IJCEM Copyright © 2008-All rights reserved. Published by e-Century Publishing Corporation, Madison, WI 53711
Int J Clin Exp Med 2011;4(2):91-102

Original Article
Development of targeted therapy for bladder cancer mediated by a double promoter
plasmid expressing diphtheria toxin under the control of IGF2-P3 and IGF2-P4
regulatory sequences

Doron Amit, Sagi Tamir, Tatiana Birman, Ofer N Gofrit, Abraham Hochberg

Department of Biological Chemistry, Hebrew University of Jerusalem, Jerusalem Israel; Department of Urology, Hadassah Hebrew
University Medical Center, Jerusalem, Israel.

Received April 14, 2011; accepted April 25, 2011; Epub April 30, 2010; published May 15, 2011

Abstract: BACKGROUND: The human IGF2-P3 and IGF2-P4 promoters are highly active in bladder carcinoma, while existing at a
nearly undetectable level in the surrounding normal tissue. A double promoter DTA-expressing vector was created, carrying on a single
construct two separate genes expressing diphtheria toxin A-fragment (DTA), from two different regulatory sequences, selected from the
cancer-specific promoters IGF2-P3 and IGF2-P4. METHODS: IGF2-P3 and IGF2-P4 gene expression was tested in samples of
urothelial carcinoma (UC) of the bladder (n=67) by RT-PCR or by ISH. The therapeutic potential of single promoter expression vectors
(P3-DTA and P4-DTA) was tested and compared to the double promoter toxin vector P4-DTA-P3-DTA in UC cell lines and in heterotopic
and orthotopic animal models for bladder cancer. RESULTS: Nearly 86% of UC patients highly expressed IGF2-P4 and IGF2-P3, as
determined by ISH. The double promoter vector (P4-DTA-P3-DTA) exhibited superior ability to inhibit tumor development by 68%
(P=0.004) compared to the single promoter expression vectors, in heterotopic bladder tumors. The average size of the P4-DTA-P3-DTA
bladder tumors (in orthotopically treated mice) was 83% smaller (P<0.001) than that of the control group. CONCLUSIONS: Overall, the
double promoter vector exhibited enhanced anti-cancer activity relative to single promoter expression vectors carrying either gene alone
Our findings show that bladder tumors may be successfully treated by intravesical instillation of the double promoter vector
P4-DTA-P3-DTA. (IJCEM1104001).

Keywords: IGF2, bladder cancer cells, cancer, targeted cancer therapy

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Address all correspondence to:
Dr. Doron Amit,
The Department of Biological Chemistry
Institute of Life Sciences
Edmond Safra Campus, Givat Ram
Jerusalem, Israel, 91904
Tel: 972-54-2404163
Fax: 972-2-5610250