Project description:Background: Glioblastoma (GBM) is the most aggressive and lethal brain tumor. Although the histone deacetylase (HDAC)/Sp1 axis promotes growth and temozolomide (TMZ) resistance in glioblastoma, whether HDACs including HDAC6 are involved in modulating long non-coding RNAs (lncRNAs) to affect glioblastoma malignancy remains obscure. Methods: Integrative analysis of microarray and RNA-seq was performed to identify lncRNAs governed by HDAC6. Half-life measurement and RNA-protein pull-down assay combined with iTRAQ-based proteomic analysis were conducted to identify RNA modulators. The effect of LINC00461 on glioblastoma malignancy was evaluated using animal models and cell proliferation-related assays. Functional analysis of the LINC00461 downstream network was performed comprehensively using ingenuity pathway analysis and public databases. Results: We identified a lncRNA, LINC00461, which was substantially increased in TMZ-resistant glioblastoma cells. It was inversely correlated with the survival of mice bearing glioblastoma and was stabilized by interaction between HDAC6 and RNA-binding proteins (RBPs) such as CNOT6 and FUS. Targeting LINC00461 using MPT0B291, an HDAC6 inhibitor, decreased cell division-related proteins via the lncRNA-microRNA (miRNA)-mRNA network and caused cell cycle arrest, thereby suppressing proliferation in parental and TMZ-resistant glioblastoma cells and prolonging the survival of mice bearing glioblastoma. Conclusions: This study sheds light on the role of LINC00461 in glioblastoma malignancy and provides a novel therapeutic strategy for targeting the HDAC6/RBP/LINC00461 axis and its downstream effectors in patients with GBM.
Project description:Histone deacetylase 6 (HDAC6) is an epigenetic modifier that is an attractive pharmacological target in cancer. In this work, we show that HDAC6 is elevated in glioblastoma, the most malignant and common brain tumor in adults, and in glioma stem cells. Moreover, we identified a new small-molecule inhibitor of HDAC6, called JOC1, which presents strong sensitivity for HDAC6 inhibition and exerts high cytotoxic activity, alone or in combination with temozolomide. Moreover, it is able to significantly reduce tumor growth in vivo. Transcriptomic analysis of patient derived glioma stem cells revealed an increase in cell differentiation and cell death as well as decrease in cell cycle activity and cell division as relevant cellular pathways whose activities are significantly altered by the treatment with JOC1. In conclusion, our data reveal the efficacy of a novel HDAC6 inhibitor in glioblastoma pre-clinical setting
Project description:E3 ubiquitin ligase E6AP and histone deacetylase HDAC6 play essential roles in the progress and development of various cancers. To explore the mechanism of E6AP and HDAC6 in liver cancer, we performed proteomic analysis with E6AP knockdown, HDAC6 knockdown and negative control HepG2 cells. We identified proteins were significantly regulated upon knockdown of E6AP or HDAC6. Pathway analysis confirmed the known phenotypic effect of E6AP and HDAC6. Overall, results from our investigation provide potential biological pathways and target genes controlled by E6AP and HDAC6 in liver cancer cells.
Project description:Glioblastoma progression and recurrence are suggested to be derived by glioblastoma stem-like cells (GSCs). There is limited knowledge about the expression and therapy response of LGR5 in GSCs. We have investigated the role of LGR5 in glioblastoma by over-expression LGR5 using lentiviral vectors containing LGR5 cDNA (oeLGR5) or control (oeCTL).
Project description:Glioblastoma progression and recurrence are suggested to be derived by glioblastoma stem-like cells (GSCs). There is limited knowledge about the expression and therapy response of LGR5 in GSCs. We have investigated the role of LGR5 in glioblastoma by knocking down LGR5 using short hairpin RNA targeting LGR5 mRNA (shLGR5) and non-target RNA (shNT) as control.
Project description:Triple-negative breast cancer (TNBC) has a highly aggressive nature and distinct molecular characteristics from other subtypes of breast cancer and lacks effective targeted therapy. The molecular and genetic basis of cysteine/cystine dependency in TNBC is complex. We found that cysteine addiction associates with the expression of a set of Claudin genes in TNBC. The Claudin-high TNBCs are independent on cystine, while the Claudin-low TNBCs undergo rapid ferroptosis upon cystine deprivation or inhibition of cystine transport by erastin. To overcome the resistance of Claudin-high TNBC and luminal breast cancer to the potential targeted cystine-addiction therapy, we explored the synthetic lethality of cysteine by an epigenetic compound library screen. Several potent HDAC6 inhibitors were identified and rendered the Claudin-high TNBCs and luminal cancer cells dependent on extracellular cystine and undergoing ferroptosis upon cystine deprivation. The transcriptomic profiling showed that the HDAC6 inhibitor tubacin in combination with erastin activates a synthetic-lethal transcriptional program. Together, we have identified the HDAC6 inhibitors as potent therapy-sensitizers to revive the targeted cysteine-addiction therapy for various subtypes of breast cancer, not limit in the Claudin-low TNBC.
Project description:The Tip60 (also known as Kat5) lysine acetyltransferase functions broadly as a transcriptional co-activator that acetylates histones. In contrast, Tip60 functions in embryonic stem cells (ESCs) both to silence genes that promote differentiation and to activate genes required for proliferation. The mechanism by which Tip60 functions as a repressor is unknown. Here we show that the class II histone deacetylase Hdac6 co-purifies with Tip60-p400 complex from ESCs and is necessary for complete silencing of most differentiation genes targeted by Tip60. In contrast to differentiated cells, where Hdac6 is mainly cytoplasmic and does not interact with Tip60, Hdac6 is largely nuclear in ESCs and neural stem cells (NSCs) and interacts with Tip60-p400 in both cell types. Hdac6 is enriched at promoters bound by Tip60-p400 in ESCs, but while Tip60 binds on both sides of transcription start sites (TSSs), Hdac6 binding overlaps with only the downstream Tip60 peak. Surprisingly, Hdac6 does not deacetylate histones at these sites, but rather is required for Tip60 binding. These data suggest that nuclear exclusion of Hdac6 during differentiation plays a major role in modulation of Tip60-p400 function. We determined the genome-wide localization of Tip60 and Hdac6 in mouse ES cells, and examined genomic binding profiles of Tip60 and Hdac6 upon indicated knockdown by ChIP-seq. We examined genomic binding profiles of p400 upon indicated knockdown by ChIP-seq.
Project description:Foxp3+ T-regulatory cells (Tregs) are key to immune homeostasis such that their diminished numbers or function can cause autoimmunity and allograft rejection. Foxp3+ Tregs express histone/protein deacetylases (HDACs) that regulate chromatin remodeling, gene expression and protein function. Pan-HDAC inhibitors developed for oncology enhance Treg production and suppression but have limited non-oncologic applications given their broad effects. We show, using HDAC6-deficient mice and WT mice treated with HDAC6-specific inhibitors, that HDAC6 inhibition promotes Treg suppressive activity in models of inflammation and autoimmunity, including multiple forms of experimental colitis and fully MHC-incompatible cardiac allograft rejection. Many of the beneficial effects of HDAC6 targeting are also achieved by inhibition of the HDAC6-regulated protein, HSP90. Hence, selective targeting of a single HDAC isoform, HDAC6, or its downstream target, HSP90, can promote Treg-dependent suppression of autoimmunity and transplant rejection. RNA from three independent samples from magnetically separated CD4+CD25+ Treg of HDAC6 knock out, compared to wild type (C57BL6) control
Project description:Analysis of mouse ESCs overexpressing HDAC6. Histone deacetylase 6 (Hdac6) was discovered as a deacetylase of α-tubulin and functions in cell migration, immunity and resistance to virus infection in vitro. HDAC6 overexpression ESCs and control ESCs were selected for RNA extraction and hybridization on Agilent microarrays. Results provide insight into the role of HDAC6 in the mouse ESCs.