Potent Lysine Specific Demethylase 1 Inhibitors Research Articles

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</i>. 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</i>. 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.

Unveiling Arformoterol as a potent LSD1 inhibitor for breast cancer treatment: A comprehensive study integrating 3D-QSAR pharmacophore modeling, molecular docking, molecular dynamics simulations and in vitro assays

Lysine Specific Demethylase 1 (LSD1) has been identified as a chromatin-modifying enzyme implicated in various cancer pathogeneses, highlighting the potential for novel epigenetic cancer treatments through the development of effective inhibitors. We employed 3D-QSAR pharmacophore modeling, molecular docking, and molecular dynamics simulations to identify a promising drug candidate for LSD1 inhibition. RMSD, RMSF, H-bond, and DSSP analysis demonstrated that ZINC02599970 (Arformoterol) and ZINC13453966 exhibited the highest LSD1 inhibitory potential.Experimental validation using MCF-7 and MDA-MB-231 cell lines revealed that Arformoterol displayed potent antiproliferative activity with IC50 values of 12.30 ± 1.48 μM and 19.69 ± 1.15 μM respectively. In contrast, the IC50 values obtained for the control (tranylcypromine) in exposure to MCF-7 and MDA-MB-231 cells were 104.6 ± 1.69 μM and 77 ± 0.67 μM, respectively. Arformoterol demonstrated greater LSD1 inhibitory potency in MCF-7 cells compared to MDA-MB-231 cells. Also, the expression of genes involved in chromatin rearrangement (LSD1), angiogenesis (VEGF1), cell migration (RORα), signal transduction (S100A8), apoptosis, and cell cycle (p53) were investigated. Arformoterol enhanced apoptosis and induced cell cycle arrest at the G2/M phase, both in MCF-7 and MDA-MB-231 cancer cells. Based on our findings, we propose that Arformoterol represents a promising candidate for breast cancer treatment, owing to its potent LSD1 inhibitory activity.

Discovery of Pyrrolo[2,3-c]pyridines as Potent and Reversible LSD1 Inhibitors.

Lysine specific demethylase 1 (LSD1) acts as an epigenetic eraser by specifically demethylating mono- and histone 3 lysine 4 (H3K4) and H3 lysine 9 (H3K9) residues. LSD1 has been pursued as a promising therapeutic target for the treatment of human cancer, and a number of LSD1 inhibitors have been advanced into clinical development. In the present study, we describe our discovery of pyrrolo[2,3-c]pyridines as a new class of highly potent and reversible LSD1 inhibitors, designed on the basis of a previously reported LSD1 inhibitor GSK-354. Among them, 46 shows an IC50 value of 3.1 nM in inhibition of LSD1 enzymatic activity and inhibits cell growth with IC50 values of 0.6 nM in the MV4;11 acute leukemia cell line and 1.1 nM in the H1417 small-cell lung cancer cell line. Compound 46 (LSD1-UM-109) is a novel, highly potent, and reversible LSD1 inhibitor and serves as a promising lead compound for further optimization.

Discovery of new tetrahydroisoquinolines as potent and selective LSD1 inhibitors for the treatment of MLL-rearranged leukemia

Histone lysine-specific demethylase 1 (LSD1) is a promising target for cancer therapy. Here, we performed the design, synthesis, and extensive structure-activity relationship (SAR) studies based on our previously discovered natural LSD1 inhibitor, higenamine. We found that the tetracyclic tetrahydroisoquinoline FY-21 is a potent and selective inhibitor of LSD1 (IC50 = 340 nM). FY-21 inhibited leukemia cell proliferation and colony formation and increased the level of p53 expression. Meanwhile, FY-21 reduced the mRNA levels of the transcription factors HOXA9 and MEIS1. Furthermore, FY-21 significantly induced leukemia cell differentiation. In vivo studies showed that FY-21 prolonged the survival rate of leukemia mice. Collectively, FY-21 is a potent, selective LSD1 inhibitor and can serve as a lead compound for the development of novel and highly effective LSD1 inhibitors for AML treatment.

Phenothiazine-Based LSD1 Inhibitor Promotes T-Cell Killing Response of Gastric Cancer Cells.

Histone lysine specific demethylase 1 (LSD1) has been recognized as an important epigenetic target for cancer treatment. Although several LSD1 inhibitors have entered clinical trials, the discovery of novel potent LSD1 inhibitors remains a challenge. In this study, the antipsychotic drug chlorpromazine was characterized as an LSD1 inhibitor (IC50 = 5.135 μM), and a series of chlorpromazine derivatives were synthesized. Among them, compound 3s (IC50 = 0.247 μM) was the most potent one. More importantly, compound 3s inhibited LSD1 in the cellular level and downregulated the expression of programmed cell death-ligand 1 (PD-L1) in BGC-823 and MFC cells to enhance T-cell killing response. An in vivo study confirmed that compound 3s can inhibit MFC cell proliferation without significant toxicity in immunocompetent mice. Taken together, our findings indicated that the novel LSD1 inhibitor 3s tethering a phenothiazine scaffold may serve as a lead compound for further development to activate T-cell immunity in gastric cancer.

6-Heterocyclic carboxylic ester derivatives of gliotoxin lead to LSD1 inhibitors in gastric cancer cells

Gliotoxin is a representative compound of the epipolythiodioxopiperazine (ETP) class of fungal metabolites. Histone Lysine Specific Demethylase 1 (LSD1) is highly expressed in a variety of cancers. Herein, a series of 6-heterocyclic carboxylic ester derivatives of gliotoxin was designed and synthesized as new LSD1 inhibitors and their biological evaluations in human gastric MGC-803 and HGC-27 cells were carried out. All of the derivatives effectively suppressed the enzymatic activities of LSD1. In particular, compound 4e exhibited excellent LSD1 inhibition with IC50 = 62.40 nM, as well as anti-proliferation against MGC-803 and HGC-27 cells with IC50 values of 0.31 μM and 0.29 μM, respectively. 4e also had a remarkable capacity to inhibit the colony formation, suppress migration and induce the apoptosis of these two cancer cell lines. In sum, our findings identified and characterized the 6-heterocyclic carboxylic ester derivatives of gliotoxin as potent and cellular active LSD1 inhibitors, which may provide a novel chemotype of LSD1 inhibitors for gastric cancer treatment.

Abstract 1048: Synergistic drug combination of LSD1 and ABL2 inhibitors for Ewing's sarcoma identified in an arrayed CRISPR screen approach

Abstract Background: Ewing's Sarcoma (ES) is a rare and aggressive pediatric bone tumor that is driven by a chromosomal translocation and fusion between EWS and FLI1 genes resulting in a chimeric protein. Nearly 85% of ES cases express the EWS/FLI protein which functions as a transcription factor and drives oncogenesis. EWS/FLI interacts with lysine-specific demethylase 1 (LSD1) that is highly expressed in pediatric sarcomas, to repress critical tumor suppressors. We have developed a potent reversible LSD1 inhibitor, SP-2577 (Seclidemstat), that shows the ability to impair tissue culture cell viability in multiple ES cell lines and is currently in clinical trials. A more favorable therapeutic response to SP-2577 may be obtained by combining drugs that target multiple pathways and/or inhibit resistance mechanisms. Experimental Design: In this study, we applied an arrayed CRISPR screening (Synthego) to identify survival genes that can be candidates for molecularly targeted drugs. Gene candidates were validated using western blot, qPCR, soft agar assay. Ewing’s Sarcoma A673 ABL2i knockdown and scramble cell lines were generated, implanted into nude mice, and treated with SP-2577. Lastly, combinational drug treatments using FDA-approved inhibitors with SP-2577 were tested in 2D and 3D cultures. Results: CRISPR druggable library screen identified that downregulation of several genes resulted in increased SP-2577 cytotoxicity in multiple ES cell lines. Importantly, ABL2 knockdown was found to have a significant synergy in combination with SP-2577 treatment, both in vitro and in vivo. siRNA knockdown of ABL2 in combination with SP-2577 treatment revealed an increase in JNK signaling and Cleaved Caspases-3 activation with decreased Src phosphorylation. This data suggests that downregulation of ABL2 in combination with SP-2577 treatment promotes activation of apoptosis pathways in ES. In addition, combination treatment of SP-2577 with drugs targeting ABL2 pathway showed high synergy in vitro. Conclusion: This study highlights the potential for a combination treatment of SP-2577 with ABL2 inhibitors in ES patients. Further, our observations support the capability of arrayed CRISPR screening to identify new therapeutic strategies in ES. Citation Format: Samuel Sampson, Trason Thode, Kevin Drenner, Ryan Rodriguez Del Villar, Annika Ozols, Mohan Kaadige, Alexis Weston, Serina Ng, Tithi Ghosh Halder, Shelby Rheinschmidt, David Anderson, Kevin Holden, Raffaella Soldi, Sunil Sharma. Synergistic drug combination of LSD1 and ABL2 inhibitors for Ewing's sarcoma identified in an arrayed CRISPR screen approach [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1048.

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.

Structure-Activity Relationship Study of Indolin-5-yl-cyclopropanamine Derivatives as Selective Lysine Specific Demethylase 1 (LSD1) Inhibitors.

LSD1 is identified as an essential drug target, which is closely correlated to the development of several tumor types. In this work, on the basis of comprehensive analysis of the binding site of LSD1 and other FAD-dependent enzymes, a novel series of potent and selective LSD1 inhibitors were designed by incorporation of privileged indoline scaffold strategies. Representative compound 7e (LSD1; IC50 = 24.43 nM, selectivity over LSD2 and MAOs of >200- and 4000-fold) possessed selective antiproliferative activities against MV-4-11 cell lines. Further study indicates that 7e could activate CD86 expression (EC50 = 470 nM) and induce differentiation of AML cell lines. More importantly, compound 7e demonstrated an acceptable oral PK profile and good in vivo antitumor efficacy with a T/C value of 30.89% in an MV-4-11 xenograft mouse model. Collectively, this work provides a promising lead compound for the development of novel LSD1 inhibitors for the treatment of AML.

Discovery of natural product-like spirooxindole derivatives as highly potent and selective LSD1/KDM1A inhibitors for AML treatment

Histone lysine specific demethylase 1 (LSD1) is a promising new therapeutic target for cancer therapy. Following the work on the discovery of natural LSD1 inhibitor higenamine, we herein performed further structure-based design, synthesis, and extensive structure–activity relationship (SAR) studies, affording structurally new spirooxindole derivatives. Particularly, FY-56 was identified to be a highly potent LSD1 inhibitor (IC50 = 42 nM) and showed high selectivity over monoamine oxidases (MAO-A/B). Mechanistic studies showed that FY-56 moderately inhibited the proliferation and clone formation of leukemia cells, induced H3K4me1/2 accumulation and p53 activation as well as reduced the mRNA levels of the transcription factors HOXA9 and MEIS1. Meanwhile, FY-56 induced differentiation of MOLM-13 and MV4-11 cells, accompanied by an enhanced percentage of markers characteristic to differentiated macrophages and monocytes. Further in vivo studies showed that FY-56 obviously reduced the proportion of CD45+/CD33+ leukocytes in peripheral blood and spleen, and significantly prolonged the survival rate of mice. Collectively, FY-56 represents a structurally novel, highly potent and selective LSD1 inhibitor and exhibits therapeutic promise for AML treatment. The spirooxindole scaffold derived from FY-56 could be used to design structurally new LSD1 inhibitors for treating human diseases.

Discovery of quinazoline derivatives as a novel class of potent and invivo efficacious LSD1 inhibitors by drug repurposing.

Histone lysine-specific demethylase 1 (LSD1) is an important epigenetic modulator, and is implicated in malignant transformation and tumor pathogenesis in different ways. Therefore, the inhibition of LSD1 provides an attractive therapeutic target for cancer therapy. Based on drug repurposing strategy, we screened our in-house chemical library toward LSD1, and found that the EGFR inhibitor erlotinib, an FDA-approved drug for lung cancer, possessed low potency against LSD1 (IC50=35.80μM). Herein, we report our further medicinal chemistry effort to obtain a highly water-soluble erlotinib analog 5k (>100mg/mL) with significantly enhanced inhibitory activity against LSD1 (IC50=0.69μM) as well as higher specificity. In MGC-803cells, 5k suppressed the demethylation of LSD1, indicating its cellular activity against the enzyme. In addition, 5k had a remarkable capacity to inhibit colony formation, suppress migration and induce apoptosis of MGC803cells. Furthermore, in MGC-803 xenograft mouse model, 5k treatment resulted in significant reduction in tumor size by 81.6% and 96.1% at dosages of 40 and 80mg/kg/d, respectively. Our findings indicate that erlotinib-based analogs provide a novel structural set of LSD1 inhibitors with potential for further investigation, and may serve as novel candidates for the treatment of LSD1-overexpressing cancers.

LSD1 Inhibition Leads to Differentiation in Hoxa9/Meis1- but Not in MN1-Induced Acute Myeloid Leukemia

Lysine specific demethylase 1 (LSD1) represents a promising epigenetic target in the treatment of acute myeloid leukemia (AML) and inhibition of LSD1 has been demonstrated to facilitate a response of AML cells to all- trans retinoic acid (ATRA). We have previously shown that LSD1 depletion or inhibition using tranylcypromine or its derivatives induces granulocytic differentiation, reduces leukemia-initiating cell (LIC) frequency and leads to a survival benefit in Hoxa9/Meis1 (H/M)-driven AML. We have now modeled the effect of pharmacological or genetic inactivation of LSD1 in another murine leukemia model based on the retroviral overexpression of MN1.We transformed lineage-depleted bone marrow cells from conditional LSD1 knock-out (KO) mice with MN1 and induced the LSD1 KO by treatment with 4-hydroxy-tamoxifen (4-OHT). As a control we compared the results observed in this system with results from cells transformed with the combination of Hoxa9 and Meis1 (H/M). We analyzed short-term proliferation based on XTT assays and differentiation based on cell morphology as well as surface marker expression. We observed a 61% reduction in proliferation in H/M cells, while we only found 28% reduction in proliferation in MN1 cells. LSD1 KO induced marked granulocytic differentiation in H/M cells, but we did not observe any signs of granulocytic differentiation in MN1 cells. While LSD1 KO led to a reduction in the expression of c-Kit and upregulation of Ly-6G in H/M cells, c-Kit expression remained unchanged in MN1 cells. There were also no changes in Gr1 and Mac1, but MN1 cells acquired Sca1 and FcεR1. LSD1 inhibition has been shown to enhance the sensitivity of leukemic cells towards a treatment with ATRA. We therefore now compared the influence of LSD1 KO on the effect of ATRA treatment in H/M and MN1 cells. We saw a 95 % reduction in proliferation in H/M cells with LSD1 KO upon treatment with 0.1 µM of ATRA. In MN1 cells with LSD1 KO we only observed a reduction in proliferation of 28 % at this concentration.We previously found a differentiating effect of irreversible LSD1 inhibitors in H/M transformed cells. We therefore also tested different potent LSD1 inhibitors (derivatives of tranylcypromine) in MN1 cells (trans-N-((2-methoxypyridin-3-yl)methyl)-2-phenylcyclopropan-1-amine (ORY86, AW69), (1S,2R)-2-phenyl-N-(piperidin-4-ylmethyl) cyclopropanamine (AW84), GSK-LSD1). Again we observed no signs of granulocytic differentiation, but an acquisition of the surface markers Sca1 and FcεR1 without concomitant changes in the expression of c-Kit, Gr1 and Mac1. Treatment with AW69 leads to a strong reduction in LIC frequency in the H/M model system. We now investigated if pre-treatment with AW69 in vitro for 96 h also affected the ability of MN1 cells to induce leukemia in mice. In this experiment we observed no change in leukemia development upon transplantation of 20.000 cells per mouse. However while 2 of 3 mice transplanted with control treated cells developed leukemia upon transplantation of 2.000 cells per mouse, no leukemia development was seen at this cell dose with AW69-treated cells. We therefore cannot exclude a moderate effect on LIC frequency in the MN1 model.In order to test if our findings can be transferred to human AML we characterized the expression of MN1, HOXA9 and MEIS1 in 6 primary human AML cell cultures. We then treated these cells with GSK-LSD1 and assessed the expression of CD86, a known differentiation marker induced by LSD1 inhibition. In these experiments we observed a particularly strong upregulation of CD86 in samples expressing higher levels of MEIS1.In summary, our results show that while pharmacological or genetic inactivation of LSD1 potently induces differentiation in H/M-induced AML, it is not sufficient to induce differentiation in MN1-driven AML. This finding could be relevant for selecting patients for treatment with LSD1 inhibitors and warrants further molecular investigations. DisclosuresBug:Astellas: Other: Travel Funding; Janssen: Other: Travel Funding; Amgen: Honoraria; Novartis: Honoraria, Research Funding; Jazz Pharmaceuticals: Other: Travel Funding; Celgene: Honoraria, Other: Travel funding. Lübbert:Celgene: Other: Travel Funding; Janssen-Cilag: Other: Travel Funding, Research Funding; Ratiopharm: Other: Study drug valproic acid. Berg:Astellas: Other: Travel Funding; Riemser: Consultancy; Alexion: Other: Travel Funding; Celgene: Other: Travel Funding; Abbvie: Other: Travel Funding.

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=0.065μM, 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±0.49μM, 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 10μM. Remarkably, H460 xenograft tumors studies revealed that 17i demonstrated robust invivo antitumor efficacy without significant side effects. All the results demonstrated that compound 17i could represent a promising lead for further development.

Phase I Study of Lysine-Specific Demethylase 1 Inhibitor, CC-90011, in Patients with Advanced Solid Tumors and Relapsed/Refractory Non-Hodgkin Lymphoma

Lysine-specific demethylase 1 (LSD1) is implicated in multiple tumor types, and its expression in cancer stem cells is associated with chemoresistance. CC-90011 is a potent, selective, and reversible oral LSD1 inhibitor. We examined CC-90011 in advanced solid tumors and relapsed/refractory (R/R) non-Hodgkin lymphoma (NHL). CC-90011-ST-001 (NCT02875223; 2015-005243-13) is a phase I, multicenter, first-in-human dose-escalation study. Nine dose levels of CC-90011 (1.25-120 mg) given once per week were explored. Primary objectives were to determine safety, maximum tolerated dose (MTD), and/or recommended phase II dose (RP2D). Secondary objectives were to evaluate preliminary efficacy and pharmacokinetics. Fifty patients were enrolled, 49 with solid tumors (27 neuroendocrine tumors/carcinomas) and 1 with R/R NHL. Median age was 61 years (range, 22-75). Patients received a median of three (range, 1-9) prior anticancer regimens. The RP2D was 60 mg once per week; the nontolerated dose (NTD) and MTD were 120 mg once per week and 80 mg once per week, respectively. Grade 3/4 treatment-related toxicities were thrombocytopenia (20%; an on-target effect unassociated with clinically significant bleeding), neutropenia (8%; in the context of thrombocytopenia at the highest doses), and fatigue (2%). The patient with R/R NHL had a complete response, currently ongoing in cycle 34, and 8 patients with neuroendocrine tumors/carcinomas had stable disease ≥6 months, including bronchial neuroendocrine tumors, kidney tumor, and paraganglioma. CC-90011 is well tolerated, with the RP2D established as 60 mg once per week. The MTD and NTD were determined to be 80 mg once per week and 120 mg once per week, respectively. Further evaluation of CC-90011 is warranted.

Nitroreductase-Mediated Release of Inhibitors of Lysine-Specific Demethylase 1 (LSD1) from Prodrugs in Transfected Acute Myeloid Leukaemia Cells.

Lysine‐specific demethylase 1 (LSD1) has evolved as a promising therapeutic target for cancer treatment, especially in acute myeloid leukaemia (AML). To approach the challenge of site‐specific LSD1 inhibition, we developed an enzyme‐prodrug system with the bacterial nitroreductase NfsB (NTR) that was expressed in the virally transfected AML cell line THP1‐NTR+. The cellular activity of the NTR was proven with a new luminescent NTR probe. We synthesised a diverse set of nitroaromatic prodrugs that by design do not affect LSD1 and are reduced by the NTR to release an active LSD1 inhibitor. The emerging side products were differentially analysed using negative controls, thereby revealing cytotoxic effects. The 2‐nitroimidazolyl prodrug of a potent LSD1 inhibitor emerged as one of the best prodrug candidates with a pronounced selectivity window between wild‐type and transfected THP1 cells. Our prodrugs are selectively activated and release the LSD1 inhibitor locally, proving their suitability for future targeting approaches.

New tranylcypromine derivatives containing sulfonamide motif as potent LSD1 inhibitors to target acute myeloid leukemia: Design, synthesis and biological evaluation.

Lysine-specific demethylase 1 (LSD1) is frequently elevated in acute myeloid leukemia (AML) and often leads to tumorigenesis. In recent years, numerous LSD1 inhibitors based on tranylcypromine (TCP) scaffolding have reached clinical trials. Most TCP derivatives were modified at the amino site of cyclopropane motif. Herein, we for the first time introduced a sulfonamide group in TCP benzene ring of series a compounds and performed a systematical study on structure and activity relationships by varying sulfonamide groups. The introduction of sulfonamide significantly increased the targeting capacity of TCP against LSD1. Moreover, we discovered that the Boc attached LSD1 inhibitors (labelled as series b compounds) substantially improved their anti-proliferation capacity towards AML cells. The intracellular thermal shift and LC-MS/MS results implied that Boc enhanced the drug lipophilicity and might be removed under the cancerous acidic environment to release the real pharmacophore, evidenced by the fact that a structurally similar but acidic inert pivaloyl to replace Boc dramatically dropped the cellular anti-proliferation effect. Finally, a benzyl group installed at the amino site to appropriately increase lipophilicity led to trans-4-(2-(benzylamino)-cyclopropyl)-N,N-diethylbenzenesulfonamide a10 that showed better anti-proliferation activity in AML cells and enzymatic inhibition against LSD1. Taken together, our work offers a novel TCP-based structure and provides a prodrug strategy for the discovery of potent LSD1 inhibitors by having appropriate lipophilicity.

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.

Natural protoberberine alkaloids, identified as potent selective LSD1 inhibitors, induce AML cell differentiation.

Natural protoberberine alkaloids were first identified and characterized as potent, selective and cellular active lysine specific demethylase 1 (LSD1) inhibitors. Due to our study, isoquinoline-based tetracyclic scaffold was identified as the key structural element for their anti-LSD1 activity, subtle changes of substituents attached to the core structure led to dramatic changes of the activity. Among these protoberberine alkaloids, epiberberine potently inhibited LSD1 (IC50=0.14±0.01μM) and was highly selective to LSD1 over MAO-A/B. Furthermore, epiberberine could induce the expression of CD86, CD11b and CD14 in THP-1 and HL-60 cells, confirming its cellular activity of inducing acute myeloid leukemia (AML) cells differentiation. Moreover, epiberberine prolonged the survival of THP-1 cells bearing mice and inhibited the growth of AML cells in vivo without obvious global toxicity. These findings give the potential application of epiberberine in AML treatment, and the isoquinoline-based tetracyclic scaffold could be used for further development of LSD1 inhibitors.

1,2,3]Triazolo[4,5-d]pyrimidine derivatives incorporating (thio)urea moiety as a novel scaffold for LSD1 inhibitors

Lysine specific demethylase 1 (LSD1) plays an essential role in maintaining a balanced methylation status at histone tails. Overexpression of LSD1 has been involved in the development of a variety of human diseases, including cancers. Herein, on the basis of our previously developed LSD1 inhibitors, two series of new [1,2,3]triazolo[4,5-d]pyrimidine derivatives incorporating (thio)urea moiety were designed and evaluated for their LSD1 inhibitory abilities, leading to a novel chemical class of LSD1 inhibitors. Among them, compound 31 was found to moderately inhibit LSD1 activity, as well as increase the expression of H3K4me2 at the cellular level. This compound also showed good selectivity against MAO-A/-B, and a panel of kinases such as CDK and BTK. Besides, the MTT assay suggested that the selected compounds could inhibit the proliferation of LSD1-overexpressed cancer cells. Although this class of compounds only showed moderate anti-LSD1 activity in the micromolar range, this work presents a novel chemotype of LSD1 inhibitors with good enzyme selectivity as well as cellular LSD1 inhibitory activity, and could provide a useful template for the development of more potent LSD1 inhibitors for cancer treatment.

TSPAN8 promotes colorectal cancer cell growth and migration in LSD1-dependent manner

AimsColorectal cancer (CRC) is the fourth leading cause of cancer-related mortality worldwide. Over-expression of tetraspanin 8 (TSPAN8) is related to the development and progression of CRC. Whether TSPAN8 plays a role in the growth of colorectal cancer and its epigenetic mechanisms regulated by Lysine Specific Demethylase 1 (LSD1) are still unknown. Main methodsIn this study, RT-PCR and western blotting were used to analyze the mRNA and protein expression, respectively; cell viability was assayed with MTS analysis; cell migration was measured with Trans-well analysis. Key findingsIn the present study, the results indicated that the mRNA levels of LSD1 and TSPAN8 in CRC were significantly higher than that in corresponding adjacent non-tumor tissue. Down-regulation of LSD1 or TSPAN8 as well as LSD1 inhibitor Tranylcypromine hemisulfate inhibited the proliferation and migration of CRC cells, while over-expression of LSD1 exhibited opposite effects. LSD1 up-regulated TSPAN8 expression and reduced H3K9me2 occupancy on the TSPAN8 promoter in CRC cells. TSPAN8 promoted epithelial-mesenchymal transition (EMT) in CRC cells in LSD1-dependent manner. SignificanceTSPAN8 may be considered as a promising biomarker for the diagnosis and prognosis in patients with CRC. Furthermore, TSPAN8 could be a novel therapeutic target and potent LSD1 inhibitors could be designed and developed in the treatment of CRC.