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Arrigo De Benedetti, PhD Louisiana State University Health Sciences – Shreveport Areas of Research: Cancer Virotherapy and Vector Development One promising strategy of cancer gene therapy is based on the herpes thymidine kinase (HTK)/ganciclovir (GCV) system. Most of the work has been directed at targeting primary tumors, whereas treatment of metastasis requires methods of specific delivery. We propose a novel approach targeting a characteristic that distinguishes cancer from normal cells, i.e., elevated eukaryotic translation initiation factor (eIF4E), and ultimately allowing for selective killing. eIF4E is a component of the helicase that unwinds excess structure in the 5'UTR of mRNAs. Elevated eIF4E specifically facilitates the translation of mRNAs with a long and structured 5'UTR. With this in mind, the expression of HTK was selectively regulated by placing the 5'UTR of FGF2, previously found to be translationally regulated, upstream of the HTK open reading frame. The idea behind this construct is to obtain a more selective target to GCV killing by limiting the expression of HTK to cancer cells while sparing the population of normal cells, which are unable translate this mRNA. This is important, because in addition to selectively kill cancer cells at the primary tumor site, the ability to selectively attack metastasis could be possible. Experiments are proposed with a panel of normal and cancer cell lines to determine the general applicability of the system: pattern of HTK expression, differential sensitivity to GCV, and enzymatic activity. Additional constructs with synthetic hairpins at 5'UTR will also be tested. Modulation of HTK mRNA level by induction of the vector promoter, in relation to translational regulation will be established. Lipo-transfection of some of these constructs in mice will follow to determine efficacy (i.e., tumor regression) vs. toxicity to distal organs. Selected Publications Chu. Q., Sun, L., Li, J., Byrnes, K., Chervanak, D., De Benedetti, A., Mathis, J.M., and Li, B. Rat adenocarcinoma cell line infected with an adenovirus carrying a novel herpes-simplex virus-thymidine kinase suicide gene construct dies by apoptosis upon treatment with ganciclovir, Journal of Surgical Research, (2007) Byrnes, K., White, S., Chu, Q., Meschonat, C., Yu, H., Johnson, L.W., De Benedetti, A., Abreo, F., Turnage, R.H., McDonald J.C., and Li, B.D. High eIF4E, VEGF, and microvessel density in stage I to III breast cancer. Annuals of Surgery, (2006) 243(5):683-690 Wolfort, R., De Benedetti, A., Nuthalapaty, Y., Chu, Q., and Lu, B. Upregulation of TLK1B by eIF4E overexpression predicts cancer recurrence in irradiated breat cancer patients. Surgery, (2006) 140(2): 161-169 Mathis, J.M., Williams, B.J., Sibley, D.A., Carroll, J.L., Li, J., Odaka, Y., Barlow, S., Nathan, C.A., Li, B.D., and De Benedetti, A. Cancer-specific targeting of an adenovirus-delivered herpes simplex virus thymidines kinase suicide gene using translational control. Journal of Gene Medicine, (2006) 8:1105-1120 Yu, D., Scott, C., Jia, W.W., De Benedetti, A., Williams, B.J., Fazli, L., Gleave, M., Nelson, C., and Rennie, P.S. Targeting and killing of prostate cancer cells using lentiviral constructs containing a sequence recognized by translation factor eIF4E and a prostate-specific promoter. Cancer Gene Therapy, (2005) |
