Project description:Antiprolifereative effects of CREBBP/EP300 inhibitors were tested in human leukemia and lymphoma cell lines and the molecular mechanisms responsible for such effects were explored.
Project description:We found that the bone marrow microenvironment of Crebbp+/- mice was unable to properly maintain the immature stem - and progenitor pools. Instead, it stimulates myeloid differentiation that progresses into a myeloproliferative-like disease. Since CREBBP is a transcriptional co-activator, we used gene expression analysis to globally assess functional deficiencies in Crebbp+/- bone marrow stroma cells at a molecular level. Ep300 encodes a protein which is highly similar in structure and function to CREBBP; nevertheless, Ep300+/- mice suffer neither excessive myeloid differentiation nor loss of HSCs. Therefore, to identify expression changes specifically related to Crebbp heterozygosity, we focused on genes that showed significant differences in expression levels between Crebbp+/- and wild-type bone marrow stroma but no difference between Ep300+/- and wild-type. Bone marrow stroma was established from wild-type, Crebbp+/- and Ep300+/- mice that were 3-4 months old for RNA extraction and hybridization on Affymetrix microarrays. There are 4 biological replicates for each genotype used.
Project description:Inactivating mutations of the CREBBP acetyltransferase and, at lower frequencies, its paralogue EP300 are among the most common genetic alterations in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL), the two most frequent B cell malignancies. Here we uncover unexpected distinct functions for CREBBP and EP300 in the germinal center (GC), i.e. the target structure for most human B cell lymphomas. We show that these proteins modulate non-overlapping transcriptional programs that are preferentially enriched in biological functions associated with the separate anatomic compartments of the GC. Consistently, deletion of CREBBP or EP300 have opposing effects on GC formation in vivo. Nonetheless, these proteins partially compensate for each other to maintain a minimal threshold of acetyltransferase activity and guarantee homeostatic control of the GC, which is completely abrogated by their combined loss. This synthetic lethal interaction is retained in DLBCL cells, identifying an Achille’s heel in CREBBP-mutant lymphomas that could be pharmacologically targeted by using a novel, selective small molecule inhibitor of the CREBBP/EP300 bromodomain. These data shed light on the unique roles of CREBBP and EP300 in the physiology and pathology of GC B cells, and provide a proof-of-principle for the development and testing of EP300 inhibition as a therapeutic strategy in these diseases.
Project description:We found that the bone marrow microenvironment of Crebbp+/- mice was unable to properly maintain the immature stem - and progenitor pools. Instead, it stimulates myeloid differentiation that progresses into a myeloproliferative-like disease. Since CREBBP is a transcriptional co-activator, we used gene expression analysis to globally assess functional deficiencies in Crebbp+/- bone marrow stroma cells at a molecular level. Ep300 encodes a protein which is highly similar in structure and function to CREBBP; nevertheless, Ep300+/- mice suffer neither excessive myeloid differentiation nor loss of HSCs. Therefore, to identify expression changes specifically related to Crebbp heterozygosity, we focused on genes that showed significant differences in expression levels between Crebbp+/- and wild-type bone marrow stroma but no difference between Ep300+/- and wild-type.
Project description:The androgen receptor (AR) serves as the primary target for therapeutic intervention in prostate cancer (PCa), and AR-targeted treatments constitute the cornerstone of clinical management for this malignancy. Nevertheless, their effectiveness is often compromised by the emergence of resistance mechanisms. These resistant forms of PCa persist in activating AR signaling, highlighting the urgent need for new therapeutic strategies to combat therapy-resistant PCa. Resistance to AR-targeted therapies can manifest through a multitude of mechanisms, including the overexpression of AR splice variants and altered activities of other transcription factors, such as the glucocorticoid receptor (GR) and FOXA1. A shared characteristic among these transcription factors is their dependence on a common set of coregulators, with EP300/CREBBP being a prominent example. This suggests a compelling rationale for employing coregulatory-targeted therapies in the management of treatment-resistant PCa. Here, we aimed to explore the impact of EP300/CREBBP acetyltransferase inhibition on steroid receptor and FOXA1 signaling in PCa cells, employing genome-wide techniques. Our findings illuminate that EP300/CREBBP inhibition exerts a substantial disruptive effect on the AR-regulated transcriptome and receptor chromatin binding, primarily by downregulating the AR-gene. Similarly, the transcriptome regulated by GR and the chromatin binding of the receptor were also hindered, although this was not associated with decreased GR expression levels. Instead, EP300/CREBBP acetyltransferase inhibition leads to a significant reduction in FOXA1 chromatin binding, consequently constraining GR signaling. In summary, our results emphasize how EP300/CREBBP acetyltransferase inhibition distinctly curtails the signaling activities of oncogenic transcription factors, underscoring the potential effectiveness of coregulatory-targeted therapies in PCa.
Project description:The androgen receptor (AR) serves as the primary target for therapeutic intervention in prostate cancer (PCa), and AR-targeted treatments constitute the cornerstone of clinical management for this malignancy. Nevertheless, their effectiveness is often compromised by the emergence of resistance mechanisms. These resistant forms of PCa persist in activating AR signaling, highlighting the urgent need for new therapeutic strategies to combat therapy-resistant PCa. Resistance to AR-targeted therapies can manifest through a multitude of mechanisms, including the overexpression of AR splice variants and altered activities of other transcription factors, such as the glucocorticoid receptor (GR) and FOXA1. A shared characteristic among these transcription factors is their dependence on a common set of coregulators, with EP300/CREBBP being a prominent example. This suggests a compelling rationale for employing coregulatory-targeted therapies in the management of treatment-resistant PCa. Here, we aimed to explore the impact of EP300/CREBBP acetyltransferase inhibition on steroid receptor and FOXA1 signaling in PCa cells, employing genome-wide techniques. Our findings illuminate that EP300/CREBBP inhibition exerts a substantial disruptive effect on the AR-regulated transcriptome and receptor chromatin binding, primarily by downregulating the AR-gene. Similarly, the transcriptome regulated by GR and the chromatin binding of the receptor were also hindered, although this was not associated with decreased GR expression levels. Instead, EP300/CREBBP acetyltransferase inhibition leads to a significant reduction in FOXA1 chromatin binding, consequently constraining GR signaling. In summary, our results emphasize how EP300/CREBBP acetyltransferase inhibition distinctly curtails the signaling activities of oncogenic transcription factors, underscoring the potential effectiveness of coregulatory-targeted therapies in PCa.
Project description:The androgen receptor (AR) serves as the primary target for therapeutic intervention in prostate cancer (PCa), and AR-targeted treatments constitute the cornerstone of clinical management for this malignancy. Nevertheless, their effectiveness is often compromised by the emergence of resistance mechanisms. These resistant forms of PCa persist in activating AR signaling, highlighting the urgent need for new therapeutic strategies to combat therapy-resistant PCa. Resistance to AR-targeted therapies can manifest through a multitude of mechanisms, including the overexpression of AR splice variants and altered activities of other transcription factors, such as the glucocorticoid receptor (GR) and FOXA1. A shared characteristic among these transcription factors is their dependence on a common set of coregulators, with EP300/CREBBP being a prominent example. This suggests a compelling rationale for employing coregulatory-targeted therapies in the management of treatment-resistant PCa. Here, we aimed to explore the impact of EP300/CREBBP acetyltransferase inhibition on steroid receptor and FOXA1 signaling in PCa cells, employing genome-wide techniques. Our findings illuminate that EP300/CREBBP inhibition exerts a substantial disruptive effect on the AR-regulated transcriptome and receptor chromatin binding, primarily by downregulating the AR-gene. Similarly, the transcriptome regulated by GR and the chromatin binding of the receptor were also hindered, although this was not associated with decreased GR expression levels. Instead, EP300/CREBBP acetyltransferase inhibition leads to a significant reduction in FOXA1 chromatin binding, consequently constraining GR signaling. In summary, our results emphasize how EP300/CREBBP acetyltransferase inhibition distinctly curtails the signaling activities of oncogenic transcription factors, underscoring the potential effectiveness of coregulatory-targeted therapies in PCa.
Project description:Various mechanisms have been reported to be responsible for enzalutamide resistance in prostate cancer. In our previous studies, we have demonstrated that the histone acetyltransferase EP300 is highly expressed in castration therapy-resistant prostate cancer. In the present study, we investigated the role of EP300/CREBBP in enzalutamide-resistant prostate cancer. Enzalutamide resistant and control DuCaP cells generatd previously were treated with histone acetyltransferase (C646) and bromodomain (I-CBP112) inhibitors of EP300/CREBBP. Additionally Enzalutamide resistant cells under 5 µM enzalutamide treatment and control LNCaP cells were analyzed. DuCaP and LNCaP cells were seeded in 6-well-plates at 8 x 10^5 and 6 x 10^5 cells per well. The following day, DuCaP cells were treated with 8 µM enzalutamide, 10 µM C646, 10 µM I-CBP112 or DMSO equivalent for 24 hr.