Design of immuno-enzymosomes with maximum enzyme targeting capability: effect of the enzyme density on the enzyme targeting capability and cell binding properties.
Immuno-enzymosomes have been proposed for the targeting of enzymes to cancer cells to achieve site specific activation of anticancer prodrugs. Previously, we reported that the enzyme beta-glucuronidase (GUS), capable of activating anthracycline-glucuronide prodrugs, can be coupled to the surface of inmunoliposomes directed against human ovarian cancer cells (OVCAR-3). This study aimed at the design of an immuno-enzymosome formulation with maximum enzyme targeting capability. By purification of the commercially available enzyme beta-glucuronidase (GUS), a 2-fold increase in the enzyme specific activity and a 4-fold increase in the enzymatic activity of immuno-enzymosomes was achieved. As a result, upon incubation with human ovarian cancer cells (OVCAR-3), cell-associated enzymatic activity increased correspondingly. The optimized immuno-enzymosomes were shown to bind to the target cells in a specific fashion. Above a GUS/Fab' molar ratio of 0.5, impairment of the target cell binding ability of the immuno-enzymosomes was observed. This was likely due to a steric hindrance effect mediated by the presence of large amounts of bulky GUS molecules on the liposome surface. Nevertheless, increasing the GUS density on the surface of the immuno-enzymosomes to levels by far exceeding the GUS/Fab' molar ratio of 0.5, yielded a considerably improved enzyme targeting capability.
Fonseca
M J
MJ
Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, P.O. Box 80.082, 3508 TB, Utrecht, The Netherlands.
Haisma
H J
HJ
Klaassen
S
S
Vingerhoeds
M H
MH
Storm
G
G
D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology; D000912:Antibodies, Neoplasm / Q000737:chemistry*; D000970:Antineoplastic Agents / Q000737:chemistry*; D002448:Cell Adhesion; D004337:Drug Carriers; D015195:Drug Design; D004798:Enzymes / Q000737:chemistry*; D005966:Glucuronidase / Q000737:chemistry / Q000302:isolation & purification; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry / Q000276:immunology; D008081:Liposomes / Q000737:chemistry* / Q000276:immunology; D008562:Membrane Glycoproteins / Q000276:immunology; D014407:Tumor Cells, Cultured / Q000276:immunology
C064108:323-A3 antigen, human; D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D000970:Antineoplastic Agents; D004337:Drug Carriers; D004798:Enzymes; D007140:Immunoglobulin Fab Fragments; D008081:Liposomes; D008562:Membrane Glycoproteins; D005966:Glucuronidase