Abstract
The human transferrin receptor (hTfR1) is a membrane-bound protein involved in transferrin (Tf)-mediated iron uptake and is highly expressed on malignant cells. A second version of the receptor (hTfR2) also mediates Tf-dependent iron import. We previously developed a protein composed of avidin fused to a mouse/human chimeric IgG3 specific for hTfR (anti-hTfR IgG3-Av) that was originally designed to deliver biotinylated drugs into cancer cells. We have now found that anti-hTfR IgG3-Av does not cross-react with hTfR2 and binds hTfR1 expressed on the surface of cells, attached to a solid surface, and in solution. We also found that the hemochromatosis protein (HFE), another ligand of the TfR, does not inhibit the binding of anti-hTfR IgG3-Av to the receptor. In addition, using live cell laser scanning confocal microscopy (LCLSCM) we demonstrated that anti-hTfR IgG3-Av and anti-hTfR IgG3 are internalized into cells expressing hTfR1 at a similar rate. Furthermore, our proliferation and morphological studies demonstrated the effective cytotoxicity of a biotinylated toxin delivered by anti-hTfR IgG3-Av only into cells expressing hTfR1. Our results better define the properties of anti-hTfR IgG3-Av and pave the way for the rational design of future in vitro and in vivo studies for the treatment of human malignancies.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Antibodies, Monoclonal / administration & dosage
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Antibodies, Monoclonal / metabolism
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Antibodies, Monoclonal / pharmacology*
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Antigens, CD / biosynthesis
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Antigens, CD / immunology
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Antineoplastic Agents / administration & dosage
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Antineoplastic Agents / metabolism
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Antineoplastic Agents / pharmacology*
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Avidin / administration & dosage
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Avidin / metabolism
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Avidin / pharmacology*
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Biotinylation
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CHO Cells
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Cell Survival / drug effects
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Cricetinae
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Cricetulus
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Drug Delivery Systems
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Enzyme-Linked Immunosorbent Assay
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Humans
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Immunoconjugates / administration & dosage
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Immunoconjugates / metabolism
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Immunoconjugates / pharmacology*
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Immunoglobulin G / administration & dosage
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Immunoglobulin G / metabolism
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Immunoglobulin G / pharmacology
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Iron / metabolism
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Ligands
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Mice
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Microscopy, Confocal
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Protein Binding
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Receptors, Transferrin / antagonists & inhibitors*
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Receptors, Transferrin / biosynthesis
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Receptors, Transferrin / immunology
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Recombinant Fusion Proteins / administration & dosage
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Recombinant Fusion Proteins / metabolism
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Recombinant Fusion Proteins / pharmacology*
Substances
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Antibodies, Monoclonal
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Antigens, CD
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Antineoplastic Agents
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CD71 antigen
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Immunoconjugates
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Immunoglobulin G
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Ligands
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Receptors, Transferrin
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Recombinant Fusion Proteins
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Avidin
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Iron