title: DAPK plays an important role in panobinostat-induced autophagy and commits cells to apoptosis under autophagy deficient conditions.
abstract: The histone deacetylase inhibitor (HDACi) LBH589 has been verified as an effective anticancer agent. The identification and characterization of new targets for LBH589 action would further enhance our understanding of the molecular mechanisms involved in HDACi therapy. The role of the tumor suppressor death-associated protein kinase (DAPK) in LBH589-induced cytotoxicity has not been investigated to date. Stable DAPK knockdown (shRNA) and DAPK overexpressing (DAPK+++) cell lines were generated from HCT116 wildtype colon cancer cells. LBH589 inhibited cell proliferation, reduced the long-term survival, and up-regulated and activated DAPK in colorectal cancer cells. Moreover, LBH589 significantly suppressed the growth of colon tumor xenografts and in accordance with the in vitro studies, increased DAPK levels were detected immunohistochemically. LBH589 induced a DAPK-dependent autophagy as assessed by punctuate accumulation of LC3-II, the formation of acidic vesicular organelles, and degradation of p62 protein. LBH589-induced autophagy seems to be predominantly caused by DAPK protein interactions than by its kinase activity. Caspase inhibitor zVAD increased autophagosome formation, decreased the cleavage of caspase 3 and PARP but didn't rescue the cells from LBH589-induced cell death in crystal violet staining suggesting both caspase-dependent as well as caspase-independent apoptosis pathways. Pre-treatment with the autophagy inhibitor Bafilomycin A1 caused caspase 3-mediated apoptosis in a DAPK-dependent manner. Altogether our data suggest that DAPK induces autophagy in response to HDACi-treatment. In autophagy deficient cells, DAPK plays an essential role in committing cells to HDACi-induced apoptosis.
authors.affiliation: Experimental Tumorpathology, Department of Pathology, University of Erlangen-Nürnberg, Universitätsstr. 22, 91054 Erlangen, Germany.
authors.forename: Muktheshwar
authors.initials: M
authors.lastname: Gandesiri
authors.forename: Saritha
authors.initials: S
authors.lastname: Chakilam
authors.forename: Jelena
authors.initials: J
authors.lastname: Ivanovska
authors.forename: Natalya
authors.initials: N
authors.lastname: Benderska
authors.forename: Matthias
authors.initials: M
authors.lastname: Ocker
authors.forename: Pietro
authors.initials: P
authors.lastname: Di Fazio
authors.forename: Maria
authors.initials: M
authors.lastname: Feoktistova
authors.forename: Hala
authors.initials: H
authors.lastname: Gali-Muhtasib
authors.forename: Margret
authors.initials: M
authors.lastname: Rave-Fränk
authors.forename: Olaf
authors.initials: O
authors.lastname: Prante
authors.forename: Hans
authors.initials: H
authors.lastname: Christiansen
authors.forename: Martin
authors.initials: M
authors.lastname: Leverkus
authors.forename: Arndt
authors.initials: A
authors.lastname: Hartmann
authors.forename: Regine
authors.initials: R
authors.lastname: Schneider-Stock
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D001343:Autophagy / Q000187:drug effects*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000503:physiopathology*; D064550:Death-Associated Protein Kinases; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology*; D008297:Male; D051379:Mice; D000077767:Panobinostat
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D007211:Indoles; D000077767:Panobinostat; D064550:Death-Associated Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases