Reversible inhibition of lysine specific demethylase 1 is a novel anti-tumor strategy for poorly differentiated endometrial carcinoma

Lysine demethylase LSD1 is associated with stemness in EBV-positive B cell lymphoma

EBV-infected lymphoma has a poor prognosis and various treatment strategies are being explored. Reports suggesting that B cell lymphoma can be induced by epigenetic regulation have piqued interest in studying mechanisms targeting epigenetic regulation. Here, we set out to identify an epigenetic regulator drug that acts synergistically with doxorubicin in EBV-positive lymphoma. We expressed the major EBV protein, LMP1, in B-cell lymphoma cell lines and used them to screen 100 epigenetic modifiers in combination with doxorubicin. The screening results identified TCP, which is an inhibitor of LSD1. Further analyses revealed that LMP1 increased the activity of LSD1 to enhance stemness ability under doxorubicin treatment, as evidenced by colony-forming and ALDEFLUOR activity assays. Quantseq 3' mRNA sequencing analysis of potential targets regulated by LSD1 in modulating stemness revealed that the LMP1-induced upregulation of CHAC2 was decreased when LSD1 was inhibited by TCP or downregulated by siRNA. We further observed that SOX2 expression was altered in response to CHAC2 expression, suggesting that stemness is regulated. Collectively, these findings suggest that LSD1 inhibitors could serve as promising therapeutic candidates for EBV-positive lymphoma, potentially reducing stemness activity when combined with conventional drugs to offer an effective treatment approach.

Epigenome editing in cancer: Advances and challenges for potential therapeutic options

Cancers are diseases caused by genetic and non-genetic environmental factors. Epigenetic alterations, some attributed to non-genetic factors, can lead to cancer development. Epigenetic changes can occur in tumor suppressors or oncogenes, or they may contribute to global cell state changes, making cells abnormal. Recent advances in gene editing technology show potential for cancer treatment. Herein, we will discuss our current knowledge of epigenetic alterations occurring in cancer and epigenetic editing technologies that can be applied to developing therapeutic options.

LSD1 promotes prostate cancer reprogramming by repressing TP53 signaling independently of its demethylase function

Lysine-specific demethylase 1 (LSD1) is a histone demethylase that promotes stemness and cell survival in cancers such as prostate cancer. Most prostate malignancies are adenocarcinomas with luminal differentiation. However, some tumors undergo cellular reprogramming to a more lethal subset termed neuroendocrine prostate cancer (NEPC) with neuronal differentiation. The frequency of NEPC is increasing since the widespread use of potent androgen receptor signaling inhibitors. Currently, there are no effective treatments for NEPC. We previously determined that LSD1 promotes survival of prostate adenocarcinoma tumors. However, the role of LSD1 in NEPC is unknown. Here, we determined that LSD1 is highly upregulated in NEPC versus adenocarcinoma patient tumors. LSD1 suppression with RNAi or allosteric LSD1 inhibitors - but not catalytic inhibitors - reduced NEPC cell survival. RNA-Seq analysis revealed that LSD1 represses pathways linked to luminal differentiation, and TP53 was the top reactivated pathway. We confirmed that LSD1 suppressed the TP53 pathway by reducing TP53 occupancy at target genes while LSD1's catalytic function was dispensable for this effect. Mechanistically, LSD1 inhibition disrupted LSD1-HDAC interactions, increasing histone acetylation at TP53 targets. Finally, LSD1 inhibition suppressed NEPC tumor growth in vivo. These findings suggest that blocking LSD1's noncatalytic function may be a promising treatment strategy for NEPC.

Targeting LSD1 in tumor immunotherapy: rationale, challenges and potential

Lysine-specific demethylase 1 (LSD1) is an enzyme that removes lysine methylation marks from nucleosome histone tails and plays an important role in cancer initiation, progression, metastasis, and recurrence. Recent research shows that LSD1 regulates tumor cells and immune cells through multiple upstream and downstream pathways, enabling tumor cells to adapt to the tumor microenvironment (TME). As a potential anti-tumor treatment strategy, immunotherapy has developed rapidly in the past few years. However, most patients have a low response rate to available immune checkpoint inhibitors (ICIs), including anti-PD-(L)1 therapy and CAR-T cell therapy, due to a broad array of immunosuppressive mechanisms. Notably, inhibition of LSD1 turns "cold tumors" into "hot tumors" and subsequently enhances tumor cell sensitivity to ICIs. This review focuses on recent advances in LSD1 and tumor immunity and discusses a potential therapeutic strategy for combining LSD1 inhibition with immunotherapy.

A ciprofloxacin derivative with four mechanisms of action overcomes paclitaxel resistance in p53-mutant and MDR1 gene-expressing type II human endometrial cancer

Dysfunction of the p53 gene and the presence of the MDR1 gene are associated with many malignant tumors including endometrial cancer and are responsible for cancer therapeutic resistance and poor survival. Thus, there is a critical need to devise novel combinatorial therapies with multiple mechanisms of action to overcome drug resistance. Here, we report a new ciprofloxacin derivative (CIP2b) tested either alone or in combination with taxanes against four human endometrial cancer cell lines. In vitro studies revealed that a combination of paclitaxel + CIP2b had synergistic cytotoxic effects against MDR1-expressing type-II human endometrial cancer cells with loss-of-function p53 (Hec50co LOFp53). Enhanced antitumor effects were confirmed by substantial increases in caspase-3 expression, cell population shifts toward the G2/M phase, and reduction of cdc2 phosphorylation. It was found that CIP2b targets multiple pathways including the inhibition of MDR1, topoisomerase I, and topoisomerase II, as well as enhancing the effects of paclitaxel (PTX) on microtubule assembly. In vivo treatment with the combination of PTX + CIP2b also led to significantly increased accumulation of PTX in tumors (compared to CIP2b alone) and reduction in tumor growth. Enhanced in vivo cytotoxic effects were confirmed by histological and immunohistochemical examination of the tumor tissues. Complete blood count and blood biochemistry data confirmed the absence of any apparent off-target toxicity. Thus, combination therapy involving PTX and CIP2b targeted multiple pathways and represents an approach that could result in improved tolerance and efficacy in patients with type-II endometrial cancer harboring the MDR1 gene and p53 mutations.

KDM1A inhibition augments the efficacy of rapamycin for the treatment of endometrial cancer

Endometrial cancer (EC) often exhibit aberrant activation of PI3K/Akt/mTOR signaling and targeted therapies using mTOR inhibitors showed limited success. The epigenetic modifier, lysine-specific histone demethylase-1A (KDM1A/LSD1) is overexpressed in EC, however, the mechanistic and therapeutic implications of KDM1A in EC are poorly understood. Here, using 119 FDA-approved drugs screen, we identified that KDM1A inhibition is highly synergistic with mTOR inhibitors. Combination therapy of KDM1A and mTOR inhibitors potently reduced the cell viability, survival, and migration of EC cells. Mechanistic studies demonstrated that KDM1A inhibition attenuated the activation of mTOR signaling cascade and abolished rapamycin induced feedback activation of Akt. RNA-seq analysis identified that KDM1A inhibition downregulated the expression of genes involved in rapamycin induced activation of Akt, including the mTORC2 complex. Chromatin immunoprecipitation experiments confirmed KDM1A recruitment to the promoter regions of mTORC2 complex genes and that KDM1A inhibition promoted enrichment of repressive H3K9me2 marks at their promoters. Combination therapy of KDM1A inhibitor and rapamycin reduced the tumor growth in EC xenograft and patient derived xenograft models in vivo and patient derived tumor explants ex vivo. Importantly, in silico analysis of TCGA EC patients data sets revealed that KDM1A expression positively correlated with the levels of PI3K/Akt/mTOR genes. Collectively, our results provide compelling evidence that KDM1A inhibition potentiates the activity of mTOR inhibitors by attenuating the feedback activation of Akt survival signaling. Furthermore, the use of concurrent KDM1A and mTOR inhibitors may be an attractive targeted therapy for EC patients.

Epigenetic Deregulation of Apoptosis in Cancers

Cancer cells possess the ability to evade apoptosis. Genetic alterations through mutations in key genes of the apoptotic signaling pathway represent a major adaptive mechanism of apoptosis evasion. In parallel, epigenetic changes via aberrant modifications of DNA and histones to regulate the expression of pro- and antiapoptotic signal mediators represent a major complementary mechanism in apoptosis regulation and therapy response. Most epigenetic changes are governed by the activity of chromatin modifying enzymes that add, remove, or recognize different marks on histones and DNA. Here, we discuss how apoptosis signaling components are deregulated at epigenetic levels, particularly focusing on the roles of chromatin-modifying enzymes in this process. We also review the advances in cancer therapies with epigenetic drugs such as DNMT, HMT, HDAC, and BET inhibitors, as well as their effects on apoptosis modulation in cancer cells. Rewiring the epigenome by drug interventions can provide therapeutic advantage for various cancers by reverting therapy resistance and leading cancer cells to undergo apoptotic cell death.

Roles of lysine-specific demethylase 1 (LSD1) in homeostasis and diseases

Lysine-specific demethylase 1 (LSD1) targets mono- or di-methylated histone H3K4 and H3K9 as well as non-histone substrates and functions in the regulation of gene expression as a transcriptional repressor or activator. This enzyme plays a pivotal role in various physiological processes, including development, differentiation, inflammation, thermogenesis, neuronal and cerebral physiology, and the maintenance of stemness in stem cells. LSD1 also participates in pathological processes, including cancer as the most representative disease. It promotes oncogenesis by facilitating the survival of cancer cells and by generating a pro-cancer microenvironment. In this review, we discuss the role of LSD1 in several aspects of cancer, such as hypoxia, epithelial-to-mesenchymal transition, stemness versus differentiation of cancer stem cells, as well as anti-tumor immunity. Additionally, the current understanding of the involvement of LSD1 in various other pathological processes is discussed.

Targeting Epigenetic Regulators for Endometrial Cancer Therapy: Its Molecular Biology and Potential Clinical Applications

Endometrial cancer is one of the most frequently diagnosed gynecological malignancies worldwide. However, its prognosis in advanced stages is poor, and there are only few available treatment options when it recurs. Epigenetic changes in gene function, such as DNA methylation, histone modification, and non-coding RNA, have been studied for the last two decades. Epigenetic dysregulation is often reported in the development and progression of various cancers. Recently, epigenetic changes in endometrial cancer have also been discussed. In this review, we give the main points of the role of DNA methylation and histone modification in endometrial cancer, the diagnostic tools to determine these modifications, and inhibitors targeting epigenetic regulators that are currently in preclinical studies and clinical trials.

Histone Modifying Enzymes in Gynaecological Cancers

Simple Summary

Epigenetics is a process that allows genetic control, without the involvement of sequence changes to DNA or genes. In cancer, epigenetics is a key event in tumour development that can alter the expression of cancer driver genes and result in genomic instability. Due to the critical role of epigenetics in malignant transformation, therapies that target these processes have been developed to treat cancer. Here, we provide a summary of the epigenetic changes that have been described in a variety of gynaecological cancers. We then highlight how these changes are being targeted in preclinical models and clinical trials for gynaecological cancers.

Abstract

Genetic and epigenetic factors contribute to the development of cancer. Epigenetic dysregulation is common in gynaecological cancers and includes altered methylation at CpG islands in gene promoter regions, global demethylation that leads to genome instability and histone modifications. Histones are a major determinant of chromosomal conformation and stability, and unlike DNA methylation, which is generally associated with gene silencing, are amenable to post-translational modifications that induce facultative chromatin regions, or condensed transcriptionally silent regions that decondense resulting in global alteration of gene expression. In comparison, other components, crucial to the manipulation of chromatin dynamics, such as histone modifying enzymes, are not as well-studied. Inhibitors targeting DNA modifying enzymes, particularly histone modifying enzymes represent a potential cancer treatment. Due to the ability of epigenetic therapies to target multiple pathways simultaneously, tumours with complex mutational landscapes affected by multiple driver mutations may be most amenable to this type of inhibitor. Interrogation of the actionable landscape of different gynaecological cancer types has revealed that some patients have biomarkers which indicate potential sensitivity to epigenetic inhibitors. In this review we describe the role of epigenetics in gynaecological cancers and highlight how it may exploited for treatment.

Biological roles of LSD1 beyond its demethylase activity

It is well-established that Lysine-specific demethylase 1 (LSD1, also known as KDM1A) roles as a lysine demethylase canonically acting on H3K4me1/2 and H3K9me1/2 for regulating gene expression. Though the discovery of non-histone substrates methylated by LSD1 has largely expanded the functions of LSD1 as a typical demethylase, recent groundbreaking studies unveiled its non-catalytic functions as a second life for this demethylase. We and others found that LSD1 is implicated in the interaction with a line of proteins to exhibit additional non-canonical functions in a demethylase-independent manner. Here, we present an integrated overview of these recent literatures charging LSD1 with unforeseen functions to re-evaluate and summarize its non-catalytic biological roles beyond the current understanding of its demethylase activity. Given LSD1 is reported to be ubiquitously overexpressed in a variety of tumors, it has been generally considered as an innovative target for cancer therapy. We anticipate that these non-canonical functions of LSD1 will arouse the consideration that extending the LSD1-based drug discovery to targeting LSD1 protein interactions non-catalytically, not only its demethylase activity, may be a novel strategy for cancer prevention.

An organoid-based drug screening identified a menin-MLL inhibitor for endometrial cancer through regulating the HIF pathway

Tumor organoids recapitulate pathological properties and would serve as an excellent ex vivo model for drug discovery. Here, we performed an unbiased drug screening on drivers-defined tumor organoids from mouse endometrial cancer, the most prevalent gynecological malignancy in human, with a small molecule library targeting epigenetic factors. Among them, menin-MLL inhibitors MI-136 and MI-463 scored. The therapeutic capacity of MI-136 was further validated in tumor organoids in vitro and an orthotopic model in vivo. CRISPR/cas9-mediated mutations of major components of the menin-MLL complex, Men1, Kmt2a and Ash2l, inhibited the growth of tumor organoids, suggesting that the complex was the target of MI-136. Transcriptome analysis showed that the hypoxia-inducible factor (HIF) pathway was the most significantly downregulated pathway by MI-136 treatment. Consistently, Men1, Kmt2a, and Ash2l knockout also repressed the expressions of the HIF target genes. Loss of Hif1a or Hif1b partially phenocopied the inhibition of the menin-MLL complex by MI-136 or mutations in term of tumor organoid growth. Further, we found that MEN1 was upregulated in human endometrial cancers, which were tightly correlated with the expression levels of HIF1A, and associated with poor prognosis. Importantly, MI-136 also significantly inhibited the growth of endometrial cancer organoids derived from patients. Thus, our study identified MI-136 as a potential inhibitor for endometrial cancer through regulating the HIF pathway, a novel molecular mechanism distinguished from those in AML and prostate cancer.

LSD1/KDM1A, a Gate-Keeper of Cancer Stemness and a Promising Therapeutic Target

A new exciting area in cancer research is the study of cancer stem cells (CSCs) and the translational implications for putative epigenetic therapies targeted against them. Accumulating evidence of the effects of epigenetic modulating agents has revealed their dramatic consequences on cellular reprogramming and, particularly, reversing cancer stemness characteristics, such as self-renewal and chemoresistance. Lysine specific demethylase 1 (LSD1/KDM1A) plays a well-established role in the normal hematopoietic and neuronal stem cells. Overexpression of LSD1 has been documented in a variety of cancers, where the enzyme is, usually, associated with the more aggressive types of the disease. Interestingly, recent studies have implicated LSD1 in the regulation of the pool of CSCs in different leukemias and solid tumors. However, the precise mechanisms that LSD1 uses to mediate its effects on cancer stemness are largely unknown. Herein, we review the literature on LSD1's role in normal and cancer stem cells, highlighting the analogies of its mode of action in the two biological settings. Given its potential as a pharmacological target, we, also, discuss current advances in the design of novel therapeutic regimes in cancer that incorporate LSD1 inhibitors, as well as their future perspectives.

Identification of key genes and pathways between type I and type II endometrial cancer using bioinformatics analysis

Endometrial carcinoma (EC) is a common malignant neoplasm of the female reproductive tract. The malignant degree of type II EC is much greater than that of type I EC, usually presenting with a high recurrence rate and a poor prognosis. Therefore, the present study aimed to examine the principal genes associated with the degree of differentiation in type I and type II EC and reveal their potential mechanisms. Differentially expressed genes (DEGs) were selected from the gene expression profiles derived from The Cancer Genome Atlas. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were conducted. In the present study, the KEGG pathway enrichment analysis revealed that 5,962 upregulated DEGs were significantly enriched in the ‘p53 signaling pathway’ and involved in ‘lysine degradation’. In addition, 3,709 downregulated DEGs were enriched in ‘pathways in cancer’, as well as ‘tight junction regulation’, the ‘cell cycle’ and the ‘Wnt signaling pathway’. The 13 top hub genes MAPK1, PHLPP1, ESR1, MDM2, CDKN2A, CDKN1A, AURKA, BCL2L1, POLQ, PIK3R3, RHOQ, EIF4E and LATS2 were identified via the protein-protein interaction network. Furthermore, the OncoPrint algorithm from cBioPortal declared that 25% of EC cases carried genetic alterations. The altered DEGs (MAPK1, MDM2, AURKA, EIF4E and LATS2) may be involved in tumor differentiation and may be valuable diagnostic biomarkers. In conclusion, a number of principal genes were identified in the present study that may be determinants of poorly differentiated type II EC carcinogenesis, which may contribute to future research into potential molecular mechanisms. In addition, these genes may help identify candidate biomarkers and novel therapeutic targets for type II EC.

Genome-wide ChIP-seq data with a transcriptome analysis reveals the groups of genes regulated by histone demethylase LSD1 inhibition in esophageal squamous cell carcinoma cells

Expression of genes is controlled by histone modification, histone acetylation and methylation, but abnormalities of these modifications have been observed in carcinogenesis and cancer development. The effect of the lysine-specific histone demethylase 1 (LSD1) inhibitor, a demethylating enzyme of histones, is thought to be caused by controlling the expression of genes. The aim of the present study is to elucidate the efficacies of the LSD1 inhibitor on the gene expression of esophageal cancer cell lines using chromatin immunoprecipitation (ChIP)-Seq. A comprehensive analysis of gene expression changes in esophageal squamous cell carcinoma (ESCC) cell lines induced by the LSD1 inhibitor NCL1 was clarified via analysis using microarray. In addition, ChIP-seq analysis was conducted using a SimpleChIP plus Enzymatic Chromatin IP kit. NCL1 strongly suppressed the proliferation of T.Tn and TE2 cells, which are ESCC cell lines, and further induced apoptosis. According to the combinatory analysis of ChIP-seq and microarray, 17 genes were upregulated, and 16 genes were downregulated in both cell lines. The comprehensive gene expression study performed in the present study is considered to be useful for analyzing the mechanism of the antitumor effect of the LSD1 inhibitor in patients with ESCC.

Pharmacological Inhibition of LSD1 for Cancer Treatment

Lysine-specific demethylase 1A (LSD1, also named KDM1A) is a demethylase that can remove methyl groups from histones H3K4me1/2 and H3K9me1/2. It is aberrantly expressed in many cancers, where it impedes differentiation and contributes to cancer cell proliferation, cell metastasis and invasiveness, and is associated with inferior prognosis. Pharmacological inhibition of LSD1 has been reported to significantly attenuate tumor progression in vitro and in vivo in a range of solid tumors and acute myeloid leukemia. This review will present the structural aspects of LSD1, its role in carcinogenesis, a comparison of currently available approaches for screening LSD1 inhibitors, a classification of LSD1 inhibitors, and its potential as a drug target in cancer therapy.

Preclinical studies reveal that LSD1 inhibition results in tumor growth arrest in lung adenocarcinoma independently of driver mutations

Lung adenocarcinoma (LUAD) is the most prevalent subtype of non-small cell lung cancer. Despite the development of novel targeted and immune therapies, the 5-year survival rate is still only 21%, indicating the need for more efficient treatment regimens. Lysine-specific demethylase 1 (LSD1) is an epigenetic eraser that modifies histone 3 methylation status, and is highly overexpressed in LUAD. Using representative human cell culture systems and two autochthonous transgenic mouse models, we investigated inhibition of LSD1 as a novel therapeutic option for treating LUAD. The reversible LSD1 inhibitor HCI-2509 significantly reduced cell growth with an IC₅₀ of 0.3-5 μmin vitro, which was linked to an enhancement of histone 3 lysine methylation. Most importantly, growth arrest, as well as inhibition of the invasion capacities, was independent of the underlying driver mutations. Subsequent expression profiling revealed that the cell cycle and replication machinery were prominently affected after LSD1 inhibition. In addition, our data provide evidence that LSD1 blockade significantly interferes with EGFR downstream signaling. Finally, our in vitro results were confirmed by preclinical therapeutic approaches, including the use of two autochthonous transgenic LUAD mouse models driven by either EGFR or KRAS mutations. Importantly, LSD1 inhibition resulted in significantly lower tumor formation and a strong reduction in tumor progression, which were independent of the underlying mutational background of the mouse models. Hence, our findings provide substantial evidence indicating that tumor growth of LUAD can be markedly decreased by HCI-2509 treatment, suggesting its use as a single agent maintenance therapy or combined therapeutical application in novel concerted drug approaches.

LSD1 activates a lethal prostate cancer gene network independently of its demethylase function

Medical castration that interferes with androgen receptor (AR) function is the principal treatment for advanced prostate cancer. However, clinical progression is universal, and tumors with AR-independent resistance mechanisms appear to be increasing in frequency. Consequently, there is an urgent need to develop new treatments targeting molecular pathways enriched in lethal prostate cancer. Lysine-specific demethylase 1 (LSD1) is a histone demethylase and an important regulator of gene expression. Here, we show that LSD1 promotes the survival of prostate cancer cells, including those that are castration-resistant, independently of its demethylase function and of the AR. Importantly, this effect is explained in part by activation of a lethal prostate cancer gene network in collaboration with LSD1's binding protein, ZNF217. Finally, that a small-molecule LSD1 inhibitor-SP-2509-blocks important demethylase-independent functions and suppresses castration-resistant prostate cancer cell viability demonstrates the potential of LSD1 inhibition in this disease.

Reversible LSD1 inhibition with HCI-2509 induces the p53 gene expression signature and disrupts the MYCN signature in high-risk neuroblastoma cells

Lysine-Specific Demethylase 1 (LSD1) over-expression correlates with poorly differentiated neuroblastoma and predicts poor outcome despite multimodal therapy. We have studied the efficacy of reversible and specific LSD1 inhibition with HCI-2509 in neuroblastoma cell lines and particularly the effect of HCI-2509 on the transcriptomic profile in MYCN amplified NGP cells. Cell survival assays show that HCI-2509 is cytotoxic to poorly differentiated neuroblastoma cell lines in low micromole or lower doses. Transcriptional profiling of NGP cells treated with HCI-2509 shows a significant effect on p53, cell cycle, MYCN and hypoxia pathway gene sets. HCI-2509 results in increased histone methyl marks and p53 levels along with cell cycle arrest in the G2/M phase and inhibition of colony formation of NGP cells. Our findings indicate that LSD1 inhibition with HCI-2509 has a multi-target effect in neuroblastoma cell lines, mediated in part via p53. MYCN-amplified neuroblastoma cells have a targeted benefit as HCI-2509 downregulates the MYCN upregulated gene set.

Lysine-specific demethylase 1 (LSD1) destabilizes p62 and inhibits autophagy in gynecologic malignancies

Lysine-specific demethylase 1 (LSD1) – also known as KDM1A – is the first identified histone demethylase. LSD1 is highly expressed in numerous human malignancies and has recently emerged as a target for anticancer drugs. Owing to the presence of several functional domains, we speculated that LSD1 could have additional functions other than histone demethylation. P62 – also termed sequestasome 1 (SQSTM1) – plays a key role in malignant transformation, apoptosis, and autophagy. Here, we show that a high LSD1 expression promotes tumorigenesis in gynecologic malignancies. Notably, LSD1 inhibition with either siRNA or pharmacological agents activates autophagy. Mechanistically, LSD1 decreases p62 protein stability in a demethylation-independent manner. Inhibition of LSD1 reduces both tumor growth and p62 protein degradation in vivo. The combination of LSD1 inhibition and p62 knockdown exerts additive anticancer effects. We conclude that LSD1 destabilizes p62 and inhibits autophagy in gynecologic cancers. LSD1 inhibition reduces malignant cell growth and activates autophagy. The combinations of LSD1 inhibition and autophagy blockade display additive inhibitory effect on cancer cell viability. A better understanding of the role played by p62 will shed more light on the anticancer effects of LSD1 inhibitors.

Epigenetics in endometrial carcinogenesis - part 2: histone modifications, chromatin remodeling and noncoding RNAs

Carcinogenesis is a multistep multifactorial process that involves the accumulation of genetic and epigenetic alterations. In the past two decades, there has been an exponential growth of knowledge establishing the importance of epigenetic changes in cancer. Our work focused on reviewing the main role of epigenetics in the pathogenesis of endometrial carcinoma, highlighting the reported results concerning each epigenetic mechanistic layer. In a previous review, we assessed DNA methylation alterations. The present review examines the contribution of histone modifications, chromatin remodeling and noncoding RNA alterations for endometrial carcinogenesis.

The promise of epigenetic therapy: reprogramming the cancer epigenome

Epigenetics refers to heritable molecular determinants of phenotype independent of DNA sequence. Epigenetic features include DNA methylation, histone modifications, non-coding RNAs, and chromatin structure. The epigenetic status of cells plays a crucial role in determining their differentiation state and proper function within multicellular organisms. Disruption of these processes is now understood to be a major contributor to cancer development and progression, and recent efforts have attempted to pharmacologically reverse such altered epigenetics. In this mini-review we introduce the concept of epigenetic drivers of cancer and discuss how aberrant DNA methylation, histone modifications, and chromatin states are being targeted using drugs either in preclinical, or clinical development, and how they fit in the context of existing therapies.

Therapeutic opportunities in Ewing sarcoma: EWS-FLI inhibition via LSD1 targeting

Ewing sarcoma is an aggressive primary pediatric bone tumor, often diagnosed in adolescents and young adults. A pathognomonic reciprocal chromosomal translocation results in a fusion gene coding for a protein which derives its N-terminus from a FUS/EWS/TAF15 (FET) protein family member, commonly EWS, and C-terminus containing the DNA-binding domain of an ETS transcription factor, commonly FLI1. Nearly 85% of cases express the EWS-FLI protein which functions as a transcription factor and drives oncogenesis. As the primary genomic lesion and a protein which is not expressed in normal cells, disrupting EWS-FLI function is an attractive therapeutic strategy for Ewing sarcoma. However, transcription factors are notoriously difficult targets for the development of small molecules. Improved understanding of the oncogenic mechanisms employed by EWS-FLI to hijack normal cellular programming has uncovered potential novel approaches to pharmacologically block EWS-FLI function. In this review we examine targeting the chromatin regulatory enzymes recruited to conspire in oncogenesis with a focus on the histone lysine specific demethylase 1 (LSD1). LSD1 inhibitors are being aggressively investigated in acute myeloid leukemia and the results of early clinical trials will help inform the future use of LSD1 inhibitors in sarcoma. High LSD1 expression is observed in Ewing sarcoma patient samples and mechanistic and preclinical data suggest LSD1 inhibition globally disrupts the function of EWS-ETS proteins.

LSD1 sustains estrogen-driven endometrial carcinoma cell proliferation through the PI3K/AKT pathway via di-demethylating H3K9 of cyclin D1

A recent study reported that histone lysine specific demethylase 1 (LSD1, KDM1A) is overexpressed in endometrioid endometrial carcinoma (EEC) and associated with tumor progression as well as poor prognosis. However, the physiological function and mechanism of LSD1 in endometrial cancer (EC) remains largely unknown. In this study, we demonstrate that β-estradiol (E2) treatment increased LSD1 expression via the GPR30/PI3K/AKT pathway in endometrial cancer cells. Both siGPR30 and the PI3K inhibitor LY294002 block this effect. RNAi-mediated silencing of LSD1 abolished estrogen-driven endometrial cancer cell (ECC) proliferation, and induced G1 cell arrest and apoptosis. Mechanistically, we find that LSD1 silencing results in PI3K/AKT signal inactivation, but without the elevation of PTEN expression as expected. This is because the inhibition of LSD1 induces dimethylation of lysine 9 on histone H3 (H3K9m2) accumulation at the promoter region of cyclin D1. Interfering with cyclin D1 leads to PI3K/AKT signal suppression. Re-overexpression of cyclin D1 in LSD1-knockdown ECCs reverses the LSD1 inhibitory action. Our finding connects estrogen signaling with epigenetic regulation in EEC and provides novel experimental support for LSD1 as a potential target for endometrial cancer therapeutics.

Histone Lysine Demethylase Inhibitors

The dynamic regulation of covalent modifications to histones is essential for maintaining genomic integrity and cell identity and is often compromised in cancer. Aberrant expression of histone lysine demethylases has been documented in many types of blood and solid tumors, and thus demethylases represent promising therapeutic targets. Recent advances in high-throughput chemical screening, structure-based drug design, and structure-activity relationship studies have improved both the specificity and the in vivo efficacy of demethylase inhibitors. This review will briefly outline the connection between demethylases and cancer and will provide a comprehensive overview of the structure, specificity, and utility of currently available demethylase inhibitors. To date, a select group of demethylase inhibitors is being evaluated in clinical trials, and additional compounds may soon follow from the bench to the bedside.

Imiquimod Induces Apoptosis in Human Endometrial Cancer Cells In vitro and Prevents Tumor Progression In vivo

PURPOSE

The increasing incidence of endometrial cancer (EC), in younger age at diagnosis, calls for new tissue-sparing treatment options. This work aims to evaluate the potential of imiquimod (IQ) in the treatment of low-grade EC.

METHODS

Effects of IQ on the viabilities of Ishikawa and HEC-1A cells were evaluated using MTT assay. The ability of IQ to induce apoptosis was evaluated by testing changes in caspase 3/7 levels and expression of cleaved caspase-3, using luminescence assay and western blot. Apoptosis was confirmed by flow cytometry and the expression of cleaved PARP. Western blot was used to evaluate the effect of IQ on expression levels of Bcl-2, Bcl-xL, and BAX. Finally, the in vivo efficacy of IQ was tested in an EC mouse model.

RESULTS

There was a decrease in EC cell viability following IQ treatment as well as increased caspase 3/7 activities, cleaved caspase-3 expression, and Annexin-V/ 7AAD positive cell population. Western blot results showed the ability of IQ in cleaving PARP, decreasing Bcl-2 and Bcl-xL expressions, but not affecting BAX expression. In vivo study demonstrated IQ's ability to inhibit EC tumor growth and progression without significant toxicity.

CONCLUSIONS

IQ induces apoptosis in low-grade EC cells in vitro, probably through its direct effect on Bcl-2 family protein expression. In, vivo, IQ attenuates EC tumor growth and progression, without an obvious toxicity. Our study provides the first building block for the potential role of IQ in the non-surgical management of low-grades EC and encouraging further investigations.

KDM4B and KDM4A promote endometrial cancer progression by regulating androgen receptor, c-myc, and p27kip1

Epidemiological evidence suggests that elevated androgen levels and genetic variation related to the androgen receptor (AR) increase the risk of endometrial cancer (EC). However, the role of AR in EC is poorly understood. We report that two members of the histone demethylase KDM4 family act as major regulators of AR transcriptional activityin EC. In the MFE-296 cell line, KDM4B and AR upregulate c-myc expression, while in AN3CA cells KDM4A and AR downregulate p27kip1. Additionally, KDM4B expression is positively correlated with AR expression in EC cell lines with high baseline AR expression, while KDM4A and AR expression are positively correlated in low-AR cell lines. In clinical specimens, both KDM4B and KDM4A expression are significantly higher in EC tissues than that in normal endometrium. Finally, patients with alterations in AR, KDM4B, KDM4A, and c-myc have poor overall and disease-free survival rates. Together, these findings demonstrate that KDM4B and KDM4A promote EC progression by regulating AR activity.

Overexpression of Lysine-Specific Demethylase 1 Is Associated With Tumor Progression and Unfavorable Prognosis in Chinese Patients With Endometrioid Endometrial Adenocarcinoma

OBJECTIVE

Lysine-specific demethylase 1 (LSD1) is a kind of flavin adenine dinucleotide-dependent amine oxidase that regulates normal cellular differentiation, gene activation, tumorigenesis, and progression. This study aims to detect the expression level of LSD1 in endometrial cancer and to explore its role in the progression and prognosis of endometrioid endometrial adenocarcinoma (EEA).

METHODS

Immunohistochemistry was used to examine the expression of LSD1 in 206 EEA specimens, 50 benign endometrial lesion specimens, and 45 normal endometrium specimens. χ Analysis, Kaplan-Meier method, and multivariate Cox proportional hazard analysis were applied for the statistical analysis.

RESULTS

Compared with normal endometrium and benign endometrial lesion (both P < 0.001), LSD1 was overexpressed in EEA. LSD1 expression was correlated with histological grade, International Federation of Gynecology and Obstetrics (FIGO) stage, vascular/lymphatic invasion, depth of myometrial invasion, and lymph node metastasis. Results of the Kaplan-Meier analysis indicated that LSD1 expression was associated with overall survival (OS) and disease-free survival (DFS) of EEA. The negative expression LSD1 group had longer OS and DFS than did the positive expression group. The difference was significant (both P < 0.001, log-rank test). Multivariate Cox regression analysis revealed that the LSD1 expression status was an independent prognostic factor for both OS (P = 0.027) and DFS (P = 0.016) of patients with EEA.

CONCLUSIONS

Overexpression of LSD1 may contribute to the progression of EEA and may thus serve as a new biomarker to predict the prognosis of EEA.

GFI1 functions in transcriptional control and cell fate determination require SNAG domain methylation to recruit LSD1

Proper hematopoietic cell fate decisions require co-ordinated functions of transcription factors, their associated co-regulators, and histone-modifying enzymes. Growth factor independence 1 (GFI1) is a zinc finger transcriptional repressor and master regulator of normal and malignant hematopoiesis. While several GFI1-interacting proteins have been described, how GFI1 leverages these relationships to carry out transcriptional repression remains unclear. Here, we describe a functional axis involving GFI1, SMYD2, and LSD1 that is a critical contributor to GFI1-mediated transcriptional repression. SMYD2 methylates lysine-8 (K8) within a -(8)KSKK(11)- motif embedded in the GFI1 SNAG domain. Methylation-defective GFI1 SNAG domain lacks repressor function due to failure of LSD1 recruitment and persistence of promoter H3K4 di-methyl marks. Methylation-defective GFI1 also fails to complement GFI1 depletion phenotypes in developing zebrafish and lacks pro-growth and survival functions in lymphoid leukemia cells. Our data show a discrete methylation event in the GFI1 SNAG domain that facilitates recruitment of LSD1 to enable transcriptional repression and co-ordinate control of hematopoietic cell fate in both normal and malignant settings.

Reversible lysine-specific demethylase 1 antagonist HCI-2509 inhibits growth and decreases c-MYC in castration- and docetaxel-resistant prostate cancer cells

Background:

Lysine-specific demethylase 1 (LSD1 or KDM1A) overexpression correlates with poor survival and castration resistance in prostate cancer. LSD1 is a coregulator of ligand-independent androgen receptor signaling promoting c-MYC expression. We examined the antitumor efficacy of LSD1 inhibition with HCI-2509 in advanced stages of prostate cancer.

Methods:

Cell survival, colony formation, histone methylation, c-MYC level, c-MYC expression, cell cycle changes and in vivo efficacy were studied in castration-resistant prostate cancer cells upon treatment with HCI-2509. In vitro combination studies, using HCI-2509 and docetaxel, were performed to assess the synergy. Cell survival, colony formation, histone methylation and c-myc levels were studied in docetaxel-resistant prostate cancer cells treated with HCI-2509.

Results:

HCI-2509 is cytotoxic and inhibits colony formation in castration-resistant prostate cancer cells. HCI-2509 treatment causes a dose-dependent increase in H3K9me2 (histone H3lysine 9) levels, a decrease in c-MYC protein, inhibition of c-MYC expression and accumulation in the G0/G1 phase of the cell cycle in these cells. PC3 xenografts in mice have a significant reduction in tumor burden upon treatment with HCI-2509 with no associated myelotoxicity or weight loss. More synergy is noted at sub-IC₅₀ (half-maximal inhibitory concentration) doses of docetaxel and HCI-2509 in PC3 cells than in DU145 cells. HCI-2509 has growth-inhibitory efficacy and decreases the c-myc level in docetaxel-resistant prostate cancer cells.

Conclusions:

LSD1 inhibition with HCI-2509 decreases the c-MYC level in poorly differentiated prostate cancer cell lines and has a therapeutic potential in castration- and docetaxel-resistant prostate cancer.

TCPs: privileged scaffolds for identifying potent LSD1 inhibitors for cancer therapy

Since the first lysine-specific demethylase (KDM), lysine-specific demethylase 1 (LSD1), was characterized in 2004, several families of KDMs have been identified. LSD1 can specifically demethylate H3K4me1/2, H3K9me1/2 as well as some nonhistone substrates. It has been demonstrated to be an oncogene as well as a drug target. Hence, tens of small-molecule LSD1 inhibitors have been designed, synthesized and applied for cancer treatment. However, the two LSD1 inhibitors that have been advanced into early phase clinical trials are trans-2-phenylcyclopropylamine (TCP) derivatives, which indicate that TCP is a druggable scaffold for LSD1 inhibitor. Here, we review the design, synthesis and properties of reported TCP-based LSD1 inhibitors as well as their biological roles.

Histone demethylases and their roles in cancer epigenetics

The genetic abnormalities that drive tumorigenesis are usually coupled with epigenetic alterations, such as DNA methylation and aberrant histone modifications, which may help oncogenic drivers accelerate cancer progression, metastasis, and therapy resistance. The discovery of histone demethylases has provided us new insight for understanding the epigenetic landscape of the chromatin environment of cancer cells. This review aims to summarize the current knowledge on the human histone lysine demethylases and their functions in cancers, and recent advances in development of small molecule inhibitors to target histone demethylases in cancer treatment.

Medicinal chemistry insights in the discovery of novel LSD1 inhibitors

LSD1 is an epigenetic modulator associated with transcriptional regulation of genes involved in a broad spectrum of key cellular processes, and its activity is often altered under pathological conditions. LSD1 inhibitors are considered to be candidates for therapy of cancer, viral diseases and neurodegeneration. Many LSD1 inhibitors with various scaffolds have been disclosed, and a few potent molecules are in different stages of clinical development. In this review, we summarize recent biological findings on the roles of LSD1 and the current understanding of the clinical significance of LSD1, and focus on the medicinal chemistry strategies used in the design and development of LSD1 inhibitors as drug-like epigenetic modulators since 2012, including a brief consideration of structure–activity relationships.

Multimodal Imaging of Orthotopic Mouse Model of Endometrial Carcinoma

BACKGROUND

Orthotopic endometrial cancer models provide a unique tool for studies of tumour growth and metastatic spread. Novel preclinical imaging methods also have the potential to quantify functional tumour characteristics in vivo, with potential relevance for monitoring response to therapy.

METHODS

After orthotopic injection with luc-expressing endometrial cancer cells, eleven mice developed disease detected by weekly bioluminescence imaging (BLI). In parallel the same mice underwent positron emission tomography-computed tomography (PET-CT) and magnetic resonance imaging (MRI) employing 18F-fluorodeoxyglocose (18F-FDG) or 18F- fluorothymidine (18F-FLT) and contrast reagent, respectively. The mice were sacrificed when moribund, and post-mortem examination included macroscopic and microscopic examination for validation of growth of primary uterine tumours and metastases. PET-CT was also performed on a patient derived model (PDX) generated from a patient with grade 3 endometrioid endometrial cancer.

RESULTS

Increased BLI signal during tumour growth was accompanied by increasing metabolic tumour volume (MTV) and increasing MTV x mean standard uptake value of the tumour (SUVmean) in 18F-FDG and 18F-FLT PET-CT, and MRI conspicuously depicted the uterine tumour. At necropsy 82% (9/11) of the mice developed metastases detected by the applied imaging methods. 18F-FDG PET proved to be a good imaging method for detection of patient derived tumour tissue.

CONCLUSIONS

We demonstrate that all imaging modalities enable monitoring of tumour growth and metastatic spread in an orthotopic mouse model of endometrial carcinoma. Both PET tracers, 18F-FDG and 18F-FLT, appear to be equally feasible for detecting tumour development and represent, together with MRI, promising imaging tools for monitoring of patient-derived xenograft (PDX) cancer models.

Integrated genomic analyses identify KDM1A's role in cell proliferation via modulating E2F signaling activity and associate with poor clinical outcome in oral cancer

The histone demethylase KDM1A specifically demethylates lysine residues and its deregulation has been implicated in the initiation and progression of various cancers. However, KDM1A's molecular role and its pathological consequences, and prognostic significance in oral cancer remain less understood. In the present study, we sought to investigate the expression of KDM1A and its downstream role in oral cancer pathogenesis. By comparing mRNA expression profiles, we identified an elevated KDM1A expression in oral tumors when compared to normal oral tissues. In silico pathway prediction identified the association between KDM1A and E2F1 signaling in oral cancer. Pathway scanning, functional annotation analysis and In vitro assays showed the KDM1A's involvement in oral cancer cell proliferation and the cell cycle. Moreover, real time PCR and luciferase assays confirmed KDM1A's role in regulation of E2F1 signaling activity in oral cancer. Elevated KDM1A expression is associated with poor clinical outcome in oral cancer. Our data indicate that deregulated KDM1A expression is positively associated with proliferative phenotype of oral cancer and confers poor clinical outcome. These cumulative data suggest that KDM1A might be a potential diagnostic and therapeutic target for oral cancer.

KDM1 class flavin-dependent protein lysine demethylases

Flavin-dependent, lysine-specific protein demethylases (KDM1s) are a subfamily of amine oxidases that catalyze the selective posttranslational oxidative demethylation of methyllysine side chains within protein and peptide substrates. KDM1s participate in the widespread epigenetic regulation of both normal and disease state transcriptional programs. Their activities are central to various cellular functions, such as hematopoietic and neuronal differentiation, cancer proliferation and metastasis, and viral lytic replication and establishment of latency. Interestingly, KDM1s function as catalytic subunits within complexes with coregulatory molecules that modulate enzymatic activity of the demethylases and coordinate their access to specific substrates at distinct sites within the cell and chromatin. Although several classes of KDM1-selective small molecule inhibitors have been recently developed, these pan-active site inhibition strategies lack the ability to selectively discriminate between KDM1 activity in specific, and occasionally opposing, functional contexts within these complexes. Here we review the discovery of this class of demethylases, their structures, chemical mechanisms, and specificity. Additionally, we review inhibition of this class of enzymes as well as emerging interactions with coregulatory molecules that regulate demethylase activity in highly specific functional contexts of biological and potential therapeutic importance.

KDM1 histone lysine demethylases as targets for treatments of oncological and neurodegenerative disease

Histone methylation and demethylation are important processes associated with the regulation of gene transcription, and alterations in histone methylation status have been linked to a large number of human diseases. Initially thought to be an irreversible process, histone methylation is now known to be reversed by two families of proteins containing over 30 members that act to remove methyl groups from specific lysine residues present in the tails of histone H3 and histone H4. A rapidly growing number of reports have implicated the FAD-dependent lysine specific demethylase (KDM1) family in cancer, and several small-molecule inhibitors are in development for the treatment of cancer. An additional role has emerged for KDM1 in brain function, offering additional opportunities for the development of novel therapeutic strategies in neurodegenerative disease. A decade after the identification of KDM1A as a histone demethylase, the first selective inhibitors have now reached the clinic.