title: Superior antitumoral activity of dimerized targeted single-chain TRAIL fusion proteins under retention of tumor selectivity.
abstract: Although targeting of the death receptors (DRs) DR4 and DR5 still appears a suitable antitumoral strategy, the limited clinical responses to recombinant soluble TNF-related apoptosis inducing ligand (TRAIL) necessitate novel reagents with improved apoptotic activity/tumor selectivity. Apoptosis induction by a single-chain TRAIL (scTRAIL) molecule could be enhanced >10-fold by generation of epidermal growth factor receptor (EGFR)-specific scFv-scTRAIL fusion proteins. By forcing dimerization of scFv-scTRAIL based on scFv linker modification, we obtained a targeted scTRAIL composed predominantly of dimers (Db-scTRAIL), exceeding the activity of nontargeted scTRAIL ∼100-fold on Huh-7 hepatocellular and Colo205 colon carcinoma cells. Increased activity of Db-scTRAIL was also demonstrated on target-negative cells, suggesting that, in addition to targeting, oligomerization equivalent to an at least dimeric assembly of standard TRAIL per se enhances apoptosis signaling. In the presence of apoptosis sensitizers, such as the proteasomal inhibitor bortezomib, Db-scTRAIL was effective at picomolar concentrations in vitro (EC(50) ∼2 × 10(-12) M). Importantly, in vivo, Db-scTRAIL was well tolerated and displayed superior antitumoral activity in mouse xenograft (Colo205) tumor models. Our results show that both targeting and controlled dimerization of scTRAIL fusion proteins provides a strategy to enforce apoptosis induction, together with retained tumor selectivity and good in vivo tolerance.
authors.affiliation: Institute of Cell Biology and Immunology, University of Stuttgart, Allmandring 31, D-70569 Stuttgart, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Siegemund
authors.forename: N
authors.initials: N
authors.lastname: Pollak
authors.forename: O
authors.initials: O
authors.lastname: Seifert
authors.forename: K
authors.initials: K
authors.lastname: Wahl
authors.forename: K
authors.initials: K
authors.lastname: Hanak
authors.forename: A
authors.initials: A
authors.lastname: Vogel
authors.forename: A K
authors.initials: AK
authors.lastname: Nussler
authors.forename: D
authors.initials: D
authors.lastname: Göttsch
authors.forename: S
authors.initials: S
authors.lastname: Münkel
authors.forename: H
authors.initials: H
authors.lastname: Bantel
authors.forename: R E
authors.initials: RE
authors.lastname: Kontermann
authors.forename: K
authors.initials: K
authors.lastname: Pfizenmaier
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000188:drug therapy*; D019281:Dimerization; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D056945:Hep G2 Cells; D006801:Humans; D019169:Jurkat Cells; D051379:Mice; D008819:Mice, Nude; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000494:pharmacology / Q000627:therapeutic use; D057127:Single-Chain Antibodies / Q000235:genetics / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics / Q000494:pharmacology* / Q000627:therapeutic use; D014183:Transplantation, Heterologous
chemical_list: D000970:Antineoplastic Agents; D011993:Recombinant Fusion Proteins; D057127:Single-Chain Antibodies; D053221:TNF-Related Apoptosis-Inducing Ligand; D066246:ErbB Receptors