title: Critical role of mitochondria-mediated apoptosis for JNJ-26481585-induced antitumor activity in rhabdomyosarcoma.
abstract: JNJ-26481585 is a second-generation histone deacetylase inhibitor with broad-range efficacy and improved pharmacodynamic properties. In the present study, we investigated the therapeutic potential of JNJ-26481585 and its molecular mechanisms of action in rhabdomyosarcoma (RMS). Here, we report that JNJ- 26481585's anticancer activity critically depends on an intact mitochondrial pathway of apoptosis. JNJ-26481585 induces apoptosis and also inhibits long-term clonogenic survival of several RMS cell lines at nanomolar concentrations that cause histone acetylation. Importantly, JNJ-26481585 significantly suppresses tumor growth in vivo in two preclinical RMS models, that is, the chorioallantoic membrane model and a xenograft mouse model. Mechanistically, we identify activation of the mitochondrial pathway of apoptosis as a key event that is critically required for JNJ-26481585-mediated cell death. JNJ-26481585 upregulates expression levels of several BH3-only proteins including Bim, Puma and Noxa, which all contribute to JNJ-26481585-mediated apoptosis, as knockdown of Bim, Puma or Noxa significantly inhibits cell death. This shift toward proapoptotic Bcl-2 proteins promotes activation of Bax and Bak as a critical event, as genetic silencing of Bax or Bak protects against JNJ-26481585-induced apoptosis. Intriguingly, rescue experiments reveal that JNJ-26481585 triggers Bax/Bak activation independently of caspase activation and activates caspase-9 as the initiator caspase in the cascade, as Bcl-2 overexpression, but not the broad-range caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD.fmk) blocks JNJ-26481585-induced Bax/Bak activation and caspase-9 cleavage. In conclusion, JNJ-26481585 exerts potent antitumor activity against RMS in vitro and in vivo by engaging mitochondrial apoptosis before caspase activation and represents a promising therapeutic for further investigation in RMS.
authors.affiliation: Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Heinicke
authors.affiliation: Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Kupka
authors.affiliation: Experimental Pharmacology and Oncology GmbH, Berlin-Buch, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Fichter
authors.affiliation: Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany.|German Cancer Consortium (DKTK), Heidelberg, Germany.|German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Fulda
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002642:Chick Embryo; D049033:Chorioallantoic Membrane / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D008297:Male; D008815:Mice, Inbred Strains; D008819:Mice, Nude; D008928:Mitochondria / Q000378:metabolism*; D032446:Myoblasts / Q000166:cytology / Q000187:drug effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012208:Rhabdomyosarcoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000235:genetics / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; C541788:quisinostat