title: Construction and characterization of a fusion protein of single-chain anti-carcinoma antibody 323/A3 and human beta-glucuronidase.
abstract: We report the construction and expression of a fusion protein between a single-chain antibody specific for human carcinomas and human beta-glucuronidase by recombinant DNA technology. The sequences encoding the murine monoclonal antibody 323/A3 light- and heavy-chain variable genes were joined by a synthetic sequence encoding a 15-amino-acid linker and combined with human beta-glucuronidase by a synthetic sequence encoding a 6-amino-acid linker. The construct was placed under the control of the cytomegalovirus promotor and expressed in COS-7 cells. The yield of active fusion protein was 10 ng/ml transfectoma supernatant. Antibody affinity, antibody specificity and enzyme activity were fully retained by the fusion protein. Biochemical characterization of the fusion protein by sodium dodecyl sulfate/polyacrylamide gel electrophoresis showed a molecular mass of 100 kDa under denaturing conditions. Gel-filtration analysis indicated that the enzymatically active form is a tetramer of approximately 400 kDa. The non-toxic prodrug N-[4-doxorubicin-N-carbonyl(oxymethyl)phenyl]-O-beta-glucuronyl carbamate was activated to the cytotoxic drug doxorubicin by the fusion protein with a hydrolysis rate similar to that of human beta-glucuronidase. The growth inhibition of tumor cells coated with the fusion protein and exposed to prodrug was similar to that obtained with doxorubicin. This study shows the feasibility of constructing eukaryotic fusion proteins consisting of a single-chain antibody and human beta-glucuronidase for use in the specific activation of anticancer prodrugs.
authors.affiliation: Department of Otolaryngology/Head and Neck Surgery, Academic Hospital Vrije Universiteit, Amsterdam, The Netherlands. hj.haisma.oncol@med.vu.nl
authors.forename: H J
authors.initials: HJ
authors.lastname: Haisma
authors.forename: R H
authors.initials: RH
authors.lastname: Brakenhoff
authors.forename: I
authors.initials: I
authors.lastname: vd Meulen-Muileman
authors.forename: H M
authors.initials: HM
authors.lastname: Pinedo
authors.forename: E
authors.initials: E
authors.lastname: Boven
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis* / Q000235:genetics*; D000912:Antibodies, Neoplasm / Q000096:biosynthesis* / Q000235:genetics* / Q000276:immunology; D000918:Antibody Specificity; D001711:Biotransformation; D019556:COS Cells / Q000378:metabolism / Q000502:physiology; D005966:Glucuronidase / Q000096:biosynthesis* / Q000235:genetics*; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis / Q000235:genetics; D007147:Immunoglobulin Light Chains / Q000096:biosynthesis / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000096:biosynthesis / Q000235:genetics; D011355:Prodrugs / Q000493:pharmacokinetics; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D014162:Transfection
chemical_list: D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D011355:Prodrugs; D011993:Recombinant Fusion Proteins; D005966:Glucuronidase