title: Histone Deacetylase Inhibitor RGFP109 Overcomes Temozolomide Resistance by Blocking NF-κB-Dependent Transcription in Glioblastoma Cell Lines.
abstract: Glioblastoma (GBM) is the most frequent and aggressive tumour in the central nervous system. Many studies have demonstrated that upregulation of the NF-κB onco-pathway is accompanied by the acquisition of Temozolomide (TMZ) resistance in GBM cells. Here, we show that RGFP109, a selective histone deacetylase (HDAC1 and HDAC3) inhibitor, overcomes TMZ resistance and downregulates the expression of NF-κB-regulated pro-survival genes in a TMZ-resistant (TR) GBM cell line. RGFP109 did not alter the phosphorylation levels of NF-κB/p65 or inhibitory κBα (IκBα). Immunofluorescence microscopy showed that RGFP109 does not block the nuclear translocation of NF-κB/p65. However, co-immunoprecipitation assays revealed that RGFP109 induces the hyperacetylation of NF-κB/p65 and histones, and blocks interactions between NF-κB/p65 and its coactivators, p300 and p300/CBP-associated factor (PCAF). These results indicate that RGFP109-mediated post-translational nuclear acetylation may be involved in the regulation of NF-κB. Electrophoretic mobility shift assays revealed that RGFP109 reduces NF-κB/p65 binding to κB-DNA and decreased the transcriptional level of κB-mediated genes, suggesting that RGFP109-induced hyperacetylation leads to attenuated transcription of the κB gene. In addition, RGFP109 elevates the expression of inhibitor of growth 4 (ING4), which is typically downregulated in GBM cells. Importantly, we found that RGFP109 enhances ING4 recognition and binding to NF-κB/p65, which may be positively correlated with reduced interactions between NF-κB/p65 and p300/PCAF, thereby effecting transcription of the κB gene. Finally, we show that knockdown of ING4 with plasmids containing pcDNA3.1-ING4 shRNA abolished the effect of RGFP109. Therefore, ING4 may act as a corepressor and facilitate RGFP109-triggered suppression of the NF-κB pathway. Taken together, our data show that RGFP109, an HDAC inhibitor, in combination with TMZ may be a therapeutic candidate for patients with temozolomide-resistant GBM.
authors.affiliation: Brain Center, Department of Neurosurgery, Shenzhen Key Laboratory of Neurosurgery, Shenzhen Second People's Hospital, The Clinical College of Anhui Medical University, Shenzhen University 1st Affiliated Hospital, 3002# Sungang Road, Futian district, Shenzhen, 518035, China.
authors.forename: Zong-Yang
authors.initials: ZY
authors.lastname: Li
authors.affiliation: Brain Center, Department of Neurosurgery, Shenzhen Key Laboratory of Neurosurgery, Shenzhen Second People's Hospital, The Clinical College of Anhui Medical University, Shenzhen University 1st Affiliated Hospital, 3002# Sungang Road, Futian district, Shenzhen, 518035, China.|Shantou University Medical College, 22# Xinling Road, Shantou, Guangdong, China.
authors.forename: Qing-Zhong
authors.initials: QZ
authors.lastname: Li
authors.affiliation: Brain Center, Department of Neurosurgery, Shenzhen Key Laboratory of Neurosurgery, Shenzhen Second People's Hospital, The Clinical College of Anhui Medical University, Shenzhen University 1st Affiliated Hospital, 3002# Sungang Road, Futian district, Shenzhen, 518035, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.affiliation: Brain Center, Department of Neurosurgery, Shenzhen Key Laboratory of Neurosurgery, Shenzhen Second People's Hospital, The Clinical College of Anhui Medical University, Shenzhen University 1st Affiliated Hospital, 3002# Sungang Road, Futian district, Shenzhen, 518035, China.
authors.forename: Bao-Dong
authors.initials: BD
authors.lastname: Chen
authors.affiliation: Brain Center, Department of Neurosurgery, Shenzhen Key Laboratory of Neurosurgery, Shenzhen Second People's Hospital, The Clinical College of Anhui Medical University, Shenzhen University 1st Affiliated Hospital, 3002# Sungang Road, Futian district, Shenzhen, 518035, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.affiliation: Brain Center, Department of Neurosurgery, Shenzhen Key Laboratory of Neurosurgery, Shenzhen Second People's Hospital, The Clinical College of Anhui Medical University, Shenzhen University 1st Affiliated Hospital, 3002# Sungang Road, Futian district, Shenzhen, 518035, China.
authors.forename: Xie-Jun
authors.initials: XJ
authors.lastname: Zhang
authors.affiliation: Brain Center, Department of Neurosurgery, Shenzhen Key Laboratory of Neurosurgery, Shenzhen Second People's Hospital, The Clinical College of Anhui Medical University, Shenzhen University 1st Affiliated Hospital, 3002# Sungang Road, Futian district, Shenzhen, 518035, China. wpli@szu.edu.cn.|Shantou University Medical College, 22# Xinling Road, Shantou, Guangdong, China. wpli@szu.edu.cn.
authors.forename: Wei-Ping
authors.initials: WP
authors.lastname: Li
mesh_terms: D000107:Acetylation; D021581:Active Transport, Cell Nucleus; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D017209:Apoptosis; D001549:Benzamides / Q000494:pharmacology*; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D016543:Central Nervous System Neoplasms; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004357:Drug Synergism; D005909:Glioblastoma; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D000077204:Temozolomide; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D018906:Antineoplastic Agents, Alkylating; D001549:Benzamides; D018797:Cell Cycle Proteins; D056572:Histone Deacetylase Inhibitors; D018398:Homeodomain Proteins; C483230:ING4 protein, human; C000615636:N-(6-(2-aminophenylamino)-6-oxohexyl)-4-methylbenzamide; D016328:NF-kappa B; D051996:Transcription Factor RelA; D025521:Tumor Suppressor Proteins; D003606:Dacarbazine; D000077204:Temozolomide
keywords: Histone deacetylase; ING4; NF-κB; RGFP109; Temozolomide