Targeted delivery of a designed sTRAIL mutant results in superior apoptotic activity towards EGFR-positive tumor cells

• Published in: Journal of molecular medicine (Berlin, Germany) Germany), 2008-08, Vol.86 (8), p.909-924
• Main Authors: Bremer, Edwin, de Bruyn, Marco, Samplonius, Douwe F., Bijma, Theo, ten Cate, Bram, de Leij, Lou F. M. H., Helfrich, Wijnand
• Format: Article
• Language: English
• Subjects: Antibodies, Monoclonal - metabolism; Antineoplastic Agents - therapeutic use; Apoptosis; Binding Sites; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Cell Line, Tumor; ErbB Receptors - antagonists & inhibitors; ErbB Receptors - metabolism; Gene Transfer Techniques; General aspects; Human Genetics; Humans; Internal Medicine; Jurkat Cells; Ligands; Medical sciences; Molecular Medicine; Mutation; Neoplasms - metabolism; Original; Original Article; Receptors, TNF-Related Apoptosis-Inducing Ligand - agonists; Receptors, TNF-Related Apoptosis-Inducing Ligand - metabolism; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Recombinant Fusion Proteins - therapeutic use; Signal Transduction; TNF-Related Apoptosis-Inducing Ligand - genetics; TNF-Related Apoptosis-Inducing Ligand - metabolism; TNF-Related Apoptosis-Inducing Ligand - therapeutic use
• ISSN: 0946-2716; 1432-1440
• DOI: 10.1007/s00109-008-0348-9

Previously, we have shown that epidermal growth factor receptor (EGFR)-selective delivery of soluble tumor necrosis factor-related apoptosis-inducing ligand (sTRAIL), by genetic fusion to antibody fragment scFv425, enhances the tumor-selective pro-apoptotic activity of sTRAIL. Insight into the respective contribution of the agonistic receptors TRAIL-R1 and TRAIL-R2 to TRAIL-induced apoptosis may provide a rational approach to further optimize TRAIL-based therapy. Recently, this issue has been investigated using sTRAIL mutants designed to selectively bind to either receptor. However, the relative contribution of the respective TRAIL receptors, in particular TRAIL-R1, in TRAIL signaling is still unresolved. Here, we fused scFv425 to designed sTRAIL mutant sTRAILmR1–5, reported to selectively activate TRAIL-R1, and investigated the therapeutic apoptotic activity of this novel fusion protein. EGFR-specific binding of scFv425:sTRAILmR1–5 potently induced apoptosis, which was superior to the apoptotic activity of scFv425:sTRAIL-wt and a nontargeted MOCK-scFv:sTRAILmR1–5. During cotreatment with cisplatin or the histone deacetylase inhibitor valproic acid, scFv425:sTRAILmR1–5 retained its superior pro-apoptotic activity compared to scFv425:sTRAIL-wt. However, in catching-type Enzyme-Linked ImmunoSorbent Assays with TRAIL-R1:Fc and TRAIL-R2:Fc, scFv425:sTRAILmR1–5 was found to not only bind to TRAIL-R1 but also to TRAIL-R2. Binding to TRAIL-R2 also had functional consequences because the apoptotic activity of scFv425:sTRAILmR1–5 was strongly inhibited by a TRAIL-R2 blocking monoclonal antibody. Moreover, scFv425:sTRAILmR1–5 retained apoptotic activity upon selective knockdown of TRAIL-R1 using small inhibitory RNA. Collectively, these data indicate that both agonistic TRAIL receptors are functionally involved in TRAIL signaling by scFv425:sTRAILmR1–5 in solid tumor cells. Moreover, the superior target cell-restricted apoptotic activity of scFv425:sTRAILmR1–5 indicates its therapeutic potential for EGFR-positive solid tumors.