title: A conjugate of an anti-midkine single-chain variable fragment to doxorubicin inhibits tumor growth.
abstract: Doxorubicin (DOX) was conjugated to a single-chain variable fragment (scFv) against human midkine (MK), and the conjugate (scFv-DOX) was used to target the chemotherapeutic agent to a mouse solid tumor model in which the tumor cells expressed high levels of human MK. The His-tagged recombinant scFv was expressed in bacteria, purified by metal affinity chromatography, and then conjugated to DOX using oxidative dextran (Dex) as a linker. The molecular formula of this immunoconjugate was scFv(Dex)1.3(DOX)20. In vitro apoptosis assays showed that the scFv-DOX conjugate was more cytotoxic against MK-transfected human adenocarcinoma cells (BGC823-MK) than untransfected cells (55.3 ± 2.4 vs 22.4 ± 3.8%) for three independent experiments. Nude mice bearing BGC823-MK solid tumors received scFv-DOX or equivalent doses of scFv + DOX for 2 weeks and tumor growth was more effectively inhibited by the scFv-DOX conjugate than by scFv + DOX (51.83% inhibition vs 40.81%). Histological analysis of the tumor tissues revealed that the highest levels of DOX accumulated in tumors from mice treated with scFv-DOX and this resulted in more extensive tumor cell death than in animals treated with the equivalent dose of scFv + DOX. These results show that the scFv-DOX conjugate effectively inhibited tumor growth in vivo and suggest that antigen-specific scFv may be competent drug-carriers.
authors.affiliation: Immunology and Reproductive Biology Laboratory, Medical School & State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, 22 Hankou Road, Nanjing, Jiangsu, China.
authors.forename: Shuli
authors.initials: S
authors.lastname: Zhao
authors.forename: Guangfeng
authors.initials: G
authors.lastname: Zhao
authors.forename: Hao
authors.initials: H
authors.lastname: Xie
authors.forename: Yahong
authors.initials: Y
authors.lastname: Huang
authors.forename: Yayi
authors.initials: Y
authors.lastname: Hou
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D016207:Cytokines / Q000276:immunology* / Q000378:metabolism; D004317:Doxorubicin / Q000737:chemistry / Q000494:pharmacology*; D004354:Drug Screening Assays, Antitumor; D005260:Female; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D000078792:Midkine; D009414:Nerve Growth Factors / Q000187:drug effects; D057127:Single-Chain Antibodies; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D016207:Cytokines; D018796:Immunoconjugates; C066254:MDK protein, human; D009414:Nerve Growth Factors; D057127:Single-Chain Antibodies; D000078792:Midkine; D004317:Doxorubicin