Conformation/activity studies of rationally designed potent anti‐adhesive RGD peptides

Abstract

The Arg-Gly-Asp (RGD) sequence is a universal cell-recognition site of various extracellular proteins that interact with integrin cell-surface receptors. In order to design low-molecular-mass RGD protein antagonists, the determination of the biologically active conformation is a prerequisite. We present a method that yields detailed insight into the steric factors which govern the binding of the ligands to their receptors by systematically scanning the conformational space accessible for the tripeptide sequence RGD. The investigation is based on the conformationally controlled design of homodetic cyclic oligopeptides and their structural determination, coupled with biological assays. For this purpose, a whole set of cyclic pentapeptides and hexapeptides has been synthesized and their three-dimensional structures in solution analyzed by modern two-dimensional NMR techniques in combination with restrained and free molecular dynamics simulations. Their biological activity was compared with that of linear GRGDS in inhibition assays of tumor cell adhesion to laminin P1 and vitronectin substrates. An up to 100-fold, and in part selective, increase in activity was observed for two cyclic pentapeptides. Most other peptides showed a decreased activity which, however, was useful to correlate activity with rather small variations in conformation.Detailed comparative studies of the systematically designed conformations and the corresponding anti-adhesive activities offer an access to lead structures for a rational indirect drug design of peptide and peptidomimetic pharmaceuticals with strong interfering activity for integrin-mediated cell -cell and cell -matrix interactions.The interactions of a variety of cell-surface receptors with extracellular matrix components cause the complexity of celladhesive and cell-migratory mechanisms of several physiologically important processes including hemostasis, thrombosis, wound healing and tumor cell invasion [l]. Interactions between adhesion receptors on cell surfaces, termed integrins [2], and extracellular glycoproteins like fibrinogen, fibronectin, vitronectin and laminin form the molecular basis of cell -cell and cell -matrix contacts [3,4]. These phenomena are linked extracellularly with adhesive interactions between those substrates and their specific receptors and intracellularly with Abbreviation. cTrt, o-chlorotritylchloride; DQF, double-quantum-filtered; Fmoc, 9-fluorenylmethoxycarbonyl; HMBCS, heteronuclear multiple bond correlation with selective pulses; HMQC, heteronuclear multiple quantum coherence; inhibitory capacity (molar concentration for 50% inhibition); MD, molecular dynamics; Mtr, 4-methoxy-2,3,6-trimethylbenzenesulfonyl; NOESY, nuclear Overhauser enhancement and exchange spectroscopy; Pmc, 2,2,5,7,8-pentamethylchroman-6-sulfonyl; ROESY, rotating frame nuclear Overhauser enhancement and exchange spectroscopy; Sasrin, 2-methoxy-4-alkoxybenzylalcohol resin; TOCSY, total correlated spectroscopy. signal transduction responses [5,6]. Hence, adhesion receptors not onl...

Inhibition of the alpha-ν integrins with a cyclic RGD peptide impairs angiogenesis, growth and metastasis of solid tumours in vivo

“…Recent observations revealed that they play an important role in tumour angiogenesis and metastasis (Brooks et al, 1994b;Marshall and Hart, 1996). Cyclic RGD peptides have been developed as selective inhibitors for the a v -integrins (Gurrath et al, 1992;Dechantsreiter et al, 1999). The present study was based on earlier observations showing a potent inhibitory effect on tumour angiogenesis using RGD peptides as a v -Integrin antagonists (Eliceiri and Cheresh, 1999).…”

Identification of an Endogenously Generated Cryptic Collagen Epitope (XL313) That May Selectively Regulate Angiogenesis by an Integrin Yes-associated Protein (YAP) Mechano-transduction Pathway

“…However, the ability of an integrin to bind distinct RGD epitopes depends in part on its orientation within the parent molecule and the C-terminal amino acid sequences flanking the RGD motif (25)(26)(27). Given our observations, we sought to identify potential cell surface receptors that mediate interactions with the RGDKGE, containing collagen P-2 peptide.…”

Microenvironment and tumor progression of melanoma: New therapeutic prospectives

“…Studies on animal models have shown such agents to have a strong capacity to inhibit neoplastic cell progression. In particular, cyclic RGD peptides have been created that selectively inhibit α(v) integrins (Gurrath et al, 1992;Dechantsreiter et al, 1999). At the present time, synthetic peptides against α5β1 and α(v)β3 integrins are already used in pre-clinical studies (Carron et al, 1998;Reinmuth et al, 2003;Stoeltzing et al, 2003).…”