Project description:The identification of recurrent somatic mutations in genes encoding epigenetic enzymes, coupled with biochemical studies demonstrating aberrant recruitment of epigenetic enzymes such as histone deacetylases (HDACs) and histone methyltransferases (HMTs) to promoter regions through association with oncogenic fusion proteins such as PML-RARM-NM-1 and AML1-ETO has provided a strong rationale for the development compounds that target the epigenome for the treatment of cancer. HDAC inhibitors (HDACi) are potent inducers of tumor cell apoptosis but it remains unclear why tumor cells are selectively sensitive to HDACi-induced cell death. Herein we assessed the biological and molecular responses of normal and transformed cells to the FDA-approved HDACi vorinostat. Both HDACi selectively killed cells of diverse tissue origin that had been transformed through the serial introduction of different oncogenes. Time course microarray expression profiling revealed that normal and transformed cells transcriptionally responded to vorinostat treatment. Over 4200 genes responded differently to vorinostat in normal and transformed cells and gene ontology and pathway analyses identified a tumor-cell-selective pro-apoptotic gene-expression signature that consisted of BCL2 family genes. In particular, HDACi induced tumor cell-selective upregulation of the pro-apoptotic gene BMF and downregulation of the pro-survival gene BCL2A1 encoding BFL-1. Maintenance of BFL-1 levels in transformed cells through forced expression conferred vorinostat resistance indicating that specific and selective engagement of the intrinsic apoptosis pathways underlies the tumor cell-selective apoptotic activities of these agents. The ability of HDACi to affect the growth and survival of tumor cells whilst leaving normal cells relatively unharmed is fundamental to their successful clinical application. This study provides new insight into the transcriptional effects of HDACi in human donor-matched normal and transformed cells, and identifies molecules and pathways that could underpin the tumor-selective cytotoxic activity of these compounds. Whole genome expression profiling was performed for vorinostat-treated samples and control samples (DMSO vehicle control). Fourteen samples were included in this study. Each sample has three biological replicates, making forty-two arrays in total.
Project description:Histone deacetylase (HDAC) inhibition has been shown in previous studies to disrupt the synovial sarcoma oncoprotein complex, resulting in apoptosis. To understand the molecular effects of HDAC inhibition, RNA-Seq transcriptome analysis was undertaken in six human synovial sarcoma cell lines. HDAC inhibition induced pathways of cell cycle arrest, neuronal differentiation and response to oxygen-containing species, effects also observed in other cancers treated with this class of drugs. More specific to synovial sarcoma, polycomb-group targets were reactivated including tumor suppressor CDKN2A, and pro-apoptotic transcriptional patterns were induced. Functional analyses revealed that ROS-mediated FOXO activation and pro-apoptotic factors BIK, BIM and BMF were important to apoptosis induction following HDAC-inhibition in synovial sarcoma
Project description:The identification of recurrent somatic mutations in genes encoding epigenetic enzymes, coupled with biochemical studies demonstrating aberrant recruitment of epigenetic enzymes such as histone deacetylases (HDACs) and histone methyltransferases (HMTs) to promoter regions through association with oncogenic fusion proteins such as PML-RARα and AML1-ETO has provided a strong rationale for the development compounds that target the epigenome for the treatment of cancer. HDAC inhibitors (HDACi) are potent inducers of tumor cell apoptosis but it remains unclear why tumor cells are selectively sensitive to HDACi-induced cell death. Herein we assessed the biological and molecular responses of normal and transformed cells to the FDA-approved HDACi vorinostat. Both HDACi selectively killed cells of diverse tissue origin that had been transformed through the serial introduction of different oncogenes. Time course microarray expression profiling revealed that normal and transformed cells transcriptionally responded to vorinostat treatment. Over 4200 genes responded differently to vorinostat in normal and transformed cells and gene ontology and pathway analyses identified a tumor-cell-selective pro-apoptotic gene-expression signature that consisted of BCL2 family genes. In particular, HDACi induced tumor cell-selective upregulation of the pro-apoptotic gene BMF and downregulation of the pro-survival gene BCL2A1 encoding BFL-1. Maintenance of BFL-1 levels in transformed cells through forced expression conferred vorinostat resistance indicating that specific and selective engagement of the intrinsic apoptosis pathways underlies the tumor cell-selective apoptotic activities of these agents. The ability of HDACi to affect the growth and survival of tumor cells whilst leaving normal cells relatively unharmed is fundamental to their successful clinical application. This study provides new insight into the transcriptional effects of HDACi in human donor-matched normal and transformed cells, and identifies molecules and pathways that could underpin the tumor-selective cytotoxic activity of these compounds.
Project description:Pan and selective HDAC inhibition is synthetically lethal with TRAP1 inhibition in various model systems of glioblastoma, including patient derived xenograft (PDX) cells. Mechanistically, this occurs through several mechanisms, including the induction of metabolic stress by interference with tumor cell energy metabolism accompanied by modulation of pro- and anti-apoptotic Bcl-2 family proteins and the induction of a cell death with apoptotic features.
Project description:This model is from the article:
Heterogeneity Reduces Sensitivity of Cell Death for TNF-Stimuli
Schliemann M, Bullinger E, Borchers S, Allgower F, Findeisen R, Scheurich P. BMC Syst Biol.
2011 Dec 28;5(1):204. 22204418
,
Abstract:
BACKGROUND:
Apoptosis is a form of programmed cell death essential for the maintenance of homeostasis and the removal of potentially damaged cells in multicellular organisms. By binding its cognate membrane receptor, TNF receptor type 1 (TNF-R1), the proinflammatory cytokine Tumor Necrosis Factor (TNF) activates pro-apoptotic signaling via caspase activation, but at the same time also stimulates nuclear factor kappaB (NF-kappaB)-mediated survival pathways. Differential dose-response relationships of these two major TNF signaling pathways have been described experimentally and using mathematical modeling. However, the quantitative analysis of the complex interplay between pro- and anti-apoptotic signaling pathways is an open question as it is challenging for several reasons: the overall signaling network is complex, various time scales are present, and cells respond quantitatively and qualitatively in a heterogeneous manner.
RESULTS:
This study analyzes the complex interplay of the crosstalk of TNF-R1 induced pro- and anti-apoptotic signaling pathways based on an experimentally validated mathematical model. The mathematical model describes the temporal responses on both the single cell level as well as the level of a heterogeneous cell population, as observed in the respective quantitative experiments using TNF-R1 stimuli of different strengths and durations. Global sensitivity of the heterogeneous population was quantified by measuring the average gradient of time of death versus each population parameter. This global sensitivity analysis uncovers the concentrations of Caspase-8 and Caspase-3, and their respective inhibitors BAR and XIAP, as key elements for deciding the cell's fate. A simulated knockout of the NF-kappaB-mediated anti-apoptotic signaling reveals the importance of this pathway for delaying the time of death, reducing the death rate in the case of pulse stimulation and significantly increasing cell-to-cell variability.
CONCLUSIONS:
Cell ensemble modeling of a heterogeneous cell population including a global sensitivity analysis presented here allowed us to illuminate the role of the different elements and parameters on apoptotic signaling. The receptors serve to transmit the external stimulus; procaspases and their inhibitors control the switching from life to death, while NF-kappaB enhances the heterogeneity of the cell population. The global sensitivity analysis of the cell population model further revealed an unexpected impact of heterogeneity, i.e. the reduction of parametric sensitivity.
Note:
SBML model generated from Matlab system description
on 12-July-2011 21:08:15 by
exportSBML Copyright Eric Bullinger 2007-2011
Project description:Regulated by histone acetyltransferases and deacetylases (HDACs), histone acetylation is a key epigenetic mechanism controlling chromatin structure, DNA accessibility, and gene expression. HDAC inhibitors induce growth arrest, differentiation, and apoptosis of tumor cells and are used as anticancer agents. Here we describe the effects of HDAC inhibitors on microbial sensing by macrophages and dendritic cells in vitro and host defenses against infection in vivo. HDAC inhibitors down-regulated the expression of numerous host defense genes, including pattern recognition receptors, kinases, transcription regulators, cytokines, chemokines, growth factors, and costimulatory molecules as assessed by genome-wide microarray analyses or innate immune responses of macrophages and dendritic cells stimulated with Toll-like receptor agonists. HDAC inhibitors induced the expression of Mi-2β and enhanced the DNA-binding activity of the Mi-2/NuRD complex that acts as a transcriptional repressor of macrophage cytokine production. In vivo, HDAC inhibitors increased the susceptibility to bacterial and fungal infections but conferred protection against toxic and septic shock. Thus, these data identify an essential role for HDAC inhibitors in the regulation of the expression of innate immune genes and host defenses against microbial pathogens.
Project description:Activation of Signal Transducer and Activator of Transcription 3 (STAT3) is common in prostate cancers. STAT3 may induce cell proliferation and resistance to apoptosis, as well as promote tumor angiogenesis, invasion, and migration by activating gene expression. Many STAT3-dependent transcriptional responses are mediated through protein-protein interactions that involve the amino-terminal domain (N-domain). In this study, we found that inhibition of the STAT3 N-domain using novel inhibitor ST3-Hel2A-2 induces apoptotic death in prostate cancer cells. The cell death was accomponied by robust activation of pro-apoptotic gene. Using chromatin immunoprecipitation and tiling human promoter arrays (ChIP-chip), we have defined genome-wide targets of STAT3 in DU145 prostate cancer cells. We found that upregulated pro-apoptotic genes were bound by STAT3 in prostate cancer cells, and that STAT3 binding was decreased following inhibition of the STAT3 N-domain. DU145 cells were treated with ST3-Hel2A-2 or DMSO as a control for 3 hr. Total RNA has been extracted and prepared for hybridization on Affymetrix HG-U133A 2.0 arrays.
Project description:Activation of Signal Transducer and Activator of Transcription 3 (STAT3) is common in prostate cancers. STAT3 may induce cell proliferation and resistance to apoptosis, as well as promote tumor angiogenesis, invasion, and migration by activating gene expression. Many STAT3-dependent transcriptional responses are mediated through protein-protein interactions that involve the amino-terminal domain (N-domain). In this study, we found that inhibition of the STAT3 N-domain using novel inhibitor ST3-Hel2A-2 induces apoptotic death in prostate cancer cells. The cell death was accomponied by robust activation of pro-apoptotic gene. Using chromatin immunoprecipitation and tiling human promoter arrays (ChIP-chip), we have defined genome-wide targets of STAT3 in DU145 prostate cancer cells. We found that upregulated pro-apoptotic genes were bound by STAT3 in prostate cancer cells, and that STAT3 binding was decreased following inhibition of the STAT3 N-domain. STAT3 siRNA knockdow confirmed specificity of STAT3 binding and changes in gene expression. DU145 cells were treated with STAT3 siRNA or scrambled siRNA for 48hr. Total RNA has been extracted and prepared for hybridization on Affymetrix HG-U133A 2.0 arrays.
Project description:A better understanding of how p53 differentially activates cell cycle arrest or cell death is important to maximize benefits of therapeutic strategies dependant by wild-type p53. Here, we report that activation of pro-apoptotic p53 transcriptional targets in colorectal cancer cells imposes a critical, targetable dependence on the long splice form of the caspase-8 regulator FLIP (FLIPL) for survival. Upon Nutlin-3A induced stabilisation p53 directly upregulates FLIPL expression in a manner dependent on Class-I HDAC activity. Preventing FLIPL upregulation with the clinically relevant Class-I selective inhibitor Entinostat promotes apoptosis in response to Nutlin-3A , which predominantly induces growth arrest despite upregulating a range of pro-apoptotic target genes. Cell death in response to Nutlin-3A in FLIPL-depleted cells is mediated through two of p53's canonical transcriptional targets TRAIL-R2 and BAX and is caspase-8-dependent. This work uncovers novel, clinically relevant biology that identifies FLIPL as a key target for overcoming resistance to p53-activating agents.