IJCEM Copyright © 2008-All rights reserved. Published by e-Century Publishing Corporation, Madison, WI 53711
Int J Clin Exp Med 2010;3(4):270-282

Original Article
Targeting Diphtheria toxin and TNF alpha expression in ovarian tumors using the
H19 regulatory sequences---A novel approach combines delivery and expression of
the DT-A and TNF-alpha genes driven by H19 regulatory sequences to treat ovarian

Aya Mizrahi, Abraham Hochberg, Smadar Amiur, Jennifer Gallula, Imad Matouk,  Tatiana Birman, Tally Levy, Patricia Ohana

The Hebrew University of Jerusalem, Biological Chemistry, Jerusalem, Israel 91905;
Sheba Medical Center, Department of General and Hepatobiliary Surgery, Tel Hashomer, Israel 52621;
E.Wolfson Medical Center, Genecology Oncology, Holon, Israel 58100;
E.Wolfson Medical Center Department of Surgery “A”, E.Wolfson Medical Center, Holon, Israel

Received May 30, 2010, accepted June, 2010, available online June, 2010

Abstract: There are currently no effective therapies for the treatment of ovarian cancer ascites fluid (OCAF). H19 is an RNA oncofetal
gene that is present at high levels in human cancer tissues (ovarian cancer and OCAF among them), while existing at a nearly
undetectable level in the surrounding normal tissue. There is evidence for a synergistic effect in cell cytotoxicity mediated by TNF and
diphtheria toxin in sensitive and resistant human ovarian tumor cell line. Thus, we tested the cytotoxic effect of TNF-beta cytokine,
together with the diphtheria toxin, in the therapy of ovarian cancer. Methods: The therapeutic potential of toxin vectors carrying the DT-A
gene alone (pH19-DTA), or in combination with the TNF- gene (pH19-TNF-DTA), driven by H19 regulatory sequences were tested in
ovarian carcinoma cell lines and in a heterotopic ovarian cancer model. Results: The toxin vectors showed a high killing capacity when
transfected into different ovarian cancer cell lines. In addition, intratumoral injection of the toxin vector into ectopically developed tumors
caused 40% inhibition of tumor growth. The killing effect after injection of pH19-TNF-DTA plasmid into ectopically developed tumors
was significantly higher than that showed by the pH19-DTA plasmid alone, particularly in diphtheria toxin and TNF resistant tumors.
These observations may be the first step towards a major breakthrough in the treatment of human ovarian cancer. It should enable us
to identify likely non-responders in advance, and to treat patients who are resistant to all known therapies, thereby avoiding treatment
failure coupled with unnecessary suffering and cost. (IJCEM1005006).

Key words: H19, TNF, DT-A, IRES, Ascites, ovarian cancer

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Address all correspondence to:
Aya Mizrahi, MD
The Department of Biological Chemistry
Institute of Life Sciences
Edmond Safra Campus, Givat Ram
Jerusalem 91904, Israel
E-mail: amizrah25@gmail.com
Telephone number: 972-2-6585457
Fax: 972-2-5610250