Bromodomain and extra terminal domain (BET) proteins are important epigenetic regulators facilitating the transcription of genes in chromatin areas linked to acetylated histones. JQ1, a BET protein inhibitor, has antiproliferative activity against many cancers, mainly through inhibition of c-MYC and upregulation of p21. In this research, we investigated the use of JQ1 for human osteosarcoma (OS) treatment. JQ1 significantly inhibited the proliferation and survival of OS cells inducing G1 cell cycle arrest, premature senescence, but little effect on apoptosis. Interestingly, c-MYC protein levels in JQ1-treated cells remained unchanged, whereas the upregulation of p21 protein was still observable. Although effective in vitro, JQ1 alone failed to reduce the size of the MNNG/HOS xenografts in immunocompromised mice. To overcome the resistance of OS cells to JQ1 treatment, we combined JQ1 with rapamycin, an mTOR inhibitor. JQ1 and rapamycin synergistically inhibited the growth and survival of OS cells in vitro and in vivo. We also identified that RUNX2 is a direct target of BRD4 inhibition by JQ1 in OS cells. Chromatin immunoprecipitation (ChIP) showed that enrichment of BRD4 protein around RUNX2 transcription start sites diminished with JQ1 treatment in MNNG/HOS cells. Overexpression of RUNX2 protected JQ1-sensitive OS cells from the effect of JQ1, and siRNA-mediated inhibition of RUNX2 sensitized the same cells to JQ1. In conclusion, our findings suggest that JQ1, in combination with rapamycin, is an effective chemotherapeutic option for OS treatment. We also show that inhibition of RUNX2 expression by JQ1 partly explains antiproliferative activity of JQ1 in OS cells.
Synergistic effect of JQ1 and rapamycin for treatment of human osteosarcoma.
Specimen part, Cell line
View SamplesThe combination of JQ1 and Vemurafenib acted synergistically in BRAF-mutant cell lines, resulting in marked apoptosis in vitro, with up-regulation of pro-apoptotic proteins. In vivo, combination treatment suppressed tumor growth and significantly improved survival compared to either drug alone. RNA sequencing of tumor tissues revealed almost four thousand genes that were uniquely modulated by the combination, with several anti-apoptotic genes significantly down-regulated. Overall design: 16 samples analyzed from 8 mice (each mouse was bearing two tumors, one on each flank) in 4 treatment groups (control, vemurafenib alone, JQ1 alone, JQ1+vemurafenib)
BET and BRAF inhibitors act synergistically against BRAF-mutant melanoma.
Cell line, Treatment, Subject
View SamplesJQ1 is a small-molecule (BET family) bromodomain inhibitor that causes a contraceptive effect in mice by blocking spermatogenesis and reducing sperm motility.
Small-molecule inhibition of BRDT for male contraception.
Sex, Specimen part
View SamplesUnrestrained receptor tyrosine kinase (RTK) signaling and epigenetic deregulation are root causes of tumorigenesis. We establish linkage between these processes by demonstrating that aberrant RTK signaling unleashed by oncogenic HRasG12V or loss of negative feedback through Sprouty gene deletion remodels histone modifications associated with active typical and super-enhancers. However, while both lesions disrupt the Ras-Erk axis, the expression programs, enhancer signatures, and transcription factor networks modulated upon HRasG12V-transformation or Sprouty deletion are largely distinct. Oncogenic HRasG12V elevates histone 3 lysine 27 acetylation (H3K27ac) levels at enhancers near the transcription factor Gata4 and the kinase Prkcb, as well as their expression levels. We show that Gata4 is necessary for the aberrant gene expression and H3K27ac marking at enhancers, and Prkcb is required for the oncogenic effects of HRasG12V-driven cells. Taken together, our findings demonstrate that dynamic reprogramming of the cellular enhancer landscape is a major effect of oncogenic RTK signaling. Overall design: We assessed gene expression changes upon loss of feedback regulation through Sprouty (Spry) deletion, and upon unrestrained signaling driven by mutant oncogenes. RNA-seq was performed in biological triplicate; replicate number is included in the sample name. Spry124fl/fl (VEC) and Spry124-/- (CRE) MEFs were profiled in three conditions: unsynchronized (U), serum starved (S), and serum starved and FGF treated (F). Spry124fl/fl (VEC) MEFs transduced with empty vector (EV) control or the indicated oncogenes (KRasG12V, HRasG12V, and BRafV600E) as well as Spry124-/- (CRE) MEFs transduced with EV control were profiled in the unsynchronized state.
Deregulation of the Ras-Erk Signaling Axis Modulates the Enhancer Landscape.
No sample metadata fields
View SamplesNOTCH proteins regulate signaling pathways involved in cellular differentiation, proliferation and death. Overactive Notch signaling as been observed in numerous cancers and has been extensively studied in the context of T-cell acute lymphoblastic leukemia (T-ALL) where more than 50% of pateints harbour mutant NOTCH1. Small molecule modulators of these proteins would be important for understanding the role of NOTCH proteins in malignant and normal biological processes.
Direct inhibition of the NOTCH transcription factor complex.
Specimen part, Cell line
View SamplesFoxp3+ 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.
Histone deacetylase 6 and heat shock protein 90 control the functions of Foxp3(+) T-regulatory cells.
No sample metadata fields
View SamplesEpigenetic regulators have emerged as exciting targets for cancer therapy. Additionally, restoration of antitumor immunity by blocking the PD-L1 signaling using antibodies has proven to be beneficial in cancer therapy. Here we show that BET bromodomain inhibition suppresses PD-L1 expression and restores antitumor immunity in ovarian cancer. CD274 (encoding PD-L1) is a direct target of BRD4-mediated gene transcription. In mouse models, treatment with the BET inhibitor JQ1 significantly reduced PD-L1 expression on tumor cells and tumor-associated dendritic cells and macrophages, which correlated with an increase in the activity of antitumor cytotoxic T cells. Together, these data demonstrate an epigenetic approach to block PD-L1 signaling to restore antitumor immunity. Given the fact that BET inhibitors have been proven safe with manageable reversible toxicity in clinical trials, our findings indicate that pharmacological BET inhibitors represent a novel treatment strategy for targeting PD-L1 expression. Overall design: RNA-seq for JQ1 treated and shBRD4 knockdown cells with controls
BET Bromodomain Inhibition Promotes Anti-tumor Immunity by Suppressing PD-L1 Expression.
Treatment, Subject
View SamplesTargeting BET bromodomain proteins utilizing small molecules in an emerging anti-cancer strategy with clinical evaluation of at least six inhibitors now underway. While MYC downregulation was initially proposed as a key mechanistic property of BET inhibitors, recent evidence suggests that additional anti-tumor activities are important. Using the Eµ-Myc model of B-cell lymphoma we demonstrate that BET inhibition with JQ1 is a potent inducer of p53-independent apoptosis that occurs in the absence of effects on Myc gene expression. JQ1 skews the expression of pro-apoptotic (Bim) and anti-apoptotic (BCL-2/BCL-xL) BCL-2 family members to directly engage the mitochondrial apoptotic pathway. Consistent with this, Bim knockout or Bcl-2 overexpression inhibited apoptosis induction by JQ1. We identified lymphomas that were either intrinsically resistant to JQ1-mediated death or acquired resistance following in vivo exposure. Strikingly, in both instances BCL-2 was strongly upregulated and was concomitant with activation of RAS pathways. Eµ-Myc lymphomas engineered to express activated Nras upregulated BCL-2 and acquired a JQ1-resistance phenotype. These studies provide important information on mechanisms apoptosis induction and resistance to BET-inhibition, while providing further rationale for the translation of BET inhibitors in aggressive B-cell lymphomas. Overall design: RNA-Sequencing of JQ1 resistant and sensitive Eµ-Myc cell lines
BET Inhibition Induces Apoptosis in Aggressive B-Cell Lymphoma via Epigenetic Regulation of BCL-2 Family Members.
Cell line, Subject
View SamplesLarge-scale genomic studies have identified multiple somatic aberrations in breast cancer, including copy number alterations, translocations, and point mutations. Still, identifying causal variants and emergent vulnerabilities that arise as a consequence of genetic alterations remain major challenges. We performed whole genome shRNA “dropout screens” on 77 breast cancer cell lines. Using a new hierarchical linear regression algorithm to score our screen results and integrate them with accompanying detailed genetic and proteomic information, we identify novel vulnerabilities in breast cancer, including new candidate “drivers,” and reveal general functional genomic properties of cancer cells. Comparisons of gene essentiality with drug sensitivity data suggest potential resistance mechanisms, novel effects of existing anti-cancer drugs, and new opportunities for combination therapy. Finally, we demonstrate the utility of this large dataset by identifying BRD4 as a potential target in luminal breast cancer, and PIK3CA mutations as a resistance determinant for BET-inhibitors. Additional formatted data can be found at http://neellab.github.io/bfg/. Code and tutorials for the siMEM algorithm can be found at http://neellab.github.io/simem/. Overall design: RNA-Seq expression profiling of 82 breast cancer cell lines without replicates or control samples
Functional Genomic Landscape of Human Breast Cancer Drivers, Vulnerabilities, and Resistance.
No sample metadata fields
View SamplesTo determine the global transcriptome changes in mantle cell lymphoma cells following treatment with the BET bromodomain antagonist, JQ1
Synergistic activity of BET protein antagonist-based combinations in mantle cell lymphoma cells sensitive or resistant to ibrutinib.
Specimen part, Treatment
View Samples