Purine Nucleoside Phosphorylase Targeted by Annexin V to Breast Cancer Vasculature for Enzyme Prodrug Therapy
Open Access
- 3 October 2013
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLOS ONE
- Vol. 8 (10), e76403
- https://doi.org/10.1371/journal.pone.0076403
Abstract
The targeting of therapeutics is a promising approach for the development of new cancer treatments that seek to reduce the devastating side effects caused by the systemic administration of current drugs. This study evaluates a fusion protein developed as an enzyme prodrug therapy targeted to the tumor vasculature. Cytotoxicity would be localized to the site of the tumor using a protein fusion of purine nucleoside phosphorylase (PNP) and annexin V. Annexin V acts as the tumor-targeting component of the fusion protein as it has been shown to bind to phosphatidylserine expressed externally on cancer cells and the endothelial cells of the tumor vasculature, but not normal vascular endothelial cells. The enzymatic component of the fusion, PNP, converts the FDA-approved cancer therapeutic, fludarabine, into a more cytotoxic form. The purpose of this study is to determine if this system has a good potential as a targeted therapy for breast cancer. A fusion of E. coli purine nucleoside phosphorylase and human annexin V was produced in E. coli and purified. Using human breast cancer cell lines MCF-7 and MDA-MB-231 and non-confluent human endothelial cells grown in vitro, the binding strength of the fusion protein and the cytotoxicity of the enzyme prodrug system were determined. Endothelial cells that are not confluent expose phosphatidylserine and therefore mimic the tumor vasculature. The purified recombinant fusion protein had good enzymatic activity and strong binding to the three cell lines. There was significant cell killing (p<0.001) by the enzyme prodrug treatment for all three cell lines, with greater than 80% cytotoxicity obtained after 6 days of treatment. These results suggest that this treatment could be useful as a targeted therapy for breast cancer.Keywords
This publication has 39 references indexed in Scilit:
- In search of a novel target — Phosphatidylserine exposed by non-apoptotic tumor cells and metastases of malignancies with poor treatment efficacyBiochimica et Biophysica Acta (BBA) - Biomembranes, 2011
- Validation of the catalytic mechanism of Escherichia coli purine nucleoside phosphorylase by structural and kinetic studiesBiochimie, 2011
- Cytotoxic activity of 2-Fluoro-ara-AMP and 2-Fluoro-ara-AMP-loaded erythrocytes against human breast carcinoma cell linesInternational Journal of Oncology, 2010
- Humanized ADEPT comprised of an engineered human purine nucleoside phosphorylase and a tumor targeting peptide for treatment of cancerMolecular Cancer Therapeutics, 2009
- Ocular toxicity of fludarabine: a purine analogExpert Review of Ophthalmology, 2008
- Delivery of replication-competent retrovirus expressing Escherichia coli purine nucleoside phosphorylase increases the metabolism of the prodrug, fludarabine phosphate and suppresses the growth of bladder tumor xenograftsCancer Gene Therapy, 2007
- Molecular architecture of E. coli purine nucleoside phosphorylase studied by analytical ultracentrifugation and CD spectroscopyProtein Science, 2006
- Excellent In vivo Bystander Activity of Fludarabine Phosphate against Human Glioma Xenografts that Express the Escherichia coli Purine Nucleoside Phosphorylase GeneCancer Research, 2004
- Gene therapy of hepatocellular carcinomain vitro andin vivo in nude mice by adenoviral transfer of theescherichia coli purine nucleoside phosphorylase geneHepatology, 2000
- Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4Nature, 1970