title: Antitumor response elicited by a superantigen-transmembrane sequence fusion protein anchored onto tumor cells.
abstract: Superantigens stimulate T cells bearing certain TCR beta-chain variable regions when bound to MHC II molecules. We investigated whether the superantigen toxic shock syndrome toxin-1 (TSST1) could induce an antitumor immune response when anchored onto MHC II-negative tumor cells. Our approach was to facilitate association of TSST1 with cell membranes by fusing its coding region to the transmembrane region (TM) sequence of the proto-oncogene c-erb-B-2. TSST1-TM was expressed in bacteria with an N-terminal histidine tag and purified using nickel-agarose affinity chromatography. Purified TSST1-TM added to cultures of several different MHC II-negative tumor cells spontaneously associated with cell membranes, as detected by flow cytometry. Because superantigens can direct cell-mediated cytotoxicity against MHC II-positive cells, a TM fusion protein lacking the TSST1 MHC II binding domain (TSST(88-194)-TM) was also constructed. Tumor cells precoated with TSST1-TM or TSST(88-194)-TM stimulated proliferation of human peripheral blood lymphocytes in vitro whereas uncoated tumor cells did not. Mice preimmunized with TSST1-TM- or TSST(88-194)-TM-coated tumor cells mounted a systemic response that resulted in significant antitumor immunity as measured by regression of a parental tumor challenge. TSST1-TM and TSST(88-194)-TM fusion proteins represent a useful new strategy for attaching superantigens or potentially other proteins onto tumor cell surfaces without genetic manipulation.
authors.affiliation: Department of Pharmacology, University of Minnesota, Minneapolis 55455, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Wahlsten
authors.forename: C D
authors.initials: CD
authors.lastname: Mills
authors.forename: S
authors.initials: S
authors.lastname: Ramakrishnan
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D000954:Antigens, Surface / Q000737:chemistry / Q000276:immunology*; D001427:Bacterial Toxins; D019496:Cancer Vaccines; D018827:Carcinoma, Lewis Lung / Q000276:immunology* / Q000473:pathology; D003602:Cytotoxicity, Immunologic; D004768:Enterotoxins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D005260:Female; D006681:HLA-D Antigens / Q000032:analysis; D006801:Humans; D007114:Immunization; D008213:Lymphocyte Activation; D016399:Lymphoma, T-Cell / Q000276:immunology* / Q000473:pathology; D012515:Mast-Cell Sarcoma / Q000276:immunology* / Q000473:pathology; D008565:Membrane Proteins / Q000737:chemistry / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D009368:Neoplasm Transplantation; D010051:Ovarian Neoplasms / Q000276:immunology* / Q000473:pathology; D000090063:Proto-Oncogene Mas; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000276:immunology*; D017384:Sequence Deletion; D013211:Staphylococcus aureus / Q000235:genetics / Q000276:immunology; D018089:Superantigens / Q000235:genetics / Q000276:immunology*; D014407:Tumor Cells, Cultured
chemical_list: D000942:Antigens, Bacterial; D000954:Antigens, Surface; D001427:Bacterial Toxins; D019496:Cancer Vaccines; D004768:Enterotoxins; D006681:HLA-D Antigens; D008565:Membrane Proteins; D000090063:Proto-Oncogene Mas; D018719:Erb-b2 Receptor Tyrosine Kinases; D011993:Recombinant Fusion Proteins; D018089:Superantigens; C000715470:MAS1 protein, human; C030107:enterotoxin F, Staphylococcal