authors.forename: Ralf
authors.initials: R
authors.lastname: Dressel
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Kremmer
authors.forename: Alan G
authors.initials: AG
authors.lastname: Pockley
authors.forename: Lars
authors.initials: L
authors.lastname: Friedrich
authors.forename: Laszlo
authors.initials: L
authors.lastname: Vigh
authors.forename: Arne
authors.initials: A
authors.lastname: Skerra
authors.forename: Gabriele
authors.initials: G
authors.lastname: Multhoff
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry; D045744:Cell Line, Tumor; D002784:Cholesterol / Q000737:chemistry; D006098:Granulocytes / Q000166:cytology; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry*; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism; D007694:Killer Cells, Natural / Q000166:cytology; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009368:Neoplasm Transplantation; D011485:Protein Binding; D017434:Protein Structure, Tertiary
chemical_list: D000911:Antibodies, Monoclonal; D018840:HSP70 Heat-Shock Proteins; D007376:Interleukin-2; C081884:heat-shock protein 70.1; D002784:Cholesterol