title: Targeting of methotrexate-containing liposomes with a monoclonal antibody against human renal cancer.
abstract: The potential of monoclonal antibody-linked small unilamellar vesicles containing methotrexate [(MTX)SUVs] in cancer chemotherapy was investigated. (MTX)SUVs prepared by probe sonication [50 +/- 20 (SD) nm in diameter] were linked covalently to Dal K29 (an IgG1 monoclonal antibody against human renal cancer), normal mouse IgG, or a nonspecific mouse myeloma IgG1. After incubation with a human kidney cancer cell line, CaKi-1, for 2 h, Dal K29-linked (MTX)SUVs showed 6 and 8 times more binding to CaKi-1 cells than nonspecific mouse myeloma IgG1-linked (MTX)SUV or (MTX)SUVs unlinked. After incubation with Dal K29-linked ([3H]MTX)SUVs, a higher amount of radioactivity was associated with CaKi-1 cells at 37 degrees C than at 4 degrees C. Membrane immunofluorescence revealed aggregation and capping of Dal K29-linked SUVs around CaKi-1 cells after incubation at 37 degrees C for 2 h and endocytosis at 4 and 6 h. Electron microscopic examination confirmed the aggregation of Dal K29-linked SUVs on the surface of CaKi-1 cells and their presence in endocytic vesicles at 4 and 6 h. After incubation with Dal K29-linked gold containing SUVs at 37 degrees C, gold-containing SUVs were seen on the surface as well as inside endocytic vesicle of CaKi-1 cells at 2 and 4 h. A colony inhibition assay showed that Dal K29-linked (MTX)SUVs were 5 and 40 times more potent than Dal K29-MTX and equimolar amounts of free untrapped MTX in inhibiting the growth of the target CaKi-1 cells but were not toxic to a human melanoma line (that did not react with Dal K29).
authors.affiliation: College of Pharmacy, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Singh
authors.forename: T
authors.initials: T
authors.lastname: Ghose
authors.forename: G
authors.initials: G
authors.lastname: Faulkner
authors.forename: J
authors.initials: J
authors.lastname: Kralovec
authors.forename: M
authors.initials: M
authors.lastname: Mezei
mesh_terms: D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D002460:Cell Line; D004337:Drug Carriers; D005455:Fluorescent Antibody Technique; D006801:Humans; D007680:Kidney Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000648:ultrastructure; D008081:Liposomes; D008727:Methotrexate / Q000008:administration & dosage* / Q000378:metabolism / Q000627:therapeutic use; D008854:Microscopy, Electron
chemical_list: D000911:Antibodies, Monoclonal; D004337:Drug Carriers; D008081:Liposomes; D008727:Methotrexate