Smac mimetic and oleanolic acid synergize to induce cell death in human hepatocellular carcinoma cells.
Chemotherapy resistance of hepatocellular carcinoma (HCC) is still a major unsolved problem highlighting the need to develop novel therapeutic strategies. Here, we identify a novel synergistic induction of cell death by the combination of the Smac mimetic BV6, which antagonizes Inhibitor of apoptosis (IAP) proteins, and the triterpenoid oleanolic acid (OA) in human HCC cells. Importantly, BV6 and OA also cooperate to suppress long-term clonogenic survival as well as tumor growth in a preclinical in vivo model of HCC underscoring the clinical relevance of our findings. In contrast, BV6/OA cotreatment does not exert cytotoxic effects against normal primary hepatocytes, pointing to some tumor selectivity. Mechanistic studies show that BV6/OA cotreatment leads to DNA fragmentation and caspase-3 cleavage, while supply of the pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD.fmk) revealed a cell type-dependent requirement of caspases for BV6/OA-induced cell death. The receptor interacting protein (RIP)1 kinase Inhibitor Necrostatin-1 (Nec-1) or genetic knockdown of RIP1 fails to rescue BV6/OA-mediated cell death, indicating that BV6/OA cotreatment does not primarily engage necroptotic cell death. Notably, the addition of several reactive oxygen species (ROS) scavengers significantly decreases BV6/OA-triggered cell death, indicating that ROS production contributes to BV6/OA-induced cell death. In conclusion, cotreatment of Smac mimetic and OA represents a novel approach for the induction of cell death in HCC and implicates further studies.
Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany; General and Visceral Surgery, Goethe-University, Frankfurt, Germany; German Cancer Consortium (DKTK), Heidelberg, Germany; German Cancer Research Center (DKFZ), Heidelberg, Germany.
Juliane
J
Liese
Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany.
Behnaz Ahangarian
BA
Abhari
Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany; German Cancer Consortium (DKTK), Heidelberg, Germany; German Cancer Research Center (DKFZ), Heidelberg, Germany. Electronic address: simone.fulda@kgu.de.
Simone
S
Fulda
D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D032701:Biomimetics; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D053148:Caspase 3 / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002642:Chick Embryo; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004789:Enzyme Activation; D016166:Free Radical Scavengers / Q000494:pharmacology; D056945:Hep G2 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000494:pharmacology; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D024101:Mitochondrial Proteins / Q000494:pharmacology; D009828:Oleanolic Acid / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D047368:Tumor Burden / Q000187:drug effects
D051017:Apoptosis Regulatory Proteins; C582180:BV6 peptide; C412403:DIABLO protein, human; D016166:Free Radical Scavengers; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D009842:Oligopeptides; D017382:Reactive Oxygen Species; D009828:Oleanolic Acid; C505407:CASP3 protein, human; D053148:Caspase 3
Cancer; Cell death; IAP proteins; Smac