Knockdown Of LSD1 Research Articles

Abstract 1379: INCB059872, a novel FAD-directed LSD1 Inhibitor, is active in prostate cancer models and impacts prostate cancer stem-like cells

Abstract Cancer of the prostate is one of the most common malignancies and the second leading cause of cancer death in men in developed countries. There is increasing evidence that cancer stem-like cells (CSCs) are implicated in CRPC disease progression and treatment resistance. Transcriptional, epigenetic and metabolic reprogramming are key features for the acquisition and maintenance of stem-like properties. Understanding the factors regulating self-renewal and survival of prostate CSCs may offer novel targets for innovative therapeutic strategies. LSD1/KDM1A is a lysine demethylase for histone and non-histone proteins and functions as transcriptional corepressor or coactivator depending on the binding partners and substrates. LSD1 is a key epigenetic modifier controlling the fate of pluripotent stem cells in several tissues. Overexpression of LSD1 is found in many human cancers and has been linked to tumorigenic and CSC-like features. The involvement of LSD1 in stem cell pluripotency and differentiation suggests that LSD1 inhibitors, such as INCB059872, might be useful to target the prostate CSC subpopulation. Here, we examined the effects of INCB059872 on the growth properties, self-renewal and tumorigenic capability of prostate CSCs derived from human cell lines and the Pb-Cre4;Ptenflox/flox;Rosa26ERG/ERG (ERG/PTEN) mice, which develop highly invasive prostate adenocarcinomas. In ex vivo tumor-sphere assays, INCB059872 significantly suppressed the growth of tumor-initiating stem-like cells isolated from prostatic tumors generated in ERG/PTEN mice. Furthermore, treatment with INCB059872 inhibited colony and tumor-sphere formation by human prostate cancer cells. Conversely, the effects on proliferation and viability of bulk tumor cells were limited and required long-term exposure to the drug. These effects were observed in multiple prostate cancer cell lines, irrespective of the distinctive genetic features and AR status. Importantly, genetic knockdown of LSD1 by siRNAs and shRNAs recapitulated the effects of INCB059872. Both transient and stable knockdown of LSD1 had limited effects on proliferation and viability of bulk tumor cells, whereas they significantly reduced growth of colony and tumor-sphere forming stem-like cancer cells. Furthermore, LSD1 knockdown drastically reduced tumor growth and tumorigenic stem-like cells in subcutaneous xenografts of human prostate cancer cells in nude mice. These results support the hypothesis that LSD1 has a major role in sustaining the stem-like and tumorigenic subpopulation in prostate tumors and its inhibition by chemical or genetic approaches prevents survival and self-renewal capability of prostate CSCs. These data suggest that INCB059872 could be a valid addition to the current treatment strategies for prostate cancer. INCB059872 is currently in phase1/2 clinical studies Citation Format: Gianluca Civenni, Giada Zoppi, Ramiro Vazquez, Dhreeraj Shinde, Alyssa Paganoni, Aleksandra Kokanovic, Sang Hyun Lee, Bruce Ruggeri, Giuseppina M. Carbone, Carlo V. Catapano. INCB059872, a novel FAD-directed LSD1 Inhibitor, is active in prostate cancer models and impacts prostate cancer stem-like cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1379.

Histone demethylase LSD1 regulates bone mass by controlling WNT7B and BMP2 signaling in osteoblasts

Multiple regulatory mechanisms control osteoblast differentiation and function to ensure unperturbed skeletal formation and remodeling. In this study we identify histone lysine-specific demethylase 1(LSD1/KDM1A) as a key epigenetic regulator of osteoblast differentiation. Knockdown of LSD1 promoted osteoblast differentiation of human mesenchymal stem cells (hMSCs) in vitro and mice lacking LSD1 in mesenchymal cells displayed increased bone mass secondary to accelerated osteoblast differentiation. Mechanistic in vitro studies revealed that LSD1 epigenetically regulates the expression of WNT7B and BMP2. LSD1 deficiency resulted in increased BMP2 and WNT7B expression in osteoblasts and enhanced bone formation, while downregulation of WNT7B- and BMP2-related signaling using genetic mouse model or small-molecule inhibitors attenuated bone phenotype in vivo. Furthermore, the LSD1 inhibitor tranylcypromine (TCP) could increase bone mass in mice. These data identify LSD1 as a novel regulator of osteoblast activity and suggest LSD1 inhibition as a potential therapeutic target for treatment of osteoporosis.

Enhancer Activation by Pharmacologic Displacement of LSD1 from GFI1 Induces Differentiation in Acute Myeloid Leukemia

SummaryPharmacologic inhibition of LSD1 promotes blast cell differentiation in acute myeloid leukemia (AML) with MLL translocations. The assumption has been that differentiation is induced through blockade of LSD1’s histone demethylase activity. However, we observed that rapid, extensive, drug-induced changes in transcription occurred without genome-wide accumulation of the histone modifications targeted for demethylation by LSD1 at sites of LSD1 binding and that a demethylase-defective mutant rescued LSD1 knockdown AML cells as efficiently as wild-type protein. Rather, LSD1 inhibitors disrupt the interaction of LSD1 and RCOR1 with the SNAG-domain transcription repressor GFI1, which is bound to a discrete set of enhancers located close to transcription factor genes that regulate myeloid differentiation. Physical separation of LSD1/RCOR1 from GFI1 is required for drug-induced differentiation. The consequent inactivation of GFI1 leads to increased enhancer histone acetylation within hours, which directly correlates with the upregulation of nearby subordinate genes.

LSD1 dual function in mediating epigenetic corruption of the vitamin D signaling in prostate cancer

BackgroundLysine-specific demethylase 1A (LSD1) is a key regulator of the androgen (AR) and estrogen receptors (ER), and LSD1 levels correlate with tumor aggressiveness. Here, we demonstrate that LSD1 regulates vitamin D receptor (VDR) activity and is a mediator of 1,25(OH)2-D3 (vitamin D) action in prostate cancer (PCa).MethodsAthymic nude mice were xenografted with CWR22 cells and monitored weekly after testosterone pellet removal. Expression of LSD1 and VDR (IHC) were correlated with tumor growth using log-rank test. TRAMP tumors and prostates from wild-type (WT) mice were used to evaluate VDR and LSD1 expression via IHC and western blotting. The presence of VDR and LSD1 in the same transcriptional complex was evaluated via immunoprecipitation (IP) using nuclear cell lysate. The effect of LSD1 and 1,25(OH)2-D3 on cell viability was evaluated in C4-2 and BC1A cells via trypan blue exclusion. The role of LSD1 in VDR-mediated gene transcription was evaluated for Cdkn1a, E2f1, Cyp24a1, and S100g via qRT-PCR-TaqMan and via chromatin immunoprecipitation assay. Methylation of Cdkn1a TSS was measured via bisulfite sequencing, and methylation of a panel of cancer-related genes was quantified using methyl arrays. The Cancer Genome Atlas data were retrieved to identify genes whose status correlates with LSD1 and DNA methyltransferase 1 (DNMT1). Results were correlated with patients’ survival data from two separate cohorts of primary and metastatic PCa.ResultsLSD1 and VDR protein levels are elevated in PCa tumors and correlate with faster tumor growth in xenograft mouse models. Knockdown of LSD1 reduces PCa cell viability, and gene expression data suggest a dual coregulatory role of LSD1 for VDR, acting as a coactivator and corepressor in a locus-specific manner. LSD1 modulates VDR-dependent transcription by mediating the recruitment of VDR and DNMT1 at the TSS of VDR-targeted genes and modulates the epigenetic status of transcribed genes by altering H3K4me2 and H3K9Ac and DNA methylation. Lastly, LSD1 and DNMT1 belong to a genome-wide signature whose expression correlates with shorter progression-free survival and overall survival in primary and metastatic patients’ samples, respectively.ConclusionsResults demonstrate that LSD1 has a dual coregulatory role as corepressor and coactivator for VDR and defines a genomic signature whose targeting might have clinical relevance for PCa patients.

Abstract 2563: LSD1 maintains differentiation and survival of mammary luminal cells and suppresses invasion of luminal breast cancer cells via GATA3

Abstract LSD1 (also known as KDM1A) is a histone demethylase that has been shown to play both oncogenic and tumor suppressor roles in breast cancer. However, the exact context under which it functions as a tumor suppressor or oncoprotein remains largely elusive. To address this, we characterized its role in normal mammary epithelial cells (MECs) and found MEC-specific ablation of Lsd1 largely phenocopied that of Gata3, which encodes a master regulatory transcription factor for luminal MECs. In the luminal lineage, LSD1-loss led to reduction in both mature ductal and alveolar luminal subpopulations. In human luminal breast cancer cells, we found LSD1 interacts with GATA3 and their common target genes are highly related to breast cancer. In particular, we found LSD1 might be recruited by GATA3 to the GATA3 promoter region, to positively regulate GATA3 expression via demethylation of H3K9me2. Knockdown of LSD1 led to increased invasion of luminal breast cancer cells, in part via downregulation of GATA3 and multiple cell junction genes (e.g., CDH1, VCL, CTNNA1), as well as upregulation of mammary stem/progenitor cell genes (e.g., ELF5, ITGB1). However, LSD1 knockdown also led to reduced proliferation of luminal breast cancer cells, in part via downregulation of RBBP4 (encoding a Histone-binding protein) and upregulation of CDKN1A (encoding p21). Collectively, our data suggest that LSD1 is required for maintaining luminal MEC differentiation and survival and for suppressing luminal breast cancer cell invasion, in part via GATA3. As inhibitors of LSD1 are currently under clinical trials (e.g., in leukemia), our data suggest that although treatment of luminal breast cancer by the LSD1 inhibitor may lead to reduced tumor cell proliferation (and thus tumor shrinkage), the treatment may also lead to increased invasion of surviving breast cancer cells. Thus, our study is expected to have important implications for developing better epigenetic therapy in an individualized, context-dependent fashion. Citation Format: Xin Hu, Dongxi Xiang, Luwei Tao, Ying Xie, Yue Jin, Yidi Guo, Luca Pinello, Guo-Cheng Yuan, Zhe Li. LSD1 maintains differentiation and survival of mammary luminal cells and suppresses invasion of luminal breast cancer cells via GATA3 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2563. doi:10.1158/1538-7445.AM2017-2563

Abstract 5068: A novel dual action inhibitor of histone deacetylase and demethylase in melanoma

Abstract Epigenetic agents have drawn great attention as anti-cancer therapies, with several HDAC inhibitors approved for a subset of hematologic malignancies. One of the biggest challenges in targeting epigenetic mechanisms of tumorigenesis is the wide spectrum of effects which restrict the therapeutic window for these compounds. We have developed a series of potent small molecule inhibitors with specificity towards the CoREST epigenetic corepressor complex through a dual-action mechanism targeting LSD1 and HDAC1. These compounds show a unique profile of pharmacologic action with an improved therapeutic window in a variety of cell types. Screening of tumor cell lines for growth inhibitory effects revealed variable efficacy in a broad spectrum of cancers with the most consistent and potent effects seen in human melanomas. The growth of a number of melanoma cell lines was found to be potently inhibited by one of these compounds, Corin 2; however, primary human melanocytes were relatively resistant to this agent. Transcriptomic analysis revealed that Corin2 was a more potent inducer of tumor suppressor genes compared to the parent HDAC and LSD1 compounds. Genetic knockdown of CoREST or LSD1 in cancer cell lines abolished the differences in potency of Corin2 vs. the parent HDAC inhibitor, Entinostat, suggesting that Corin2's favorable pharmacologic effects rely on an intact CoREST complex. Corin2 was also effective in slowing tumor growth in a melanoma mouse xenograft model. These dual action inhibitors demonstrate a novel, potent, and specific therapeutic approach to targeting epigenetic pathways in human melanomas which may lead to improved therapeutic benefits in patients with advanced disease. Note: This abstract was not presented at the meeting. Citation Format: Muzhou WU, Jay Kalin, Byungwoo Ryu, Philip Cole, Rhoda Alani. A novel dual action inhibitor of histone deacetylase and demethylase in melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5068. doi:10.1158/1538-7445.AM2017-5068

LSD1 knockdown reveals novel histone lysine methylation in human breast cancer MCF-7 cells

Histone lysine methylation, which plays an important role in the regulation of gene expression, genome stability, chromosome conformation and cell differentiation, is a dynamic process that is collaboratively regulated by lysine methyltransferases (KMTs) and lysine demethylases (KDMs). LSD1, the first identified KDMs, catalyzes the demethylation of mono- and di-methylated H3K4 and H3K9. Here, we systematically investigated the effects of LSD1 knockdown on histone methylations. Surprisingly, in addition to H3K4 and H3K9, the methylation level on other histone lysines, such as H3K27, H3K36 and H3K79, are also increased. The expression of SOX2, E-cadherin and FoxA2 are increased upon LSD1 knockdown, and the methylation level of H3K4, H3K27 and H3K36 in the promoter region of these genes are all changed after LSD1 knockdown. Our results show that LSD1 knockdown has a broad effect on histone lysine methylation, which indicates that LSD1 regulates histone lysine methylation in collaboration with other KMTs and KDMs.

A Novel LSD1 Inhibitor T-3775440 Disrupts GFI1B-Containing Complex Leading to Transdifferentiation and Impaired Growth of AML Cells.

Dysregulation of lysine (K)-specific demethylase 1A (LSD1), also known as KDM1A, has been implicated in the development of various cancers, including leukemia. Here, we describe the antileukemic activity and mechanism of action of T-3775440, a novel irreversible LSD1 inhibitor. Cell growth analysis of leukemia cell lines revealed that acute erythroid leukemia (AEL) and acute megakaryoblastic leukemia cells (AMKL) were highly sensitive to this compound. T-3775440 treatment enforced transdifferentiation of erythroid/megakaryocytic lineages into granulomonocytic-like lineage cells. Mechanistically, T-3775440 disrupted the interaction between LSD1 and growth factor-independent 1B (GFI1B), a transcription factor critical for the differentiation processes of erythroid and megakaryocytic lineage cells. Knockdown of LSD1 and GFI1B recapitulated T-3775440-induced transdifferentiation and cell growth suppression, highlighting the significance of LSD1-GFI1B axis inhibition with regard to the anti-AML effects of T-3775440. Moreover, T-3775440 exhibited significant antitumor efficacy in AEL and AMKL xenograft models. Our findings provide a rationale for evaluating LSD1 inhibitors as potential treatments and indicate a novel mechanism of action against AML, particularly AEL and AMKL. Mol Cancer Ther; 16(2); 273-84. ©2016 AACR.

LSD1 collaborates with EZH2 to regulate expression of interferon-stimulated genes.

Histone methylation is a complicate and dynamic epigenetic modification that regulates gene transcription, chromosomal structure and cell differentiation. Here, we discovered the interaction between the H3K4 demethylase, lysine specific demethylase 1 (LSD1, an important component of CoREST repressor complex) and the H3K27 methyltransferase, enhancer of zeste homolog 2 (EZH2, an essential component of PRC2). Immuno-precipitation and GST-pull down assay were performed to observe the interaction between the proteins. The MCF-7 cells were cultured and transfected with the siRNA. The mRNA and proteins were examined by using the real-time polymerase chain reaction (RT-PCR) and western blot assay, respectively. HPLC and LC-MS/MS analysis were performed to purify the proteins. RT-PCR-based quantitative ChIP analysis were performed. LSD1 interacts with histone modification protein EZH2 in MCF-7 cells. LSD1 and EZH2 target a few common genes. LSD1 knockdown and EZH2 knockdown affect protein expression. LSD1 knockdown and EZH2 knockdown affect the proteins involving in IFN signaling pathway. LSD1 and EZH2 modify histone methylation at IRF9 gene locus. We systematically analyzed the proteins that are affected by either LSD1 or EZH2 knockdown with proteomic approaches and identified that the interferon pathway and some other pathways are commonly affected. The interaction between LSD1 and EZH2 stabilizes the binding of LSD1 to the promoter region of IRF9, which is a key transcription factor of the interferon pathway. In conclusion, our study revealed that the coordination between histone demethylases and methyl-transferases might serve as a double lock system to suppress the expression of interferon stimulated genes.

Histone Demethylase LSD1 Promotes Adipocyte Differentiation through Repressing Wnt Signaling

Adipose tissue plays important roles in animals. White fat stores energy in lipids, while brown fat is responsible for nonshivering thermogenesis through UCP1-mediated energy dissipation. Although epigenetic mechanisms modulate differentiation in multiple lineages, the epigenetic regulation of brown adipocyte differentiation is poorly understood. By screening acollection of epigenetic compounds, we found that Lysine-Specific Demethylase 1 (LSD1) inhibitors repress brown adipocyte differentiation. RNAi-mediated Lsd1 knockdown causes a similar effect, which can be rescued by expression of wild-type but not catalytic-inactive LSD1. Mechanistically, LSD1 promotes brown adipogenesis by demethylating H3K4 on promoter regions of Wnt signaling components and repressing the Wnt pathway. Furthermore, deletion of Lsd1 in mice leads to inhibition of brown adipogenesis, validating the pivotal role of LSD1 in brownfat development invivo. Our work identifies LSD1 as a key epigenetic regulator in brown adipogenesis. The link between LSD1 and the Wnt pathway provides potential opportunities to modulate brown fat differentiation.

Phosphorylation of LSD1 at Ser112 is crucial for its function in induction of EMT and metastasis in breast cancer.

LSD1 is overexpressed in various cancers including breast cancer, but its functional roles in tumourigenesis are not fully understood. This study aims at revealing the role of LSD1 in breast cancer development. In addition, it has been reported that phosphorylation of the Serine 112 residue of LSD1 by PKCα is crucial for its function in gene regulation. We also explored whether this phosphorylation affects LSD1's role in breast cancer development. This study includes LSD1 IHC data generated with tissue microarrays of 163 cases of breast cancer samples and 72 normal tissues. In vitro, role of LSD1, LSD1 S112D mutant (a phosphorylation simulation) and LSD1 S112A mutant (an unphosphorylation simulation) in induction of EMT is evaluated. Mechanismly, we checked the role of LSD1 and its mutant on E-cadherin promoter histone modifications. We also investigated the role of LSD1 and its mutants in metastasis with a nude mice model. We found LSD1 is expressed at a higher level in breast cancer tissues compared with that in normal tissues, and LSD1 expression is closely linked to breast cancer metastasis. LSD1 potentiates EMT in breast epithelia cells by repressing E-cadherin expression through demethylating H3K4me at gene's promoter, during which phosphorylation of LSD1 Ser112 is crucial for its binding and demethylation activity. In vivo, knockdown of LSD1 impairs the metastatic ability of MDA-MB-231 breast cancer cells in nude mice. Ectopic overexpression of either LSD1 or LSD1 S112D mutant (a phosphorylation simulation) facilitates metastasis, whereas the LSD1 S112A mutant (an unphosphorylation simulation) fails to affect the metastasis. Data presented in this report indicate that LSD1 is able to induce EMT and to promote metastasis in breast cancer, and phosphorylation at LSD1 Ser112 is crucial for these functions.

Function of Lipid Storage Droplet 1 (Lsd1) in Wing Development of Drosophila melanogaster.

Perilipins are evolutionarily conserved from Drosophila to humans, the lipid storage droplet 1 (Lsd1) is a Drosophila homolog of human perilipin 1. The function of Lsd1 as a regulator of lipolysis in Drosophila has been demonstrated, as the Lsd1 mutant causes an increase of lipid droplet size. However, the functions of this gene during development are still under investigation. In order to determine the function of Lsd1 during development, Lsd1 was knocked down in Drosophila using the GAL4-UAS system. Selective knockdown of Lsd1 in the dorsal wing disc caused an atrophied wing phenotype. The generation of reactive oxygen species in the wing pouch compartment of the Lsd1-knockdown flies was significantly higher than in the control. Immunostaining with caspase-3 antibody revealed a greater number of apoptotic cells in Lsd1-knockdown wing discs than in the control. Cell death by autophagy was also induced in the knockdown flies. Moreover, cells deprived of Lsd1 showed mitochondrial expansion and decreased ATP levels. These results strongly suggest that knockdown of Lsd1 induces mitochondrial stress and the production of reactive oxygen species that result in cell death, via apoptosis and the autophagy pathway. These results highlight the roles of Drosophila Lsd1 during wing development.

Lysine-specific demethylase 1 mediates epidermal growth factor signaling to promote cell migration in ovarian cancer cells.

Epigenetic abnormalities play a vital role in the progression of ovarian cancer. Lysine-specific demethylase 1 (LSD1/KDM1A) acts as an epigenetic regulator and is overexpressed in ovarian tumors. However, the upstream regulator of LSD1 expression in this cancer remains elusive. Here, we show that epidermal growth factor (EGF) signaling upregulates LSD1 protein levels in SKOV3 and HO8910 ovarian cancer cells overexpressing both LSD1 and the EGF receptor. This effect is correlated with a decrease in the dimethylation of H3K4, a major substrate of LSD1, in an LSD1-dependent manner. We also show that inhibition of PI3K/AKT, but not MEK, abolishes the EGF-induced upregulation of LSD1 and cell migration, indicating that the PI3K/PDK1/AKT pathway mediates the EGF-induced expression of LSD1 and cell migration. Significantly, LSD1 knockdown or inhibition of LSD1 activity impairs both intrinsic and EGF-induced cell migration in SKOV3 and HO8910 cells. These results highlight a novel mechanism regulating LSD1 expression and identify LSD1 as a promising therapeutic target for treating metastatic ovarian cancer driven by EGF signaling.

Abstract 2887: Epigenetic silencing of the DNA repair genes, BRCA1 and MLH1, induced by hypoxic stress in a pathway dependent on the histone demethylase, LSD1

Abstract Hypoxia is a key microenviromental stress in solid tumors that is associated with poor prognosis. It has been indicated that hypoxia induces genetic instability through multiple mechanisms. Previously, we have shown that BRCA1 and RAD51, in the homology dependent repair (HDR) pathway, and MLH1 and MSH2, key components of MMR, are down-regulated at the transcriptional level in response to hypoxia. Here we show that hypoxia also drives epigenetic modification of the BRCA1 and MLH1 promoters, with decreased H3K4 methylation as a key repressive modification produced by the lysine specific histone demethylase, LSD1. In cells containing the BRCA1 promoter driving a selectable HPRT gene, long-term silencing of the promoter was observed following exposure to hypoxic stress. The silenced clones showed decreased H3K4 methylation and decreased H3K9 acetylation in the BRCA1 promoters, consistent with the acute effects of hypoxic stress. Similarly, we also found that hypoxia causes durable long-term silencing of the MLH1 promoter in a pathway that requires LSD1. Knockdown of LSD1 or its co-repressor, CoREST, also prevents the re-silencing (and associated cytosine DNA methylation) of the endogenous MLH1 promoter in RKO colon cancer cells following transient reactivation by treatment with the DNA methyltransferase inhibitor 5-aza-2′-deoxycytidine (5-aza-dC). These results suggest that hypoxia is a driving force for long-term silencing of DNA repair genes, including BRCA1 and MLH1, thereby promoting genome instability and tumor progression. Citation Format: Yuhong Lu, Adrian Chu, Narendra Wajapeyee, Mitchell S. Turker, Peter M. Glazer. Epigenetic silencing of the DNA repair genes, BRCA1 and MLH1, induced by hypoxic stress in a pathway dependent on the histone demethylase, LSD1. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2887. doi:10.1158/1538-7445.AM2015-2887

Histone demethylase LSD1-mediated repression of GATA-2 is critical for erythroid differentiation.

BackgroundThe transcription factor GATA-2 is predominantly expressed in hematopoietic stem and progenitor cells and counteracts the erythroid-specific transcription factor GATA-1, to modulate the proliferation and differentiation of hematopoietic cells. During hematopoietic cell differentiation, GATA-2 exhibits dynamic expression patterns, which are regulated by multiple transcription factors.MethodsStable LSD1-knockdown cell lines were established by growing murine erythroleukemia (MEL) or mouse embryonic stem cells together with virus particles, in the presence of Polybrene® at 4 μg/mL, for 24–48 hours followed by puromycin selection (1 μg/mL) for 2 weeks. Real-time polymerase chain reaction (PCR)-based quantitative chromatin immunoprecipitation (ChIP) analysis was used to test whether the TAL1 transcription factor is bound to 1S promoter in the GATA-2 locus or whether LSD1 colocalizes with TAL1 at the 1S promoter. The sequential ChIP assay was utilized to confirm the role of LSD1 in the regulation of H3K4me2 at the GATA-2 locus during erythroid differentiation. Western blot analysis was employed to detect the protein expression. The alamarBlue® assay was used to examine the proliferation of the cells, and the absorbance was monitored at optical density (OD) 570 nm and OD 600 nm.ResultsIn this study, we showed that LSD1 regulates the expression of GATA-2 during erythroid differentiation. Knockdown of LSD1 results in increased GATA-2 expression and inhibits the differentiation of MEL and embryonic stem cells. Furthermore, we demonstrated that LSD1 binds to the 1S promoter of the GATA-2 locus and suppresses GATA-2 expression, via histone demethylation.ConclusionOur data revealed that LSD1 mediates erythroid differentiation, via epigenetic modification of the GATA-2 locus.

Lysine-specific demethylase (LSD1/KDM1A) and MYCN cooperatively repress tumor suppressor genes in neuroblastoma

The chromatin-modifying enzyme lysine-specific demethylase 1, KDM1A/LSD1 is involved in maintaining the undifferentiated, malignant phenotype of neuroblastoma cells and its overexpression correlated with aggressive disease, poor differentiation and infaust outcome. Here, we show that LSD1 physically binds MYCN both in vitro and in vivo and that such an interaction requires the MYCN BoxIII. We found that LSD1 co-localizes with MYCN on promoter regions of CDKN1A/p21 and Clusterin (CLU) suppressor genes and cooperates with MYCN to repress the expression of these genes. KDM1A needs to engage with MYCN in order to associate with the CDKN1A and CLU promoters. The expression of CLU and CDKN1A can be restored in MYCN-amplified cells by pharmacological inhibition of LSD1 activity or knockdown of its expression. Combined pharmacological inhibition of MYCN and LSD1 through the use of small molecule inhibitors synergistically reduces MYCN-amplified Neuroblastoma cell viability in vitro. These findings demonstrate that LSD1 is a critical co-factor of the MYCN repressive function, and suggest that combination of LSD1 and MYCN inhibitors may have strong therapeutic relevance to counteract MYCN-driven oncogenesis.

Pharmacological Inhibitors of LSD1 Promote Differentiation of Myeloid Leukemia Cells through a Mechanism Independent of Histone Demethylation

Lysine Specific Demethylase 1 (LSD1 or KDM1A) is one of a number of epigenetic regulators which have recently emerged as candidate therapeutic targets in acute myeloid leukaemia (AML). It is a flavin adenine dinucleotide (FAD) dependent homolog of the amine oxidase family with an ability to demethylate monomethyl or dimethyl lysine 4 (K4) of histone H3, in addition to other substrates. Pharmacological inhibitors of LSD1 such as the tranylcypromine derivatives have already commenced evaluation in early phase clinical trials. While it has been widely assumed that these compounds promote differentiation of AML cells through inhibition of the demethylase activity of LSD1, the precise mechanisms by which LSD1 inhibitors function has not yet been determined.If changes in histone methylation are a central and critical mediator of the effects of LSD1 inhibitors in promoting AML cell differentiation, it would be expected that global changes in transcription would be tightly linked temporally to changes in histone methylation following drug treatment of cells. Through RNA sequencing and ChIP sequencing experiments performed in human THP1 AML cells treated for 24 hours with a potent and specific tranylcypromine-derivative LSD1 inhibitor (ORY86, trans-N-((2-methoxypyridin-3-yl)methyl)-2-phenylcyclopropan-1-amine), we have established that wholescale up regulation of a myeloid differentiation transcription programme occurs in the absence of any significant genome-wide changes in mono- and di-methyl H3K4 and H3K9 (which are key enzymatic targets of LSD1). Thus LSD1 inhibitor-induced up regulation of myeloid differentiation gene expression is not downstream of changes in histone methylation.We further demonstrated that non-enzymatic functions of LSD1 are essential in AML cells by expressing either wild-type (WT) or catalytically inactive LSD1 (K661A) in LSD1 knockdown (KD) THP1 cells. While LSD1 KD cells exhibit myeloid differentiation and loss of clonogenic potential, both the WT and mutant versions of LSD1 were able to rescue the in vitro clonogenic potential of KD cells to an equivalent extent. Thus the histone demethylase activity of LSD1 is not required to sustain AML blasts in an undifferentiated state.Comparison of the transcriptional consequences of LSD1 inhibition with the transcriptional consequences of transcription factor knockdown in THP1 AML cells using GSEA revealed that pharmacological inhibition of LSD1 mimics depletion of GFI1. Immunoprecipitation experiments confirmed the previously described physical association of GFI1 with LSD1. Critically, the physical interactions of LSD1 with GFI1 was reversed by pharmacological inhibition of LSD1 with ORY86. Furthermore, in ChIP sequencing experiments drug treatment led to dissociation of LSD1 from promoters and enhancers. By contrast, there was no disruption of the endogenous level interaction of LSD1 with RCOR1, HDAC1 and HDAC2 (i.e. the CoREST complex) following drug treatment.To determine whether the inhibitor-induced separation of LSD1 from GFI1 is required for induction of myeloid differentiation by ORY86, we performed experiments using a GFI1-LSD1 fusion construct expressed in THP1 cells under the control of a doxycycline-regulated promoter. This construct tethers LSD1 directly to the transcription factor and circumvents any drug induced physical separation. THP1 cells expressing GFI1-LSD1 were drug resistant (as determined by immunophenotyping and clonogenic potential), in contrast to control cells expressing GFI1, LSD1 or an empty vector in the same inducible system. Thus, drug-induced physical separation of GFI1 from LSD1 is required for THP1 AML cells to undergo differentiation.Our data support a model whereby the physical association of LSD1 with transcription factors such as GFI1 is essential to maintain the differentiation block in AML. Unexpectedly, tranylcypromine-derivative inhibitors target this novel scaffolding function of LSD1, rather than its histone demethylase activity, to promote differentiation of AML cells. DisclosuresLynch:Astra Zeneca: Employment. Ciceri:Oryzon Genomics: Employment. Somervaille:Oryzon Genomics: Research Funding; Imago Biosciences: Consultancy.

Histone Demethylase LSD1-Mediated Repression of GATA-2 Is Critical for Erythroid Differentiation

GATA-2 transcription factor is predominantly expressed in hematopoietic stem and progenitor cells (HS/PCs), and counteracts erythroid specific transcription factor GATA-1 to modulate proliferation and differentiation of hematopoietic cells. During hematopoietic cell differentiation, GATA-2 exhibits dynamic expression patterns, regulated by collaborations between GATA-1 and epigenetic regulators. Here, we show that histone specific demethylase1 (LSD1) regulates the expression of GATA-2 gene during erythroid differentiation. Knockdown of LSD1 leads to increased GATA-2 expression and inhibits induced MEL and embryonic stem cell differentiation. Furthermore, we demonstrate that LSD1 binds at the 1S promoter of GATA-2 gene locus, and suppresses GATA-2 expression through histone demethylation. Thus, our data reveals that LSD1 mediates erythroid cell differentiation by epigenetic modification of GATA-2 gene locus. DisclosuresNo relevant conflicts of interest to declare.

Epigenetic regulation of Atrophin1 by lysine-specific demethylase 1 is required for cortical progenitor maintenance.

Lysine-specific demethylase 1 (LSD1) is involved in gene regulation and development; however, its precise function, molecular targets and underlying mechanisms during development are poorly understood. Here we show that LSD1 is required for neuronal progenitor cell (NPC) maintenance during cortical development. A ChIP-seq analysis identified a LSD1-binding site (LBAL) downstream of Atrophin1 (ATN1). Surprisingly, tranylcypromine (LSD1 inhibitor) treatment increased H3K4 methylation at LBAL, leading to ATN1 repression and NPC differentiation. Knockdown of LSD1 and ATN1 phenocopied each other in inducing NPC premature differentiation and depletion, which could be rescued by ATN1 overexpression, suggesting that LSD1 controls NPC differentiation via regulation of ATN1 methylation status and expression. The involvement of LSD1 in ATN1 expression and NPC maintenance were confirmed in knockout mice. These findings hint at the potential application for the clinical drug, tranylcypromine, in the prevention and/or treatment of ATN1-associated degenerative disease, dentatorubral-pallidoluysian atrophy.

Silencing of the DNA Mismatch Repair Gene MLH1 Induced by Hypoxic Stress in a Pathway Dependent on the Histone Demethylase LSD1

Silencing of MLH1 is frequently seen in sporadic colorectal cancers. We show here that hypoxia causes decreased histone H3 lysine 4 (H3K4) methylation at the MLH1 promoter via the action of the H3K4 demethylases LSD1 and PLU-1 and promotes durable long-term silencing in a pathway that requires LSD1. Knockdown of LSD1 or its corepressor, CoREST, also prevents the resilencing (and associated cytosine DNA methylation) of the endogenous MLH1 promoter in RKO colon cancer cells following transient reactivation by treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-aza-dC). The results demonstrate that hypoxia is a driving force for silencing of MLH1 and that the LSD1/CoREST complex is necessary for this process. The results reveal a mechanism by which hypoxia promotes cancer cell evolution to drive malignant progression through epigenetic modulation. Our findings suggest that LSD1/CoREST acts as a colon cancer oncogene by epigenetically silencing MLH1 and also identify the LSD1/CoREST complex as a potential target for therapy.