Discovery of new tranylcypromine derivatives as highly potent LSD1 inhibitors.

Tranylcypromine (TCP)-based structural modifications lead to the discovery of new LSD1 inhibitors, of which compounds 26b and 29b effectively inhibit LSD1 with the IC50 values of 17 and 11 nM, respectively and also show good selectivity over MAO-B. Mechanistic studies showed that compound 29b concentration-dependently induced H3K4me1/2 accumulation in LSD1 overexpressed MGC-803 cells and also inhibited metastasis of MGC-803 cells. Collectively, both compounds could be promising lead compounds for further investigation.

Synthesis of Carboxamide-Containing Tranylcypromine Analogues as LSD1 (KDM1A) Inhibitors Targeting Acute Myeloid Leukemia.

Lysine-specific demethylase 1 (LSD1/KDM1A) oxidatively removes methyl groups from histone proteins, and its aberrant activity has been correlated with cancers including acute myeloid leukemia (AML). We report a novel series of tranylcypromine analogues with a carboxamide at the 4-position of the aryl ring. These compounds, such as 5 a and 5 b with benzyl and phenethylamide substituents, respectively, had potent sub-micromolar IC50 values for the inhibition of LSD1 as well as cell proliferation in a panel of AML cell lines. The dose-dependent increase in cellular expression levels of H3K4me2, CD86, CD11b and CD14 supported a mechanism involving LSD1 inhibition. The tert-butyl and ethyl carbamate derivatives of these tranylcypromines, although inactive in LSD1 inhibition, were of similar potency in cell-based assays with a more rapid onset of action. This suggests that carbamates can act as metabolically labile tranylcypromine prodrugs with superior pharmacokinetics.

Tranylcypromine and 6-trifluoroethyl thienopyrimidine hybrid as LSD1 inhibitor.

Tranylcypromine moiety extracted from LSD1 inhibitors and 6-trifluoroethyl thienopyrimidine moiety from menin-MLL1 PPI inhibitors were merged to give new chemotypes for medicinal chemistry study. Among 15 new compounds prepared in this work, some exhibited nanomolar LSD1 activity and good selectivity over MAO-A/B, low micromolar menin-MLL1 PPI inhibitory activity, as well as submicromolar MV4-11 antiprofilative activities. Intracellular LSD1 engagement of compounds with higher enzymatic and antiproliferative activities was confirmed by CD86 mRNA up-regulation experiments.

Structure-activity studies on N-Substituted tranylcypromine derivatives lead to selective inhibitors of lysine specific demethylase 1 (LSD1) and potent inducers of leukemic cell differentiation.

FAD-dependent lysine-specific demethylase 1 (LSD1) is overexpressed or deregulated in many cancers such as AML and prostate cancer and hence is a promising anticancer target with first inhibitors in clinical trials. Clinical candidates are N-substituted derivatives of the dual LSD1-/monoamine oxidase-inhibitor tranylcypromine (2-PCPA) with a basic amine function in the N-substituent. These derivatives are selective over monoamine oxidases. So far, only very limited information on structure-activity studies about this important class of LSD1 inhibitors is published in peer reviewed journals. Here, we show that N-substituted 2-PCPA derivatives without a basic function or even a polar group are still potent inhibitors of LSD1 in vitro and effectively inhibit colony formation of leukemic cells in culture. Yet, these lipophilic inhibitors also block the structurally related monoamine oxidases (MAO-A and MAO-B), which may be of interest for the treatment of neurodegenerative disorders, but this property is undesired for applications in cancer treatment. The introduction of a polar, non-basic function led to optimized structures that retain potent LSD1 inhibitors but exhibit selectivity over MAOs and are highly potent in the suppression of colony formation of cultured leukemic cells. Cellular target engagement is shown via a Cellular Thermal Shift Assay (CETSA) for LSD1.

Discovery of tranylcypromine analogs with an acylhydrazone substituent as LSD1 inactivators: Design, synthesis and their biological evaluation.

Lysine specific demethylase 1 (LSD1), the first identified histone demethylase, plays an important role in epigenetic regulation of gene activation and repression, has been reported to be up-regulated and involved in numbers of solid malignant tumors. In this study, we identified a series of phenylalanyl hydrazones based LSD1 inhibitors, and the most potent one, compound 4q, can inactivate LSD1 with IC50 = 91.83 nM. In cellular level, compound 4q can induce the accumulation of CD86 as well as H3K4me2, and inhibit gastric cancer cell proliferation by inactivating LSD1. Our findings indicated that compound 4q may serve as a potential leading compound to target LSD1 overexpressed gastric cancer.

Development of (4-Cyanophenyl)glycine Derivatives as Reversible Inhibitors of Lysine Specific Demethylase 1.

Inhibition of lysine specific demethylase 1 (LSD1) has been shown to induce the differentiation of leukemia stem cells in acute myeloid leukemia (AML). Irreversible inhibitors developed from the nonspecific inhibitor tranylcypromine have entered clinical trials; however, the development of effective reversible inhibitors has proved more challenging. Herein, we describe our efforts to identify reversible inhibitors of LSD1 from a high throughput screen and subsequent in silico modeling approaches. From a single hit (12) validated by biochemical and biophysical assays, we describe our efforts to develop acyclic scaffold-hops from GSK-690 (1). A further scaffold modification to a (4-cyanophenyl)glycinamide (e.g., 29a) led to the development of compound 32, with a Kd value of 32 nM and an EC50 value of 0.67 µM in a surrogate cellular biomarker assay. Moreover, this derivative does not display the same level of hERG liability as observed with 1 and represents a promising lead for further development.

Novel potent inhibitors of the histone demethylase KDM1A (LSD1), orally active in a murine promyelocitic leukemia model.

BACKGROUND: Histone lysine demethylases (KDMs) are well-recognized targets in oncology drug discovery. They function at the post-translation level controlling chromatin conformation and gene transcription. KDM1A is a flavin adenine dinucleotide-dependent amine oxidase, overexpressed in several tumor types, including acute myeloid leukemia, neuroblastoma and non-small-cell lung cancer. Among the many known monoamine oxidase inhibitors screened for KDM1A inhibition, tranylcypromine emerged as a moderately active hit, which irreversibly binds to the flavin adenine dinucleotide cofactor. MATERIAL & METHODS: The KDM1A inhibitors 5a-w were synthesized and tested in vitro and in vivo. The biochemical potency was determined, modulation of target in cells was demonstrated on KDM1A-dependent genes and the anti-clonogenic activity was performed in murine acute promyelocytic Leukemia (APL) blasts. An in vivo efficacy experiment was conducted using an established murine promyelocytic leukemia model. RESULTS: We report a new series of tranylcypromine derivatives substituted on the cyclopropyl moiety, endowed with high potency in both biochemical and cellular assays. CONCLUSION: The most interesting derivative (5a) significantly improved survival rate after oral administration in a murine model of promyelocitic leukemia.

Fluorinated tranylcypromine analogues as inhibitors of lysine-specific demethylase 1 (LSD1, KDM1A).

We report a series of tranylcypromine analogues containing a fluorine in the cyclopropyl ring. A number of compounds with additional m- or p-substitution of the aryl ring were micromolar inhibitors of the LSD1 enzyme. In cellular assays, the compounds inhibited the proliferation of acute myeloid leukemia cell lines. Increased levels of the biomarkers H3K4me2 and CD86 were consistent with LSD1 target engagement.

Novel Tranylcypromine/Hydroxylcinnamic Acid Hybrids as Lysine-Specific Demethylase 1 Inhibitors with Potent Antitumor Activity.

Novel tranylcypromine/hydroxylcinnamic acid hybrids 15a, b, and 19a-l were designed and synthesized by connecting tranylcypromine with hydroxylcinnamic acid, and their biological activities were evaluated. The in vitro assay of their inhibitory activities against lysine-specific demethylase 1 (LSD1) showed that most of the target compounds displayed high potency with IC50 values ranging from submicromolar to single-digit micromolar levels. In particular, compound 19l had robust, selective LSD1 inhibitory activity, which was obviously higher than the inhibitory activity against homologues monoamine oxidase-A (MAO-A) and MAO-B, respectively. Furthermore, the most potent compound 19l selectively inhibited cancer cell but not nontumor colon cell proliferation in vitro. In addition, compound 19l also dose-dependently increased the expression of H3K4me2 at the cellular level. Our findings suggest that tranylcypromine/hydroxylcinnamic acid hybrids as LSD1 inhibitors may hold great promise as therapeutic agents for the treatment of human cancers.

RN-1, a potent and selective lysine-specific demethylase 1 inhibitor, increases γ-globin expression, F reticulocytes, and F cells in a sickle cell disease mouse model.

Increased levels of fetal hemoglobin are associated with decreased symptoms and increased lifespan in patients with sickle cell disease (SCD). Hydroxyurea, the only drug currently approved for SCD, is not effective in a large fraction of patients, and therefore, new agents are urgently needed. Recently it was found that lysine demethylase 1, an enzyme that removes monomethyl and dimethyl residues from the lysine 4 residue of histone H3, is a repressor of γ-globin gene expression. In this article, we have compared the ability of tranylcypromine (TCP) and a more potent TCP derivative, RN-1, to increase γ-globin expression in cultured baboon erythroid progenitor cells and in the SCD mouse model. The results indicate that the ability of RN-1 to induce F cells and γ-globin mRNA in SCD mice is similar to that of decitabine, the most powerful fetal hemoglobin-inducing drug known, and greater than that of either TCP or hydroxyurea. We conclude that RN-1 and other lysine demethylase 1 inhibitors may be promising new γ-globin-inducing agents for the treatment of SCD that warrant further studies in other preclinical models, such as nonhuman primates.

Tranylcypromine substituted cis-hydroxycyclobutylnaphthamides as potent and selective dopamine D3 receptor antagonists.

We report a class of potent and selective dopamine D3 receptor antagonists based upon tranylcypromine. Although tranylcypromine has a low affinity for the rat D3 receptor (K(i) = 12.8 µM), our efforts have yielded (1R,2S)-11 (CJ-1882), which has K(i) values of 2.7 and 2.8 nM at the rat and human dopamine D3 receptors, respectively, and displays respective selectivities of >10000-fold and 223-fold over the rat and human D2 receptors. Evaluation in a ß-arrestin functional assay showed that (1R,2S)-11 is a potent and competitive antagonist at the human D3 receptor.

An overview of phenylcyclopropylamine derivatives: biochemical and biological significance and recent developments.

trans-2-Phencylcyclopropylamine (2-PCPA), a potent, clinically used antidepressant, affects monoamine neurotransmitter levels by inhibiting the main metabolizing enzymes, monoamine oxidases (MAOs). However, the antidepressant action of this compound was not fully explained by its effects on MAOs due to its wide variety of biological effects. 2-PCPA also affects depression-associated pathophysiological pathways, and linked with increased levels of trace amines in brain, upregulation of GABAB receptors (where GABA is gamma amino butyric acid), modulation of phospholipid metabolism, and interference with various cytochrome P450 (CYP) enzymes. Consequently, despite its adverse effects and limited clinical applicability, 2-PCPA has attracted interest as a structural scaffold for the development of mechanism-based inhibitors of various enzymes, including lysine-specific demethylase 1 (LSD1), which is a possible target for cancer chemotherapy. In the recent years, many reports have appeared in the literature based on 2-PCPA scaffold and their potential medicinal implications. This review mainly focuses on the medicinal chemistry aspects including drug design, structure-activity relationships (SAR), biological and biochemical properties, and mechanism of actions of 2-PCPA and its derivatives. Furthermore, we also highlight recent advance in this area and discuss their future applications for beneficial therapeutic effects.

TCP-FA4: a derivative of tranylcypromine showing improved blood-brain permeability.

A variety of approaches have been taken to improve the brain penetration of pharmaceutical agents. The amphipathic character of a compound can improve its interaction with the lipid bilayer within cell membranes, and as a result improve permeability. Fatty acid chains or lipoamino acids of various lengths were attached to tranylcypromine (TCP), in an attempt to improve the blood-brain barrier (BBB) permeability by increasing the lipophilicity as well as the amphiphatic character of the drug. TCP-FA4, one of the derivatives containing a four carbon alkyl acid chain, showed the greatest improvement in permeability. This molecule was slightly neuroprotective in a beta-amyloid-induced neurodegeneration assay and may also be capable of upregulating brain derived neurotrophic factor (BDNF), as indicated by cell culture assays using human umbilical vein endothelial cells. Since decreased levels of BDNF are observed in many CNS disorders, and direct injection of BDNF is not a viable option due to its poor permeability across the BBB, small molecules capable of regulating BDNF that also cross the BBB may be an interesting treatment option.

Selective 5-hydroxytryptamine 2C receptor agonists derived from the lead compound tranylcypromine: identification of drugs with antidepressant-like action.

We report here the design, synthesis, and pharmacological properties of a series of compounds related to tranylcypromine (9), which itself was discovered as a lead compound in a high-throughput screening campaign. Starting from 9, which shows modest activity as a 5-HT(2C) agonist, a series of 1-aminomethyl-2-phenylcyclopropanes was investigated as 5-HT(2C) agonists through iterative structural modifications. Key pharmacophore feature of this new class of ligands is a 2-aminomethyl-trans-cyclopropyl side chain attached to a substituted benzene ring. Among the tested compounds, several were potent and efficacious 5-HT(2C) receptor agonists with selectivity over both 5-HT(2A) and 5-HT(2B) receptors in functional assays. The most promising compound is 37, with 120- and 14-fold selectivity over 5-HT(2A) and 5-HT(2B), respectively (EC(50) = 585, 65, and 4.8 nM at the 2A, 2B, and 2C subtypes, respectively). In animal studies, compound 37 (10-60 mg/kg) decreased immobility time in the mouse forced swim test.

Facile synthesis of substituted trans-2-arylcyclopropylamine inhibitors of the human histone demethylase LSD1 and monoamine oxidases A and B.

A facile synthetic route to substituted trans-2-arylcyclopropylamines was developed to provide access to mechanism-based inhibitors of the human flavoenzyme oxidase lysine-specific histone demethylase LSD1 and related enzyme family members such as monoamine oxidases A and B.

Enhancement of drug affinity for cell membranes by conjugation with lipoamino acids II. Experimental and computational evidence using biomembrane models.

Lipoamino acids (LAAs) are promoieties able to enhance the amphiphilicity of drugs, facilitating their interaction with cell membranes. Experimental and computational studies were carried out on two series of lipophilic amide conjugates between a model drug (tranylcypromine, TCP) and LAA or alkanoic acids containing a short, medium or long alkyl side chain (C-4 to C-16). The effects of these compounds were evaluated by monolayer surface tension analysis and differential scanning calorimetry using dimyristoylphosphatidylcholine monolayers and liposomes as biomembrane models. The experimental results were related to independent calculations to determine partition coefficient and blood-brain partitioning. The comparison of TCP-LAA conjugates with the related series of TCP alkanoyl amides confirmed that the ability to interact with the biomembrane models is not due to the mere increase of lipophilicity, but mainly to the amphipatic nature and the kind of LAA residue.

Fluorinated phenylcyclopropylamines. 2. Effects of aromatic ring substitution and of absolute configuration on inhibition of microbial tyramine oxidase.

A series of para-substituted diastereopure cis- and trans-2-fluoro-2-arylcyclopropylamines were synthesized and these were investigated as inhibitors of microbial tyramine oxidase from Arthrobacter sp. All compounds were shown to be competitive inhibitors of this enzyme. The nature of the para-substituents in the more potent trans-isomer (cis-relationship between fluorine and the amino group) of 2-fluoro-2-arylcyclopropylamine influenced the inhibitory potency in a consistent fashion. Thus, electron-withdrawing groups (F, Cl) slightly decreased the activity, while the methyl group (+ I substituent) increased the activity by a factor of ca. 7 compared to trans-2-fluoro-2-phenylcyclopropylamine and by a factor of 90 compared to tranylcypromine. Activity also was strongly dependent on the absolute configuration. The (1S,2S)-enantiomer of 2-fluoro-2-phenylcyclopropylamine was an excellent inhibitor of tyramine oxidase whereas the (1R,2R)-enantiomer was essentially devoid of activity.

Fluorinated phenylcyclopropylamines. Part 3: Inhibition of monoamine oxidase A and B.

Fluorinated phenylcyclopropylamines and alkylamines were examined as inhibitors of recombinant human liver monoamine oxidase A (MAO A) and B (MAO B). For a series of trans- and cis-2-fluoro-2-phenylcyclopropylamine analogues, the presence of fluorine attached to a cyclopropane ring was found to result in an increase in inhibitory activity towards both MAO A and B. In addition, p-substitution of electron-withdrawing groups such as Cl and F in the aromatic ring of the trans-isomers increased the inhibition of both enzymes. (1S,2S)-2-Fluoro-2-phenylcyclopropylamine was a more potent inhibitor of both MAO A and B than was the (1R,2R)-enantiomer, indicating that the presence of fluorine has no influence on the enantioselectivity of MAO inhibition, since a similar effect of stereochemistry has been reported for tranylcypromine. Interestingly, fluorination at the 2-position of 1-phenycyclopropylamine, which is known as a selective inhibitor of MAO B relative to MAO A, reversed the selectivity and resulted in a potent inhibitor selective for MAO A. All inhibitors showed time- and concentration-dependent inhibition for both enzymes, with the exception of trans-2-fluoro-2-phenylcyclopropyl ethylamine, which acts as a competitive and reversible MAO A selective inhibitor.

Fluorinated phenylcyclopropylamines. 1. Synthesis and effect of fluorine substitution at the cyclopropane ring on inhibition of microbial tyramine oxidase.

Two series of diastereopure phenylcyclopropylamine analogues, 2-fluoro-2-phenylcyclopropylamines and 2-fluoro-2-phenylcyclopropylalkylamines, as well as 2-fluoro-1-phenylcyclopropylamines and 2-fluoro-1-phenylcyclopropylmethylamines, were synthesized in order to study the effects of fluorine substitution on monoamine oxidase inhibition. Inhibitory activity was assayed using commercially available microbial tyramine oxidase. Characterization of tyramine oxidase, carried out prior to the inhibition experiments, confirmed earlier suggestions that this enzyme is a semicarbazide-sensitive copper-containing monoamine oxidase. The most potent competitive inhibitor was trans-2-fluoro-2-phenylcyclopropylamine, which had an IC(50) value 10 times lower than that of the nonfluorinated compound, tranylcypromine. 2-Fluoro-1-phenylcyclopropylmethylamine was found to be a weak noncompetitive inhibitor of tyramine oxidase. The presence of a free amino group, directly bonded to the cyclopropane ring, and a fluorine atom in a relationship cis to the amino group were structural features that increased tyramine oxidase inhibition.

4-Methoxytranylcypromine, a monoamine oxidase inhibitor: effects on biogenic amines in rat brain following chronic administration.

4-Methoxytranylcypromine (MeOTCP), a ring-substituted analogue of the monoamine oxidase (MAO)-inhibiting antidepressant tranylcypromine (TCP), was investigated in the rat after chronic (28-day) administration and the results compared with those observed with TCP using equimolar doses of both drugs. At the dose tested, MeOTCP produced a greater inhibition of type A MAO in brain, liver, and heart than did TCP. Both drugs caused a reduction in the specific binding to beta-adrenergic and tryptamine receptors in cortex from brain. MeOTCP produced a marked increase in 5-hydroxytryptamine levels in pons-medulla, hypothalamus, and hippocampus relative to values in vehicle-treated rats and also produced a significant increase in these levels over those observed in the TCP-treated rats.