Synthetic Disintegrins as Mediators of Cell-Matrix Interactions: Implication for Cancer and Regenerative Therapies

The term disintegrin was coined in the early 90s to describe a class of proteins found in snake venoms. The same term is used today for molecules that can recognise and bind to integrins: membrane receptors that are responsible for the activation of many vital pathways that lead to cell proliferation. By binding integrins, disintegrins can stop the internal cellular signalling, which can result in apoptosis, induced cell death. Laminin is a trimeric glycoprotein, found in the extracellular matrix, formed from three different chains: α, β and γ and is also involved in the binding of integrins. Recently it was shown that the N-terminal region of the β-chain of laminin incorporates a conserved sequence: YIGSR, located in a turn rich region, where its conformation is fixed by disulphide bridges, responsible to impose a biological conformation. This epitope was found to promote cell attachment, proliferation and migration. In this work we have looked into creating more stable and pronounced conformations of YIGSR mimetics. This has been achieved designing and synthesising the constructs in a cyclic fashion. The different cyclo-peptides obtained were than screened using celladhesion and migration assays, revealing that turn-like structures exhibit stronger activities. The secondary structure of these mimetics was probed by circular dichroism and NMR spectroscopy and was visualised by MD simulations, collectively suggesting the presence of a type II β-turn conformation proving that the latter is essential for the activity. The mimetics inhibited cell attachment and migration of several cancers lines indicating their potential as antimetastatic agents. In parallel, the potential use of these mimetics in regenerative medicine has been also investigated biomimetic matrices. These scaffolds assemble from polypeptide chains that fold into coiled coil structures, to give stable materials with fibrils that range from nano- to micrometres in length and 20- 50 nm in diameter. Introduction of the disintegrins-like peptides into such fibrous matrices, as cell-adhesion baits, stimulated cell proliferation and migration suggesting their use in tissue engineering and wound healing.