title: In vitro and in vivo interactions between the HDAC6 inhibitor ricolinostat (ACY1215) and the irreversible proteasome inhibitor carfilzomib in non-Hodgkin lymphoma cells.
abstract: Interactions between the HDAC6 inhibitor ricolinostat (ACY1215) and the irreversible proteasome inhibitor carfilzomib were examined in non-Hodgkin lymphoma (NHL) models, including diffuse large B-cell lymphoma (DLBCL), mantle cell lymphoma (MCL), and double-hit lymphoma cells. Marked in vitro synergism was observed in multiple cell types associated with activation of cellular stress pathways (e.g., JNK1/2, ERK1/2, and p38) accompanied by increases in DNA damage (γH2A.X), G2-M arrest, and the pronounced induction of mitochondrial injury and apoptosis. Combination treatment with carfilzomib and ricolinostat increased reactive oxygen species (ROS), whereas the antioxidant TBAP attenuated DNA damage, JNK activation, and cell death. Similar interactions occurred in bortezomib-resistant and double-hit DLBCL, MCL, and primary DLBCL cells, but not in normal CD34(+) cells. However, ricolinostat did not potentiate inhibition of chymotryptic activity by carfilzomib. shRNA knockdown of JNK1 (but not MEK1/2), or pharmacologic inhibition of p38, significantly reduced carfilzomib-ricolinostat lethality, indicating a functional contribution of these stress pathways to apoptosis. Combined exposure to carfilzomib and ricolinostat also markedly downregulated the cargo-loading protein HR23B. Moreover, HR23B knockdown significantly increased carfilzomib- and ricolinostat-mediated lethality, suggesting a role for this event in cell death. Finally, combined in vivo treatment with carfilzomib and ricolinostat was well tolerated and significantly suppressed tumor growth and increased survival in an MCL xenograft model. Collectively, these findings indicate that carfilzomib and ricolinostat interact synergistically in NHL cells through multiple stress-related mechanisms, and suggest that this strategy warrants further consideration in NHL.
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Girija
authors.initials: G
authors.lastname: Dasmahapatra
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, Virginia Commonwealth University, Richmond, Virginia.
authors.forename: Hiral
authors.initials: H
authors.lastname: Patel
authors.affiliation: James T. Wilmot Cancer Center, University of Rochester Medical Center, Rochester, New York. Department of Medicine, University of Rochester Medical Center, Rochester, New York. Department of Biostatistics and Computational Biology, University of Rochester Medical Center, Rochester, New York.
authors.forename: Johnathan
authors.initials: J
authors.lastname: Friedberg
authors.affiliation: Acetylon Pharmaceuticals Inc., Boston, Massachusetts.
authors.forename: Steven N
authors.initials: SN
authors.lastname: Quayle
authors.affiliation: Acetylon Pharmaceuticals Inc., Boston, Massachusetts.
authors.forename: Simon S
authors.initials: SS
authors.lastname: Jones
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, Virginia Commonwealth University, Richmond, Virginia. Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia. Virginia Institute of Molecular Medicine, Virginia Commonwealth University, Richmond, Virginia. stgrant@vcu.edu.
authors.forename: Steven
authors.initials: S
authors.lastname: Grant
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D045744:Cell Line, Tumor; D045643:DNA Repair Enzymes / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004195:Disease Models, Animal; D004347:Drug Interactions; D004357:Drug Synergism; D005260:Female; D055785:Gene Knockdown Techniques; D000073864:Histone Deacetylase 6; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D008228:Lymphoma, Non-Hodgkin / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009842:Oligopeptides / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D061988:Proteasome Inhibitors / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D004268:DNA-Binding Proteins; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D009842:Oligopeptides; D061988:Proteasome Inhibitors; D011743:Pyrimidines; C513287:RAD23B protein, human; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C524865:carfilzomib; C433811:HDAC6 protein, human; D000073864:Histone Deacetylase 6; D006655:Histone Deacetylases; D045643:DNA Repair Enzymes; C572255:ricolinostat