Bromodomain and extra-terminal motif inhibitors: a review of preclinical and clinical advances in cancer therapy (original) (raw)
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Bromodomain-Selective BET Inhibitors Are Potent Antitumor Agents against MYC-Driven Pediatric Cancer
Cancer Research, 2020
Inhibition of members of the bromodomain and extraterminal (BET) family of proteins has proven a valid strategy for cancer chemotherapy. All BET identified to date contain two bromodomains (BD; BD1 and BD2) that are necessary for recognition of acetylated lysine residues in the N-terminal regions of histones. Chemical matter that targets BET (BETi) also interact via these domains. Molecular and cellular data indicate that BD1 and BD2 have different biological roles depending upon their cellular context, with BD2 particularly associated with cancer. We have therefore pursued the development of BD2-selective molecules both as chemical probes and as potential leads for drug development. Here we report the structure-based generation of a novel series of tetrahydroquinoline analogs that exhibit >50-fold selectivity for BD2 versus BD1. This selective targeting resulted in engagement with BD-containing proteins in cells, resulting in modulation of MYC proteins and downstream targets. Th...
The bromodomain: from epigenome reader to druggable target
Biochimica et biophysica acta, 2014
Lysine acetylation is a fundamental post-translational modification that plays an important role in the control of gene transcription in chromatin in an ordered fashion. The bromodomain, the conserved structural module present in transcription-associated proteins, functions exclusively to recognize acetyl-lysine on histones and non-histone proteins. The structural analyses of bromodomains' recognition of lysine-acetylated peptides derived from histones and cellular proteins provide detailed insights into the differences and unifying features of biological ligand binding selectivity by the bromodomains. Newly developed small-molecule inhibitors targeting bromodomain proteins further highlight the functional importance of bromodomain/acetyl-lysine binding as a key mechanism in orchestrating molecular interactions and regulation in chromatin biology and gene transcription. These new studies argue that modulating bromodomain/acetyl-lysine interactions with small-molecule chemicals o...
BET Bromodomain Inhibition as a Therapeutic Strategy to Target c-Myc
Cell, 2011
MYC contributes to the pathogenesis of a majority of human cancers, yet strategies to modulate the function of the c-Myc oncoprotein do not exist. Toward this objective, we have targeted MYC transcription by interfering with chromatin-dependent signal transduction to RNA polymerase, specifically by inhibiting the acetyl-lysine recognition domains (bromodomains) of putative co-activator proteins implicated in transcriptional initiation and elongation. Using a selective smallmolecule bromodomain inhibitor, JQ1, we identify BET bromodomain proteins as regulatory factors for c-Myc. BET inhibition by JQ1 downregulates MYC transcription, followed by genomewide downregulation of Myc-dependent target genes. In experimental models of multiple myeloma, a Myc-dependent hematologic malignancy, JQ1 produces a potent antiproliferative effect associated with cell cycle arrest and cellular senescence. Efficacy of JQ1 in three murine models of multiple myeloma establishes the therapeutic rationale for BET bromodomain inhibition in this disease and other malignancies characterized by pathologic activation of c-Myc.
Inhibition of BET bromodomain proteins as a therapeutic approach in prostate cancer
Oncotarget, 2013
BET (bromodomain and extra-terminal) proteins regulate gene expression through their ability to bind to acetylated chromatin and subsequently activate RNA PolII-driven transcriptional elongation. Small molecule BET inhibitors prevent binding of BET proteins to acetylated histones and inhibit transcriptional activation of BET target genes. BET inhibitors attenuate cell growth and survival in several hematologic cancer models, partially through the down-regulation of the critical oncogene, MYC. We hypothesized that BET inhibitors will regulate MYC expression in solid tumors that frequently over-express MYC. Here we describe the effects of the highly specific BET inhibitor, I-BET762, on MYC expression in prostate cancer models. I-BET762 potently reduced MYC expression in prostate cancer cell lines and a patient-derived tumor model with subsequent inhibition of cell growth and reduction of tumor burden in vivo. Our data suggests that I-BET762 effects are partially driven by MYC down-reg...
Bromodomains as therapeutic targets in cancer
Briefings in functional genomics, 2013
The malleability of the epigenome has long been recognized as a unique opportunity for therapeutic intervention. Interest in targeting components of the epigenetic machinery for therapeutic gain had initially been aimed at chromatin modifying enzymes. However, advances in medicinal chemistry have now made it possible to exploit pro-tein^protein interactions at the chromatin interface. Bromodomains (BRD) are a conserved motif used by a large number of chromatin-associated proteins to recognize and bind acetylated histone tails. Small molecules with high specificity for the Bromodomain and Extra Terminal family of proteins (BRD2, BRD3, BRD4 and BRDT) have recently been shown to have remarkable pre-clinical efficacy in various malignancies. These findings have provided the impetus for exploring other BRD proteins as novel targets in cancer therapy.
Cancers, 2019
Alterations in protein-protein and DNA-protein interactions and abnormal chromatin remodeling are a major cause of uncontrolled gene transcription and constitutive activation of critical signaling pathways in cancer cells. Multiple epigenetic regulators are known to be deregulated in several hematologic neoplasms, by somatic mutation, amplification, or deletion, allowing the identification of specific epigenetic signatures, but at the same time providing new therapeutic opportunities. While these vulnerabilities have been traditionally addressed by hypomethylating agents or histone deacetylase inhibitors, pharmacological targeting of bromodomain-containing proteins has recently emerged as a promising approach in a number of lymphoid and myeloid malignancies. Indeed, preclinical and clinical studies highlight the relevance of targeting the bromodomain and extra-terminal (BET) family as an efficient strategy of target transcription irrespective of the presence of epigenetic mutations....
Cold Spring Harbor perspectives in biology, 2014
In cancer, epigenetic proteins are intensely studied targets for therapeutic drug discovery, showing great promise. These proteins include the chromatin-modifying enzymes that "write" and "erase" histone posttranslational modifications (PTM), and those that "read" these marks through binding modules. In an effort to find a compound that could disrupt the protein-protein interactions between a PTM and reader, JQ1 has proven to be a first-in-class, drug-like inhibitor of the "bromodomain and extraterminal domain" epigenetic readers (BETs), which recognize histone lysine acetylation marks. JQ1 has facilitated the mechanistic study and therapeutic application in cancer of this kind of epigenetic inhibition. By using this chemical probe, we have discovered that the bromodomain inhibitors (BETi) have compelling activity in preclinical models of multiple myeloma and acute myeloid leukemia. In particular, BETi down-regulates the MYC, IL-7R, and E2F tr...
Targeting MYC dependence in cancer by inhibiting BET bromodomains
Proceedings of the National Academy of Sciences, 2011
The MYC transcription factor is a master regulator of diverse cellular functions and has been long considered a compelling therapeutic target because of its role in a range of human malignancies. However, pharmacologic inhibition of MYC function has proven challenging because of both the diverse mechanisms driving its aberrant expression and the challenge of disrupting protein-DNA interactions. Here, we demonstrate the rapid and potent abrogation of MYC gene transcription by representative small molecule inhibitors of the BET family of chromatin adaptors. MYC transcriptional suppression was observed in the context of the natural, chromosomally translocated, and amplified gene locus. Inhibition of BET bromodomain-promoter interactions and subsequent reduction of MYC transcript and protein levels resulted in G 1 arrest and extensive apoptosis in a variety of leukemia and lymphoma cell lines. Exogenous expression of MYC from an artificial promoter that is resistant to BET regulation significantly protected cells from cell cycle arrest and growth suppression by BET inhibitors. MYC suppression was accompanied by deregulation of the MYC transcriptome, including potent reactivation of the p21 tumor suppressor. Treatment with a BET inhibitor resulted in significant antitumor activity in xenograft models of Burkitt's lymphoma and acute myeloid leukemia. These findings demonstrate that pharmacologic inhibition of MYC is achievable through targeting BET bromodomains. Such inhibitors may have clinical utility given the widespread pathogenetic role of MYC in cancer.
A chemical toolbox for the study of bromodomains and epigenetic signaling
Nature Communications, 2019
Bromodomains (BRDs) are conserved protein interaction modules which recognize (read) acetyl-lysine modifications, however their role(s) in regulating cellular states and their potential as targets for the development of targeted treatment strategies is poorly understood. Here we present a set of 25 chemical probes, selective small molecule inhibitors, covering 29 human bromodomain targets. We comprehensively evaluate the selectivity of this probe-set using BROMOscan and demonstrate the utility of the set identifying roles of BRDs in cellular processes and potential translational applications. For instance, we discovered crosstalk between histone acetylation and the glycolytic pathway resulting in a vulnerability of breast cancer cell lines under conditions of glucose deprivation or GLUT1 inhibition to inhibition of BRPF2/3 BRDs. This chemical probe-set will serve as a resource for future applications in the discovery of new physiological roles of bromodomain proteins in normal and disease states, and as a toolset for bromodomain target validation.