BRD4 inhibition leads to MDSC apoptosis and enhances checkpoint blockade therapy.
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ABSTRACT:
PROVIDER: PRJNA1292467 | ENA |
REPOSITORIES: ENA
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Project description:BRD4 is an epigenetic reader protein that regulates oncogenes such as myc in cancer. However, its additional role in shaping immune responses via regulation of inflammatory and myeloid cell responses is not yet fully understood. This work further characterized the multifaceted role of BRD4 in anti-tumor immunity. NanoString gene expression analysis of EMT6 tumors treated with a BRD4 inhibitor identified a reduction in myeloid gene expression signatures. Additionally, BRD4 inhibition significantly reduced myeloid derived suppressor cells (MDSC) in the spleens and tumors of mice in multiple tumor models and also decreased the release of tumor-derived MDSC growth and chemotactic factors. Pharmacologic inhibition of BRD4 in MDSC induced apoptosis and modulated expression of apoptosis regulatory proteins. A BRD4-myeloid specific knockout model suggested that the dominant mechanism of MDSC reduction after BRD4 inhibition was primarily through a direct effect on MDSC. BRD4 inhibition enhanced anti-PD-L1 therapy in the EMT6, 4T1 and LLC tumor models, and the efficacy of the combination treatment was dependent on CD8+ T cells and on BRD4 expression in the myeloid compartment. These results identify BRD4 as a regulator of MDSC survival and provide evidence to further investigate BRD4 inhibitors in combination with immune based therapies.
2025-07-24 | GSE302852 | GEO
Project description:Myeloid derived suppressor cells (MDSC) playing the immune suppressive roles in tumor bearing host consists of two major subsets of granulocytic and monocytic cells. Granulocytic MDSC (G-MDSC) express CD11b+ Gr-1high Ly6G+ Ly6Clow and produce high level of reactive oxygen species (ROS). Interestingly, neutrophils are well known ROS producing cells during immune defensive process and share same surface markers with G-MDSC. These similar features always brought the fundamental questions what’s the difference between G-MDSC and neutrophils but it’s not yet proven clearly. In this study, we examined the gene expression of G-MDSC and neutrophils using Affymetrix microarray G-MDSC (CD11b+Ly6G+Ly6Clow) were purifed from splenocytes in EL4 lymphoma tumor bearing mice by positive selection of Ly6G using microbeads isolation. Neutrophils were purified from ascitic fluids induced after injection of milk protein, casein by negative selection of F4/80 and positive selection of Ly6G using microbeads isolation. Their RNA was extracted and gene expression was analyzed using Affymetrix microarray.
2011-03-10 | E-GEOD-24102 | biostudies-arrayexpress
Project description:Myeloid-derived suppressor cells (MDSC) represent a heterogeneous population of immature myeloid cells that accumulate in blood, liver, spleen and tumors upon chronic inflammation and tumor development in patients and mice. Acute hepatitis is characterized by a fast infiltration of inflammatory cells in the liver and increased enzymatic activity at this organ that could lead into liver fibrosis and cirrhosis. We have studied the biology of hepatic MDSC in acute hepatitis. Unexpectedly, hepatic MDSC, which accumulate in the liver of mice bearing subcutaneous tumors, failed to suppress inflammatory responses upon Con A injection, but instead were responsible for exacerbating acute liver damage. Phenotypic, genetic and functional studies demonstrated rapid changes of hepatic MDSC from a suppressor phenotype into a pro-inflammatory subset as early as 3 hours after Con A injection. An increase in the expression of pro-inflammatory cytokines, costimulatory molecules such as CD80, CD86 and CD40 along with a loss of suppressor function was noticed in mice upon Con A treatment. These changes were CD40-dependent and not found in CD40-/- MDSC. Interestingly, CD40 ligation of human MDSC in vitro resulted in down-regulation of arginase I expression and suppressor function. Finally, blockade of ROS production in hepatic MDSC ameliorated hepatocyte damage suggesting that MDSC mediated toxicity was ROS dependent. We believe that these findings reflect how MDSC plasticity can be modulated to promote inflammation, opening a new path for therapies targeting innate suppressive cells in cancer patients. EL4 tumors were established in C57BL/6 mice, then mice were injected either with PBS (n=3) or 12.5mg/kg Con A (n=3). Three hours later mice were sacrificed, liver CD11b+Gr-1+ cells were sorted and samples were processed for gene expression analysis.
2015-09-01 | E-GEOD-50949 | biostudies-arrayexpress
Project description:DNA damage activates a complex signaling network in cells that blocks cell cycle progression, recruits factors involved in DNA repair, and/or triggers programs that control senescence or programmed cell death. Alterations in chromatin structure are known to be important for the initiation and propagation of the DNA damage response, although the molecular details are unclear. We investigated the role of chromatin structure in the DNA damage response by monitoring multiple timedependent checkpoint signaling and response events with a high-content multiplex image-based RNAi screen of chromatin modifying and interacting genes. We discovered that Brd4, a double bromodomain-containing protein, functions as an endogenous inhibitor of DNA damage signaling by binding to acetylated histones at sites of open chromatin and altering chromatin accessibility. Loss of Brd4 or disruption of acetyl-lysine binding results in an increase in both the number and size of radiation-induced !H2AX nuclear foci while overexpression of a Brd4 splice isoform completely suppresses !H2AX formation, despite equivalent double strand break formation. Brd4 knock-down cells displayed altered chromatin structure, prolonged cell cycle checkpoint arrest and enhanced survival after irradiation, while overexpression of Brd4 isoform B results in enhanced radiationinduced lethality. Brd4 is the target of the t(15;19) chromosomal translocation in a rare form of cancer, NUT Midline Carcinoma. Acetyl lysine-bromodomain interactions of the Brd4-NUT fusion protein suppresses !H2AX foci in discrete nuclear compartments, rendering cells more radiosensitive, mimicking overexpression of Brd4 isoform B. NUT Midline Carcinoma is sensitive to radiotherapy, however tumor material from this rare cancer is scarce. We therefore investigated Brd4 expression in another human cancer commonly treated with radiotherapy, glioblastoma multiforme, and found that expression of Brd4 isoform B correlated specifically with treatment response to radiotherapy. These data implicate Brd4 as an endogenous insulator of DNA damage signaling through recognition of epigenetic modifications in chromatin and suggest that expression of the Brd4 in human cancer can modulate the clinical response to DNA-damaging cancer therapy. Two replicates each of U2OS cells expressing either Brd4 shRNA or a control shRNA
2013-07-14 | E-GEOD-30700 | biostudies-arrayexpress
Project description:Myeloid derived suppressor cells (MDSC) playing the immune suppressive roles in tumor bearing host consists of two major subsets of granulocytic and monocytic cells. Granulocytic MDSC (G-MDSC) express CD11b+ Gr-1high Ly6G+ Ly6Clow and produce high level of reactive oxygen species (ROS). Interestingly, neutrophils are well known ROS producing cells during immune defensive process and share same surface markers with G-MDSC. These similar features always brought the fundamental questions what’s the difference between G-MDSC and neutrophils but it’s not yet proven clearly. In this study, we examined the gene expression of G-MDSC and neutrophils using Affymetrix microarray
2011-03-10 | GSE24102 | GEO
Project description:Myeloid-derived suppressor cells (MDSC) represent a heterogeneous population of immature myeloid cells that accumulate in blood, liver, spleen and tumors upon chronic inflammation and tumor development in patients and mice. Acute hepatitis is characterized by a fast infiltration of inflammatory cells in the liver and increased enzymatic activity at this organ that could lead into liver fibrosis and cirrhosis. We have studied the biology of hepatic MDSC in acute hepatitis. Unexpectedly, hepatic MDSC, which accumulate in the liver of mice bearing subcutaneous tumors, failed to suppress inflammatory responses upon Con A injection, but instead were responsible for exacerbating acute liver damage. Phenotypic, genetic and functional studies demonstrated rapid changes of hepatic MDSC from a suppressor phenotype into a pro-inflammatory subset as early as 3 hours after Con A injection. An increase in the expression of pro-inflammatory cytokines, costimulatory molecules such as CD80, CD86 and CD40 along with a loss of suppressor function was noticed in mice upon Con A treatment. These changes were CD40-dependent and not found in CD40-/- MDSC. Interestingly, CD40 ligation of human MDSC in vitro resulted in down-regulation of arginase I expression and suppressor function. Finally, blockade of ROS production in hepatic MDSC ameliorated hepatocyte damage suggesting that MDSC mediated toxicity was ROS dependent. We believe that these findings reflect how MDSC plasticity can be modulated to promote inflammation, opening a new path for therapies targeting innate suppressive cells in cancer patients.
2015-09-01 | GSE50949 | GEO
Project description:Despite the curative potential of checkpoint blockade immunotherapy, most patients remain unresponsive to existing treatments. Glyco-immune checkpoints – interactions of cell-surface glycans with lectin, or glycan-binding, immunoreceptors – have emerged as prominent mechanisms of immune evasion and therapeutic resistance in cancer. Here, we describe antibody-lectin chimeras (AbLecs), a modular platform for glyco-immune checkpoint blockade. AbLecs are bispecific antibody-like molecules comprising a cell-targeting antibody domain and a lectin “decoy receptor” domain that directly binds glycans and blocks their ability to engage inhibitory lectin receptors. AbLecs potentiate anticancer immune responses including phagocytosis and cytotoxicity, outperforming most existing therapies and combinations tested. By targeting a distinct axis of immunological regulation, AbLecs synergize with blockade of established immune checkpoints. AbLecs can be readily designed to target numerous tumor and immune cell subsets as well as glyco-immune checkpoints, and therefore represent a new modality for cancer immunotherapy.
2025-08-13 | PXD063934 | Pride
Project description:Hypoxia activated TH-302 with VEGFR-2 blockade elicits G-MDSC accumulation in pancreatic cancer
| PRJNA909239 | ENA
Project description:Combining TIGIT blockade with MDSC inhibition hinders breast cancer bone metastasis by activating anti-tumor immunity
| PRJNA1065817 | ENA
Project description:Nociceptor neurons impact tumor immunity. Removing nociceptor neurons reduced myeloid-derived suppressor cell (MDSCs) tumor infiltration in mouse models of head and neck carcinoma and melanoma. Carcinoma-released small extracellular vesicles (sEVs) attract nociceptive nerves to tumors. sEV-deficient tumors fail to develop in mice lacking nociceptor neurons. Exposure of dorsal root ganglia (DRG) neurons to cancer sEVs elevated expression of Substance P, IL-6 and injury-related neuronal markers while treatment with cancer sEVs and cytotoxic CD8 T-cells induced an immunosuppressive state (increased exhaustion ligands and cytokines). Cancer patient sEVs enhanced DRG responses to capsaicin, indicating increased nociceptor sensitivity. Conditioned media from DRG and cancer cell co-cultures promoted expression of MDSC markers in primary bone marrow cells while DRG conditioned media together with cancer sEVs induced checkpoint expression on T-cells. Our findings indicate that nociceptor neurons facilitate CD8+ T cell exhaustion and enhance MDSC infiltration. Targeting nociceptor-released IL-6 emerges as a novel strategy to disrupt harmful neuro-immune interactions in cancer and enhance anti-tumor immunity.
2025-08-07 | GSE300787 | GEO