Synthesis and Biological Evaluation of Paclitaxel Conjugates Involving Linkers Cleavable by Lysosomal Enzymes and αVβ3-Integrin Ligands for Tumor Targeting

Paula López Rivas, Ivan Ranđelović, André Raposo Moreira Dias, Arianna Pina, Daniela Arosio, József Tóvári, Gábor Mező, Alberto Dal Corso, Luca Pignataro, Cesare Gennari

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Abstract

Two cyclo[DKP-RGD]-PTX (PTX = paclitaxel) and two cyclo[RGDfK]-PTX conjugates containing the Gly-Phe-Leu-Gly (GFLG) linker, which is cleavable by lysosomal enzymes, were synthesized and compared to two cyclo[DKP-RGD]-Val-Ala-PTX conjugates. The conjugates were evaluated for their ability to inhibit biotinylated vitronectin binding to the isolated αvβ3 receptor, retaining good binding affinity, in the same nanomolar range of the free ligands. Cell viability assays were performed for the six conjugates in the αvβ3+ U87 and in the αvβ3– HT29 cell lines. Loss of potency was observed for all the conjugates, attenuated by the presence of a tetraethylene glycol (PEG-4) spacer. A good Targeting Index (TI = Relative Potency in the αvβ3+ U87/Relative Potency in the αvβ3– HT29) was displayed by the conjugates, in particular by cyclo[DKP-RGD]-PEG-4-Val-Ala-PTX 9 (TI = 533). This conjugate was tested in the αvβ3+ U87 cell line in the presence of 50-fold excess free cyclo[DKP-RGD] ligand 2. In this competition experiment, a fivefold decrease of the conjugate cytotoxicity was calculated, suggesting that the conjugate is possibly internalized by an αvβ3 integrin-mediated process.

Original languageEnglish
Pages (from-to)2902-2909
Number of pages8
JournalEuropean Journal of Organic Chemistry
Volume2018
Issue number23
DOIs
Publication statusPublished - Jun 22 2018

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Keywords

  • Antitumor agents
  • Drug delivery
  • Integrins
  • Linker technology
  • Peptidomimetics

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry

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