title: An anti-transferrin receptor-avidin fusion protein exhibits both strong proapoptotic activity and the ability to deliver various molecules into cancer cells.
abstract: We have developed an antibody fusion protein (anti-rat TfR IgG3-Av) with the ability to deliver different molecules into cancer cells. It consists of avidin genetically fused to the C(H)3 region of a human IgG3 specific for the rat transferrin receptor. It forms strong, noncovalent interactions with biotinylated molecules such as glucose oxidase and beta-galactosidase, and delivers them into the rat myeloma cell line Y3-Ag1.2.3 through receptor-mediated endocytosis. Importantly, the beta-galactosidase retains activity after internalization. Furthermore, we have unexpectedly discovered that anti-rat TfR IgG3-Av, but not a recombinant anti-rat TfR IgG3 or a nonspecific IgG3-Av, possesses proapoptotic activities against Y3-Ag1.2.3 and the rat T cell lymphoma cell line C58 (NT) D.1.G.OVAR.1. These activities were not observed in two rat cell lines of nonhematopoietic lineage (bladder carcinoma BC47 and gliosarcoma 9L). Anti-human TfR IgG3-Av also demonstrated proapoptotic activity against the human erythroleukemia cell line K562. Studies showed that anti-rat TfR IgG3-Av exists as a dimer, suggesting that cross-linking of the surface transferrin receptor may be responsible for the cytotoxic activity. These findings demonstrate that it is possible to transform an antibody specific for a growth factor receptor that does not exhibit inhibitory activity into a drug with significant intrinsic cytotoxic activity against selected cells by fusing it with avidin. The antitumor activity may be enhanced by delivering biotinylated therapeutics into cancer cells. Further development of this technology may lead to effective therapeutics for in vivo eradication of hematological malignancies, and ex vivo purging of cancer cells in autologous transplantation.
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics and Molecular Biology Institute, University of California, Los Angeles, CA 90095-1489, USA.
authors.forename: Patrick P
authors.initials: PP
authors.lastname: Ng
authors.forename: Jay S
authors.initials: JS
authors.lastname: Dela Cruz
authors.forename: David N
authors.initials: DN
authors.lastname: Sorour
authors.forename: James M
authors.initials: JM
authors.lastname: Stinebaugh
authors.forename: Seung-Uon
authors.initials: SU
authors.lastname: Shin
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Shin
authors.forename: Sherie L
authors.initials: SL
authors.lastname: Morrison
authors.forename: Manuel L
authors.initials: ML
authors.lastname: Penichet
mesh_terms: D000818:Animals; D000906:Antibodies / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000378:metabolism / Q000494:pharmacology; D017209:Apoptosis; D001360:Avidin / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D001710:Biotin; D002455:Cell Division; D003432:Cross-Linking Reagents; D019281:Dimerization; D016503:Drug Delivery Systems; D004705:Endocytosis; D016650:Fluorescein-5-isothiocyanate / Q000008:administration & dosage; D005949:Glucose Oxidase / Q000378:metabolism; D006801:Humans; D018796:Immunoconjugates / Q000008:administration & dosage / Q000494:pharmacology*; D007074:Immunoglobulin G / Q000235:genetics / Q000378:metabolism; D020014:K562 Cells; D051381:Rats; D011990:Receptors, Transferrin / Q000008:administration & dosage / Q000276:immunology / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D000906:Antibodies; D000970:Antineoplastic Agents; D003432:Cross-Linking Reagents; D018796:Immunoconjugates; D007074:Immunoglobulin G; D011990:Receptors, Transferrin; D011993:Recombinant Fusion Proteins; D001360:Avidin; D001710:Biotin; D005949:Glucose Oxidase; D016650:Fluorescein-5-isothiocyanate