Project description:Mutations within the catalytic domain of the histone methyltransferase (HMT) EZH2 have been identified in subsets of Non-Hodgkin Lymphoma (NHL) patients. These genetic alterations are hypothesized to confer an oncogenic dependency on EZH2 enzymatic activity in these cancers. We previously reported the discovery of a potent, selective, S-adenosyl-methionine-competitive and orally bioavailable small molecule inhibitor of EZH2, EPZ-6438. EPZ-6438 selectively inhibits intracellular lysine 27 of histone H3 (H3K27) methylation in a concentration- and time-dependent manner in both EZH2 wild type and mutant lymphoma cells. Inhibition of H3K27 trimethylation (H3K27Me3) led to selective cell killing of human lymphoma cell lines bearing EZH2 catalytic domain point mutations. Treatment of xenograft-bearing mice with EPZ-6438 leads to dose-dependent tumor growth inhibition and eradication of genetically altered NHL with correlative diminution of H3K27Me3 levels in tumors and selected normal tissues. Mice dosed orally with EPZ-6438 for 28 days remained tumor free for up to 63 day after stopping compound treatment in two EZH2 mutant xenograft models. These data confirm the dependency of mutant NHL on EZH2 activity and portend the utility of EZH2-targeted drugs for the treatment of these genetically defined cancers. To identify potential biomarker and gain mechanistic insights in EPZ6438 treated lymphoma, lymphoma cell lines with or without EZH2 Y641 mutation were treated with EPZ6438 at Lowest Cytotoxic Concentration (LCC) and 10xLCC. Transcriptomes were profiled on Affemetrix U133 Plus2 chips. Differentially expressed genes and pathways upon compound treatment were anayzed. Lymphoma cell lines WSU-DLCL2, SU-DHL6, Pfeiffer, and Karpas422 were treated by EPZ6438 for 2 days, 4 days and 6 days. Treatment doses are LCC and 10xLCC of each cell lines. KARPAS_422, SUDHL6, and WSU_DLCL2 have the EZH2 Y641 mutation. PFEIFFER does not have the EZH2 Y641 mutation.
Project description:Follicular lymphoma (FL) is an indolent, but incurable subtype of non-Hodgkin lymphoma. These tumor harbor t (14;18) translocation in at least 90% of patients. Recently, activating EZH2 mutations have been Follicular lymphoma (FL) is an indolent, but incurable subtype of non-Hodgkin lymphoma. These tumor harbor t (14;18) translocation in at least 90% of patients. Recently, activating EZH2 mutations have been found in a significant number of patients with FL. Gene expression profiling (GEP) was performed to determine differential gene-expression between the EZH2 mutated vs unmutated subgroups in FL.
Project description:Mutations within the catalytic domain of the histone methyltransferase (HMT) EZH2 have been identified in subsets of Non-Hodgkin Lymphoma (NHL) patients. These genetic alterations are hypothesized to confer an oncogenic dependency on EZH2 enzymatic activity in these cancers. We previously reported the discovery of a potent, selective, S-adenosyl-methionine-competitive and orally bioavailable small molecule inhibitor of EZH2, EPZ-6438. EPZ-6438 selectively inhibits intracellular lysine 27 of histone H3 (H3K27) methylation in a concentration- and time-dependent manner in both EZH2 wild type and mutant lymphoma cells. Inhibition of H3K27 trimethylation (H3K27Me3) led to selective cell killing of human lymphoma cell lines bearing EZH2 catalytic domain point mutations. Treatment of xenograft-bearing mice with EPZ-6438 leads to dose-dependent tumor growth inhibition and eradication of genetically altered NHL with correlative diminution of H3K27Me3 levels in tumors and selected normal tissues. Mice dosed orally with EPZ-6438 for 28 days remained tumor free for up to 63 day after stopping compound treatment in two EZH2 mutant xenograft models. These data confirm the dependency of mutant NHL on EZH2 activity and portend the utility of EZH2-targeted drugs for the treatment of these genetically defined cancers. To identify potential biomarker and gain mechanistic insights in EPZ6438 treated lymphoma, lymphoma cell lines with or without EZH2 Y641 mutation were treated with EPZ6438 at Lowest Cytotoxic Concentration (LCC) and 10xLCC. Transcriptomes were profiled on Affemetrix U133 Plus2 chips. Differentially expressed genes and pathways upon compound treatment were anayzed.
Project description:Pharmacological inhibition of the histone lysine methyltransferase EZH2 has emerged as a therapeutic strategy for the treatment of non-Hodgkin Lymphoma (NHL), in particular for cases with mono-allelic mutations in the EZH2 catalytic domain. Potent, selective EZH2 small molecule inhibitors have achieved tumor regression in mutant EZH2-containing preclinical lymphoma models and several of these inhibitors are currently engaged in cancer-focused clinical trials. Here, we show that the presence of EZH2 mutations do not always confer EZH2 inhibitor sensitivity. We discovered that EZH2 is usurped by lymphoma cells to attenuate JAK/STAT signaling and to repress pro-apoptotic interferon response genes. EZH2 inhibition results in the broad induction of interferon-stimulated genes (ISGs) in several phenotypically sensitive NHL cell models. In mutant EZH2-containing insensitive models, EZH2 inhibitors synergize specifically with type I interferons (IFNs) in vitro and in vivo to induce ISGs and apoptosis. The profound combinatorial activity of EZH2 inhibitors and type I IFNs is not restricted to NHL models with mutant EZH2 and, is preferentially observed in models that are not affected by either single agent. Molecular consequences of EZH2 inhibitor and type I IFN combinatorial treatment include STAT1 activation, binding of STAT transcription factor complexes to ISGs, reduction of H3K27me3 levels and increase of H3K4me3 levels at ISG transcriptional start sites, and ISG transcriptional activation. The molecular and anti-proliferative effects of the combination can be suppressed by inactivation of the JAK/STAT signaling pathway, by using the JAK inhibitor ruxolitinib. We suggest that EZH2 inhibitors can be therapeutically combined with type I IFNs for the treatment of NHL.
Project description:Pharmacological inhibition of the histone lysine methyltransferase EZH2 has emerged as a therapeutic strategy for the treatment of non-Hodgkin Lymphoma (NHL), in particular for cases with mono-allelic mutations in the EZH2 catalytic domain. Potent, selective EZH2 small molecule inhibitors have achieved tumor regression in mutant EZH2-containing preclinical lymphoma models and several of these inhibitors are currently engaged in cancer-focused clinical trials. Here, we show that the presence of EZH2 mutations do not always confer EZH2 inhibitor sensitivity. We discovered that EZH2 is usurped by lymphoma cells to attenuate JAK/STAT signaling and to repress pro-apoptotic interferon response genes. EZH2 inhibition results in the broad induction of interferon-stimulated genes (ISGs) in several phenotypically sensitive NHL cell models. In mutant EZH2-containing insensitive models, EZH2 inhibitors synergize specifically with type I interferons (IFNs) in vitro and in vivo to induce ISGs and apoptosis. The profound combinatorial activity of EZH2 inhibitors and type I IFNs is not restricted to NHL models with mutant EZH2 and, is preferentially observed in models that are not affected by either single agent. Molecular consequences of EZH2 inhibitor and type I IFN combinatorial treatment include STAT1 activation, binding of STAT transcription factor complexes to ISGs, reduction of H3K27me3 levels and increase of H3K4me3 levels at ISG transcriptional start sites, and ISG transcriptional activation. The molecular and anti-proliferative effects of the combination can be suppressed by inactivation of the JAK/STAT signaling pathway, by using the JAK inhibitor ruxolitinib. We suggest that EZH2 inhibitors can be therapeutically combined with type I IFNs for the treatment of NHL.
Project description:Follicular lymphoma (FL) is an indolent, but incurable subtype of non-Hodgkin lymphoma. These tumor harbor t (14;18) translocation in at least 90% of patients. Recently, activating EZH2 mutations have been Follicular lymphoma (FL) is an indolent, but incurable subtype of non-Hodgkin lymphoma. These tumor harbor t (14;18) translocation in at least 90% of patients. Recently, activating EZH2 mutations have been found in a significant number of patients with FL. Gene expression profiling (GEP) was performed to determine differential gene-expression between the EZH2 mutated vs unmutated subgroups in FL. Total RNA extracted from fresh frozen specimens with FL diagnosis were processed for hybridization to Affymetrix HG-U133 plus 2 arrays. To enhance the identification of differential gene expression in FL tumor cells only, FL cases with a high B-cell content (enriched B-cell signature of >2-fold above the mean of the B-cell signature (pan B-cell markers) in the entire FL data set) were chosen for analysis.
Project description:We studied transcriptional changes by Affymetrix human microarrays in 2 DLBCL cell lines as a result of shRNA mediated knockdown of EZH2. In eukaryotes, epigenetic post-translational modification of histones is critical for regulation of chromatin structure and gene expression. EZH2 is the catalytic subunit of the Polycomb Repressive Complex 2 (PRC2) and is responsible for repressing target gene expression through methylation of histone H3 on lysine 27 (H3K27). Over-expression of EZH2 is implicated in tumorigenesis and correlates with poor prognosis in multiple tumor types. Recent reports have identified somatic heterozygous mutations of Y641 and A677 residues within the catalytic SET domain of EZH2 in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). The Y641 residue is the most frequently mutated residue, with 22% of GCB (Germinal Cell B-cell) DLBCL and FL harboring mutations at this site. These lymphomas exhibit increased H3K27 tri-methylation (H3K27me3) due to altered substrate preferences of the mutant enzymes. However, it is unknown whether direct inhibition of EZH2 methyltransferase activity alone will be effective in treating lymphomas carrying activating EZH2 mutations. Herein, we demonstrate that GSK126, a potent, highly-selective, SAM-competitive, small molecule inhibitor of EZH2 methyltransferase activity, decreases global H3K27me3 levels and reactivates silenced PRC2 target genes. GSK126 effectively inhibits the proliferation of EZH2 mutant DLBCL cell lines and dramatically inhibits the growth of EZH2 mutant DLBCL xenografts in mice. Together, these data demonstrate that pharmacological inhibition of EZH2 activity may provide a promising treatment for EZH2 mutant lymphoma. Pfeiffer and KARPAS-422 cells were treated with either shRNA targeting EZH2 (shEZH2) or a non targeting control (shNTC) for 10 days.
Project description:We studied transcriptional changes by Affymetrix human microarrays in DLBCL cell lines as a result of treatment with GSK126, a potent, highly-selective, SAM-competitive, small molecule inhibitor of EZH2 In eukaryotes, epigenetic post-translational modification of histones is critical for regulation of chromatin structure and gene expression. EZH2 is the catalytic subunit of the Polycomb Repressive Complex 2 (PRC2) and is responsible for repressing target gene expression through methylation of histone H3 on lysine 27 (H3K27). Over-expression of EZH2 is implicated in tumorigenesis and correlates with poor prognosis in multiple tumor types. Recent reports have identified somatic heterozygous mutations of Y641 and A677 residues within the catalytic SET domain of EZH2 in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). The Y641 residue is the most frequently mutated residue, with 22% of GCB (Germinal Cell B-cell) DLBCL and FL harboring mutations at this site. These lymphomas exhibit increased H3K27 tri-methylation (H3K27me3) due to altered substrate preferences of the mutant enzymes. However, it is unknown whether direct inhibition of EZH2 methyltransferase activity alone will be effective in treating lymphomas carrying activating EZH2 mutations. Herein, we demonstrate that GSK126, a potent, highly-selective, SAM-competitive, small molecule inhibitor of EZH2 methyltransferase activity, decreases global H3K27me3 levels and reactivates silenced PRC2 target genes. GSK126 effectively inhibits the proliferation of EZH2 mutant DLBCL cell lines and dramatically inhibits the growth of EZH2 mutant DLBCL xenografts in mice. Together, these data demonstrate that pharmacological inhibition of EZH2 activity may provide a promising treatment for EZH2 mutant lymphoma. 10 DLBCL cell lines (7 mutant and 3 wild type EZH2), that were differentially sensitive to GSK126 in proliferation assays, were treated for 72 hours, in duplicate (n=2), with either DMSO (vehicle) or 500nM of GSK126, a potent selective EZH2 inhibitor. EZH2 mutant cell lines are Pfeiffer, KARPAS-422, WSU-DLCL2, SU-DHL-10, SU-DHL-6, DB and SU-DHL-4. EZH2 wildtype cell lines are HT, OCI-LY-19 and Toledo.