Anti-heparanase aptamers as potential diagnostic and therapeutic agents for oral cancer.

Suzanne C Simmons,Hannaleena Jämsä,Paul E C Brenchley,Tuula Salo,Pia Nyberg,Carlos E B Dealmeida,Sirpa Salo,Celia M Cortez,Edward A Mckenzie,Juha Risteli,Carolina C Bitu,Dilson Silva,Sini Nurmenniemi,Sotiris Missailidis

doi:10.1371/journal.pone.0096846

Abstract

Heparanase is an endoglycosidase enzyme present in activated leucocytes, mast cells, placental tissue, neutrophils and macrophages, and is involved in tumour metastasis and tissue invasion. It presents a potential target for cancer therapies and various molecules have been developed in an attempt to inhibit the enzymatic action of heparanase. In an attempt to develop a novel therapeutic with an associated diagnostic assay, we have previously described high affinity aptamers selected against heparanase. In this work, we demonstrated that these anti-heparanase aptamers are capable of inhibiting tissue invasion of tumour cells associated with oral cancer and verified that such inhibition is due to inhibition of the enzyme and not due to other potentially cytotoxic effects of the aptamers. Furthermore, we have identified a short 30 bases aptamer as a potential candidate for further studies, as this showed a higher ability to inhibit tissue invasion than its longer counterpart, as well as a reduced potential for complex formation with other non-specific serum proteins. Finally, the aptamer was found to be stable and therefore suitable for use in human models, as it showed no degradation in the presence of human serum, making it a potential candidate for both diagnostic and therapeutic use.

Highlights

Heparanase is a b-1,4-endoglycosidase enzyme [1] that participates in extracellular matrix (ECM) degradation and remodeling [1]
Heparanase activity is associated with activated leukocytes, mast cells, placental tissue and macrophages and the enzyme is secreted by activated CD4 + T cells [7,8,9], platelets [3], neutrophils and metastatic cells [10]
In this study we have explored the potential of previously selected aptamers against heparanase as promising diagnostic and therapeutic agents against oral cancer

Summary

Introduction

Heparanase is a b-1,4-endoglycosidase enzyme [1] that participates in extracellular matrix (ECM) degradation and remodeling [1]. The 50 and 8 kDa polypeptides associate to form a heterodimeric active enzyme, whilst the 6 kDa linker is excised and degraded [5,6]. Heparanase activity is associated with activated leukocytes, mast cells, placental tissue and macrophages and the enzyme is secreted by activated CD4 + T cells [7,8,9], platelets [3], neutrophils and metastatic cells [10]. Upon secretion of heparanase from metastatic tumour cells, the enzyme hydrolyses the glycosidic bonds of heparan sulfate chains attached to proteoglycans to a product of 10–20 sugar units in length [11], leading to penetration of the endothelial cells of blood vessels and target organs by the tumor cell. Levels of heparanase expression in tumour cells correlate with their metastatic potential; elevated levels of heparanase mRNA and protein have been found in cancer patients who show significantly shorter postoperative survival times than patients whose heparanase levels are normal [13,14]

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Results

Conclusion