title: Vorinostat synergizes with EGFR inhibitors in NSCLC cells by increasing ROS via up-regulation of the major mitochondrial porin VDAC1 and modulation of the c-Myc-NRF2-KEAP1 pathway.
abstract: In non-small-cell lung cancer (NSCLC) patients, the activation of alternative pathways contributes to the limited efficacy of the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib. The present study examines a panel of EGFR wild-type, K-Ras mutated, NSCLC lines, which were all intrinsically resistant to EGFR-TKIs, and demonstrates that the histone deacetylase inhibitor vorinostat can improve the therapeutic efficacy of gefitinib or erlotinib, inducing strong synergistic antiproliferative and pro-apoptotic effects that are paralleled by reactive oxygen species accumulation and by increased DNA damage. By knockdown experiments, we suggested that the up-regulation of voltage-dependent anion-selective channel protein 1 (VDAC1), the major mitochondrial porin of the outer mitochondrial membrane, which was induced by vorinostat and further increased by the combination, could be functionally involved in oxidative stress-dependent apoptosis. Significantly, we also observed the attenuation of the expression of both the enzyme hexokinase1, a negative VDAC1 regulator, and the anti-apoptotic porin VDAC2, only in the combination setting, suggesting convergent mechanisms that enhanced mitochondria-dependent apoptosis by targeting VDAC protein functions. Furthermore, the prosurvival capacities of the cells were also inhibited by the combination treatments, as shown by complete pAKT deactivation, increased GSK3β expression, and c-Myc down-regulation. Finally, we observed that the combination treatment of vorinostat and either of the EGFR-TKIs induced the down-regulation of the c-Myc-regulated nuclear factor erythroid 2-related factor 2 (NRF2) transcription factor and the up-regulation of the NRF2 repressor Kelch-like ECH-associated protein 1 regulator (KEAP1). These two genes are crucial for the redox stress response, often dysfunctional in NSCLC, and involved in EGFR-TKI resistance. Taken together, these results are the first to demonstrate that altering redox homeostasis is a new mechanism underlying the observed synergism between vorinostat and EGFR TKIs in NSCLC.
authors.affiliation: Experimental Pharmacology Unit, Istituto Nazionale Tumori Fondazione G. Pascale-IRCCS, 80131 Naples, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Leone
authors.affiliation: Experimental Pharmacology Unit, Istituto Nazionale Tumori Fondazione G. Pascale-IRCCS, 80131 Naples, Italy.
authors.forename: Maria Serena
authors.initials: MS
authors.lastname: Roca
authors.affiliation: Experimental Pharmacology Unit, Istituto Nazionale Tumori Fondazione G. Pascale-IRCCS, 80131 Naples, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Ciardiello
authors.affiliation: Experimental Pharmacology Unit, Istituto Nazionale Tumori Fondazione G. Pascale-IRCCS, 80131 Naples, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Terranova-Barberio
authors.affiliation: Experimental Pharmacology Unit, Istituto Nazionale Tumori Fondazione G. Pascale-IRCCS, 80131 Naples, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Vitagliano
authors.affiliation: Scientific Direction, Istituto Nazionale Tumori Fondazione G. Pascale-IRCCS, 80131 Naples, Italy.
authors.forename: Gennaro
authors.initials: G
authors.lastname: Ciliberto
authors.affiliation: Department of Surgery "P.Valdoni" and Department of Clinical and Molecular Medicine, La Sapienza University, 00161 Rome, Italy.
authors.forename: Rita
authors.initials: R
authors.lastname: Mancini
authors.affiliation: Experimental Pharmacology Unit, Istituto Nazionale Tumori Fondazione G. Pascale-IRCCS, 80131 Naples, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Di Gennaro
authors.affiliation: Experimental Pharmacology Unit, Istituto Nazionale Tumori Fondazione G. Pascale-IRCCS, 80131 Naples, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Bruzzese
authors.affiliation: Experimental Pharmacology Unit, Istituto Nazionale Tumori Fondazione G. Pascale-IRCCS, 80131 Naples, Italy. Electronic address: a.budillon@istitutotumori.na.it.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Budillon
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004357:Drug Synergism; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D000077156:Gefitinib; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D000072019:Kelch-Like ECH-Associated Protein 1; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D050995:Voltage-Dependent Anion Channel 1 / Q000235:genetics / Q000378:metabolism*; D000077337:Vorinostat
chemical_list: D006877:Hydroxamic Acids; D047908:Intracellular Signaling Peptides and Proteins; C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1; C489427:MYC protein, human; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D047428:Protein Kinase Inhibitors; D016271:Proto-Oncogene Proteins c-myc; D011799:Quinazolines; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; C494762:VDAC1 protein, human; D000077337:Vorinostat; D050995:Voltage-Dependent Anion Channel 1; C512478:EGFR protein, human; D066246:ErbB Receptors; D000077156:Gefitinib
keywords: EGFR tyrosine kinase inhibitors; HDACi; KEAP1; NRF2; NSCLC cancer; Oxidative stress; ROS; VDAC1