title: Design, synthesis, and biological evaluation of a dual tumor-specific motive containing integrin-targeted plasmin-cleavable doxorubicin prodrug.
abstract: The design, synthesis, and initial biological evaluation of a doxorubicin prodrug that contains a dual tumor specific moiety, which allows enhanced tumor recognition potential, is reported. Both a tumor-specific recognition site and a tumor selective enzymatic activation sequence are incorporated in the prodrug. The first tumor-specific sequence is the bicyclic CDCRGDCFC (RGD-4C) peptide that selectively binds alpha v beta 3 and alpha v beta 5 integrins. These integrins are highly overexpressed on invading tumor endothelial cells. The second tumor-specific sequence is a D-Ala-Phe-Lys tripeptide that is selectively recognized by the tumor-associated protease plasmin, which is involved in tumor invasion and metastasis. An aminocaproyl residue was incorporated as a spacer between the two peptide sequences, whereas a self-eliminating 4-aminobenzyl alcohol spacer was inserted between the plasmin substrate and doxorubicin. Although the prodrug showed a decreased binding affinity as compared with the unconjugated reference peptide, it was still a potent ligand for alpha v beta 3 and alpha v beta 5 integrin receptors. The synthesized construct also possessed plasmin substrate properties as demonstrated by doxorubicin release from 1 upon incubation with plasmin. The release of doxorubicin from 1 was not complete, possibly related to low prodrug solubility. In vitro prodrug 1 showed plasmin-dependent cytotoxicity for endothelial cells and HT1080 fibrosarcoma cells. On the basis of these in vitro results, derivatives of 1 with improved water solubility are considered good candidates for additional development and in vivo evaluation of this dual targeting concept.
authors.affiliation: Department of Organic Chemistry, NSR-Center for Molecular Structure, Design and Synthesis, University of Nijmegen, 6525 ED Nijmegen, The Netherlands. fmhdegroot@syntarga.com
authors.forename: Franciscus M H
authors.initials: FM
authors.lastname: de Groot
authors.forename: Henk J
authors.initials: HJ
authors.lastname: Broxterman
authors.forename: Hans P H M
authors.initials: HP
authors.lastname: Adams
authors.forename: Alexandra
authors.initials: A
authors.lastname: van Vliet
authors.forename: Godefridus I
authors.initials: GI
authors.lastname: Tesser
authors.forename: Yvonne W
authors.initials: YW
authors.lastname: Elderkamp
authors.forename: Astrid J
authors.initials: AJ
authors.lastname: Schraa
authors.forename: Robert Jan
authors.initials: RJ
authors.lastname: Kok
authors.forename: Grietje
authors.initials: G
authors.lastname: Molema
authors.forename: Herbert M
authors.initials: HM
authors.lastname: Pinedo
authors.forename: Hans W
authors.initials: HW
authors.lastname: Scheeren
mesh_terms: D000595:Amino Acid Sequence; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D001592:Benzyl Alcohols / Q000494:pharmacology; D001665:Binding Sites; D002448:Cell Adhesion; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology*; D015195:Drug Design; D004727:Endothelium / Q000166:cytology; D004730:Endothelium, Vascular / Q000166:cytology; D005341:Fibrinolysin / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D020128:Inhibitory Concentration 50; D039302:Integrin alphaVbeta3 / Q000378:metabolism; D016023:Integrins / Q000737:chemistry / Q000378:metabolism; D008024:Ligands; D008956:Models, Chemical; D008969:Molecular Sequence Data; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D009842:Oligopeptides; D010455:Peptides / Q000737:chemistry; D011355:Prodrugs / Q000138:chemical synthesis / Q000494:pharmacology*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D019030:Receptors, Vitronectin / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D001592:Benzyl Alcohols; D039302:Integrin alphaVbeta3; D016023:Integrins; D008024:Ligands; D009842:Oligopeptides; D010455:Peptides; D011355:Prodrugs; D019030:Receptors, Vitronectin; C064660:integrin alphaVbeta5; C006503:4-aminobenzyl alcohol; C047981:arginyl-glycyl-aspartic acid; D004317:Doxorubicin; D005341:Fibrinolysin