title: Conjugated platinum(IV)-peptide complexes for targeting angiogenic tumor vasculature.
abstract: The integrins alpha vbeta3 and alpha vbeta5 and the membrane-spanning surface protein aminopeptidase N (APN) are highly expressed in tumor-induced angiogenesis, making them attractive targets for therapeutic intervention. Both integrins and APN recognize a broad range of peptides containing RGD (Arg-Gly-Asp) and NGR (Asn-Gly-Arg) motifs, respectively. Here, we describe the design, synthesis, and characterization of a series of mono- and difunctionalized platinum(IV) complexes in which a conjugated peptide motif, containing RGD, (CRGDC)c, (RGDfK)c, or NGR, is appended as a "tumor-homing device" to target tumor endothelial cells selectively over healthy cells. Platinum(IV)-peptide complexes with nonspecific amino acids or peptide moieties were prepared as controls. Concentration-response curves of these compounds were evaluated against primary proliferating endothelial cells and tumor cell lines and compared to those of cisplatin, a well-described platinum-based chemotherapeutic agent. The Pt(IV)-RGD conjugates were highly and specifically cytotoxic to cell lines containing alpha vbeta3 and alpha vbeta5, approaching the activity of cisplatin. The Pt(IV)-NGR complexes were less active than Pt(IV)-RGD-containing compounds but more active than nonspecific Pt-peptide controls. Integrin alpha vbeta3 mediated, at least in part, the anti-proliferative effect of a Pt(IV)-RGD conjugate, as demonstrated by a decreased inhibitory response when endothelial cells were either (1) incubated with an excess of alpha vbeta3/alpha vbeta5-specific RGD pentapeptides or (2) transfected with RNAi for beta 3, but not beta 1, integrins. These results suggest a rational approach to improved chemotherapy with Pt(IV)-peptide conjugates by selective drug delivery to the tumor compartment.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Sumitra
authors.initials: S
authors.lastname: Mukhopadhyay
authors.forename: Carmen M
authors.initials: CM
authors.lastname: Barnés
authors.forename: Ariel
authors.initials: A
authors.lastname: Haskel
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Short
authors.forename: Katie R
authors.initials: KR
authors.lastname: Barnes
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lippard
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D018826:CD13 Antigens / Q000378:metabolism; D002417:Cattle; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000166:cytology / Q000473:pathology; D006801:Humans; D020128:Inhibitory Concentration 50; D039564:Integrin alphaV / Q000378:metabolism; D009369:Neoplasms / Q000098:blood supply* / Q000473:pathology; D009389:Neovascularization, Pathologic; D009842:Oligopeptides / Q000032:analysis; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology*; D010984:Platinum / Q000737:chemistry*
chemical_list: D039564:Integrin alphaV; D009842:Oligopeptides; D009942:Organometallic Compounds; D010455:Peptides; D010984:Platinum; C047981:arginyl-glycyl-aspartic acid; D018826:CD13 Antigens; D002945:Cisplatin