IL13 Fused Pseudomonas Exotoxin Targets Various Cancers In Vitro

Damla Uludağ and Nihal Karakaş

Abstract

Background/Aim: Pseudomonas exotoxin (PE) is one of the most widely used toxins in the construction of therapeutic fusion proteins in pre-clinical studies followed by phase trials. In principle, PE acts by blocking protein synthesis through catalyzing the inactivation of elongation factor-2 (EF-2). The interleukin-13 fused PE (IL13-PE) cytotoxin was previously designed to target GBM cells. In this study, the cytotoxic effects of IL13-PE were evaluated in 5 different types of cancers and the therapeutic effects were further analyzed in a lung cancer cell line, NCI-H460. Conceptually, in another lung cancer cell line (A549), IL13Rα2 was overexpressed by lentiviruses (A549-IL13Rα2) and evaluated for cytotoxic efficacy of IL13-PE. Materials and Methods: The expression profile of IL13Rα2 in different cancer cell lines was determined by RT-PCR. Secretable toxin fusion was expressed in the toxin resistant HEK-293T cell line (293T-TxR) by using a plasmid coding for IL13-PE and IRES-GFP (LV-IL13-PE-IRES/GFP). Next, the cells were shown to produce and secrete functional IL13-PE by dot blot analysis, followed by cell viability assays and cell death analysis. Results: Upon treatment with IL13-PE, a significant decrease in cell viability was selectively demonstrated in cancer cells with cognate receptor expression. IL13-PE treatment increased the apoptotic/necrotic cell populations in the NCI-H460 cell line. Conclusion: Our results demonstrate that IL13-PE can be a therapeutic target for tumors bearing mostly IL13Rα2 positive cell populations. Our findings also suggest a cell-based delivery option for the recombinant toxins in the treatment of different cancers which can provide a solution for the clinical use of toxin therapy.

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