Synthesis of a novel legumain-cleavable colchicine prodrug with cell-specific toxicity.

Abstract

Conventional chemotherapy has undesirable toxic side-effects to healthy tissues due to low cell selectivity of cytotoxic drugs. One approach to increase the specificity of a cytotoxic drug is to make a less toxic prodrug which becomes activated at the tumour site. The cysteine protease legumain have remarkable restricted substrate specificity and is the only known mammalian asparaginyl (Asn) endopeptidase. Over-expression of legumain is reported in cancers and unstable atherosclerotic plaques, and utilizing legumain is a promising approach to activate prodrugs. In this study we have synthesized the legumain-cleavable peptide sequence N-Boc-Ala-Ala-Asn-Val-OH. The peptide was subsequently conjugated to deacetyl colchicine during three steps to produce Suc-Ala-Ala-Asn-Val-colchicine (prodrug) with >90% chemical purity. Several cell lines with different expressions and activities of legumain were used to evaluate the general toxicity, specificity and efficacy of the microtubule inhibitor colchicine, valyl colchicine and the legumain-cleavable colchicine prodrug. The prodrug was more toxic to the colorectal cancer HCT116 cells (expressing both the 36kDa active and 56kDa proform of legumain) than SW620 cells (only expressing the 56kDa prolegumain) indicating a relationship between toxicity of the prodrug and activity of legumain in the cells. Also, in monoclonal legumain over-expressing HEK293 cells the prodrug toxicity was higher compared to native HEK293 cells. Furthermore, co-administration of the prodrug either with the potent legumain inhibitor cystatin E/M or the endocytosis inhibitor Dyngo-4a inhibited cell death, indicating that the prodrug toxicity was dependent on both asparaginyl endopeptidase activity and endocytosis. This colchicine prodrug adds to a legumain-activated prodrug strategy approach and could possibly be of use both in targeted anticancer and anti-inflammatory therapy.

• Authors: Robert Løvsletten Smith, Ove Alexander Høgmoen Åstrand, Luan Minh Nguyen, Tina Elvestrand, Gunnar Hagelin, Rigmor Solberg, Harald Thidemann Johansen, Pål Rongved
• Journal: Bioorganic & medicinal chemistry (Bioorg Med Chem) Vol. 22 Issue 13 Pg. 3309-15 (Jul 01 2014) ISSN: 1464-3391 [Electronic] England
• PMID: 24842619 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2014 Elsevier Ltd. All rights reserved.

Chemical References

• Prodrugs
• Cysteine Endopeptidases
• asparaginylendopeptidase
• Colchicine

Topics

• Cell Proliferation (drug effects)
• Cell Survival (drug effects)
• Colchicine (chemical synthesis, chemistry, pharmacology)
• Cysteine Endopeptidases (chemistry)
• Dose-Response Relationship, Drug
• Drug Screening Assays, Antitumor
• HCT116 Cells
• HEK293 Cells
• Humans
• Molecular Structure
• Prodrugs (chemical synthesis, chemistry, pharmacology)
• Structure-Activity Relationship
• Tumor Cells, Cultured