title: Hapten-directed targeting to single-chain antibody receptors.
abstract: Artificial recombinant receptors may be useful for selectively targeting imaging and therapeutic agents to sites of gene expression. To evaluate this approach, we developed transgenes to express highly on cells a single-chain antibody (scFv) against the hapten 4-ethoxymethylene-2-phenyl-2-oxazoline-5-one (phOx). A phOx enzyme conjugate was created by covalently attaching phOx molecules to polyethylene glycol (PEG)-modified beta-glucuronidase. Cells expressing phOx scFv but not control scFv receptors were selectively killed after exposure to ss-glucuronidase derivatized with phOx and PEG (phOx-beta G-PEG) and a glucuronide prodrug (p-hydroxy aniline mustard beta-D-glucuronide, HAMG) of p-hydroxyaniline mustard. Targeted activation of HAMG produced bystander killing of receptor-negative cells in mixed populations containing as few as 10% phOx-receptor-positive cells. Functional phOx scFv receptors were stably expressed on B16-F1 melanoma tumors in vivo. Treatment of mice bearing established phOx-receptor-positive tumors with phOx-beta G-PEG and HAMG significantly (P< or =.0005) suppressed tumor growth as compared with treatment with beta G-PEG and HAMG or prodrug alone. phOx was unstable in the serum, suggesting alternative haptens may be more suitable for in vivo applications. Our results show that therapeutic agents can be targeted to artificial hapten receptors in vitro and in vivo. The expression of artificial receptors on target cells may allow preferential delivery of therapeutic or imaging molecules to sites of transgene expression.
authors.affiliation: School of Biomedical Science and Environmental Biology, and MedicoGenomic Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Tian-Lu
authors.initials: TL
authors.lastname: Cheng
authors.forename: Kuang-Wen
authors.initials: KW
authors.lastname: Liao
authors.forename: Shey-Cherng
authors.initials: SC
authors.lastname: Tzou
authors.forename: Chiu-Min
authors.initials: CM
authors.lastname: Cheng
authors.forename: Bing-Mae
authors.initials: BM
authors.lastname: Chen
authors.forename: Steve R
authors.initials: SR
authors.lastname: Roffler
mesh_terms: D000816:Aniline Mustard / Q000008:administration & dosage* / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000276:immunology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000276:immunology*; D045744:Cell Line, Tumor; D016503:Drug Delivery Systems; D015870:Gene Expression; D006241:Haptens; D007167:Immunotherapy; D007275:Injections, Intravenous; D008545:Melanoma / Q000188:drug therapy* / Q000235:genetics / Q000276:immunology; D051379:Mice; D009374:Neoplasms, Experimental / Q000235:genetics / Q000276:immunology* / Q000628:therapy; D010080:Oxazoles / Q000737:chemistry / Q000276:immunology*; D011092:Polyethylene Glycols / Q000008:administration & dosage* / Q000138:chemical synthesis; D011355:Prodrugs / Q000008:administration & dosage* / Q000138:chemical synthesis; D011956:Receptors, Cell Surface / Q000235:genetics / Q000276:immunology; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology
chemical_list: C119678:4-ethoxymethylene-2-phenyl-2-oxazoline-5-one; D000911:Antibodies, Monoclonal; D006241:Haptens; D010080:Oxazoles; D011355:Prodrugs; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; C000929:hydroxyaniline mustard; D011092:Polyethylene Glycols; D000816:Aniline Mustard