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

Edwin Bremer, Marco de Bruyn, Douwe F. Samplonius, Theo Bijma, Bram ten Cate, Lou F. M. H. de Leij, Wijnand Helfrich*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

27 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)909-924
Number of pages16
JournalJournal of Molecular Medicine
Volume86
Issue number8
DOIs
Publication statusPublished - Aug-2008

Keywords

  • TRAIL
  • targeting
  • EGFR
  • TRAIL receptor
  • mutant
  • selective
  • CYTOTOXIC LIGAND TRAIL
  • FUSION PROTEIN
  • MEDIATED APOPTOSIS
  • RECEPTOR FAMILY
  • DEATH DOMAIN
  • SPECIFICITY
  • INDUCTION
  • MEMBER
  • ACTIVATION
  • EGP2

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