Targeted delivery of melittin to cancer cells by AS1411 anti-nucleolin aptamer

Abstract

Melittin, a small water-soluble cationic amphipathic α-helical linear peptide, consisted of 26 amino acids, is the honeybee venom major constituent. Several reports have proved the lytic and apoptotic effects of melittin in several cancerous cell lines. In this study, we aimed to fabricate an AS1411 aptamer–melittin to specifically deliver melittin to nucleolin positive cells (A549). Melittin was covalently attached to antinucleolin aptamer (AS1411) and its toxicity in A549 (nucleolin positive) and L929 (nucleolin negative) was studied using MTT and Annexin V flow cytometry methods. Aptamer–melittin conjugate formation was confirmed by gel electrophoresis. Hemolytic effect of aptamer–melittin conjugate was compared to melittin alone. The aptamer–melittin conjugate showed efficient cell uptake and was more cytotoxic in A549 cells than melittin (p < .001). This complex was less toxic in control cells. Competitive inhibition assay confirmed that aptamer–melittin complex delivery occurred through receptor-ligand interaction on the cell surface. Moreover, aptamer–melittin showed a significantly less hemolytic activity as compared with free melittin. This study showed that melittin could be specifically delivered to A549 cells when it was covalently conjugated to antinucleolin aptamer (AS1411) in vitro. This system can reduce the cytotoxic effects of melittin on cells with no nucleolin receptor overexpression which comprise most of normal cells such as L929 cells.

Keywords:

• Cancer
• aptamer
• targeted delivery system
• melittin

Acknowledgements

We would like to gratefully thank the Bu Ali Research Institute. The results reported in the present study are part of the M.Sc.; thesis of S.H.R.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Financial support of this study was provided by Mashhad University of Medical Sciences.