Project description:The BET (bromodomain and extra-terminal) family of acetyl-lysine reader proteins acts as transcriptional activators. BET inhibitors showed anti-cancer efficacies. We performed microarray analysis to characterize BET inhibitor-induced gene expression alterations.
Project description:Bromodomains have emerged as attractive candidates for the development of inhibitors targeting gene transcription. Inhibitors of the bromo-and-extra-terminal (BET) family recently showed promising activity in diverse disease models. However, the pleiotropic nature of BET proteins regulating tissue specific transcription has raised safety concerns and suggested that attempts should be made for domain-specific targeting. Here we report that RVX-208, a compound currently in phase II clinical trials, is a BET bromodomain inhibitor specific for second bromodomains (BD2). Co-crystal structures revealed binding modes of RVX-208 and its synthetic precursor and fluorescent recovery after photobleaching demonstrated that RVX-208 displaces BET proteins from chromatin. However, gene expression data showed that BD2 inhibition only modestly affects BET-dependent gene transcription. Our data demonstrate the feasibility of specific targeting within the BET family resulting in different transcriptional outcomes and highlight the importance of BD1 in transcriptional regulation
Project description:Bromodomain and extra-terminal domain (BET) proteins are therapeutic targets in several cancers including the most common malignant adult brain tumor glioblastoma (GBM). Multiple small molecule inhibitors of BET proteins have been utilized in preclinical and clinical studies. Unfortunately, BET inhibitors have not shown efficacy in clinical trials enrolling GBM patients. One possible reason for this may stem from resistance mechanisms that arise after prolonged treatment within a clinical setting. However, the mechanisms and timeframe of resistance to BET inhibitors in GBM is not known. To identify the temporal order of resistance mechanisms in GBM we performed quantitative proteomics using multiplex-inhibitor bead mass spectrometry and demonstrated that resistance to BET inhibitors in GBM treatment occurs rapidly within hours and involves the fibroblast growth factor receptor 1 (FGFR1) protein. Small molecule inhibition of BET proteins and FGFR1 simultaneously induces synergy in reducing GBM tumor growth in vitro and in vivo. Further, FGFR1 knockdown synergizes with BET inhibitor mediated reduction of GBM cell proliferation. Collectively, our studies suggest that co-targeting BET and FGFR1 may dampen resistance mechanisms to yield a clinical response in GBM.
Project description:Bromodomains have emerged as attractive candidates for the development of inhibitors targeting gene transcription. Inhibitors of the bromo-and-extra-terminal (BET) family recently showed promising activity in diverse disease models. However, the pleiotropic nature of BET proteins regulating tissue specific transcription has raised safety concerns and suggested that attempts should be made for domain-specific targeting. Here we report that RVX-208, a compound currently in phase II clinical trials, is a BET bromodomain inhibitor specific for second bromodomains (BD2). Co-crystal structures revealed binding modes of RVX-208 and its synthetic precursor and fluorescent recovery after photobleaching demonstrated that RVX-208 displaces BET proteins from chromatin. However, gene expression data showed that BD2 inhibition only modestly affects BET-dependent gene transcription. Our data demonstrate the feasibility of specific targeting within the BET family resulting in different transcriptional outcomes and highlight the importance of BD1 in transcriptional regulation HepG2 Cells were treated with eitther DMSO or 0.5uM JQ1 or 5uM RVX-208. Three samples per condition, total of nine samples. Inhbitor treatment was carried out for 4h before RNA was extracted. HepG2 cells (ATCC: HB-8065) were maintained in M-NM-1-MEM (Cat.#BE12-169F; BioWhittaker) supplemented with 10 % heat-inactivated foetal calf serum (PAA #A15-152), non-essential amino acids (Cat. #M7145; Sigma), glutamine (Cat.#M11-004; PAA), and vitamins (Cat.#M6895; Sigma). Cells were grown at 37 M-BM-0C in a humidified cabinet at 5 % CO2 (Heraeus Function Line). For experiments, cells were seeded the day prior to treatment at 2x105/ml. Treatments were performed for 4 h so that a final concentration of 0.1 % DMSO (Cat.#D1435; Sigma) was achieved. At harvest, cells were washed once with PBS (Cat.#H15-002; PAA), and lysed in situ using RLT buffer supplemented with 10 M-NM-<l/ml M-NM-2-mercaptoethanol (Cat.#M7522; Sigma). Total RNA was extracted and prepared using RNeasy columns (Cat.#74106 plus; Qiagen) including a Qia shredding step (Cat.#79656; Qiagen) and an on-column DNAse digestion (Cat.#EN0521; Fermentas), according to the manufacturerM-bM-^@M-^Ys instructions. The resulting RNA was quantified and quality controlled using a Nanodrop spectrophotometer (model ND1000; Thermo Fisher). RNA integrity was assessed on a BioAnalyzer (model G2938C; Agilent Laboratories, USA) and all samples had a RNA Integrity Number (RIN) M-bM-^IM-% 9. Labelled sense ssDNA for hybridization was generated from 200 ng starting RNA with the Ambion WT expression kit (Cat.#4411973; Ambion) and the Affymetrix GeneChip WT Terminal Labelling and Controls Kit (Cat.#901525; Affymetrix) according to the manufacturerM-bM-^@M-^Ys instructions. The distribution of fragmented sense ssDNA lengths was measured on the BioAnalyser. The fragmented ssDNA was labelled and hybridized for 17 hours at 45 M-BM-0C on the Affymetrix GeneChip Human Gene 1.0 ST Array (Affymetrix). Chips were processed on an Affymetrix GeneChip Fluidics Station 450 and Scanner 3000 and the affymetrix Command Console (v.3.2.4; Affymetrix) was used to generate CEL files.
Project description:Lytic infection by the Epstein-Barr virus (EBV) poses numerous health risks, such as infectious mononucleosis and lymphoproliferative disorder. We demonstrate that JQ1 and other BET inhibitors block two different steps in the sequential cascade of the EBV life cycle: expression of the immediate-early gene BZLF1 and lytic genome replication. This represents a novel mode of action for antiviral drugs that may increase efficacy and decrease emergence of resistance. The sequenced total DNA data in this series show that JQ1 causes a decrease in EBV genome replication upon antibody induction.
Project description:Small molecule BET bromodomain inhibitors (BETi) are actively being pursued in clinical trials for the treatment of a variety of cancers, however, the mechanisms of resistance to targeted BET protein inhibitors remain poorly understood. Using a novel mass spectrometry approach that globally measures kinase signaling at the proteomic level, we evaluated the response of the kinome to targeted BET inhibitor treatment in a panel of BRD4-dependent ovarian carcinoma (OC) cell lines. Despite initial inhibitory effects of BETi, OC cells acquired resistance following sustained treatment with the BETi, JQ1. Through application of Multiplexed Inhibitor Beads (MIBs) and mass spectrometry, we demonstrate that BETi resistance is mediated by adaptive kinome reprogramming, where activation of compensatory pro-survival kinase networks overcomes BET protein inhibition. Furthermore, drug combinations blocking these kinases may prevent or delay the development of drug resistance and enhance the efficacy of BET inhibitor therapy. RNAseq was employed to identify changes in kinase RNA expression following short term (48h) or chronic (JQ1R) JQ1 treatment in three different ovarian cancer cell lines.
Project description:Members of bromodomain and extra-C terminal (BET) domain family and the histone deacetylase (HDAC) enzyme family efficiently regulate the expression of important oncogenes and tumor suppressors. HDACs induce histone hypoacetylation meanwhile BET proteins bind to acetylated lysines on histones to regulate gene transcription. Here we show that the BET inhibitor JQ1 inhibited proliferation and induced apoptosis of both triple negative and estrogen receptor positive breast cancer cells. Consistent with the critical role of histone acetylation in the regulation of gene expression, microarray analysis revealed broad transcriptional changes after JQ1 or HDAC inhibitor treatment. By examining the molecular pathways affected by the epigenetic inhibitors we found that both BET and HDAC inhibitors are suppressing similar genes that were involved in cell cycle regulation. Combining JQ1 with HDAC inhibitors, we found that the combination significantly decreased cell viability. This effect was partly mediated by the more efficient suppression of genes essential for cell-cycle progression. Furthermore, we detected a dramatic increase in the expression of several members of the USP17 family of deubiquitinating enzymes in response to the single agent treatment, which further increased by the combination treatment. Since constitutive expression of USP17 has been reported to block the Ras/MAPK pathway, our data also suggest that the blockade of the Ras/MAPK pathway might also be involved in the synergistic effect of the combination treatment. In conclusion, this study suggests that co-treatment with BET inhibitors and HDAC inhibitors could be an effective treatment regime in future breast cancer therapy.