Heat shock protein 70 surface-positive tumor exosomes stimulate migratory and cytolytic activity of natural killer cells

• Published in: Cancer research (Chicago, Ill.) Vol. 65; no. 12; pp. 5238 - 5247
• Main Authors: GASTPAR, Robert, GEHRMANN, Mathias, BAUSERO, Maria A, ASEA, Alexzander, GROSS, Catharina, SCHROEDER, Josef A, MULTHOFF, Gabriele
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 15.06.2005
• Subjects: Adaptor Proteins, Signal Transducing - immunology; Adaptor Proteins, Signal Transducing - metabolism; Adaptor Proteins, Signal Transducing - secretion; Amino Acid Sequence; Antineoplastic agents; Biological and medical sciences; Cell Line, Tumor; Cell Membrane - metabolism; Cell Movement - immunology; Colonic Neoplasms - immunology; Colonic Neoplasms - metabolism; Colonic Neoplasms - pathology; Colonic Neoplasms - secretion; Cytoplasmic Vesicles - immunology; Cytoplasmic Vesicles - metabolism; Cytoplasmic Vesicles - secretion; Cytotoxicity, Immunologic; Granzymes; HSP70 Heat-Shock Proteins - immunology; HSP70 Heat-Shock Proteins - secretion; Humans; Killer Cells, Natural - immunology; Medical sciences; Pancreatic Neoplasms - immunology; Pancreatic Neoplasms - metabolism; Pancreatic Neoplasms - pathology; Pancreatic Neoplasms - secretion; Peptide Fragments - pharmacology; Pharmacology. Drug treatments; Serine Endopeptidases - immunology; Serine Endopeptidases - metabolism; Serine Endopeptidases - secretion; Tumors; Natural killer cell; Migratory; Exosome; Heat shock protein; Activity; Heat shock protein 70; Malignant tumor
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/0008-5472.can-04-3804

Detergent-soluble membrane vesicles are actively released by human pancreas (Colo-/Colo+) and colon (CX-/CX+) carcinoma sublines, differing in their capacity to present heat shock protein 70 (Hsp70)/Bag-4 on their plasma membranes. Floating properties, acetylcholine esterase activity, and protein composition characterized them as exosomes. An enrichment of Rab-4 documented their intracellular transport route from early endosomes to the plasma membrane. After solubilization, comparable amounts of cytosolic proteins, including tubulin, Hsp70, Hsc70, and Bag-4, but not ER-residing Grp94 and calnexin, were detectable in tumor-derived exosomes. However, with respect to the exosomal surface, only Colo+/CX+ but not Colo-/CX- derived exosomes were Hsp70 membrane positive. Therefore, concomitant with an up-regulated cell surface density of activation markers, migration and Hsp70 reactivity of natural killer (NK) cells was stimulated selectively by Hsp70/Bag-4 surface-positive exosomes, but not by their negative counterparts and tumor cell lysates. Moreover, the exosome-mediated lytic activity of NK cells was blockable by Hsp70-specific antibody. As already shown for TKD stimulation, NK cells preincubated with Hsp70 surface-positive exosomes initiated apoptosis in tumors through granzyme B release. In summary, our data provide an explanation how Hsp70 reactivity in NK cells is induced by tumor-derived exosomes.