title: Novel integrin-targeted binding-triggered drug delivery system for methotrexate.
abstract: OBJECTIVE
  To design a binding-induced conformation change drug delivery system for integrin-targeted delivery of methotrexate and prove the feasibility of using hairpin peptide structure for binding triggered drug delivery.
  
  
  METHODS
  Methotrexate prodrugs were synthesized using solid phase peptide synthesis techniques by conjugating methotrexate to Arg-Gly-Asp (RGD) or a hairpin peptide, RWQYV(D)PGKFTVQRGD (hairpin-RGD). Levels of integrin α(V)β(3) in HUVEC were up-regulated using adenoviral system and knocked down using siRNA. Stability of prodrugs and methotrexate release from prodrugs were evaluated in plasma, in presence or absence of integrin α(V)β(3)-expressing cells. Molecular modeling was performed to support experimental results using MOE.
  
  
  RESULTS
  Prodrugs recognized and bound to integrin α(V)β(3)-expressing cells in integrin α(V)β(3) expression level-dependent manner. Prodrug with hairpin peptide could resist Streptomyces griseus-derived glutamic acid-specific endopeptidase (SGPE) and plasma enzyme hydrolysis. Drug release was triggered in presence of HUVEC cells and SGPE. Analysis of conformation energy supported that conformational change in MTX-hairpin-RGD led to exposure of labile link upon binding to integrin α(V)β(3)-expressing cells.
  
  
  CONCLUSIONS
  Binding-induced conformation change of hairpin peptide can be used to design integrin-targeted drug delivery system.
authors.affiliation: Department of Pharmaceutics & Medicinal Chemistry, T. J. Long School of Pharmacy & Health Sciences, University of the Pacific, Stockton, California 95211, USA.
authors.forename: Phanidhara
authors.initials: P
authors.lastname: Kotamraj
authors.forename: Wade A
authors.initials: WA
authors.lastname: Russu
authors.forename: Bhaskara
authors.initials: B
authors.lastname: Jasti
authors.forename: Jay
authors.initials: J
authors.lastname: Wu
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism; D016503:Drug Delivery Systems / Q000379:methods*; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000378:metabolism*; D008727:Methotrexate / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D009369:Neoplasms / Q000188:drug therapy; D009842:Oligopeptides / Q000737:chemistry* / Q000378:metabolism; D011355:Prodrugs / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation
chemical_list: D000964:Antimetabolites, Antineoplastic; D039302:Integrin alphaVbeta3; D009842:Oligopeptides; D011355:Prodrugs; C047981:arginyl-glycyl-aspartic acid; D008727:Methotrexate