AS1411 is a nucleolin-binding aptamer which attracted great interest as active targeting ligand for the selective delivery of therapeutic agents to tumour cells. In this work we selected three AS1411 derivatives 5?-conjugated with lipophilic tails and studied their properties in view of their application in liposomial formulations and/or lipid coated-nanoparticles for targeted therapies. The conformational behaviour of these AS1411 analogs has been investigated in comparison with the unmodified aptamer by CD, UV, PAGE, SEC-HPLC, DLS and thioflavin T (ThT) fluorescence assays to get insight in their secondary structure and aggregation properties. This study has been performed in pseudo-physiological buffers mimicking the extra- and intracellular environments, and at different concentrations in the ?M range, paying special attention to the effects of the lipophilic tail on the overall aptamer conformation. The 5?-lipidated AS1411 derivatives proved to fold into stable, parallel unimolecular G-quadruplex structures, forming large aggregates, mainly micelles, at conc. >10?M. Preliminary bioscreenings on selected cancer cells showed that these derivatives are less cytotoxic than AS1411, but maintain a similar biological behaviour. This study demonstrated that lipophilic tails dramatically favour the formation of AS1411 aggregates, however not impairing the formation and thermal stability of its peculiar G4 motifs
Exploring the conformational behaviour and aggregation properties of lipid-conjugated AS1411 aptamers
2018
Abstract
AS1411 is a nucleolin-binding aptamer which attracted great interest as active targeting ligand for the selective delivery of therapeutic agents to tumour cells. In this work we selected three AS1411 derivatives 5?-conjugated with lipophilic tails and studied their properties in view of their application in liposomial formulations and/or lipid coated-nanoparticles for targeted therapies. The conformational behaviour of these AS1411 analogs has been investigated in comparison with the unmodified aptamer by CD, UV, PAGE, SEC-HPLC, DLS and thioflavin T (ThT) fluorescence assays to get insight in their secondary structure and aggregation properties. This study has been performed in pseudo-physiological buffers mimicking the extra- and intracellular environments, and at different concentrations in the ?M range, paying special attention to the effects of the lipophilic tail on the overall aptamer conformation. The 5?-lipidated AS1411 derivatives proved to fold into stable, parallel unimolecular G-quadruplex structures, forming large aggregates, mainly micelles, at conc. >10?M. Preliminary bioscreenings on selected cancer cells showed that these derivatives are less cytotoxic than AS1411, but maintain a similar biological behaviour. This study demonstrated that lipophilic tails dramatically favour the formation of AS1411 aggregates, however not impairing the formation and thermal stability of its peculiar G4 motifsI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
