Project description:Transcriptome analysis of MCF-7 (Estrogen receptor positive breast cancer) cells treated with p300 KAT inhibitor A-485 using Affymetrix GeneChip Human Transcriptome Array 2.0.
Project description:MCF-7 (Estrogen receptor positive breast cancer) cells were treated with p300 KAT inhibitor A-485 and genome wide H3K27ac deposition was measured by ChIP-seq.
Project description:The dynamic and reversible acetylation of proteins catalyzed by histone acetyltransferases (HATs) and histone deacetylases (HDACs) was discovered more than 2 decades ago and the enzymatic function of these enzymes are established as a major epigenetic regulatory mechanism of gene transcription. Thus, these epigenetic modifiers are involved in multiple diseases and represent attractive targets for therapeutic intervention. While HDAC inhibitors have been developed and approved by the FDA to treat certain cancers, progress on the development of drug-like HAT inhibitors has lagged. The HAT paralogs p300 and CBP (here called p300/CBP) are key transcriptional co-activators that are essential for a multitude of cellular processes and also implicated in human pathological conditions, including cancer. Current p300/CBP HAT domain inhibitors including natural products and bisubstrate analogs such as Lys-CoA either lack potency and selectivity or suffer from poor cellular permeability. C646 is widely utilized as a tool to inhibit p300/CBP HAT activity, but its off-target activity and reactivity may limit its cellular specificity. Here, we describe A-485 as a potent, selective and drug-like p300/CBP catalytic inhibitor. We show the first high resolution (1.95Å) co-crystal structure of a pharmacologically active small molecule (A-485) bound to the catalytic active site of p300 HAT domain and demonstrate that A-485 is an acetyl-CoA competitive inhibitor of p300/CBP. A-485 selectively inhibited proliferation across lineage-specific tumor types, including several hematological malignancies and androgen receptor-positive prostate cancer. A-485 robustly inhibited the androgen receptor transcriptional program in both androgen sensitive and castrate resistant prostate cancer and inhibited tumor growth in a castration resistant xenograft model. These results demonstrate the feasibility of selectively drugging the catalytic activity of histone acetyltransferases, provide the framework for delineating the enzymatic functions of HATs, and pave the way for the development of novel therapeutics targeting HAT activity.
Project description:Comparison of CBP/p300 gene knock-out, bromodomain inhibitor, and acetyltransferase inhibitors Cmpd-R and A-485 in the same cell line (MEF).
Project description:Differential response to p300 inhibitor A-485 was observed in a panel of melanoma cell lines. Three melanoma cell lines were treated with A-485 and microarray was used to determine gene expession changes at 6 and 24 hours.
Project description:P300/CBP and BET inhibition have synergistic effects in NMC. To explore the molecular mechanisms of this synergistic effect, transcriptomic profiling was performed in HCC2429 cells incubated with 250 nM A-485 and 50 nM JQ1 alone or combined.
Project description:The p300 lysine acetyltransferase (KAT) can function as an oncogene or a tumor suppressor in hematologic malignancies. We have identified a tumor suppressor role for p300 in myelodysplastic syndrome (MDS) driven by Tet2 deficiency. Compared to Tet2-null hematopoietic stem and progenitor cells (HSPCs), HSPCs lacking both p300 and Tet2 (double knock out, DKO) displayed enhanced proliferation and impaired differentiation. Consequently, p300Δ/Δ Tet2-/- mice developed acute myeloid leukemia. p300 loss in Tet2-/- HSPCs induced a global epigenomic reprogramming that enhanced leukemogenicity at least in part by increasing expression of Myb, as knock-down of Myb specifically hindered the proliferation of the DKO HSPCs. We show that p300 KAT activity regulates the function of Tet2 null HSPCs, and that augmenting p300 function impairs their unlimited self-renewal. Such a strategy could prove useful in individuals with Tet2 deficient hematopoiesis or MDS.