Synthesis, structure-activity relationship studies and biological characterization of new [1,2,4]triazolo[1,5-a]pyrimidine-based LSD1/KDM1A inhibitors

Discovery of WS-384, a first-in-class dual LSD1 and DCN1-UBC12 protein-protein interaction inhibitor for the treatment of non-small cell lung cancer

Abnormally high expression of lysine-specific demethylase 1 A (LSD1) and DCN1 plays a vital role in the occurrence, development, and poor prognosis of non-small cell lung cancer (NSCLC). Accumulating evidence has shown that the development of small-molecule inhibitors dually targeting LSD1 and the DCN1-UBC12 interaction probably have therapeutic promise for cancer therapy. This work reported that WS-384 dually targeted LSD1 and DCN1-UBC12 interactions and evaluated its antitumor effects in vitro and in vivo. Specifically, WS-384 inhibited A549 and H1975 cells viability and decreased colony formation and EdU incorporation. WS-384 could also trigger cell cycle arrest, DNA damage, and apoptosis. Moreover, WS-384 significantly decreased tumor weight and volume in A549 xenograft mice. Mechanistically, WS-384 increased the gene and protein level of p21 by suppressing the neddylation of cullin 1 and decreasing H3K4 demethylation at the CDKN1A promoter. The synergetic upregulation of p21 contributed to cell cycle arrest and the proapoptotic effect of WS-384 in NSCLC cells. Taken together, our proof of concept studies demonstrated the therapeutic potential of dual inhibition of LSD1 and the DCN1-UBC12 interaction for the treatment of NSCLC. WS-384 could be used as a lead compound to develop new dual LSD1/DCN1 inhibitors for the treatment of human diseases in which LSD1 and DCN1 are dysregulated.

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.

Design, synthesis, and biological investigation of selective human carbonic anhydrase II, IX, and XII inhibitors using 7-aryl/heteroaryl triazolopyrimidines bearing a sulfanilamide scaffold

A novel library of human carbonic anhydrase (hCA) inhibitors based on the 2-sulfanilamido[1,2,4]triazolo[1,5-a]pyrimidine skeleton modified at its 7-position was prepared by an efficient convergent procedure. These derivatives were evaluated in vitro for their inhibition properties against a representative panel of hCA isoforms (hCA I, II, IV, IX, and XII). The target tumour-associated isoforms hCA IX and XII were potently inhibited with KIs in the low nanomolar range of 5-96 nM and 4-72 nM, respectively. Compounds 1d, 1j, 1v, and 1x were the most potent hCA IX inhibitors with KIs of 5.1, 8.6, 4.7, and 5.1 nM, respectively. Along with derivatives 1d and 1j, compounds 1r and 1ab potently inhibited hCA XII isoform with KIs in a single-digit nanomolar range of 8.8, 5.4, 4.3, and 9.0 nM, respectively. Compounds 1e, 1m, and 1p exhibited the best selectivity against hCA IX and hCA XII isoforms over off-target hCA II, with selectivity indexes ranging from 5 to 14.

The Myc Family and the Metastasis Suppressor NDRG1: Targeting Key Molecular Interactions with Innovative Therapeutics

Cancer is a leading cause of death worldwide, resulting in ∼10 million deaths in 2020. Major oncogenic effectors are the Myc proto-oncogene family, which consists of three members including c-Myc, N-Myc, and L-Myc. As a pertinent example of the role of the Myc family in tumorigenesis, amplification of MYCN in childhood neuroblastoma strongly correlates with poor patient prognosis. Complexes between Myc oncoproteins and their partners such as hypoxia-inducible factor-1α and Myc-associated protein X (MAX) result in proliferation arrest and pro-proliferative effects, respectively. Interactions with other proteins are also important for N-Myc activity. For instance, the enhancer of zest homolog 2 (EZH2) binds directly to N-Myc to stabilize it by acting as a competitor against the ubiquitin ligase, SCFFBXW7, which prevents proteasomal degradation. Heat shock protein 90 may also be involved in N-Myc stabilization since it binds to EZH2 and prevents its degradation. N-Myc downstream-regulated gene 1 (NDRG1) is downregulated by N-Myc and participates in the regulation of cellular proliferation via associating with other proteins, such as glycogen synthase kinase-3β and low-density lipoprotein receptor-related protein 6. These molecular interactions provide a better understanding of the biologic roles of N-Myc and NDRG1, which can be potentially used as therapeutic targets. In addition to directly targeting these proteins, disrupting their key interactions may also be a promising strategy for anti-cancer drug development. This review examines the interactions between the Myc proteins and other molecules, with a special focus on the relationship between N-Myc and NDRG1 and possible therapeutic interventions. SIGNIFICANCE STATEMENT: Neuroblastoma is one of the most common childhood solid tumors, with a dismal five-year survival rate. This problem makes it imperative to discover new and more effective therapeutics. The molecular interactions between major oncogenic drivers of the Myc family and other key proteins; for example, the metastasis suppressor, NDRG1, may potentially be used as targets for anti-neuroblastoma drug development. In addition to directly targeting these proteins, disrupting their key molecular interactions may also be promising for drug discovery.

Triazole-fused pyrimidines in target-based anticancer drug discovery

In recent decades, the development of targeted drugs has featured prominently in the treatment of cancer, which is among the major causes of mortality globally. Triazole-fused pyrimidines, a widely-used class of heterocycles in medicinal chemistry, have attracted considerable interest as potential anticancer agents that target various cancer-associated targets in recent years, demonstrating them as valuable templates for discovering novel anticancer candidates. The current review concentrates on the latest advancements of triazole-pyrimidines as target-based anticancer agents, including works published between 2007 and the present (2007-2022). The structure-activity relationships (SARs) and multiple pathways are also reviewed to shed light on the development of more effective and biotargeted anticancer candidates.

Discovery of novel tranylcypromine-based derivatives as LSD1 inhibitors for gastric cancer treatment

As an important epigenetic regulator, histone lysine specific demethylase 1 (LSD1) has become an attractive target for the discovery of anticancer agents. In this work, a series of tranylcypromine-based derivatives were designed and synthesized. Among them, compound 12u exhibited the most potent inhibitory potency on LSD1 (IC₅₀ = 25.3 nM), and also displayed good antiproliferative effects on MGC-803, KYSE450 and HCT-116 cells with IC₅₀ values of 14.3, 22.8 and 16.3 μM, respectively. Further studies revealed that compound 12u could directly act on LSD1 and inhibit LSD1 in MGC-803 cells, thereby significantly increasing the expression levels of mono-/bi-methylation of H3K4 and H3K9. In addition, compound 12u could induce apoptosis and differentiation, inhibit migration and cell stemness in MGC-803 cells. All these findings suggested that compound 12u was an active tranylcypromine-based derivative as a LSD1 inhibitor that inhibited gastric cancer.

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.

Amino Derivatives of Diaryl Pyrimidines and Azolopyrimidines as Protective Agents against LPS-Induced Acute Lung Injury

The problem of lung damage originating from excessive inflammation and cytokine release during various types of infections remains relevant and stimulates the search for highly effective and safe drugs. The biological activity of the latter may be associated with the regulation of hyperactivation of certain immune cells and enzymes. Here, we propose the design and synthesis of amino derivatives of 4,6- and 5,7-diaryl substituted pyrimidines and [1,2,4]triazolo[1,5-a]pyrimidines as promising double-acting pharmacophores inhibiting IL-6 and NO. The anti-inflammatory activity of 14 target compounds was studied on isolated primary murine macrophages after LPS stimulation. Seven compounds were identified to inhibit the synthesis of nitric oxide and interleukin 6 at a concentration of 100 µM. The most active compounds are micromolar inhibitors of IL-6 secretion and NO synthesis, showing a minimal impact on innate immunity, unlike the reference drug dexamethasone, along with acceptable cytotoxicity. Evaluation in an animal model of acute lung injury proved the protective activity of compound 6e, which was supported by biochemical, cytological and morphological markers.

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.

Crystal structure of 3-((2,4-dichlorobenzyl)thio)-5-methyl-7-(trifluoromethyl)-[1,2,4]triazolo [4,3-c]pyrimidine, C14H9Cl2F3N4S

C14H9Cl2F3N4S, monoclinic, P21/c (no. 14), a = 11.6567(3) Å, b = 4.80480(10) Å, c = 28.1051(7) Å, β = 101.336(2)°, V = 1543.40(6) Å3, Z = 4, Rgt (F) = 0.0358, wRref (F 2) = 0.1014, T = 250 K.

Design, Synthesis and Biological Evaluation of [1,2,4]Triazolo[1,5-a]pyrimidine Indole Derivatives against Gastric Cancer Cells MGC-803 via the Suppression of ERK Signaling Pathway

[1,2,4]Triazolo[1,5-a]pyrimidine and indole skeletons are widely used to design anticancer agents. Therefore, in this work, a series of [1,2,4]triazolo[1,5-a]pyrimidine indole derivatives were designed and synthesized by the molecular hybridization strategy. The antiproliferative activities of the target compounds H1-H18 against three human cancer cell lines, MGC-803, HCT-116 and MCF-7, were tested. Among them, compound H12 exhibited the most active antiproliferative activities against MGC-803, HCT-116 and MCF-7 cells, with IC₅₀ values of 9.47, 9.58 and 13.1 μM, respectively, which were more potent than that of the positive drug 5-Fu. In addition, compound H12 could dose-dependently inhibit the growth and colony formation of MGC-803 cells. Compound H12 exhibited significant inhibitory effects on the ERK signaling pathway, resulting in the decreased phosphorylation levels of ERK1/2, c-Raf, MEK1/2 and AKT. Furthermore, compound 12 induced cell apoptosis and G2/M phase arrest, and regulated cell cycle-related and apoptosis-related proteins in MGC-803 cells. Taken together, we report here that [1,2,4]triazolo[1,5-a]pyrimidine indole derivatives, used as anticancer agents via the suppression of ERK signaling pathway and the most active compound, H12, might be a valuable hit compound for the development of anticancer agents.

Design, Synthesis, and Antifungal Activity of Novel 1,2,4-Triazolo[4,3-c]trifluoromethylpyrimidine Derivatives Bearing the Thioether Moiety

Crop disease caused by fungi seriously affected food security and economic development. Inspired by the utilization of fungicide containing 1,2,4-triazole and trifluoromethylpyrimidine, a novel series of 1,2,4-triazolo[4,3-c]trifluoromethylpyrimidine derivatives bearing the thioether moiety were synthesized. Meanwhile, the antifungal activities of the title compounds were evaluated and most compounds exhibited obvious antifungal activities against cucumber Botrytis cinerea, strawberry Botrytis cinerea, tobacco Botrytis cinerea, blueberry Botrytis cinerea, Phytophthora infestans, and Pyricularia oryzae Cav. Among the compounds, 4, 5h, 5o, and 5r showed significant antifungal activities against three of the four Botrytis cinerea, which indicated the potential to become the leading structures or candidates for resistance to Botrytis cinerea.

Investigating the Therapeutic Potential of LSD1 Enzyme Activity-Specific Inhibition by TAK-418 for Social and Memory Deficits in Rodent Disease Models

Inhibition of lysine-specific demethylase 1 (LSD1) enzyme activity is a promising approach to treat diseases associated with epigenetic dysregulation, such as neurodevelopmental disorders. However, this concept has not been fully validated because genetic LSD1 deletion causes embryonic lethality and conventional LSD1 inhibitors cause thrombocytopenia via the dissociation of LSD1-cofactor complex. To characterize the therapeutic potential of LSD1 enzyme inhibition, we used TAK-418 and T-448, the LSD1 enzyme activity-specific inhibitors with minimal impact on the LSD1-cofactor complex. TAK-418 and T-448, by inhibiting brain LSD1 enzyme activity, consistently improved social deficits in animal models of neurodevelopmental disorders without causing thrombocytopenia. Moreover, TAK-418 improved memory deficits caused by aging or amyloid precursor protein overexpression. In contrast, TAK-418 did not improve memory deficits caused by miR-137 overexpression. Thus, miR-137 modulation may be involved in memory improvement by LSD1 inhibition. TAK-418 warrants further investigation as a novel therapeutic agent for diseases with epigenetic dysregulation.

Installation of Pargyline, a LSD1 Inhibitor, in the HDAC Inhibitory Template Culminated in the Identification of a Tractable Antiprostate Cancer Agent

Pragmatic insertion of pargyline, a LSD1 inhibitor, as a surface recognition part in the HDAC inhibitory pharmacophore was planned in pursuit of furnishing potent antiprostate cancer agents. Resultantly, compound 14 elicited magnificent cell growth inhibitory effects against the PC-3 and DU-145 cell lines and led to remarkable suppression of tumor growth in human prostate PC-3 and DU-145 xenograft nude mouse models. The outcome of the enzymatic assays ascertained that the substantial antiproliferative effects of compound 14 were mediated through HDAC6 isoform inhibition as well as selective MAO-A and LSD1 inhibition. Moreover, the signatory feature of LSD1 inhibition by 14 in the context of H3K4ME2 accumulation was clearly evident from the results of western blot analysis. Gratifyingly, hydroxamic acid 14 demonstrates good human hepatocytic stability and good oral bioavailability in rats and exhibits enough promise to emerge as a therapeutic for the treatment of prostate cancer in the near future.

Targeting cancer epigenetic pathways with small-molecule compounds: Therapeutic efficacy and combination therapies

Epigenetics mainly refers to covalent modifications to DNA or histones without affecting genomes, which ultimately lead to phenotypic changes in cells or organisms. Given the abundance of regulatory targets in epigenetic pathways and their pivotal roles in tumorigenesis and drug resistance, the development of epigenetic drugs holds a great promise for the current cancer therapy. However, lack of potent, selective, and clinically tractable small-molecule compounds makes the strategy to target cancer epigenetic pathways still challenging. Therefore, this review focuses on epigenetic pathways, small molecule inhibitors targeting DNA methyltransferase (DNMT) and small molecule inhibitors targeting histone modification (the main regulatory targets are histone acetyltransferases (HAT), histone deacetylases (HDACs) and histone methyltransferases (HMTS)), as well as the combination strategies of the existing epigenetic therapeutic drugs and more new therapies to improve the efficacy, which will shed light on a new clue on discovery of more small-molecule drugs targeting cancer epigenetic pathways as promising strategies in the future.

Synthesis of new 1,2,4-triazole-(thio)semicarbazide hybrid molecules: Their tyrosinase inhibitor activities and molecular docking analysis

Tyrosinase inhibition is very important in controlling melanin synthesis. If melanin synthesis is not controlled in metabolism, an unwanted increase in melanin synthesis occurs. As melanin plays a role in the formation of skin color, its unusual levels cause some skin disorders such as pregnancy scars, age spots, and especially skin cancer (melanoma). However, the tyrosinase activity is also related to Parkinson's disease and some neurodegenerative diseases. For all these reasons, the medicinal as well as the cosmetic industries focus on research on tyrosinase inhibitors for the treatment of skin disorders and some neurodegenerative diseases. In this study, 32 new 1,2,4-triazole-(thio)semicarbazide hybrid molecules (6a-p and 7a-p) were synthesized, starting from 4-amino-1-pentyl-3-phenyl-1H-1,2,4-triazole-5(4H)-one. These compounds were evaluated for their inhibitory activity against mushroom tyrosinase. The results indicated that 6h, 6m, 6n, and 6p exhibited the most effective inhibitory activity, with IC₅₀ values of 0.00162 ± 0.0109, 0.00166 ± 0.0217, 0.00165 ± 0.019, and 0.00197 ± 0.0063 μM, respectively, compared with kojic acid as the reference drug (IC₅₀  = 14.09 ± 0.02 μM). Also, molecular docking analyses were performed to suggest possible binding poses for the ligands. As a result, derivatives 6h, 6m, 6n, and 6p can be used as promising tyrosinase inhibitor candidates in the medicinal, cosmetics, or food industries.

QSAR Modeling, Molecular Docking and Molecular Dynamics Simulations Studies of Lysine-Specific Demethylase 1 (LSD1) Inhibitors as Anticancer Agents

BACKGROUND

Histone Lysine Demetylases1 (LSD1) is a promising medication to treat cancer, which plays a crucial role in epigenetic modulation of gene expression. Inhibition of LSD1with small molecules has emerged as a vital mechanism to treat cancer.

OBJECTIVE

In the present research, molecular modeling investigations, such as CoMFA, CoMFA-RF, CoMSIA and HQSAR, molecular docking and Molecular Dynamics (MD) simulations were carried out on some tranylcypromine derivatives as LSD1 inhibitors.

METHODS

The QSAR models were carried out on a series of Tranylcypromine derivatives as data set via the SYBYL-X2.1.1 program. Molecular docking and MD simulations were carried out by the MOE software and the SYBYL program, respectively. The internal and external predictability performances related to the generated models for these LSD1 inhibitors were justified by evaluating cross-validated correlation coefficient (q²), noncross- validated correlation coefficient (r²_ncv) and predicted correlation coefficient (r²_pred) of the training and test set molecules, respectively.

RESULTS

The CoMFA (q², 0.670; r²_ncv, 0.930; r²_pred, 0.968), CoMFA-RF (q², 0.694; r²_ncr, 0.926; r²_pred, 0.927), CoMSIA (q², 0.834; r²_ncv, 0.956; r²_pred, 0.958) and HQSAR models (q², 0.854; r²_ncv, 0.900; r²_pred, 0.728) for training as well as the test set of LSD1 inhibition resulted in significant findings.

CONCLUSION

These QSAR models were found to be perfect and strong with better predictability. Contour maps of all models were generated and it was proven by molecular docking studies and molecular dynamics simulation that the hydrophobic, electrostatic and hydrogen bonding fields are crucial in these models for improving the binding affinity and determining the structure-activity relationship. These theoretical results are possibly beneficial to design new strong LSD1 inhibitors with enhanced activity to treat cancer.

Identification of novel 1,3-diaryl-1,2,4-triazole-capped histone deacetylase 6 inhibitors with potential anti-gastric cancer activity

Histone deacetylase 6 (HDAC6) has emerged as a critical regulator of many cellular pathways in tumors due to its unique structure basis and abundant substrate types. Over the past few decades, the role played by HDAC6 inhibitors as anticancer agents has sparked great interest of biochemists worldwide. However, they were less reported for gastric cancer therapy. In this paper, with the help of bioisosteric replacement, in-house library screening, and lead optimization strategies, we designed, synthesized and verified a series of 1,3-diaryl-1,2,4-triazole-capped HDAC6 inhibitors with promising anti-gastric cancer activities. Amongst, compound 9r displayed the best inhibitory activity towards HDAC6 (IC₅₀ = 30.6 nM), with 128-fold selectivity over HDAC1. Further BLI and CETSA assay proved the high affinity of 9r to HDAC6. In addition, 9r could dose-dependently upregulate the levels of acetylated α-tubulin, without significant effect on acetylated histone H3 in MGC803 cells. Besides, 9r exhibited potent antiproliferative effect on MGC803 cells, and promoted apoptosis and suppressed the metastasis without obvious toxicity, suggesting 9r would serve as a potential lead compound for the development of novel therapeutic agents of gastric cancer.

Reversible Lysine Specific Demethylase 1 (LSD1) Inhibitors: A Promising Wrench to Impair LSD1

As a flavin adenine dinucleotide (FAD)-dependent monoamine oxidase, lysine specific demethylase 1 (LSD1/KDM1A) functions as a transcription coactivator or corepressor to regulate the methylation of histone 3 lysine 4 and 9 (H3K4/9), and it has emerged as a promising epigenetic target for anticancer treatment. To date, numerous inhibitors targeting LSD1 have been developed, some of which are undergoing clinical trials for cancer therapy. Although only two reversible LSD1 inhibitors CC-90011 and SP-2577 are in the clinical stage, the past decade has seen remarkable advances in the development of reversible LSD1 inhibitors. Herein, we provide a comprehensive review about structures, biological evaluation, and structure-activity relationship (SAR) of reversible LSD1 inhibitors.

Discovery of higenamine as a potent, selective and cellular active natural LSD1 inhibitor for MLL-rearranged leukemia therapy

Natural products are a rich source of lead compounds and have shown promise for epigenetic drug discovery. In this work, we discovered higenamine from our natural product library as a potent, selective and cellular active natural LSD1 inhibitor. Higenamine shows acceptable potency against LSD1 and high selectivity towards LSD1 over MAOA/B. Higenamine significantly increases expression of LSD1 substrates H3K4me1 and H3K4me2 in MLL-rearranged leukemia cells MV4-11 and MOLM-13, but nearly had no effect on LSD1 and H3K4Me3. Meanwhile, higenamine dose-dependently suppresses the levels of HOXA9 and MEIS1 that are overexpressed in leukemia cell lines. Notably, higenamine induces cell differentiation of MV4-11 and MOLM-13 cells accompanying by increased expression of CD11b, CD14 and CD86. Higenamine promotes cell apoptosis, inhibits colony formation, but does not inhibit proliferation of leukemia cells significantly. In addition, the expression levels of p53 are dramatically changed by higenamine in an LSD1-dependent manner in MV4-11 cells. Taken together, higenamine could be employed as a starting point for the development of more selective and potent LSD1 inhibitors. Our work firstly reveals the non-classical epigenetic regulation mechanism of higenamine in cancers, and also demonstrates the efficacy of higenamine for MLL-rearranged leukemia therapy.

FDA-approved pyrimidine-fused bicyclic heterocycles for cancer therapy: Synthesis and clinical application

Considerable progress has been made in the development of anticancer agents over the past few decades, and a lot of new anticancer agents from natural and synthetic sources have been produced. Among heterocyclic compounds, pyrimidine-fused bicyclic heterocycles possess a variety of biological activities such as anticancer, antiviral, etc. To date, 147 pyrimidine-fused bicyclic heterocycles have been approved for clinical assessment or are currently being used in clinic, 57 of which have been approved by FDA for clinical treatment of various diseases, and 22 of them are being used in the clinic for the treatment of different cancers. As the potentially privileged scaffolds, pyrimidine-fused bicyclic heterocycles may be used to discover new drugs with similar biological targets and improved therapeutic efficacy. This review aims to provide an overview of the anticancer applications and synthetic routes of 22 approved pyrimidine-fused bicyclic heterocyclic drugs in clinic.

An insight on medicinal attributes of 1,2,4-triazoles

The present review aims to summarize the pharmacological profile of 1,2,4-triazole, one of the emerging privileged scaffold, as antifungal, antibacterial, anticancer, anticonvulsant, antituberculosis, antiviral, antiparasitic, analgesic and anti-inflammatory agents, etc. along with structure-activity relationship. The comprehensive compilation of work carried out in the last decade on 1,2,4-triazole nucleus will provide inevitable scope for researchers for the advancement of novel potential drug candidates having better efficacy and selectivity.

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.

Exploration of 5-cyano-6-phenylpyrimidin derivatives containing an 1,2,3-triazole moiety as potent FAD-based LSD1 inhibitors

Histone lysine specific demethylase 1 (LSD1) has become a potential therapeutic target for the treatment of cancer. Discovery and develop novel and potent LSD1 inhibitors is a challenge, although several of them have already entered into clinical trials. Herein, for the first time, we reported the discovery of a series of 5-cyano-6-phenylpyrimidine derivatives as LSD1 inhibitors using flavin adenine dinucleotide (FAD) similarity-based designing strategy, of which compound 14q was finally identified to repress LSD1 with IC50 = 183 nmol/L. Docking analysis suggested that compound 14q fitted well into the FAD-binding pocket. Further mechanism studies showed that compound 14q may inhibit LSD1 activity competitively by occupying the FAD binding sites of LSD1 and inhibit cell migration and invasion by reversing epithelial to mesenchymal transition (EMT). Overall, these findings showed that compound 14q is a suitable candidate for further development of novel FAD similarity-based LSD1 inhibitors.

Histone modifications in epigenetic regulation of cancer: Perspectives and achieved progress

Epigenetic changes associated with histone modifications play an important role in the emergence and maintenance of the phenotype of various cancer types. In contrast to direct mutations in the main DNA sequence, these changes are reversible, which makes the development of inhibitors of enzymes of post-translational histone modifications one of the most promising strategies for the creation of anticancer drugs. To date, a wide variety of histone modifications have been found that play an important role in the regulation of chromatin state, gene expression, and other nuclear events. This review examines the main features of the most common and studied epigenetic histone modifications with a proven role in the pathogenesis of a wide range of malignant neoplasms: acetylation / deacetylation and methylation / demethylation of histone proteins, as well as the role of enzymes of the HAT / HDAC and HMT / HDMT families in the development of oncological pathologies. The data on the relationship between histone modifications and certain types of cancer are presented and discussed. Special attention is devoted to the consideration of various strategies for the development of epigenetic inhibitors. The main directions of the development of inhibitors of histone modifications are analyzed and effective strategies for their creation are identified and discussed. The most promising strategy is the use of multitarget drugs, which will affect multiple molecular targets of cancer. A critical analysis of the current status of approved epigenetic anticancer drugs has also been performed.

Discovery of [1,2,3]triazolo[4,5-d]pyrimidine derivatives as highly potent, selective, and cellularly active USP28 inhibitors

Ubiquitin specific peptidase 28 (USP28) is closely associated to the occurrence and development of various malignancies, and thus has been validated as a promising therapeutic target for cancer therapy. To date, only few USP28 inhibitors with moderate inhibitory activity have been reported, highly potent and selective USP28 inhibitors with new chemotypes remain to be discovered for pathologically investigating the roles of deubiquitinase. In this current study, we reported the synthesis and biological evaluation of new [1,2,3]triazolo[4,5-d]pyrimidine derivatives as potent USP28 inhibitors. Especially, compound 19 potently inhibited USP28 (IC₅₀ = 1.10 ± 0.02 μmol/L, K_d = 40 nmol/L), showing selectivity over USP7 and LSD1 (IC₅₀ > 100 μmol/L). Compound 19 was cellularly engaged to USP28 in gastric cancer cells. Compound 19 reversibly bound to USP28 and directly affected its protein levels, thus inhibiting the proliferation, cell cycle at S phase, and epithelial-mesenchymal transition (EMT) progression in gastric cancer cell lines. Docking studies were performed to rationalize the potency of compound 19. Collectively, compound 19 could serve as a new tool compound for the development of new USP28 inhibitors for exploring the roles of deubiquitinase in cancers.

Discovery of new [1,2,4] Triazolo[1,5-a]Pyrimidine derivatives that Kill gastric cancer cells via the mitochondria pathway

Mitochondria are known as "powerhouse of cells" and play the role of a bridge in redox balance, cell apoptosis, and autophagy. ROS accumulation can cause mitochondria damage, while the injured mitochondria will further enhance ROS levels reciprocally. Herein, we synthesized a novel series of [1,2,4]triazolo[1,5-a]pyrimidine-based compounds 4a-4v and tested their anti-proliferation efficacy against gastric cancer cell line MGC-803. Among them, compounds 4o and 4p inhibited gastric cancer cells at micromolar level. Compound 4o caused G2/M arrest and induced mitochondria-dependent apoptosis in MGC-803 and SGC-7901. However, inhibiting apoptosis pathway cannot prevent the inhibitory activity of compound 4o against gastric cancer cell. To our surprising, ROS level was increased by compound 4o and elevation of ROS could be rescued by NAC. In accordance with that, NAC absolutely prevented the anti-proliferation efficacy of compound 4o. We further found that autophagy inhibitor CQ rather than 3-MA partially reversed inhibitory activity of compound 4o in MGC-803 cells. Taken together, compound 4o exhibited its anti-proliferative activity via increasing ROS level and inducing autophagy, thus leading to apoptosis of gastric cancer cells. Therefore, compound 4o may support further development of lead compounds for gastric cancer therapy via mitochondria pathway.

Drug repurposing: Discovery of troxipide analogs as potent antitumor agents

Drug repurposing plays a vital role in the discovery of undescribed bioactivities in clinical drugs. Based on drug repurposing strategy, we for the first time reported a novel series of troxipide analogs and then evaluated their antiproliferative activity against MCF-7, PC3, MGC-803, and PC9 cancer cell lines and WPMY-1, most of which showed obvious selectivity toward PC-3 over the other three cancer cell lines and WPMY-1. Compound 5q, especially, could effectively inhibit PC3 with an IC₅₀ value of 0.91 μM, which exhibited around 53-fold selectivity toward WPMY-1. Data indicated that 5q effectively inhibited the colony formation, suppressed the cell migration, and induced G1/S phase arrest in PC3 cells. Also, compound 5q induced cell apoptosis by activating the two apoptotic signaling pathways in PC3 cells: death receptor-mediated extrinsic pathway and mitochondria-mediated intrinsic pathway. Compound 5q up-regulated the expression of both pro-apoptotic Bax and P53, while down-regulated anti-apoptotic Bcl-2 expression. Besides, compound 5q significantly increased the expression of cleaved caspase 3/9 and cleaved PARP. Therefore, the successful discovery of compound 5q may further validate the feasibility of this theory, which will encourage researchers to reveal undescribed bioactivities in traditional drugs.

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A novel series of troxipide analogs were designed using drug repurposing strategy.

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5q effectively inhibited PC3 (IC₅₀ = 0.91 μM), being around 53-fold selectivity toward WPMY-1.

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5q effectively inhibited the colony formation, suppressed the cell migration, and induced G1/S phase arrest in PC3 .

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5q induced apoptosis by activating death receptor-mediated extrinsic and mitochondria-mediated intrinsic pathways in PC3.

Diacetoxy iodobenzene mediated regioselective synthesis and characterization of novel [1,2,4]triazolo[4,3-a]pyrimidines: apoptosis inducer, antiproliferative activities and molecular docking studies

Prompt and regioselective synthesis of eleven novel [1,2,4]triazolo[4,3-a]pyrimidines 2a-2k, via intramolecular oxidative-cyclization of 2-(2-arylidenehydrazinyl)-4-methyl-6-phenylpyrimidine derivatives 1a-1k has been demonstrated here using diacetoxy iodobenzene (DIB) as inexpensive and ecofriendly hypervalent iodine(III) reagent in CH₂Cl₂ at room temperature. Regiochemistry of final product has been established by developing single crystal and studied X-ray crystallographic data for two derivatives 2c and 2h without any ambiguity. These prominent [1,2,4]triazolo[4,3-a]pyrimidines were evaluated for human osteosarcoma bone cancer (MG-63) and breast cancer (MCF-7) cell lines using MTT assay to find potent antiproliferative agent and also on testicular germ cells to find potent apoptotic inducing activities. All compounds show significant cytotoxicity, particularly 3-(2,4-dichlorophenyl)-5-methyl-7-phenyl-[1,2,4]triazolo[4,3-a]pyrimidine (2g) was found significant apoptotic inducing molecule, as well as the most potent cytotoxic agent against bone cancer (MG-63) and breast cancer (MCF-7) cell lines with GI₅₀ value 148.96 µM and 114.3 µM respectively. Molecular docking studies has been carried out to see the molecular interactions of synthesized compounds with the protein thymidylate synthase (PBD ID: 2G8D).Communicated by Ramaswamy H. Sarma.

Natural products as LSD1 inhibitors for cancer therapy

Natural products generally fall into the biologically relevant chemical space and always possess novel biological activities, thus making them a rich source of lead compounds for new drug discovery. With the recent technological advances, natural product-based drug discovery is now reaching a new era. Natural products have also shown promise in epigenetic drug discovery, some of them have advanced into clinical trials or are presently being used in clinic. The histone lysine specific demethylase 1 (LSD1), an important class of histone demethylases, has fundamental roles in the development of various pathological conditions. Targeting LSD1 has been recognized as a promising therapeutic option for cancer treatment. Notably, some natural products with different chemotypes including protoberberine alkaloids, flavones, polyphenols, and cyclic peptides have shown effectiveness against LSD1. These natural products provide novel scaffolds for developing new LSD1 inhibitors. In this review, we mainly discuss the identification of natural LSD1 inhibitors, analysis of the co-crystal structures of LSD1/natural product complex, antitumor activity and their modes of action. We also briefly discuss the challenges faced in this field. We believe this review will provide a landscape of natural LSD1 inhibitors.

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.

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.

Synthesis of new steroidal quinolines with antitumor properties

The incorporation of the heterocycles into the steroid nucleus has been recognized as a useful strategy to develop new steroidal agents for disease treatment. Representative examples are abiraterone and galeterone, which are presently used in clinic for the treatment of advanced prostate cancers. Herein we have developed the first Al₂O₃/KF-promoted pfitzinger reactions for the synthesis of new steroidal quinolines. These new steroidal quinolines showed moderate to good antiproliferative activity against several human lung cancer cells. Of these compounds, compound 2f exhibited the best potency toward the tested three lung cancer cells with IC₅₀ values <10 μM. Mechanistic studies showed that compound 2f concentration-dependently inhibited colony formation, morphological changes, apoptosis, and migration of A549 cells. To conclude, compound 2f could be used as a hit compound for developing steroid-based anti-lung cancer agents.