Thieno[3,2-b]pyrrole-5-carboxamides as New Reversible Inhibitors of Histone Lysine Demethylase KDM1A/LSD1. Part 2: Structure-Based Drug Design and Structure–Activity Relationship

Optimization and Biological Evaluation of Novel 1H-Pyrrolo[2,3-c]pyridin Derivatives as Potent and Reversible Lysine Specific Demethylase 1 Inhibitors for the Treatment of Acute Myelogenous Leukemia

Lysine-specific demethylase 1 (LSD1) plays a vital role in the epigenetic regulation of various cancers, making it a promising therapeutic target for anticancer treatments. Herein, we designed and synthesized a novel series of 1H-pyrrolo[2,3-c]pyridin derivatives as potent LSD1 inhibitors. A detailed structure-activity relationship exploration was carried out to discover multiple derivatives with nanomolar enzymatic IC50 values. Further biological evaluation demonstrated that these compounds acted as selective and reversible LSD1 inhibitors. The representative compounds exhibited highly potent antiproliferative activity against both AML (MV4-11 and Kasumi-1) and SCLC (NCI-H526) cell lines. Additionally, they effectively activated CD86 mRNA expression in MV4-11 cells and induced differentiation of AML cell lines. Notably, the most promising compound 23e showed a favorable oral PK profile and effectively suppressed the tumor growth in an AML xenograft model. Overall, our medicinal chemistry efforts provide compound 23e as a lead compound for developing LSD1 inhibitors for the treatment of AML and other advanced malignancies.

Pyrrole-containing hybrids as potential anticancer agents: An insight into current developments and structure-activity relationships

Cancer poses a significant threat to human health. Therefore, it is urgent to develop potent anti-cancer drugs with excellent inhibitory activity and no toxic side effects. Pyrrole and its derivatives are privileged heterocyclic compounds with significant diverse pharmacological effects. These compounds can target various aspects of cancer cells and have been applied in clinical settings or are undergoing clinical trials. As a result, pyrrole has emerged as a promising drug scaffold and has been further probed to get novel entities for the treatment of cancer. This article reviews recent research progress on anti-cancer drugs containing pyrrole. It focuses on the mechanism of action, biological activity, and structure-activity relationships of pyrrole derivatives, aiming to assist in designing and synthesizing innovative pyrrole-based anti-cancer compounds.

Mining the Dynamical Properties of Substrate and FAD Binding Pockets of LSD1: Hints for New Inhibitor Design Direction

Lysine-specific demethylase 1 (LSD1), a highly sophisticated epigenetic regulator, orchestrates a range of critical cellular processes, holding promising therapeutic potential for treating diverse diseases. However, the clinical research progress targeting LSD1 is very slow. After 20 years of research, only one small-molecule drug, BEA-17, targeting the degradation of LSD1 and CoREST has been approved by the U.S. Food and Drug Administration. The primary reason for this may be the lack of abundant structural data regarding its intricate functions. To gain a deeper understanding of its conformational dynamics and guide the drug design process, we conducted molecular dynamics simulations to explore the conformational states of LSD1 in the apo state and under the influence of cofactors of flavin adenine dinucleotide (FAD) and CoREST. Our results showed that, across all states, the substrate binding pocket exhibited high flexibility, whereas the FAD binding pocket remained more stable. These distinct dynamical properties are essential for LSD1's ability to bind various substrates while maintaining efficient demethylation activity. Both pockets can be enlarged by merging with adjacent pockets, although only the substrate binding pocket can shrink into smaller pockets. These new pocket shapes can inform inhibitor design, particularly for selectively FAD-competitive inhibitors of LSD1, given the presence of numerous FAD-dependent enzymes in the human body. More interestingly, in the absence of FAD binding, the united substrate and FAD binding pocket are partitioned by the conserved residue of Tyr761, offering valuable insights for the design of inhibitors that disrupt the crucial steric role of Tyr761 and the redox role of FAD. Additionally, we identified pockets that positively or negatively correlate with the substrate and FAD binding pockets, which can be exploited for the design of allosteric or concurrent inhibitors. Our results reveal the intricate dynamical properties of LSD1 as well as multiple novel conformational states, which deepen our understanding of its sophisticated functions and aid in the rational design of new inhibitors.

Lysine-Specific Demethylase 1 Inhibitors: A Comprehensive Review Utilizing Computer-Aided Drug Design Technologies

Lysine-specific demethylase 1 (LSD1/KDM1A) has emerged as a promising therapeutic target for treating various cancers (such as breast cancer, liver cancer, etc.) and other diseases (blood diseases, cardiovascular diseases, etc.), owing to its observed overexpression, thereby presenting significant opportunities in drug development. Since its discovery in 2004, extensive research has been conducted on LSD1 inhibitors, with notable contributions from computational approaches. This review systematically summarizes LSD1 inhibitors investigated through computer-aided drug design (CADD) technologies since 2010, showcasing a diverse range of chemical scaffolds, including phenelzine derivatives, tranylcypromine (abbreviated as TCP or 2-PCPA) derivatives, nitrogen-containing heterocyclic (pyridine, pyrimidine, azole, thieno[3,2-b]pyrrole, indole, quinoline and benzoxazole) derivatives, natural products (including sanguinarine, phenolic compounds and resveratrol derivatives, flavonoids and other natural products) and others (including thiourea compounds, Fenoldopam and Raloxifene, (4-cyanophenyl)glycine derivatives, propargylamine and benzohydrazide derivatives and inhibitors discovered through AI techniques). Computational techniques, such as virtual screening, molecular docking and 3D-QSAR models, have played a pivotal role in elucidating the interactions between these inhibitors and LSD1. Moreover, the integration of cutting-edge technologies such as artificial intelligence holds promise in facilitating the discovery of novel LSD1 inhibitors. The comprehensive insights presented in this review aim to provide valuable information for advancing further research on LSD1 inhibitors.

Exploring the potential of histone demethylase inhibition in multi-therapeutic approaches for cancer treatment

Histone demethylases play a critical role in gene transcription regulation and have been implicated in cancer. Numerous reports have highlighted the overexpression of histone demethylases, such as LSD1 and JmjC, in various malignant tumor tissues, identifying them as effective therapeutic targets for cancer treatment. Despite many histone demethylase inhibitors entering clinical trials, their clinical efficacy has been limited. Therefore, combination therapies based on histone demethylase inhibitors, along with other modulators like dual-acting inhibitors, have gained significant attention and made notable progress in recent years. In this review, we provide an overview of recent advances in drug discovery targeting histone demethylases, focusing specifically on drug combination therapy and histone demethylases-targeting dual inhibitors. We discuss the rational design, pharmacodynamics, pharmacokinetics, and clinical status of these approaches. Additionally, we summarize the co-crystal structures of LSD1 inhibitors and their target proteins as well as describe the corresponding binding interactions. Finally, we also provided the challenges and future directions for utilizing histone demethylases in cancer therapy, such as PROTACs and molecular glue etc.

Uncovering New Conformational States of the Substrate Binding Pocket of LSD1 Potential for Inhibitor Design via Funnel Metadynamics

Lysine-specific demethylase 1 (LSD1) is a promising therapeutic target for cancer therapy. So far, over 80 crystal structures of LSD1 in different complex states have been deposited in the Protein Data Bank, which are valuable resources for performing structure-based drug design. However, among all of the crystal structures of LSD1, the substrate binding pocket, which is the most efficient druggable site for designing LSD1 inhibitors at present, is very similar no matter whether LSD1 is in the apo or any holo forms, which is inconsistent with its versatile demethylase functions. To investigate whether the substrate binding pocket is rigid or exhibits other representative conformations different from the crystal conformations that are feasible for designing new LSD1 inhibitors, we performed funnel metadynamics simulations to study the conformation dynamics of LSD1 in the binding process of two effective LSD1 inhibitors (CC-90011 and 6X0, CC-90011 undergoing clinical trials). Our results showed that the entrance of the substrate binding pocket is very flexible. Two representative entrance conformations of LSD1 counting against binding with the substrate of histone H3 were detected, which may be used for structure-based LSD1 inhibitor design. Besides, alternative optimal binding modes and prebinding modes for both inhibitors were also detected, which depicted that the key interactions changed along with the binding process. Our results should provide great help for LSD1 inhibitor design.

A Quinquennial Review of Potent LSD1 Inhibitors Explored for the Treatment of Different Cancers, with Special Focus on SAR Studies

Cancer bears a significant share of global mortality. The enzyme Lysine Specific Demethylase 1 (LSD1, also known as KDM1A), since its discovery in 2004, has captured the attention of cancer researchers due to its overexpression in several cancers like acute myeloid leukaemia (AML), solid tumours, etc. The Lysine Specific Demethylase (LSD1) downregulation is reported to have an effect on cancer proliferation, migration, and invasion. Therefore, research to discover safer and more potent LSD1 inhibitors can pave the way for the development of better cancer therapeutics. These efforts have resulted in the synthesis of many types of derivatives containing diverse structural nuclei. The present manuscript describes the role of Lysine Specific Demethylase 1 (LSD1) in carcinogenesis, reviews the LSD1 inhibitors explored in the past five years and discusses their comprehensive structural activity characteristics apart from the thorough description of LSD1. Besides, the potential challenges, opportunities, and future perspectives in the development of LSD1 inhibitors are also discussed. The review suggests that tranylcypromine derivatives are the most promising potent LSD1 inhibitors, followed by triazole and pyrimidine derivatives with IC₅₀ values in the nanomolar and sub-micromolar range. A number of potent LSD1 inhibitors derived from natural sources like resveratrol, protoberberine alkaloids, curcumin, etc. are also discussed. The structural-activity relationships discussed in the manuscript can be exploited to design potent and relatively safer LSD1 inhibitors as anticancer agents.

PoseEdit: enhanced ligand binding mode communication by interactive 2D diagrams

In this article, we present PoseEdit, a new, interactive frontend of the popular pose visualization tool PoseView. PoseEdit automatically produces high-quality 2D diagrams of intermolecular interactions in 3D binding sites calculated from ligands in complex with protein, DNA, and RNA. The PoseView diagrams have been improved in several aspects, most notably in their interactivity. Thanks to the easy-to-use 2D editor of PoseEdit, the diagrams are extensively editable and extendible by the user, can be merged with other diagrams, and even be created from scratch. A large variety of graphical objects in the diagram can be moved, rotated, selected and highlighted, mirrored, removed, or even newly added. Furthermore, PoseEdit enables a synchronized 2D-3D view of macromolecule-ligand complexes simplifying the analysis of structural features and interactions. The representation of individual diagram objects regarding their visualized chemical properties, like stereochemistry, and general graphical styles, like the color of interactions, can additionally be edited. The primary objective of PoseEdit is to support scientists with an enhanced way to communicate ligand binding mode information through graphical 2D representations optimized with the scientist's input in accordance with objective criteria and individual needs. PoseEdit is freely available on the ProteinsPlus web server ( https://proteins.plus ).

LSD1-Based Reversible Inhibitors Virtual Screening and Binding Mechanism Computational Study

As one of the crucial targets of epigenetics, histone lysine-specific demethylase 1 (LSD1) is significant in the occurrence and development of various tumors. Although several irreversible covalent LSD1 inhibitors have entered clinical trials, the large size and polarity of the FAD-binding pocket and undesired toxicity have focused interest on developing reversible LSD1 inhibitors. In this study, targeting the substrate-binding pocket of LSD1, structure-based and ligand-based virtual screenings were adopted to expand the potential novel structures with molecular docking and pharmacophore model strategies, respectively. Through drug-likeness evaluation, ADMET screening, molecular dynamics simulations, and binding free energy screening, we screened out one and four hit compounds from the databases of 2,029,554 compounds, respectively. Generally, these hit compounds can be divided into two categories, amide (Lig2 and Comp2) and 1,2,4-triazolo-4,3-α-quinazoline (Comp3, Comp4, Comp7). Among them, Comp4 exhibits the strongest binding affinity. Finally, the binding mechanisms of the hit compounds were further calculated in detail by the residue free energy decomposition. It was found that van der Waals interactions contribute most to the binding, and FAD is also helpful in stabilizing the binding and avoiding off-target effects. We believe this work not only provides a solid theoretical foundation for the design of LSD1 substrate reversible inhibitors, but also expands the diversity of parent nucleus, offering new insights for synthetic chemists.

LSD1 inhibitors for cancer treatment: Focus on multi-target agents and compounds in clinical trials

Histone lysine-specific demethylase 1 (LSD1/KDM1A) was first identified in 2004 as an epigenetic enzyme able to demethylate specific lysine residues of histone H3, namely H3K4me1/2 and H3K9me1/2, using FAD as the cofactor. It is ubiquitously overexpressed in many types of cancers (breast, gastric, prostate, hepatocellular, and esophageal cancer, acute myeloid leukemia, and others) leading to block of differentiation and increase of proliferation, migration and invasiveness at cellular level. LSD1 inhibitors can be grouped in covalent and non-covalent agents. Each group includes some hybrid compounds, able to inhibit LSD1 in addition to other target(s) at the same time (dual or multitargeting compounds). To date, 9 LSD1 inhibitors have entered clinical trials, for hematological and/or solid cancers. Seven of them (tranylcypromine, iadademstat (ORY-1001), bomedemstat (IMG-7289), GSK-2879552, INCB059872, JBI-802, and Phenelzine) covalently bind the FAD cofactor, and two are non-covalent LSD1 inhibitors [pulrodemstat (CC-90011) and seclidemstat (SP-2577)]. Another TCP-based LSD1/MAO-B dual inhibitor, vafidemstat (ORY-2001), is in clinical trial for Alzheimer's diseases and personality disorders. The present review summarizes the structure and functions of LSD1, its pathological implications in cancer and non-cancer diseases, and the identification of LSD1 covalent and non-covalent inhibitors with different chemical scaffolds, including those involved in clinical trials, highlighting their potential as potent and selective anticancer agents.

Learning with uncertainty to accelerate the discovery of histone lysine-specific demethylase 1A (KDM1A/LSD1) inhibitors

Machine learning including modern deep learning models has been extensively used in drug design and screening. However, reliable prediction of molecular properties is still challenging when exploring out-of-domain regimes, even for deep neural networks. Therefore, it is important to understand the uncertainty of model predictions, especially when the predictions are used to guide further experiments. In this study, we explored the utility and effectiveness of evidential uncertainty in compound screening. The evidential Graphormer model was proposed for uncertainty-guided discovery of KDM1A/LSD1 inhibitors. The benchmarking results illustrated that (i) Graphormer exhibited comparative predictive power to state-of-the-art models, and (ii) evidential regression enabled well-ranked uncertainty estimates and calibrated predictions. Subsequently, we leveraged time-splitting on the curated KDM1A/LSD1 dataset to simulate out-of-distribution predictions. The retrospective virtual screening showed that the evidential uncertainties helped reduce false positives among the top-acquired compounds and thus enabled higher experimental validation rates. The trained model was then used to virtually screen an independent in-house compound set. The top 50 compounds ranked by two different ranking strategies were experimentally validated, respectively. In general, our study highlighted the importance to understand the uncertainty in prediction, which can be recognized as an interpretable dimension to model predictions.

Structural and Functional Landscape of FAD-Dependent Histone Lysine Demethylases for New Drug Discovery

Small molecules targeting the flavin adenine dinucleotide (FAD)-dependent histone lysine demethylase LSD family have displayed therapeutic promise against various diseases. Nine clinical candidates targeting the classic demethylase-dependent functions of the LSD family are currently being investigated for treating cancers, neurodegenerative diseases, etc. Moreover, targeting noncatalytic functions of LSDs also represents an emerging strategy for treating human diseases. In this Perspective, we provide full structural and functional landscape of the LSD family and action modes of different types of LSD inhibitors including natural products, peptides, and synthetic compounds, aiming to reveal new druggable space for the design of new LSD inhibitors. Particularly, we first classify these inhibitors into three types based on their unique binding modes. Additionally, the strategies targeting the demethylase-independent functions of LSDs are also briefly discussed. This Perspective may benefit the discovery of new LSD inhibitors for probing LSD biology and/or treating human diseases.

Discovery of new potent lysine specific histone demythelase-1 inhibitors (LSD-1) using structure based and ligand based molecular modelling and machine learning

Lysine-specific histone demethylase 1 (LSD-1) is an epigenetic enzyme that oxidatively cleaves methyl groups from monomethyl and dimethyl Lys4 of histone H3 and is highly overexpressed in different types of cancer. Therefore, it has been widely recognized as a promising therapeutic target for cancer therapy. Towards this end, we employed various Computer Aided Drug Design (CADD) approaches including pharmacophore modelling and machine learning. Pharmacophores generated by structure-based (SB) (either crystallographic-based or docking-based) and ligand-based (LB) (either supervised or unsupervised) modelling methods were allowed to compete within the context of genetic algorithm/machine learning and were assessed by Shapley additive explanation values (SHAP) to end up with three successful pharmacophores that were used to screen the National Cancer Institute (NCI) database. Seventy-five NCI hits were tested for their LSD-1 inhibitory properties against neuroblastoma SH-SY5Y cells, pancreatic carcinoma Panc-1 cells, glioblastoma U-87 MG cells and in vitro enzymatic assay, culminating in 3 nanomolar LSD-1 inhibitors of novel chemotypes.

Identification of novel indole derivatives as highly potent and efficacious LSD1 inhibitors

Lysine-specific demethylase 1 (LSD1) is a FAD-dependent histone demethylase to catalyze the demethylation of H3K4 and H3K9 and thus is an attractive target for therapeutic cancer. Starting with a high micromolar compound 17i, structure-based optimization of novel indole derivatives is described by a bioelectronic isosteric strategy. Grounded by molecular modeling, medicinal chemistry has efficiently yielded low nanomolar LSD1 inhibitors. One of the compounds, B35, exhibited excellent LSD1 inhibition (IC50 = 0.050 ± 0.005 μM) and anti-proliferation against A549 cells (IC50 = 0.74 ± 0.14 μM). The further PK studies indicated compound B35 possessed favorable metabolic stability, in which the plasma t1/2 of p.o. and i.v. were 6.27 ± 0.72 h and 8.78 ± 1.31 h, respectively. Additionally, inhibitor B35 shows a strong antitumor effect and good safety in vivo. Meanwhile, compound B35 regulated genes are closely associated with transcriptional dislocation in cancer and PI3K/AKT pathway involving IGFBP3. Taken together, B35 could be a potent LSD1 inhibitor for further drug development.

QSAR Evaluations to Unravel the Structural Features in Lysine-Specific Histone Demethylase 1A Inhibitors for Novel Anticancer Lead Development Supported by Molecular Docking, MD Simulation and MMGBSA

Using 84 structurally diverse and experimentally validated LSD1/KDM1A inhibitors, quantitative structure–activity relationship (QSAR) models were built by OECD requirements. In the QSAR analysis, certainly significant and understated pharmacophoric features were identified as critical for LSD1 inhibition, such as a ring Carbon atom with exactly six bonds from a Nitrogen atom, partial charges of lipophilic atoms within eight bonds from a ring Sulphur atom, a non-ring Oxygen atom exactly nine bonds from the amide Nitrogen, etc. The genetic algorithm–multi-linear regression (GA-MLR) and double cross-validation criteria were used to create robust QSAR models with high predictability. In this study, two QSAR models were developed, with fitting parameters like R² = 0.83–0.81, F = 61.22–67.96, internal validation parameters such as Q²_LOO = 0.79–0.77, Q²_LMO = 0.78–0.76, CCC_cv = 0.89–0.88, and external validation parameters such as, R2ext = 0.82 and CCCex = 0.90. In terms of mechanistic interpretation and statistical analysis, both QSAR models are well-balanced. Furthermore, utilizing the pharmacophoric features revealed by QSAR modelling, molecular docking experiments corroborated with the most active compound’s binding to the LSD1 receptor. The docking results are then refined using Molecular dynamic simulation and MMGBSA analysis. As a consequence, the findings of the study can be used to produce LSD1/KDM1A inhibitors as anticancer leads.

Targeting Epigenetic Regulatory Enzymes for Cancer Therapeutics: Novel Small-Molecule Epidrug Development

Dysregulation of the epigenetic enzyme-mediated transcription of oncogenes or tumor suppressor genes is closely associated with the occurrence, progression, and prognosis of tumors. Based on the reversibility of epigenetic mechanisms, small-molecule compounds that target epigenetic regulation have become promising therapeutics. These compounds target epigenetic regulatory enzymes, including DNA methylases, histone modifiers (methylation and acetylation), enzymes that specifically recognize post-translational modifications, chromatin-remodeling enzymes, and post-transcriptional regulators. Few compounds have been used in clinical trials and exhibit certain therapeutic effects. Herein, we summarize the classification and therapeutic roles of compounds that target epigenetic regulatory enzymes in cancer treatment. Finally, we highlight how the natural compounds berberine and ginsenosides can target epigenetic regulatory enzymes to treat cancer.

Design, synthesis, and biological evaluation of coumarin analogs as novel LSD1 inhibitors

The abnormal expression of lysine-specific histone demethylase 1 (LSD1) is associated with different cancer types, and it is increasingly recognized as a potential therapeutic target in oncology. Here, utilizing core hopping and conformational restriction strategies, we designed and synthesized a series of coumarin analogs that were shown to be potent LSD1 inhibitors in the enzyme assay. Furthermore, several potent compounds were selected to evaluate their antiproliferative activity on A549 cells and MGC-803 cells with high expression of LSD1. Among them, YX10 showed an anticlonogenic effect on A549 cells and MGC-803 cells, with IC₅₀ values of 1.52 ± 0.16 and 0.98 ± 0.18 μM, respectively. Modeling suggested that the inhibitors would bind to the active site of the protein located around the key residues of Asp555 and Lys661. Meanwhile, a preliminary druggability evaluation showed that compound YX10 showed favorable liver microsomal and moderate plasma stability and weak inhibitory activity against cytochrome P450 isoforms at 10 μM. All the results indicated that compound YX10 could represent a promising lead compound for further development.

Therapeutic potential of targeting LSD1/ KDM1A in cancers

LSD1 was the first histone demethylase identified by Professor Shi Yang and his team members in 2004. LSD1 employs FAD as its cofactor, which catalyzes the demethylation of H3K4 and H3K9. It is aberrantly overexpressed in different types of cancers and is associated with the growth, invasion, and metastasis of cancer cells. The knockout or inhibition of LSD1 could effectively suppress tumor development, and thus, it has become an attractive molecular target for cancer therapy. Moreover, many LSD1 inhibitors have been developed in preclinical and clinical trials to treat solid tumors and hematological malignancy. This study made an extensive review of the research obtained from the literature retrieval of electronic databases, such as PubMed, Web of Science, RCSB PDB, ClinicalTrials.gov, and EU clinical trials register. This review summarizes recent studies on the advances of LSD1 inhibitors in the literature, covering January 2015 to June 2021. It focuses on the function of LSD1 in tumor cells, summarizes the crystal structures of homo sapiens LSD1, reviews the structural characteristics of LSD1 inhibitors, compares the screening methods of LSD1 inhibitors, and proposes guidelines for the future exploitation of LSD1 inhibitors.

New Sulfanilamide Derivatives Incorporating Heterocyclic Carboxamide Moieties as Carbonic Anhydrase Inhibitors

Carbonic Anhydrases (CAs) are ubiquitous metalloenzymes involved in several disease conditions. There are 15 human CA (hCA) isoforms and their high homology represents a challenge for the discovery of potential drugs devoid of off-target side effects. For this reason, many synthetic and pharmacologic research efforts are underway to achieve the full pharmacological potential of CA modulators of activity. We report here a novel series of sulfanilamide derivatives containing heterocyclic carboxamide moieties which were evaluated as CA inhibitors against the physiological relevant isoforms hCA I, II, IX, and XII. Some of them showed selectivity toward isoform hCA II and hCA XII. Molecular docking was performed for some of these compounds on isoforms hCA II and XII to understand the possible interaction with the active site amino acid residues, which rationalized the reported inhibitory activity.

Intermolecular insights into allosteric inhibition of histone lysine-specific demethylase 1

BACKGROUND

Histone lysine-specific demethylase 1 (LSD1) has become a potential anticancer target for the novel drug discovery. Recent reports have shown that SP2509 and its derivatives strongly inhibit LSD1 as allosteric inhibitors. However, the binding mechanism of these allosteric inhibitors in the allosteric site of LSD1 is not known yet.

METHODS

The stability and binding mechanism of allosteric inhibitors in the binding site of LSD1 were evaluated by molecular docking, ligand-based pharmacophore, molecular dynamics (MD) simulations, molecular mechanics generalized born surface area (MM/GBSA) analysis, quantum mechanics/molecular mechanics (QM/MM) calculation and Hirshfeld surface analysis.

RESULTS

The conformational geometry and the intermolecular interactions of allosteric inhibitors showed high binding affinity towards allosteric site of LSD1 with the neighboring amino acids (Gly358, Cys360, Leu362, Asp375 and Glu379). Meanwhile, MD simulations and MM/GBSA analysis were performed on selected allosteric inhibitors in complex with LSD1 protein, which confirmed the high stability and binding affinity of these inhibitors in the allosteric site of LSD1.

CONCLUSION

The simulation results revealed the crucial factors accounting for allosteric inhibitors of LSD1, including different protein-ligand interactions, the positions and conformations of key residues, and the ligands flexibilities. Meanwhile, a halogen bond interaction between chlorine atom of ligand and key residues Trp531 and His532 was recurrent in our analysis confirming its importance.

GENERAL SIGNIFICANCE

Overall, our research analyzed in depth the binding modes of allosteric inhibitors with LSD1 and could provide useful information for the design of novel allosteric inhibitors.

Design, synthesis, and biological evaluation of 5-aminotetrahydroquinoline-based LSD1 inhibitors acting on Asp375

The abnormal expression of lysine-specific histone demethylase 1 (LSD1) is associated with different cancer types, and LSD1 inhibitory activity seems to have high therapeutic potential in cancer treatment. Here, we report the design, synthesis, and biochemical evaluation of novel 5-aminotetrahydroquinoline-based LSD1 inhibitors. Among them, compounds A6, A8, B1-B5, and C4 showed preferable inhibitory effects on LSD1, with IC₅₀  = 0.19-0.82 µM. Several potent compounds were selected to evaluate their antiproliferative activity on A549 cells and MCF-7 cells with a high expression of LSD1. The potential binding modes of the compounds were revealed through molecular docking to rationalize the potency of compounds toward LSD1. Our data recognized that the 5-aminotetrahydroquinoline scaffold may serve as a starting point for developing potent LSD1 inhibitors for cancer therapy.

Design, synthesis, and biological evaluation of novel dual inhibitors targeting lysine specific demethylase 1 (LSD1) and histone deacetylases (HDAC) for treatment of gastric cancer

LSD1 and HDAC are physical and functional related to each other in various human cancers and simultaneous pharmacological inhibition of LSD1 and HDAC exerts synergistic anti-cancer effects. In this work, a series of novel LSD1/HDAC bifunctional inhibitors with a styrylpyridine skeleton were designed and synthesized based on our previously reported LSD1 inhibitors. The representative compounds 5d and 5m showed potent activity against LSD1 and HDAC at both molecular and cellular level and displayed high selectivity against MAO-A/B. Moreover, compounds 5d and 5m demonstrated potent antiproliferative activities against MGC-803 and HCT-116 cancer cell lines. Notably, compound 5m showed superior in vitro anticancer potency against a panel of gastric cancer cell lines than ORY-1001 and SP-2509 with IC₅₀ values ranging from 0.23 to 1.56 μM. Compounds 5d and 5m significantly modulated the expression of Bcl-2, Bax, Vimentin, ZO-1 and E-cadherin, induced apoptosis, reduced colony formation and suppressed migration in MGC-803 cancer cells. In addition, preliminary absorption, distribution, metabolism, excretion (ADME) studies revealed that compounds 5d and 5m showed acceptable metabolic stability in human liver microsomes with minimal inhibition of cytochrome P450s (CYPs). Those results indicated that compound 5m could be a promising lead compound for further development as a therapeutic agent in gastric cancers via LSD1 and HDAC dual inhibition.

Design, synthesis and biological evaluation of novel benzofuran derivatives as potent LSD1 inhibitors

Lysine-specific demethylase 1 (LSD1) is a FAD-dependent enzyme, which has been proposed as a promising target for therapeutic cancer. Herein, a series of benzofuran derivatives were designed, synthesized and biochemical evaluated as novel LSD1 inhibitors based on scaffold hopping and conformational restriction strategy. Most of the compounds potently suppressed the enzymatic activities of LSD1 and potently inhibited tumor cells proliferation. In particular, the representative compound 17i exhibited excellent LSD1 inhibition at the molecular levels with IC₅₀ = 0.065 μM, as well as anti-proliferation against MCF-7, MGC-803, H460, A549 and THP-1 tumor cells with IC₅₀ values of 2.90 ± 0.32, 5.85 ± 0.35, 2.06 ± 0.27, 5.74 ± 1.03 and 6.15 ± 0.49 μM, respectively. The binding modes of these compounds were rationalized by molecular docking. Meanwhile, a preliminary druggability evaluation showed that compound 17i displayed favorable liver microsomal stability and weak inhibitory activity against CYPs at 10 μM. Remarkably, H460 xenograft tumors studies revealed that 17i demonstrated robust in vivo antitumor efficacy without significant side effects. All the results demonstrated that compound 17i could represent a promising lead for further development.

Annual review of LSD1/KDM1A inhibitors in 2020

Lysine-specific demethylase 1 (LSD1/KDM1A) has emerged as a promising target for the discovery of specific inhibitors as antitumor drugs. Based on the source of compounds, all LSD1 inhibitors in this review are divided into two categories: natural LSD1 inhibitors and synthetic LSD1 inhibitors. This review highlights the research progress of LSD1 inhibitors with the potential to treat cancer covering articles published in 2020. Design strategies, structure-activity relationships, co-crystal structure analysis and action mechanisms are also highlighted.

Synergetic copper/TEMPO-catalysed benzylic C–H imidation with N-fluorobenzenesulfonimide at room temperature and tandem conversions with alcohols or arenes

A remote carbamate-directed benzylic C–H imidation with NFSI at room temperature through synergetic CuCl-TEMPO catalysis and tandem alkoxylation or arylation with alcohols or arenes are described.

Histone lysine specific demethylase 1 inhibitors

LSD1 plays a pivotal role in numerous biological functions. The overexpression of LSD1 is reported to be associated with different malignancies. Over the last decade, LSD1 has emerged as an interesting target for the treatment of acute myeloid leukaemia (AML). Numerous researchers have designed, synthesized, and evaluated various LSD1 inhibitors with diverse chemical architectures. Some of these inhibitors have entered clinical trials and are currently at different phases of clinical evaluation. This comprehensive review enlists recent research developments in LSD1 targeting pharmacophores reported over the last few years.

Discovery of Reversible Inhibitors of KDM1A Efficacious in Acute Myeloid Leukemia Models

Lysine-specific demethylase 1 (LSD1 or KDM1A) is a FAD-dependent enzyme that acts as a transcription corepressor or coactivator by regulating the methylation status of histone H3 lysines K4 and K9, respectively. KDM1A represents an attractive target for cancer therapy. While, in the past, the main medicinal chemistry strategy toward KDM1A inhibition was based on the optimization of ligands that irreversibly bind the FAD cofactor within the enzyme catalytic site, we and others have also identified reversible inhibitors. Herein we reported the discovery of 5-imidazolylthieno[3,2-b]pyrroles, a new series of KDM1A inhibitors endowed with picomolar inhibitory potency, active in cells and efficacious after oral administration in murine leukemia models.

Design, synthesis and biological evaluation of tetrahydroquinoline-based reversible LSD1 inhibitors

The targeted regulation of LSD1, which is highly expressed in a variety of tumor cells, is a promising cancer therapy strategy. Several LSD1 inhibitors are currently under clinical evaluation, and most of these inhibitors are irreversible. Here, we report the design, synthesis and biochemical evaluation of novel tetrahydroquinoline-based reversible LSD1 inhibitors. Compounds 18s and 18x, which are selective to LSD1 over MAO-A/B, exhibit excellent LSD1 inhibition at the molecular levels with IC₅₀ = 55 nM and 540 nM, respectively. The classic Lineweaver-Burk plots revealed that compound 18s could reversibly bind the LSD1 enzyme in a noncompetitive manner. Molecular docking was used to reveal the potential binding-mode of the compounds and interpret the structure-activity relationships. Furthermore, compounds 18s and 18x significantly inhibited proliferation (IC₅₀ = 1.13 μM and 1.15 μM, respectively) and induced apoptosis in MGC-803 cells with high expression of LSD1. Compound 18x showed acceptable liver microsomal stability. Meanwhile, 18x did not appear to inhibit CYPs at 10 μM in vitro. Remarkably, the oral administration of compound 18x can inhibit the growth of MGC-803 xenograft tumors without significant side effects. Our findings suggest that tetrahydroquinoline-based LSD1 inhibitors deserve further investigation for the treatment of LSD1 overexpressing cancer.

Molecular docking, 3D-QSAR, and molecular dynamics simulations of thieno[3,2-b]pyrrole derivatives against anticancer targets of KDM1A/LSD1

Lysine-specific demethylase 1 (LSD1) is a histone-modifying enzyme, which has been proposed as a promising target for anticancer drug development. Extensive research on LSD1 inhibitors has been performed since its discovery. In order to get more information for lead identification and optimization, we carried out a molecular modeling study on a set of 43 thieno[3,2-b]pyrrole competitive inhibitors of LSD1 using three-dimensional quantitative structure-activity relationship (3D-QSAR), molecular docking and molecular dynamics (MD) simulations. Based on the co-crystallized conformer-based alignment (CCBA) method, 3D-QSAR model of thieno[3,2-b]pyrrole derivatives as LSD1 inhibitors was established. The significant statistics (q² = 0.595, r² = 0.959, r²_pred = 0.846) of the 3D-QSAR indicated the good predictive power and statistical reliability of this model. Based on the corresponding contour maps six LSD1 inhibitors were designed and their activities were predicted by 3D-QSAR model. Meanwhile, molecular docking was performed to simulate the probable binding modes between ligands and LSD1 protein. The molecular interactions mainly contributions to the binding affinity for LSD1 inhibitions were further supplemented by 100 ns MD simulations and binding free energy calculation.

3D-QSAR, molecular docking, and molecular dynamics simulation study of thieno[3,2-b]pyrrole-5-carboxamide derivatives as LSD1 inhibitors

Histone Lysine Specific Demethylase 1 (LSD1) is overexpressed in many cancers and becomes a new target for anticancer drugs. In recent years, small molecule inhibitors with various structures targeting LSD1 have been reported. Here we report the binding interaction modes of a series of thieno[3,2-b]pyrrole-5-carboxamide LSD1 inhibitors using molecular docking, and three-dimensional quantitative structure-activity relationships (3D-QSAR). Comparative molecular field analysis (CoMFA q 2 = 0.783, r 2 = 0.944, r pred 2 = 0.851) and comparative molecular similarity indices analysis (CoMSIA q 2 = 0.728, r 2 = 0.982, r pred 2 = 0.814) were used to establish 3D-QSAR models, which had good verification and prediction capabilities. Based on the contour maps and the information of molecular docking, 8 novel small molecules were designed in silico, among which compounds D4, D5 and D8 with high predictive activity were subjected to further molecular dynamics simulations (MD), and their possible binding modes were explored. It was found that Asn535 plays a crucial role in stabilizing the inhibitors. Furthermore, ADME and bioavailability prediction for D4, D5 and D8 were carried out. The results would provide valuable guidance for designing new reversible LSD1 inhibitors in the future.

Investigating the Binding Mode of Reversible LSD1 Inhibitors Derived from Stilbene Derivatives by 3D-QSAR, Molecular Docking, and Molecular Dynamics Simulation

Overexpression of lysine specific demethylase 1 (LSD1) has been found in many cancers. New anticancer drugs targeting LSD1 have been designed. The research on irreversible LSD1 inhibitors has entered the clinical stage, while the research on reversible LSD1 inhibitors has progressed slowly so far. In this study, 41 stilbene derivatives were studied as reversible inhibitors by three-dimensional quantitative structure-activity relationship (3D-QSAR). Comparative molecular field analysis (CoMFA q 2 = 0.623, r 2 = 0.987, r pred 2 = 0.857) and comparative molecular similarity indices analysis (CoMSIA q 2 = 0.728, r 2 = 0.960, r pred 2 = 0.899) were used to establish the model, and the structure-activity relationship of the compounds was explained by the contour maps. The binding site was predicted by two different kinds of software, and the binding modes of the compounds were further explored. A series of key amino acids Val288, Ser289, Gly314, Thr624, Lys661 were found to play a key role in the activity of the compounds. Molecular dynamics (MD) simulations were carried out for compounds 04, 17, 21, and 35, which had different activities. The reasons for the activity differences were explained by the interaction between compounds and LSD1. The binding free energy was calculated by molecular mechanics generalized Born surface area (MM/GBSA). We hope that this research will provide valuable information for the design of new reversible LSD1 inhibitors in the future.

LSD1/KDM1A inhibitors in clinical trials: advances and prospects

Histone demethylase LSD1 plays key roles during carcinogenesis, targeting LSD1 is becoming an emerging option for the treatment of cancers. Numerous LSD1 inhibitors have been reported to date, some of them such as TCP, ORY-1001, GSK-2879552, IMG-7289, INCB059872, CC-90011, and ORY-2001 currently undergo clinical assessment for cancer therapy, particularly for small lung cancer cells (SCLC) and acute myeloid leukemia (AML). This review is to provide a comprehensive overview of LSD1 inhibitors in clinical trials including molecular mechanistic studies, clinical efficacy, adverse drug reactions, and PD/PK studies and offer prospects in this field.

Epigenetic drug discovery: a success story for cofactor interference

Within the past two decades, seven epigenetic drugs have received regulatory approval and numerous other candidates are currently in clinical trials. Among the epigenetic targets are the writer and eraser enzymes that are, respectively, responsible for the reversible introduction and removal of structural modifications in the nucleosome. This review discusses the progress achieved in the design and development of inhibitors against the key writer and eraser pairs: DNA methyltransferases and Tet demethylases; lysine/arginine methyltransferases and lysine demethylases; and histone acetyltransferases and histone deacetylases. A common theme for the successful inhibition of these enzymes in a potent and selective manner is the targeting of the cofactors present in the active site, namely zinc and iron cations, S-adenosylmethione, nicotinamide adenine dinucleotide, flavin adenine dinucleotide and acetyl Coenzyme A.This article is part of a discussion meeting issue 'Frontiers in epigenetic chemical biology'.

Probing the binding mode and unbinding mechanism of LSD1 inhibitors by combined computational methods

Lysine specific demethylase 1 (LSD1) has emerged as a potential drug target in cancer therapy and a variety of inhibitors have been reported. We have recently reported the discovery of a series of triazole-dithiocarbamate based compounds, which were basically confirmed as cofactor flavin adenine dinucleotide (FAD)-competing inhibitors by experiments. However, the binding modes of the inhibitors to the binding site were undetermined. Here, we employed computational methods including molecular docking, classical molecular dynamics (MD) and steered molecular dynamics (SMD) simulations to investigate the potential binding modes of these inhibitors to LSD1. Based on the high correlation between the mean non-equilibrium pulling work W and experimental binding affinity, we identified the optimal binding modes of this class of compounds with LSD1. Using the optimal inhibitor binding conformation, we then performed SMD to study the ligand unbinding mechanism with a lower pulling velocity at 0.0005 nm ps-1. We found that residue Arg316 plays a crucial role in the binding/unbinding process. Furthermore, a gatekeeper residue Trp756 influences the ligand unbinding process by acting like a switch via steric hindrance but can enhance the hydrophobic interaction with the inhibitor. Hydrophobic interaction also dominated the interaction between LSD1 and the inhibitors. The pivotal residues and interactions between LSD1 and inhibitors determined from this study can be used to improve the inhibition activity of this series of inhibitors in development and to discover new scaffolds as FAD-competing inhibitors in compound screening.

Identifying the novel inhibitors of lysine-specific demethylase 1 (LSD1) combining pharmacophore-based and structure-based virtual screening

Lysine-specific demethylase 1 (LSD1) has been reported to connect with a range of solid tumors. Thus, the exploration of LSD1 inhibitors has emerged as an effective strategy for cancer treatment. In this study, we constructed a pharmacophore model based on a series of flavin adenine dinucleotide (FAD)-competing inhibitors bearing triazole - dithiocarbamate scaffold combining docking, structure-activity relationship (SAR) study, and molecular dynamic (MD) simulation. Meanwhile, another pharmacophore model was also constructed manually, relying on several speculated substrate-competing inhibitors and reported putative vital interactions with LSD1. On the basis of the two pharmacophore models, multi-step virtual screenings (VSs) were performed against substrate-binding pocket and FAD-binding pocket, respectively, combining pharmacophore-based and structure-based strategy to exploit novel LSD1 inhibitors. After bioassay evaluation, four compounds among 21 hits with diverse and novel scaffolds exhibited inhibition activity at the range of 3.63-101.43 μM. Furthermore, substructure-based enrichment was performed, and four compounds with a more potent activity were identified. After that, the time-dependent assay proved that the most potent compound with IC₅₀ 2.21 μM inhibits LSD1 activity in a manner of time-independent. In addition, the compound exhibited a cellular inhibitory effect against LSD1 in MGC-803 cells and may inhibit cell migration and invasion by reversing EMT in cultured gastric cancer cells. Considering the binding mode and SAR of the series of compounds, we could roughly deem that these compounds containing 3-methylxanthine scaffold act through occupying substrate-binding pocket competitively. This study presented a new starting point to develop novel LSD1 inhibitors.

Optimization of 5-arylidene barbiturates as potent, selective, reversible LSD1 inhibitors for the treatment of acute promyelocytic leukemia

Histone lysine specific demethylase 1 (LSD1) is overexpressed in diverse hematologic disorders and recognized as a promising target for blood medicines. In this study, molecular docking-based virtual screening united with bioevaluation was utilized to identify novel skeleton of 5-arylidene barbiturate as small-molecule inhibitors of LSD1. Among the synthesized derivatives, 12a exhibited reversible and potent inhibition (IC₅₀ = 0.41 μM) and high selectivity over the MAO-A and MAO-B. Notably, 12a strongly induced differentiation effect on acute promyelocytic leukemia NB4 cell line and distinctly escalated the methylation level on histone 3 lysine 4 (H3K4). Our findings indicate that 5-arylidene barbiturate may represent a new skeleton of LSD1 inhibitors and 12a deserve as a promising agent for the further research.

Crystal Structure of LSD1 in Complex with 4-[5-(Piperidin-4-ylmethoxy)-2-(p-tolyl)pyridin-3-yl]benzonitrile

Because lysine-specific demethylase 1 (LSD1) regulates the maintenance of cancer stem cell properties, small-molecule inhibitors of LSD1 are expected to be useful for the treatment of several cancers. Reversible inhibitors of LSD1 with submicromolar inhibitory potency have recently been reported, but their exact binding modes are poorly understood. In this study, we synthesized a recently reported reversible inhibitor, 4-[5-(piperidin-4-ylmethoxy)-2-(p-tolyl)pyridin-3-yl]benzonitrile, which bears a 4-piperidinylmethoxy group, a 4-methylphenyl group, and a 4-cyanophenyl group on a pyridine ring, and determined the crystal structure of LSD1 in complex with this inhibitor at 2.96 Å. We observed strong electron density for the compound, showing that its cyano group forms a hydrogen bond with Lys661, which is a critical residue in the lysine demethylation reaction located deep in the catalytic center of LSD1. The piperidine ring interacts with the side chains of Asp555 and Asn540 in two conformations, and the 4-methylphenyl group is bound in a hydrophobic pocket in the catalytic center. Our elucidation of the binding mode of this compound can be expected to facilitate the rational design of more-potent reversible LSD1 inhibitors.