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Mediators of Inflammation
Volume 2015, Article ID 460264, 11 pages
http://dx.doi.org/10.1155/2015/460264
Research Article

Construction, Expression, and Characterization of a Recombinant Immunotoxin Targeting EpCAM

1Department of Clinical Immunology, Xijing Hospital, Fourth Military Medical University, Xi’an 710032, China
2Department of Neurology, Chinese Navy General Hospital, Beijing 100048, China
3Department of Geriatric Gastroenterology, Chinese People’s Liberation Army General Hospital, Beijing 100853, China
4Department of Immunology, Fourth Military Medical University, Xi’an 710032, China

Received 17 October 2014; Accepted 4 December 2014

Academic Editor: Lijun Xin

Copyright © 2015 Minghua Lv et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Epithelial cell adhesion molecule (EpCAM) is a type I transmembrane glycoprotein overexpressed in human epithelioma but with relatively low expression in normal epithelial tissues. To exploit this differential expression pattern for targeted cancer therapy, an EpCAM-targeted immunotoxin was developed and its antitumor activity was investigated in vitro. An immunotoxin (scFv2A9-PE or APE) was constructed by genetically fusing a truncated form (PE38KDEL) of Pseudomonas aeruginosa exotoxin with an anti-EpCAM single-chain variable fragment (scFv). ELISA and flow cytometry were performed to verify immunotoxin (scFv2A9-PE or APE) antigen-binding activity with EpCAM. Cytotoxicity was measured by MTT assay. Confocal microscopy was used to observe its cellular localization. The results of ELISA and flow cytometry revealed that the immunotoxin efficiently recognized recombinant and natural EpCAM. Its antigen-binding activity was relatively lower than 2A9. MTT assay confirmed potent reduction in EpCAM-positive HHCC (human hepatocellular carcinoma) cell viability (IC50 50 pM). Immunofluorescence revealed that the immunotoxin localized to endoplasmic reticulum 24 h later. In conclusion, we described the development of an EpCAM-targeted immunotoxin with potent activity against tumor cells, which may lay the foundation for future development of therapeutic antibody for the treatment of EpCAM-positive tumors.