title: Specific targeting to murine myeloma cells of Cyt1Aa toxin from Bacillus thuringiensis subspecies israelensis.
abstract: Multiple myeloma is currently an incurable cancer of plasma B cells often characterized by overproduction of abnormally high quantities of a patient-specific, clonotypic immunoglobulin "M-protein." The M-protein is expressed on the cell membrane and secreted into the blood. We previously showed that ligand-toxin conjugates (LTC) incorporating the ribosome-inactivating Ricin-A toxin were very effective in specific cytolysis of the anti-ligand antibody-bearing target cells used as models for multiple myeloma. Here, we report on the incorporation of the membrane-disruptive Cyt1Aa toxin from Bacillus thuringiensis subsp. israelensis into LTCs targeted to murine myeloma cells. Proteolytically activated Cyt1Aa was conjugated chemically or genetically through either its amino or carboxyl termini to the major peptidic epitope VHFFKNIVTPRTP (p87-99) of the myelin basic protein. The recombinant fusion-encoding genes were cloned and expressed in acrystalliferous B. thuringiensis subsp. israelensis through the shuttle vector pHT315. Both chemically conjugated and genetically fused LTCs were toxic to anti-myelin basic protein-expressing murine hybridoma cells, but the recombinant conjugates were more active. LTCs comprising the Cyt1Aa toxin might be useful anticancer agents. As a membrane-acting toxin, Cyt1Aa is not likely to induce development of resistant cell lines.
authors.affiliation: Department of Life Sciences, Ben-Gurion University of the Negev, P. O. 653, Be'er-Sheva 84105, Israel; Department of Chemical Engineering and Biotechnology, College of Judea and Samaria, Ariel 44837, Israel.
authors.forename: Shmuel
authors.initials: S
authors.lastname: Cohen
authors.affiliation: Department of Chemical Engineering and Biotechnology, College of Judea and Samaria, Ariel 44837, Israel.
authors.forename: Rivka
authors.initials: R
authors.lastname: Cahan
authors.affiliation: Department of Life Sciences, Ben-Gurion University of the Negev, P. O. 653, Be'er-Sheva 84105, Israel; Achva Academic College, MP Shikmim 79800, Israel.
authors.forename: Eitan
authors.initials: E
authors.lastname: Ben-Dov
authors.affiliation: Department of Chemical Engineering and Biotechnology, College of Judea and Samaria, Ariel 44837, Israel.
authors.forename: Marina
authors.initials: M
authors.lastname: Nisnevitch
authors.affiliation: Department of Life Sciences, Ben-Gurion University of the Negev, P. O. 653, Be'er-Sheva 84105, Israel.
authors.forename: Arieh
authors.initials: A
authors.lastname: Zaritsky
authors.affiliation: Department of Chemical Engineering and Biotechnology, College of Judea and Samaria, Ariel 44837, Israel. Electronic address: firer@research.yosh.ac.il.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Firer
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000970:Antineoplastic Agents / Q000737:chemistry / Q000276:immunology* / Q000627:therapeutic use; D001413:Bacillus thuringiensis / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D001427:Bacterial Toxins / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000276:immunology; D004731:Endotoxins / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D015870:Gene Expression; D006460:Hemolysin Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D006825:Hybridomas; D000922:Immunotoxins / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D008024:Ligands; D051379:Mice; D008954:Models, Biological; D009101:Multiple Myeloma / Q000188:drug therapy / Q000276:immunology*; D004676:Myelin Basic Protein / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D009194:Myeloma Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology*; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D012276:Ricin / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000627:therapeutic use
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D000922:Immunotoxins; D008024:Ligands; D004676:Myelin Basic Protein; D009194:Myeloma Proteins; D010455:Peptides; D011993:Recombinant Fusion Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis; C085016:multiple myeloma M-proteins; D012276:Ricin