Project description:Epigenetic dysregulation is one of the molecular mechanisms contributing to retinoblastoma (RB) development. Consistent with this notion, human RB tumors show an aberrant expression of many chromatin regulators whereas normal retina or nontumoral retinal tissues do not have any detectable expression of such proteins. Among the chromatin regulators found to be misregulated in RB, this study focuses on a histone methyltransferase DOT1L to assess the therapeutic potential of its targeting for RB treatment. We found that pharmacological inhibition of DOT1L has growth-inhibitory effects on RB cells by itself and also can sensitize RB cells to standard chemotherapeutic drugs by inducing more robust apoptotic cell death when cells are subjected to combination treatments. To understand the molecular mechanisms underlying the growth inhibition and chemosensitization of RB cells upon DOT1L inhibition, we performed the gene expression profiling in Y79 cells treated with a DOT1L inhibitor EPZ5676 in comparison with a vehicle control by RNA-sequencing to identify differentially expressed genes. Our RNA-seq results revealed that DOT1L inhibition downregulates several genes which are known to be misregulated in cancers, including HMGA2.
Project description:Adoptive T cell therapy (ACT) is a promising therapeutic approach for cancer patients. The use of allogeneic T cell grafts will improve its applicability and versatility provided that inherent allogeneic responses are controlled. Through extensive chemical probe screening, we found that inhibiting DOT1L, a histone H3-lysine 79 methyltransferase, alleviated allogeneic T cell responses. DOT1L inhibition with SGC0946 selectively ameliorated low-avidity T cell responses but not high-avidity antitumor T cell responses mediated by the high-affinity T cell receptor or chimeric antigen receptor. The inhibition of DOT1L in T cells prevented the development of graft-versus-host disease while retaining potent antitumor activity in xenogeneic ACT models. These results suggest that DOT1L inhibition may enable the safe and effective use of allogeneic antitumor T cells by suppressing unwanted immunological reactions in ACT.
Project description:Osteoclasts are absorptive cells and play a critical role in homeostatic bone remodeling and pathological bone resorption. Emerging evidence suggests an important role for epigenetic regulation of osteoclastogenesis. In this study, we investigated the role of DOT1L, which regulates gene expression epigenetically by histone H3K79 methylation during osteoclast formation. DOT1L and H3K79me2 levels were upregulated during osteoclast differentiation. Small molecule inhibitor- (EPZ5676 or EPZ004777) or short hairpin RNA-mediated reduction in DOT1L expression promoted osteoclast differentiation and resorption. DOT1L inhibition also increased osteoclast area and accelerated bone mass reduction in a mouse ovariectomy (OVX) model of osteoporosis. DOT1L inhibitors did not alter osteoblast differentiation in vitro and in vivo. Proteomics data, together with bioinformatics analysis, revealed that DOT1L inhibition altered reactive oxygen species (ROS) generation, autophagy activation, and cell fusion-related protein expression. ROS generation increased, and autophagy activation and cell migration ability enhancement were verified subsequently by flow cytometry and transwell migration assays. DOT1L inhibition increased NFATc1 nuclear translocation and NF-κB activation and strengthend osteoclast fusion and expression of resorption-related protein CD9, and MMP9 in osteoclasts derived from RAW264.7. Our findings support a new mechanism of DOT1L-mediated H3K79me2 epigenetic regulation of osteoclast differentiation, implicating DOT1L as a new therapeutic target for osteoclast dysregulation-induced disease.
Project description:Estrogen Receptor αlpha (ERα) is the master regulator of estrogen signaling in hormone-responsive breast cancer (BC), however epigenetic mechanisms, including DNA methylation, are emerging as key processes for regulation of critical cell functions including tumorigenesis. We have recently reported the epigenetic writer DOT1L (DOT1 Like Histone Lysine Methyltransferase) to associated to ERα, part of chromatin bound multiprotein complex and that the pharmacological inhibition of this enzyme reduces the transcription rate of several genes involved in ERα-mediated signaling leading to inhibition of BC cell proliferation. Here, we investigated the functional impact of DOT1L inhibition on methylome changes in BC and its possible contribution to deregulation of transcriptional pathways associated to the progression of this disease.
Project description:Epigenetic alterations play an important role in the pathogenesis in multiple myeloma (MM), but its biological and clinical relevance is not fully understood. Here, we show that DOT1L, which catalyzes methylation of histone H3 lysine 79, is required for the survival of MM cells. Treatment with DOT1L inhibitors induced cell cycle arrest and apoptosis in MM cells, and strongly suppressed cell proliferation in vitro. Chromatin immunoprecipitation-sequencing (ChIP-seq) and microarray analysis revealed that DOT1L inhibition downregulated H3K79 dimethylation (H3K79me2) and expression levels of IRF4-MYC signaling genes in MM cells. Our data suggest that DOT1L may play an essential role in the development of MM, and DOT1L inhibition may provide a new therapy for MM treatment.
Project description:To identify DOT1L targets, associated signaling pathways and networks in chondrocytes, we used genome-wide gene expression microarray analysis in human articular chondrocytes of 5 different donors (without known or documented joint disease) treated with EPZ-5676 or vehicle for 4 days. It is known that DOT1L inhibitors require longer time of treatment in order to show effect and influence the expression of MLL target genes in leukemia cells, but we opted for this relatively short inhibition time to be able to identify early changes induced by DOT1L inhibition. Human articular chondrocytes were obtained from 5 non-OA hip fracture patients. The cells were treated with 3 μM EPZ-5676 or vehicle (DMSO) for 4 days.
Project description:Estrogen Receptor alpha (ERα), a nuclear receptor with transcriptional activity, is a master regulator of estrogen signaling, widely known as therapeutic target in hormone-responsive breast cancer (BC). Moreover, ERα is highly expressed in approximately 80% of High Grade Serous Ovarian Cancer (HGSOC), the most common epithelial ovarian carcinoma. Despite some promising clinical trials evaluating endocrine therapy in this type of tumor, the role of ERα is still unknown. Epigenetic changes, such as DNA methylation, are emerging as key contributing factors to carcinogenesis. Disruptor of telomeric silencing-1-like (DOT1L), the only known histone methyl transferase capable to produce H3K79 mono, di and tri-methylation, modulates ERα actions in hormone-responsive BC. Considering this evidence, ERα-DOT1L association was confirmed in ERα-positive OC cells, PEO1 and PEO4, by Co-IP. DOT1L pharmacological inhibition by EPZ004777 (EPZ) revealed the involvement of this epigenetic enzyme in cell proliferation, cell cycle progression and apoptosis. Transcriptome profiling after ICI (a Selective Estrogen Receptor Degrader) and EPZ treatment, in both cell lines, has underlined a deep impact of both compounds on ERα-modulated genes, including the down-regulation of ERα itself. On the other hand, functional analysis showed that commonly affected transcripts are involved in different cellular processes, such as cancer cell survival, chemoresistance and cell cycle progression. Moreover, ChIP-qPCR performed on ERα promoter highlighted ERα and DOT1L co-localization, both in PEO1 and in PEO4 cells, which was reduced after EPZ treatment, suggesting a role of this complex on receptor transcriptional activity. In addition, drug combination studies performed with EPZ and ICI showed an additive effect in cell growth inhibition. Taken together, these results suggest DOT1L as a potential therapeutic target in the treatment of OC.
Project description:Adoptive T cell therapy (ACT) is a promising therapeutic approach for cancer patients. The use of allogeneic T cell grafts will improve its applicability and versatility provided that inherent allogeneic responses are controlled. T cell activation is finely regulated by multiple signaling molecules that are transcriptionally controlled by epigenetic mechanisms. Through extensive chemical probe screening, we found that inhibiting DOT1L, a histone H3-lysine 79 methyltransferase, alleviated allogeneic T cell responses. DOT1L inhibition reduced miR-181a expression, which increased the ERK phosphatase DUSP6 expression. The inhibition of DOT1L or ectopic expression of DUSP6 in T cells prevented the development of graft-versus-host disease while retaining potent antitumor activity in multiple ACT models. These results suggest that DOT1L inhibition may enable the safe and effective use of allogeneic antitumor T cells by suppressing unwanted immunological reactions in ACT. To further explore how DOT1L inhibition differentially affects high- and low-avidity stimulation-mediated T cell responses, gene expression profiles of DMF5- (high affinity) or cl.413- (low affinity) TCR-transduced T cells with or without SGC0946 treatment were analyzed following TCR stimulation.
Project description:Patients with advanced soft-tissue sarcomas (STSs) have few therapeutic options. Protein arginine methyltransferase 5 (PRMT5), an anticancer target, has been extensively investigated in recent years in epithelial tumors. To date, no data related to the biological role of PRMT5 inhibition and its potential effect as a treatment in STS have been reported. To investigate the therapeutic potential of PRMT5 targeting in STS, we first evaluated the prognostic value of PRMT5 expression in 2 different cohorts of patients with STS. We then used the potent and selective GSK3326595 (GSK595) compound to investigate the antitumor effect of the pharmacological inhibition of PRMT5 in vitro via MTT, apoptosis, cell cycle, clonogenicity and proliferation assays. In vivo studies were performed with two animal models to evaluate the effects of GSK595 on tumor growth. The mechanisms of action were investigated by RNA sequencing, metabolic pathway analysis, Western blotting and glucose uptake/lactate production assays. High PRMT5 gene expression levels were significantly associated with worsened metastasis-free survival of STS patients. GSK595 decreased the global symmetric dimethylarginine level, the proliferation rate and clonogenicity of STS cell lines in vitro and tumor growth in vivo. Moreover, PRMT5 inhibition regulated aerobic glycolysis through downregulation of key enzymes of glycolysis as well as glucose uptake and lactate production. The present study demonstrated that PRMT5 regulates STS cell metabolism and thus represents a potential therapeutic target for STS. Additional studies in diverse sarcoma subtypes will be essential to confirm and expand upon these findings.
Project description:Through a loss-of-function approach, we identified that inhibition of the histone methyltransferase, Dot1L, accelerated somatic cell reprogramming, significantly increased the yield of induced pluripotent stem (iPS) cell colonies, and substituted for Klf4 and c-Myc in the reprogramming cocktail. To understand the mechanism by which Dot1L inhibition results in these phenotypes, we carried out gene expression profiling using Affymetrix microarrays. GSM723207-GSM723224: Embryonic stem cell-derived fibroblasts (dH1fs) were retrovirally transduced in culture with vectors expressing either a control shRNA or an shRNA targeting Dot1L. These cells were then superinfected with either Oct4, Sox2, Klf4 and c-Myc (OSKM) retroviruses or Oct4, Sox2 and c-Myc (OSM) retroviruses. Total RNA was harvested 6 days later. There were three biologic replicates for each condition. GSM880675-GSM880682: dH1fs were treated with 10uM Dot1L inhibitor (EPZ004777) and then superinfected with Oct4, Sox2, Klf4 and c-Myc (OSKM) retroviruses. Total RNA was harvested 6 days later. There were two biologic replicates for each condition.