RNA-seq of human melanoma cancer cell line A375 treated with BET inhibitor JQ1 against untreated control
Ontology highlight
ABSTRACT: To set the relevance of BRD4 as repressor, we performed gene expression profile by RNA-seq in A375 treated with BETi JQ1 to identify potential BRD4 target genes.
Project description:Small molecule inhibitors of the bromodomain and extraterminal (BET) family of proteins are in clinical trials for a variety of cancers, but patient selection strategies are limited. This is due in part to the heterogeneity of response following BET inhibition (BETi), which includes differentiation, senescence, and cell death in subsets of cancer cell lines. To elucidate the dominant features defining response to BETi, we carried out phenotypic and gene expression analysis of both treatment naïve cell lines and engineered tolerant lines. We found that both de novo and acquired tolerance to BET inhibition are driven by the robustness of the apoptotic response and that genetic or pharmacological manipulation of the apoptotic signaling network can modify the phenotypic response to BETi. We further identify that ordered expression of the apoptotic genes BCL2, BCL2L1, and BAD significantly predicts response to BETi. Our findings highlight the role of the apoptotic network in response to BETi, providing a molecular basis for patient stratification and combination therapies. Gene expression profiling of A375 melanoma cells or NOMO-1 AML cells treated with DMSO or the BET inhibitor, CPI203. Also, gene expression profiling of the respective derived BETi-tolerant cells treated with DMSO or CPI203.
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:Targeting the epigenome to modulate gene expression programs driving cancer development has emerged as an exciting avenue for therapeutic intervention. Pharmacological inhibition of the bromodomain and extraterminal (BET) family of chromatin adapter proteins has proven effective in this regard, suppressing growth of diverse cancer types mainly through downregulation of the c-MYC oncogene and its downstream transcriptional program. While initially effective, resistance to BET inhibitors (BETi) typically occurs through mechanisms that reactivate MYC expression. We have previously shown that lung adenocarcinoma (LAC) is inhibited by JQ1 through suppression of FOSL1, suggesting that the epigenetic landscape of tumor cells from different origins and differentiation states influences BETi response. Here, we assessed how these differences affect mechanisms of BETi resistance through the establishment of isogenic pairs of JQ1 sensitive and resistant LAC cell lines. We found that resistance to JQ1 in LAC occurs independent of FOSL1 while MYC levels remain unchanged between resistant cells and their JQ1 treated parental counterparts. Furthermore, while epithelial-mesenchymal transition (EMT) is observed upon resistance, TGF- induced EMT did not confer resistance in JQ1 sensitive LAC lines, suggesting this is a consequence, rather than a driver of BETi resistance in our model systems. Importantly, siRNA knockdown demonstrated that JQ1 resistant cell lines are still dependent on BRD4 expression and we found that phosphorylation of BRD4 is elevated in resistant LACs, identifying casein kinase 2 (CK2) as a candidate protein mediating this effect. Inhibition of CK2, as well as downstream transcriptional targets of phosphorylated BRD4 - including AXL and activators of the PI3K pathway - synergize with JQ1 to inhibit BETi resistant LAC. Overall, this demonstrates that the mechanism of resistance to BETi varies depending on cancer type, with LAC cells developing JQ1 resistance independent of MYC re-activation, and identifying CK2 phosphorylation of BRD4 as a potential target to overcome resistance in this cancer.
Project description:The bromodomain and extra terminal domain (BET) family of proteins, including BRD2, BRD3, and BRD4, play a key role in many cellular processes, including inflammatory gene expression, mitosis, and viral/host interaction by controlling the assembly of histone acetylation-dependent chromatin complexes. Previous studies have shown that multiple BET inhibitors (BETi), including JQ1, have therapeutic effects in cancer and cardiovascular diseases. Some BETi have entered different phases of clinical trials. Pharmacologically, JQ1 functions by displacing BET proteins from chromatin by competitively binding to the acetyl-lysine recognition pocket of BET bromodomains. JQ1 has been used as a chemical probe to investigate the role of BET bromodomains in the transcriptional regulation of cardiovascular diseases. For example, JQ1 has been shown to attenuates inflammation and experimental atherosclerosis (Mol Cell. 2014 Oct 23; 56(2): 219–231.). JQ1 has also recently been shown to reduce EndoMT and cardiac fibrosis (J Mol Cell Cardiol. 2019 Feb;127:83-96.). However, the molecular targets of JQ1 dependent or independent of BRD4 remains unknown. To depict the transcriptomic signature of JQ1 in human endothelial cells, we observed a vasoprotective and atheroprotective transcriptome by JQ1 treatment using genome-wide RNA-seq based transcriptomic profiling. JQ1 is a magic bullet in cardiovascular disease prevention. Further elucidation of new molecular targets of JQ1 will lead to the identification of potentially new therapeutic targets to treat cardiovascular diseases.
Project description:The bromodomain and extra-terminal domain inhibitors (BETi) are promising epigenetic drugs for the treatment of various cancers through suppression of oncogenic transcription factors including MYC. However, only a subset of CRC cells response to BETi, suggesting an intrinsic resistance to BETi in CRC. We investigated the effect of JQ1 on cell proliferation, apoptosis, angiogenesis and MYC expression in a panel of 11 CRC cells in vitro and in vivo. JQ1-resistant CRC cells were used for the screening for the effective combination therapies with JQ1. RNA-seq of single drug or combined drugs treatment was performed to explore the mechanism of action.
Project description:We analyzed anti-proliferative dominant-negative Brd4 mutants that compete with the function of distinct Brd4 domains. We used these Brd4 mutants to compare the Brd4-specific transcriptome with the transcriptome of JQ1 treated cells.
Project description:MAP4K5 is serine/threonine protein kinase similar to yeast SPS1/STE20 kinase. MAP4K5 activates JNK in mammalian cells, which suggests a role in stress response. MAP4K5 is involved in immune functions. We used microarray to investigate genome-wide transcriptional change from MAP4K5 knockdown in A375 cells. Total RNA's from the A375 cells where MAP4K5 was stably knocked down by shRNA were analyzed. As a control, RNA's from A375 cells were also analyzed.
Project description:To characterize the role of m6A modification in mediating BRD4-dependent biological functions, we established METTL3 reconstituting cells and treated with JQ1 BRD4 directs gene transcription through diverse mechanisms. Here, we specifically focused on BETi-dependent transcriptome or chestrated by m6A-mediated regulation. To this end, we first need to identify bona fide m6A-dependent transcripts via rescue experiments in METTL3-knockdown cells by adding back wild-type METTL3 or METTL3-CD mutant (a catalytically inactive form of METTL3)
Project description:MM1.S cells are an aggressive dexamethasone sensitive multiple myeloma cell line whose transcritional program is driven by deregulated c-Myc activity. We present ChIP-seq analysis of key transcritional regulators that are implicated the c-Myc transcriptional network in MM1.S cells treated with vehicle or 500nM JQ1. Brd4, Cdk9, cMyc, Max, Med1, RNA Pol II, and the chromatin modifications H3K4me3 and H3K27Ac were profiled in MM1.S cells treated with 500nM JQ1 for 24hr
Project description:In an effort to understand the mechanisms of acquired resistance to BRAF inhibitors, we isolated clones that acquired resistance to the BRAF inhibitor GSK2118436 derived from the A375 BRAF V600E mutant melanoma cell line. This resistance clones acquired mutations in NRAS and MEK1. One clones, 16R6-4, acquired two mutations in NRAS – Q61K and A146T. Proliferation and western blot analyses demonstrated that these clones were insensitive to single agent GSK2118436 or GSK1120212 (an allosteric MEK inhibitor) but were sensitive to the combination of GSK2118436 and GSK1120212. To further characterize this combination, global transcriptomic analysis was performed in A375 and 16R6-4 after 24 hour treatment with GSK2118436, GSK1120212 or the combination of GSK2118436 and GSK1120212. This data set was published in Molecular Cancer Therapeutics with the title “Combined inhibition of BRAF and MEK, BRAF and PI3K/mTOR, or MEK and PI3K/mTOR overcomes acquired resistance to the BRAF inhibitor GSK2118436, mediated by NRAS or MEK mutations” by Greger, J.G., et.al. A375 and 16R6-4 (an A375 derived GSK2118436 resistance clone) were treated for 24 hours with 0.1 micromolar GSK2118436, 1 micromolar GSK2118436, 0.01 micromolar GSK1120212, 0.1 micromolar GSK2118436 + 0.01 micromolar GSK1120212, or 1 micromolar GSK2118436 + 0.01 micromolar GSK1120212.