Anticancer Drugs of Lysine Specific Histone Demethylase-1 (LSD1) Display Variable Inhibition on Nucleosome Substrates.

Lysine specific demethylase-1 (LSD1) serves as a regulator of transcription and represents a promising epigenetic target for anticancer treatment. LSD1 inhibitors are in clinical trials for the treatment of Ewing's sarcoma (EWS), acute myeloid leukemia, and small cell lung cancer, and the development of robust inhibitors requires accurate methods for probing demethylation, potency, and selectivity. Here, the inhibition kinetics on the H3K4me2 peptide and nucleosome substrates was examined, comparing the rates of demethylation in the presence of reversible [CC-90011 (PD) and SP-2577 (SD)] and irreversible [ORY-1001 (ID) and tranylcypromine (TCP)] inhibitors. Inhibitors were also subject to viability studies in three human cell lines and Western blot assays to monitor H3K4me2 nucleosome levels in EWS (TC-32) cells, enabling a correlation of drug potency, inhibition in vitro, and cell-based studies. For example, SP-2577, a drug in clinical trials for EWS, inhibits activity on small peptide substrates (Ki = 60 ± 20 nM) using an indirect coupled assay but does not inhibit demethylation on H3K4me2 peptides or nucleosomes using direct Western blot approaches. In addition, the drug has no effect on H3K4me2 levels in TC-32 cells. These data show that SP-2577 is not an LSD1 enzyme inhibitor, although the drug may function independent of demethylation due to its cytotoxic selectivity in TC-32 cells. Taken together, this work highlights the pitfalls of using coupled assays to ascribe a drug's mode of action, emphasizes the use of physiologically relevant substrates in epigenetic drug targeting strategies, and provides insight into the development of substrate-selective inhibitors of LSD1.

Synergistic Effects of Tranylcypromine and NRF2 Inhibitor: A Repurposing Strategy for Effective Cancer Therapy.

Drug repurposing has emerged as an attractive strategy for accelerating drug discovery for cancer treatment. In this study, we investigated combining Tranylcypromine (TCP) with a number of well-characterized drugs. Among these combinations, NRF2 inhibitor (ML385) exhibited synergistic effects in combination with TCP. Specifically, our results showed that the combination of TCP and ML385 resulted in a significant reduction in tumor proliferation while neither drug affected cancer cell growth meaningfully on its own. While further studies are needed to understand fully the extent of the synergistic efficacy, the underlying respective mechanisms and the potential side effects of this approach, our study has yielded a promising start for the development of an effective combination cancer therapy.

Lysine-Specific Demethylase 1 (LSD1) Inhibitors: Peptides as an Emerging Class of Therapeutics.

Aberrant expression of the epigenetic regulator lysine-specific demethylase 1 (LSD1) has been associated with the incidence of many diseases, particularly cancer, and it has evolved as a promising epigenetic target over the years for treatment. The advent of LSD1 inhibitor-based clinical utility began with tranylcypromine, and it is now considered an inevitable scaffold in the search for other irreversible novel LSD1 inhibitors (IMG-7289 or bomedemstat, ORY1001 or iadademstat, ORY-2001 or vafidemstat, GSK2879552, and INCB059872). Moreover, numerous reversible inhibitors for LSD1 have been reported in the literature, including clinical candidates CC-90011 (pulrodemstat) and SP-2577 (seclidemstat). There is parallel mining for peptide-based LSD1 inhibitors, which exploits the opportunities in the LSD1 substrate binding pocket. This Review highlights the research progress on reversible and irreversible peptide/peptide-derived LSD1 inhibitors. For the first time, we comprehensively organized the peptide-based LSD1 inhibitors from the design strategy. Peptide inhibitors of LSD1 are classified as H3 peptide and SNAIL1 peptide derivatives, along with miscellaneous peptides that include naturally occurring LSD1 inhibitors.

Design, synthesis and in vitro/in vivo anticancer activity of tranylcypromine-based triazolopyrimidine analogs as novel LSD1 inhibitors.

Histone lysine specific demethylase 1 (LSD1) is responsible for the demethylation of mono-/dimethylated lysine residue on histone proteins. LSD1 plays an extensive and essential role in the pathogenesis and progression of many human diseases such as cancers, and thus is becoming an attractive therapeutic target for cancer treatment. Tranylcypromine (TCP) is an important chemical template for developing irreversible LSD1 inhibitors, representing a major chemotype of clinical candidates. Here we report a novel pool of TCP derivatives with triazolopyrimidine as a privileged heterocylic motif. Starting from ticagrelor, a clinically available antiplatelet agent, as a hit compound, our medicinal efforts have led to the identification of compound 9j with nanomolar inhibitory potency against LSD1 as well as broad-spectrum antiproliferative activities against tumor cells. Enzyme studies show that compound 9j is selective over MAO-A/B enzymes, and also cellular active to elevate the expression of H3K4me2 by inhibiting LSD1 in cells. Furthermore, in a H1650 xenograft mouse model, oral administration of compound 9j at low 10 and 20 mg/kg dosages could enable a significant reduction in tumor size and a remarkable extension of survival. The current work is expected to provide an additional strategy to achieve new TCP-based LSD1 inhibitors.

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.

Development and evaluation of transdermal delivery system of tranylcypromine for the treatment of depression.

Tranylcypromine (logP = 1.34, MW = 133.19 g/mol) is a monoamine oxidase inhibitor used in treating major depressive disorder and is available only as oral tablets. Transdermal delivery of tranylcypromine minimizes hepatic and gastrointestinal side effects associated with oral dosing and prevents systemic side effects improving patient compliance. A two-day suspension-based transdermal delivery method was developed in this study, and the delivery of tranylcypromine across dermatomed porcine ear skin was evaluated. Different penetration enhancers were screened, namely, isopropyl myristate, oleyl alcohol, oleic acid, and a combination of oleic acid and oleyl alcohol. Isopropyl myristate was chosen as the penetration enhancer, and suspension-based transdermal patches were formulated with acrylate and polyisobutylene pressure-sensitive adhesives by the solvent evaporation method. The release liner and backing membrane were chosen, and the drying time for each patch was optimized. The optimized patches were characterized for their adhesive properties, drying time, peel test, shear strength, and uniformity in drug content. In vitro permeation studies were performed on dermatomed porcine ear skin using vertical static Franz diffusion cells, and the receptor samples were collected at predetermined time points for 48 h. The samples were analyzed in a validated UPLC method. Acrylate-based suspension patch delivered a significantly higher amount of drug (712 ± 21.46 µg/cm2) as compared to passive delivery from drug dissolved in propylene glycol (461.49 ± 75.55 µg/cm2), reaching the two-day therapeutic target. However, the PIB-based suspension patch delivered 559.25 ± 12.37 µg/cm2 of tranylcypromine across the skin but did not reach the required target.

LSD1 Inhibition Enhances the Immunogenicity of Mesenchymal Stromal Cells by Eliciting a dsRNA Stress Response.

Mesenchymal stromal cells (MSCs) are commonly known for their immune-suppressive abilities. However, our group provided evidence that it is possible to convert MSCs into potent antigen presenting cells (APCs) using either genetic engineering or pharmacological means. Given the capacity of UM171a to trigger APC-like function in MSCs, and the recent finding that this drug may modulate the epigenome by inhibiting the lysine-specific demethylase 1 (LSD1), we explored whether the direct pharmacological inhibition of LSD1 could instill APC-like functions in MSCs akin to UM171a. The treatment of MSCs with the LSD1 inhibitor tranylcypromine (TC) elicits a double-stranded (ds)RNA stress response along with its associated responsive elements, including pattern recognition receptors (PRRs), Type-I interferon (IFN), and IFN-stimulated genes (ISGs). The net outcome culminates in the enhanced expression of H2-Kb, and an increased stability of the cell surface peptide: MHCI complexes. As a result, TC-treated MSCs stimulate CD8 T-cell activation efficiently, and elicit potent anti-tumoral responses against the EG.7 T-cell lymphoma in the context of prophylactic vaccination. Altogether, our findings reveal a new pharmacological protocol whereby targeting LSD1 in MSCs elicits APC-like capabilities that could be easily exploited in the design of future MSC-based anti-cancer vaccines.

Insufficient recovery of monoamine oxidase in a bioequivalence study of the monoamine oxidase inhibitor tranylcypromine: Recommendation of the tranylcypromine enantiomer test.

OBJECTIVE: To investigate the recovery of monoamine oxidase (MAO) activity in the liver and gut of healthy subjects after a dose of 10 mg of the irreversible MAO inhibitor tranylcypromine (TCP). MATERIALS AND METHODS: A bioequivalence study of TCP with a wash-out of 1 week between 2 doses of 10 mg TCP was re-analyzed for changes of the plasma concentrations of TCP enantiomers. Plasma concentrations of (+)-TCP and the ratio of (+)-TCP and (-)-TCP plasma concentrations were used as a measure of MAO activity because (+)-TCP is a more effective suicide inhibitor of MAO than (-)-TCP and, therefore considerably more metabolized by MAO. RESULTS: The area under the curve from the first to the last measured concentration (AUCt) and the maximum plasma concentration (Cmax) of (+)-TCP increased significantly in the second dose (p < 0.0001) by 43.1% (11.8%) and 66.5% (26.4%), respectively, (mean with 95%CI in each case). The ratios (+)-TCP/(-)-TCP of AUCt and Cmax also increased significantly (p < 0.0001) by 27.3% (6.4%) and 25.9% (6.2%), respectively. No changes were found for the half-lives (T1/2) of both enantiomers. CONCLUSION: For the first dose, MAO is the main drug-metabolizing enzyme of (+)-TCP. MAO activity in the liver and gut is not completely recovered within 1 week after 1 dose of TCP. One week of wash-out may be insufficient in bioequivalence studies of irreversible MAO inhibitors. Prolonged inhibition of MAO after the treatment with irreversible MAO inhibitors may explain drug interactions during the switch from another MAO inhibitor to TCP. Enantiomer plasma concentrations of TCP after a dose of racemic TCP may be used as a test for gastrointestinal and hepatic MAO activity.

Heterocycle-containing tranylcypromine derivatives endowed with high anti-LSD1 activity.

As regioisomers/bioisosteres of 1a, a 4-phenylbenzamide tranylcypromine (TCP) derivative previously disclosed by us, we report here the synthesis and biological evaluation of some (hetero)arylbenzoylamino TCP derivatives 1b-6, in which the 4-phenyl moiety of 1a was shifted at the benzamide C3 position or replaced by 2- or 3-furyl, 2- or 3-thienyl, or 4-pyridyl group, all at the benzamide C4 or C3 position. In anti-LSD1-CoREST assay, all the meta derivatives were more effective than the para analogues, with the meta thienyl analogs 4b and 5b being the most potent (IC50 values = 0.015 and 0.005 µM) and the most selective over MAO-B (selectivity indexes: 24.4 and 164). When tested in U937 AML and prostate cancer LNCaP cells, selected compounds 1a,b, 2b, 3b, 4b, and 5a,b displayed cell growth arrest mainly in LNCaP cells. Western blot analyses showed increased levels of H3K4me2 and/or H3K9me2 confirming the involvement of LSD1 inhibition in these assays.

An Update of Lysine Specific Demethylase 1 Inhibitor: A Patent Review (2016-2020).

BACKGROUND: As a FAD (Flavin Adenine Dinucleotide) - dependent histone demethylase discovered in 2004, LSD1 (lysine-specific demethylase 1) was reported to be overexpressed in diverse tumors, regulating target genes transcription associated with cancer development. Hence, LSD1 targeted inhibitors may represent a new insight in anticancer drug discovery. For these reasons, researchers in both the pharmaceutical industry and academia have been actively pursuing LSD1 inhibitors in the quest for new anti-cancer drugs. OBJECTIVES: This review summaries patents about LSD1 inhibitors in recent 5 years in the hope of providing a reference for LSD1 researchers to develop new modulators of LSD1 with higher potency and fewer adverse effects. METHODS: This review collects LSD1 inhibitors disclosed in patents since 2016. The primary ways of patent searching are Espacenet®, Google Patents, and CNKI. RESULTS: This review covers dozens of patents related to LSD1 inhibitors in recent five years. The compound structures are mainly divided into TCP (Tranylcypromine) derivatives, imidazole derivatives, pyrimidine derivatives, and other natural products and peptides. Meanwhile, the compounds that have entered the clinical phase are also described. CONCLUSION: Most of the compounds in these patents have been subjected to activity analysis with LSD1 and multi-cell lines, showing good antitumor activity in vitro and in vivo. These patents exhibited the structural diversity of LSD1 inhibitors and the potential of natural products as novel LSD1 inhibitors.

Repurposing antidepressants for anticancer drug discovery.

Drug repurposing is an attractive strategy for identifying new indications for existing drugs. Three approved antidepressants have advanced into clinical trials for cancer therapy. In particular, further medicinal chemistry efforts with tranylcypromine (TCP) have led to the discovery of several TCP-based histone lysine specific demethylase 1 (LSD1) inhibitors that display therapeutic promise for treating cancer in the clinic. Thus repurposing antidepressants could be a promising strategy for cancer treatment. In this review, we illustrate the anticancer mechanisms of action of antidepressants and also discuss the challenges and future directions of repurposing antidepressants for anticancer drug discovery, to provide an overview of approved antidepressant cancer therapies.

60 Years of Combining Tranylcypromine: A Systematic Review of Available Evidence.

BACKGROUND: Tranylcypromine is the only irreversible monoamine oxidase inhibitor that is approved in the United States and in Europe for the management of treatment-resistant major depressive disorder. Comprehensive data in the literature regarding the efficacy and tolerability of tranylcypromine (TCP) combination strategies have not been systematically investigated yet. METHODS: We conducted a systematic review of available literature based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Study types considered eligible for inclusion were studies that reported information on efficacy and/or tolerability/adverse effects of pharmacological TCP add-on or coadministration strategies among people with psychiatric disorders. RESULTS: Ninety-six articles were included in qualitative analyses. A relevant body of evidence shows that TCP combined with first- and second-generation antipsychotics seems relatively safe and might have beneficial effects in some patients with depressive disorders, although caution is needed with some second-generation antipsychotics that have proserotonergic activity. Although evidence is not entirely consistent, amitriptyline as add-on agent might be efficacious and associated with a low rate of severe adverse events. Although available data from case reports are scarce, certain other agents, such as trazodone, but also lithium, seem to have a good risk-benefit profile with regard to TCP that should be further investigated in the context of high-quality studies. CONCLUSIONS: Any combination of a psychotropic with TCP should be preceded by an evaluation of drug-to-drug interaction and an informed consent process and followed by close monitoring. Before any combination strategy, doctors should reevaluate factors of pseudo-treatment resistance, such as rapid-metabolizing status, noncompliance, trauma, alternative diagnosis, or drug abuse.

Role of CYP2A6 in Methimazole Bioactivation and Hepatotoxicity.

Methimazole (MMI) is a widely used antithyroid drug, but it can cause hepatotoxicity by unknown mechanisms. Previous studies showed that the hepatic metabolism of MMI produces N-methylthiourea, leading to liver damage. However, the specific enzyme responsible for the production of the toxic metabolite N-methylthiourea is still unclear. In this study, we screened cytochromes P450 (CYPs) in N-methylthiourea production from MMI. CYP2A6 was identified as the key enzyme in catalyzing MMI metabolism to produce N-methylthiourea. When mice were pretreated with a CYP2A6 inhibitor, formation of N-methylthiourea from MMI was remarkably reduced. Consistently, the CYP2A6 inhibitor prevented MMI-induced hepatotoxicity. These results demonstrated that CYP2A6 is essential in MMI bioactivation and hepatotoxicity.

Transdifferentiation of goat ear fibroblasts into lactating mammary epithelial cells induced by small molecule compounds.

Mammary epithelial cells are the only cells in the mammary glands that are capable of lactation and they are ideal for studying cellular and molecular biology mechanisms during growth, development and lactation of the mammary glands. The limiting factors in most of the currently available mammary epithelial cells are low cell viability, transgenerational efficiency and lactation function that renders them unsuitable for subsequent studies on mammary gland's cellular and lactation mechanisms and utilizing them as bioreactors. Hence, new methods are required to obtain mammary epithelial cells with high transgenerational efficiency and lactation function. In this study, transdifferentiation of goat ear fibroblasts (GEFs) into goat mammary epithelial cells (CiMECs) was induced in only eight days by five small molecule compounds, including 500 µg/mL VPA, 10 µM Tranylcypromine, 10 µM Forskolin, 1 µM TTNPB, 10 µM RepSox. Morphological observation, marker genes comparison, specific antigen expression and comparison of gene expression levels by transcriptome sequencing between the two types of cells that led to the primary deduction that CiMECs have similar biological properties to goat mammary epithelial cells (GMECs) and comparatively more lactation capacity. Therefore, we establish a novel reprogramming route to convert fibroblasts into CiMECs under fully chemically conditions. This study is expected to provide an in vitro platform for understanding cellular mechanisms such as mammary epithelial cells' fate determination and developmental differentiation, and also to find a new way to obtain a large number of functional mammary epithelial cells in vitro.

Cardiovascular Effects of Combining Subcutaneous or Intravenous Esketamine and the MAO Inhibitor Tranylcypromine for the Treatment of Depression: A Retrospective Cohort Study.

BACKGROUND: (Es)ketamine and monoamine oxidase inhibitors (MAOIs), e.g., tranylcypromine, are therapeutic options for treatment-resistant major depression. Simultaneous administration is currently not recommended because of concern about hypertensive crises. OBJECTIVE: Our objective was to evaluate whether changes in systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) during esketamine administration differed between patients who concomitantly received tranylcypromine and those who did not. METHODS: This was a retrospective cohort study utilizing cardiovascular monitoring data from inpatients treated for severe depression in unipolar, bipolar, and schizoaffective disorder. Primary outcomes were change in mean BP and HR during the first hour after intravenous or subcutaneous esketamine administration compared with baseline, controlled for confounders. Secondary analyses quantify differences in absolute BP during esketamine treatment and comparisons of BP peaks, temporal effects, and intraindividual comparisons before and after tranylcypromine initiation. RESULTS: Our analysis included 509 esketamine administrations in 43 patients, 14 of whom concomitantly received tranylcypromine. Controlling for creatinine and age, mean ± standard deviation (SD) BP changes were significantly increased by concomitant tranylcypromine treatment (ΔSBP: F[1,503] = 86.73, p < 0.001; ΔDBP: F[1,503] = 55.71, p < 0.001), but HR remained unaffected. Mean SBP change during esketamine administration was 2.96 ± 18.11 mmHg in patients receiving tranylcypromine (TCP+) and -8.84 ± 11.31 mmHg in those who did not (TCP-). Changes in DBP were -2.81 ± 11.20 mmHg for TCP+ and -10.77 ± 9.13 mmHg for TCP-. Moreover, we found a significant dose-response relationship between tranylcypromine dose and BP (SBP: B = 0.35, standard error [SE] = 0.12, 95% confidence interval [CI] 0.12-0.60, p = 0.004; adjusted R2 = 0.11, p = 0.008; DBP: B = 0.21, SE = 0.08, 95% CI 0.06-0.36, p = 0.007; adjusted R2 = 0.08; p = 0.023). CONCLUSIONS: Although statistically significant changes in BP were identified in patients receiving tranylcypromine and esketamine, these changes were clinically insignificant. Thus, combining esketamine and this MAOI appears to be safe at standard doses. The dose-response relationship calls for caution with higher doses of tranylcypromine.

Inhibition of Epigenetic Modifiers LSD1 and HDAC1 Blocks Rod Photoreceptor Death in Mouse Models of Retinitis Pigmentosa.

Epigenetic modifiers are increasingly being investigated as potential therapeutics to modify and overcome disease phenotypes. Diseases of the nervous system present a particular problem as neurons are postmitotic and demonstrate relatively stable gene expression patterns and chromatin organization. We have explored the ability of epigenetic modifiers to prevent degeneration of rod photoreceptors in a mouse model of retinitis pigmentosa (RP), using rd10 mice of both sexes. The histone modification eraser enzymes lysine demethylase 1 (LSD1) and histone deacetylase 1 (HDAC1) are known to have dramatic effects on the development of rod photoreceptors. In the RP mouse model, inhibitors of these enzymes blocked rod degeneration, preserved vision, and affected the expression of multiple genes including maintenance of rod-specific transcripts and downregulation of those involved in inflammation, gliosis, and cell death. The neuroprotective activity of LSD1 inhibitors includes two pathways. First, through targeting histone modifications, they increase accessibility of chromatin and upregulate neuroprotective genes, such as from the Wnt pathway. We propose that this process is going in rod photoreceptors. Second, through nonhistone targets, they inhibit transcription of inflammatory genes and inflammation. This process is going in microglia, and lack of inflammation keeps rod photoreceptors alive.SIGNIFICANCE STATEMENT Retinal degenerations are a leading cause of vision loss. RP is genetically very heterogeneous, and the multiple pathways leading to cell death are one reason for the slow progress in identifying suitable treatments for patients. Here we demonstrate that inhibition of LSD1and HDAC1 in a mouse model of RP leads to preservation of rod photoreceptors and visual function, retaining of expression of rod-specific genes, and with decreased inflammation, cell death, and Müller cell gliosis. We propose that these epigenetic inhibitors cause more open and accessible chromatin, allowing expression of neuroprotective genes. A second mechanism that allows rod photoreceptor survival is suppression of inflammation by epigenetic inhibitors in microglia. Manipulation of epigenetic modifiers is a new strategy to fight neurodegeneration in RP.

Dynamic methylation of histone H3K18 in differentiating Theileria parasites.

Lysine methylation on histone tails impacts genome regulation and cell fate determination in many developmental processes. Apicomplexa intracellular parasites cause major diseases and they have developed complex life cycles with fine-tuned differentiation events. Yet, apicomplexa genomes have few transcription factors and little is known about their epigenetic control systems. Tick-borne Theileria apicomplexa species have relatively small, compact genomes and a remarkable ability to transform leucocytes in their bovine hosts. Here we report enriched H3 lysine 18 monomethylation (H3K18me1) on the gene bodies of repressed genes in Theileria macroschizonts. Differentiation to merozoites (merogony) leads to decreased H3K18me1 in parasite nuclei. Pharmacological manipulation of H3K18 acetylation or methylation impacted parasite differentiation and expression of stage-specific genes. Finally, we identify a parasite SET-domain methyltransferase (TaSETup1) that can methylate H3K18 and represses gene expression. Thus, H3K18me1 emerges as an important epigenetic mark which controls gene expression and stage differentiation in Theileria parasites.

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.

Inhibition of monoamine oxidase attenuates social defeat-induced memory impairment in goldfish, (Carassius auratus): A possible involvement of synaptic proteins and BDNF.

Social defeat (SD) has been implicated in different modulatory effects of physiology and behaviour including learning and memory. We designed an experiment to test the functional role of monoamine oxidase (MAO) in regulation of synaptic transmission, synaptic plasticity and memory in goldfish Carassius auratus. To test this, individuals were divided into three groups: (i) control; (ii) social defeat (SD) group (individuals were subjected to social defeat for 10 min by Pseudotropheus demasoni) and (iii) SD + MAO inhibitor pre-treated group. All experimental groups were subjected to spatial learning and then memory. Our results suggest that SD affects a spatial learning and memory, whereas SD exerts no influence on MAOI pre-treated group. In addition, we noted that the expression of monoamine oxidase-A (MAO-A) was up-regulated and level of serotonin (5-hydroxytryptamine; 5-HT), expression of serotonin transporter (SERT), synaptophysin (SYP), synaptotagmin -1 (SYT-1), N-methyl-D-asparate (NMDA) receptors subunits (NR2A and NR2B), postsynaptic density-95 (PSD-95) and brain-derived neurotrophic factor (BDNF) were reduced by SD, while MAOIs pretreatment protects the effect of SD. Taken together, our results suggest that MAO is an essential component in the serotonergic system that finely tunes the level of 5-HT, which further regulates the molecules involving in synaptic transmission, synaptic plasticity and memory.