Accepted for publication in Hepatology:
Increased Apoptosis Induction in Hepatocellular Carcinoma by a Novel Tumor-Targeted TRAIL Fusion Protein combined with Bortezomib
Kristin Wahl 1, Martin Siegemund 2, Frank Lehner 3, Roland Kontermann 2, Florian Vondran 3, Andreas Nüssler 4, Florian Länger 5, Til Krech 5, Michael P. Manns 1, Klaus Schulze-Osthoff 6, Klaus Pfizenmaier 2, and Heike Bantel 1
1Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany; 2Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, Germany; 3Department of Visceral and Transplantation Surgery, Hannover Medical School, Hannover, Germany; 4Department of Trauma Surgery, University of Tübingen, Tübingen, Germany; 5Department of Pathology, Hannover Medical School, Hannover, Germany; 6Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
Owing to an increasing incidence and a prevalent therapy resistance of hepatocellular carcinoma (HCC) there is a strong need for novel strategies to enhance treatment responses in HCC. Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) has been proposed as a promising anticancer drug, since it can selectively induce apoptosis in cancer cells but not in normal cells. Nevertheless, most tumor cells show TRAIL resistance, emphasizing the requirement for apoptosis-sensitizing agents and TRAIL molecules with improved tumor specificity. In this study, we employed a recombinant TRAIL molecule, in which three TRAIL protomers were expressed as a single polypeptide chain (scTRAIL), and a novel TRAIL variant, in which scTRAIL was additionally fused to an antibody fragment recognizing epidermal growth factor receptor (EGFR) in order to improve its HCC-targeting properties. We analyzed the pro-apoptotic effects of both TRAIL versions in combination with the proteasome inhibitor bortezomib in hepatoma cells and primary human hepatocytes as well as in intact explants from HCC and healthy liver tissue. We demonstrate that EGFR-targeted TRAIL in combination with bortezomib induced significantly higher caspase activation and cell death in hepatoma cells but not in primary hepatocytes. Importantly, when incubated with fresh liver explants, the combination of EGFR-targeted TRAIL and bortezomib displayed selective cytotoxicity for HCC but not for tumor-free liver tissue, which could be even verified in liver explants from the same individuals. In conclusion, EGFR-targeted TRAIL reveals increased antitumor activity towards HCC without inducing toxicity to tumor-free liver tissue. EGFR targeting might therefore represent a promising strategy to enhance TRAIL bioactivity and to prevent off-target effects of cell death-inducing agents in EGFR-expressing HCC.