IL-13 and the hydroperoxy fatty acid 13(S)HpODE play crucial role in inducing an apoptotic pathway in cancer cells involving MAO-A/ROS/p53/p21 signaling axis

This study depicted the effect of IL-13 and 13(S)HpODE (the endogenous product during IL-13 activation) in the process of cancer cell apoptosis. We examined the role of both IL-13 and 13(S)HpODE in mediating apoptotic pathway in three different in vitro cellular models namely A549 lung cancer, HCT116 colorectal cancer and CCF52 GBM cells. Our data showed that IL-13 promotes apoptosis of A549 lung carcinoma cells through the involvement of 15-LO, PPARγ and MAO-A. Our observations demonstrated that IL-13/13(S)HpODE stimulate MAO-A-mediated intracellular ROS production and p53 as well as p21 induction which play a crucial role in IL-13-stimulated A549 cell apoptosis. We further showed that 13(S)HpODE promotes apoptosis of HCT116 and CCF52 cells through the up-regulation of p53 and p21 expression. Our data delineated that IL-13 stimulates p53 and p21 induction which is mediated through 15-LO and MAO-A in A549 cells. In addition, we observed that PPARγ plays a vital role in apoptosis as well as in p53 and p21 expression in A549 cells in the presence of IL-13. We validated our observations in case of an in vivo colon cancer tumorigenic study using syngeneic mice model and demonstrated that 13(S)HpODE significantly reduces solid tumor growth through the activation of apoptosis. These data thus confirmed that IL-13 > 15-LO>13(S)HpODE > PPARγ>MAO-A > ROS > p53>p21 axis has a major contribution in regulating cancer cell apoptosis and further identified 13(S)HpODE as a potential chemo-preventive agent which can improve the efficacy of cancer treatment as a combination compound.

Monoamine oxidase inhibitors: A concise review with special emphasis on structure activity relationship studies

Monoamine oxidase enzyme is necessary for the management of brain functions. It oxidatively metabolizes monoamines and produces ammonia, aldehyde and hydrogen peroxide as by-products. Excessive production of by-products of monoamine metabolism generates free radicals which cause cellular apoptosis and several neurodegenerative disorders for example Alzheimer's disease, Parkinson's disease, depression and autism. The inhibition of MAOs is an attractive target for the treatment of neurological disorders. Clinically approved MAO inhibitors for example selegiline, rasagiline, clorgyline, pargyline etc. are irreversible in nature and cause some adverse effects while recently studied reversible MAO inhibitors are devoid of harmful effects of old monoamine oxidase inhibitors. In this review article we have listed various synthesized molecules containing different moieties like coumarin, chalcone, thiazole, thiourea, caffeine, pyrazole, chromone etc. along with their activity, mode of action, structure activity relationship and molecular docking studies.

Antidepressant-like effect of dehydrozingerone from Zingiber officinale by elevating monoamines in brain: in silico and in vivo studies

BACKGROUND

Dehydrozingerone (DHZ) is an active ingredient of Zingiber officinale and structural half analogue of curcumin. In the present study, DHZ was evaluated for monoamine oxidase (MAO) inhibitory activity in silico and antidepressant activity in vivo.

METHOD

The binding affinity of DHZ with MAO-A (PDB ID: 2Z5Y) was assessed using Schrodinger's Maestro followed by free energy calculation, pharmacokinetic property prediction using Qikprop and Molecular dynamics simulation using Desmond. In vivo antidepressant activity of DHZ was evaluated on C57 BL/6 male mice using Escilatopram as the standard antidepressant. Open field test (OFT), forced swimming test (FST) and tail suspension test (TST) were used to evaluate the antidepressant effect of the drugs on days 1 and 7. Following the behavioural study, neurotransmitters (noradrenaline, dopamine and serotonin) were estimated using liquid chromatography-mass spectrometry.

RESULTS

DHZ demonstrated a greater binding affinity for the MAO-A enzyme compared to moclobemide in silico. Immobility in TST and FST were significantly (p < 0.05) reduced in vivo with 100mg/kg DHZ as compared to respective controls. DHZ treatment was more effective 1 h post treatment compared to vehicle control. A significant increase in levels of neurotransmitters was observed in mice brain homogenate in response to DHZ treatment, reassuring its antidepressant-like potential.

CONCLUSION

DHZ demonstrated MAO-A inhibition in silico, and the increased neurotransmitter levels in the brain in vivo were associated with an antidepressant-like effect.

Induction of monoamine oxidase A-mediated oxidative stress and impairment of NRF2-antioxidant defence response by polyphenol-rich fraction of Bergenia ligulata sensitizes prostate cancer cells in vitro and in vivo

Prostate cancer (PCa) is a major cause of mortality and morbidity in men. Available therapies yield limited outcome. We explored anti-PCa activity in a polyphenol-rich fraction of Bergenia ligulata (PFBL), a plant used in Indian traditional and folk medicine for its anti-inflammatory and antineoplastic properties. PFBL constituted of about fifteen different compounds as per LCMS analysis induced apoptotic death in both androgen-dependent LNCaP and androgen-refractory PC3 and DU145 cells with little effect on NKE and WI38 cells. Further investigation revealed that PFBL mediates its function through upregulating ROS production by enhanced catalytic activity of Monoamine oxidase A (MAO-A). Notably, the differential inactivation of NRF2-antioxidant response pathway by PFBL resulted in death in PC3 versus NKE cells involving GSK-3β activity facilitated by AKT inhibition. PFBL efficiently reduced the PC3-tumor xenograft in NOD-SCID mice alone and in synergy with Paclitaxel. Tumor tissues in PFBL-treated mice showed upregulation of similar mechanism of cell death as observed in isolated PC3 cells i.e., elevation of MAO-A catalytic activity, ROS production accompanied by activation of β-TrCP-GSK-3β axis of NRF2 degradation. Blood counts, liver, and splenocyte sensitivity analyses justified the PFBL safety in the healthy mice. To our knowledge this is the first report of an activity that crippled NRF2 activation both in vitro and in vivo in response to MAO-A activation. Results of this study suggest the development of a novel treatment protocol utilizing PFBL to improve therapeutic outcome for patients with aggressive PCa which claims hundreds of thousands of lives each year.

Synthesis and biological evaluation of 3-styrylchromone derivatives as selective monoamine oxidase B inhibitors

A series of 3-styrylchromone derivatives was synthesized and evaluated for monoamine oxidase (MAO) A and B inhibitory activities. Most of all derivatives inhibited MAO-B selectively, except compound 21. Compound 19, which had a methoxy group at R² on the chromone ring and chlorine at R⁴ on phenyl ring, potently inhibited MAO-B, with an IC₅₀ value of 2.2 nM. Compound 1 showed the highest MAO-B selectivity, with a selectivity index of >3700. Further analysis of these compounds indicated that compounds 1 and 19 were reversible and mixed-type MAO-B inhibitors, suggesting that their mode of action may be through tight-binding inhibition to MAO-B. Quantitative structure-activity relationship (QSAR) analyses of the 3-styrylchromone derivatives were conducted using their pIC₅₀ values, through Molecular Operating Environment (MOE) and Dragon. There were 1796 descriptors of MAO-B inhibitory activity, which showed significant correlations (P < 0.05). Further investigation of the 3-styrylchromone structures as useful scaffolds was performed through three-dimensional-QSAR studies using AutoGPA, which is based on the molecular field analysis algorithm using MOE. The MAO-B inhibitory activity model constructed using pIC₅₀ value index exhibited a determination coefficients (R²) of 0.972 and a Leave-One-Out cross-validated determination coefficients (Q²) of 0.914. These data suggest that the 3-styrylchromone derivatives assessed herein may be suitable for the design and development of novel MAO inhibitors.

Monoamine oxidase-A activity is required for clonal tumorsphere formation by human breast tumor cells

Background

Breast tumor growth and recurrence are driven by an infrequent population of breast tumor-initiating cells (BTIC). We and others have reported that the frequency of BTIC is orders of magnitude higher when breast tumor cells are propagated in vitro as clonal spheres, termed tumorspheres, by comparison to adherent cells. We exploited the latter to screen > 35,000 small molecules to identify agents capable of targeting BTIC. We unexpectedly discovered that selective antagonists of serotonin signaling were among the hit compounds. To better understand the relationship between serotonin and BTIC we expanded our analysis to include monoamine oxidase-A (MAO-A), an enzyme that metabolizes serotonin.

Methods

We used the Nanostring technology and Western blotting to determine whether MAO-A is expressed in human breast tumor cell lines cultured as tumorspheres by comparison to those grown as adherent cells. We then determined whether MAO-A activity is required for tumorsphere formation, a surrogate in vitro assay for BTIC, by assessing whether selective MAO-A inhibitors affect the frequency of tumorsphere-forming cells. To learn whether MAO-A expression in breast tumor cells is associated with other reported properties of BTIC such as anticancer drug resistance or breast tumor recurrence, we performed differential gene expression analyses using publicly available transcriptomic datasets.

Results

Tumorspheres derived from human breast tumor cell lines representative of every breast cancer clinical subtype displayed increased expression of MAO-A transcripts and protein by comparison to adherent cells. Surprisingly, inhibition of MAO-A activity with selective inhibitors reduced the frequency of tumorsphere-forming cells. We also found that increased MAO-A expression is a common feature of human breast tumor cell lines that have acquired anticancer drug resistance and is associated with poor recurrence-free survival (RFS) in patients that experienced high-grade, ER-negative (ER⁻) breast tumors.

Conclusions

Our data suggests that MAO-A activity is required for tumorsphere formation and that its expression in breast tumor cells is associated with BTIC-related properties. The discovery that a selective MAO-A inhibitor targets tumorsphere-forming cells with potencies in the nanomolar range provides the first evidence of this agent’s anticancer property. These data warrant further investigation of the link between MAO-A and BTIC.

2-Styrylchromone derivatives as potent and selective monoamine oxidase B inhibitors

A series of eighteen 2-styrylchromone derivatives (see Chart 1) were synthesized and evaluated for their monoamine oxidase (MAO) A and B inhibitory activities. Many of the derivatives inhibited MAO-B comparable to pargyline (a positive control), and most of them inhibited MAO-B selectively. Of the eighteen derivatives, compound 9 having methoxy group at R¹ and chlorine at R⁴ showed both the best MAO-B inhibitory activity (IC₅₀ = 17 ± 2.4 nM) and the best MAO-B selectivity (IC₅₀ for MAO-A/IC₅₀ for MAO-B = 1500). The mode of inhibition of compound 9 against MAO-B was competitive and reversible. Quantitative structure-activity relationship (QSAR) analyses of the 2-styrylchromone derivatives were conducted using their pIC₅₀ values with the use of Molecular Operating Environment (MOE) and Dragon, demonstrating that the descriptors of MAO-B inhibitory activity and MAO-B selectivity were 1734 and 121, respectively, that showed significant correlations (P < 0.05). We then examined the 2-styrylchromone structures as useful scaffolds through three-dimensional-QSAR studies using AutoGPA, which is based on the molecular field analysis algorithm using MOE. The model using pIC₅₀ value indexes for MAO-B exhibited a determination coefficient (R²) of 0.873 as well as a Leave-One-Out cross-validated determination coefficient (Q²) of 0.675. These data suggested that the 2-styrylchromone structure might be a useful scaffold for the design and development of novel MAO-B inhibitors.

Does patchouli oil change blood platelet monoamine oxidase-A activity of adult mammals?

Patchouli oil, an essential aroma oil extracted from patchouli leaf during short-term exposure with five and ten drops either inhibited (at 1 or 2 h) or stimulated (at 4 h) the platelet MAO-A activity depending on the dosages of the aroma oil mainly due to inhibition or stimulation of its K m. The long-term 15 consecutive days exposure (with two or five drops) of patchouli oil, on the other hand, maximally stimulated the platelet MAO-A activity with five drops patchouli oil for 1 h exposure, but further continuation of its exposure with same doses (two or five drops) for 30 consecutive days significantly stimulated (with two drops) and inhibited (with five drops) the platelet MAO-A activity due to stimulation and inhibition respectively of its corresponding both K m and V max. These results thus suggest that this aroma oil exposure may modulate the blood platelet serotonergic regulation depending on the dose, duration, and conditions of exposure.

5,7-Dimethoxycoumarin prevents chronic mild stress induced depression in rats through increase in the expression of heat shock protein-70 and inhibition of monoamine oxidase-A levels

The current study was aimed to investigate the role of 5,7-dimethoxycoumarin in the prevention of chronic mild stress induced depression in rats. The chronic mild stress rat model was prepared using the known protocols. The results from open-field test showed that rats in the chronic mild stress group scored very low in terms of crossings and rearings than those of the normal rats. However, pre-treatment of the rats with 10 mg/kg doses of 5,7-dimethoxycoumarin prevented decline in the locomotor activity by chronic mild stress. The level of monoamine oxidase-A in the chronic mild stress rat hippocampus was markedly higher. Chronic mild stress induced increase in the monoamine oxidase-A level was inhibited by pre-treatment with 10 mg/kg doses of 5,7-dimethoxycoumarin in the rats. Chronic mild stress caused a marked increase in the level of caspase-3 mRNA and proteins in rat hippocampus tissues. The increased level of caspase-3 mRNA and protein level was inhibited by treatment of rats with 5,7-dimethoxycoumarin (10 mg/kg). 5,7-Dimethoxycoumarin administration into the rats caused a marked increase in the levels of heat shock protein-70 mRNA and protein. The levels of heat shock protein-70 were markedly lower both in normal and chronic mild stress groups of rats compared to the 5,7-dimethoxycoumarin treated groups. Thus 5,7-dimethoxycoumarin prevented the chronic mild stress induced depression in rats through an increase in the expression of heat shock protein-70 and inhibition of monoamine oxidase-A levels.

Association of ventral striatum monoamine oxidase-A binding and functional connectivity in antisocial personality disorder with high impulsivity: A positron emission tomography and functional magnetic resonance imaging study

Impulsivity is a core feature of antisocial personality disorder (ASPD) associated with abnormal brain function and neurochemical alterations. The ventral striatum (VS) is a key region of the neural circuitry mediating impulsive behavior, and low monoamine oxidase-A (MAO-A) level in the VS has shown a specific relationship to the impulsivity of ASPD. Because it is currently unknown whether phenotypic MAO-A markers can influence brain function in ASPD, we investigated VS MAO-A level and the functional connectivity (FC) of two seed regions, superior and inferior VS (VSs, VSi). Nineteen impulsive ASPD males underwent [(11)C] harmine positron emission tomography scanning to measure VS MAO-A VT, an index of MAO-A density, and resting-state functional magnetic resonance imaging that assessed the FC of bilateral seed regions in the VSi and VSs. Subjects also completed self-report impulsivity measures. Results revealed functional coupling of the VSs with bilateral dorsomedial prefrontal cortex (DMPFC) that was correlated with VS MAO-A VT (r=0.47, p=0.04), and functional coupling of the VSi with right hippocampus that was anti-correlated with VS MAO-A VT (r=-0.55, p=0.01). Additionally, VSs-DMPFC FC was negatively correlated with NEO Personality Inventory-Revised impulsivity (r=-0.49, p=0.03), as was VSi-hippocampus FC with Barratt Impulsiveness Scale-11 motor impulsiveness (r=-0.50, p=0.03). These preliminary results highlight an association of VS MAO-A level with the FC of striatal regions linked to impulsive behavior in ASPD and suggest that phenotype-based brain markers of ASPD have relevance to understanding brain function.

Elevated Monoamine Oxidase-A Distribution Volume in Borderline Personality Disorder Is Associated With Severity Across Mood Symptoms, Suicidality, and Cognition

BACKGROUND

Monoamine oxidase-A (MAO-A) is a treatment target in neurodegenerative illness and mood disorders that increases oxidative stress and predisposition toward apoptosis. Increased MAO-A levels in prefrontal cortex (PFC) and anterior cingulate cortex (ACC) occur in rodent models of depressive behavior and human studies of depressed moods. Extreme dysphoria is common in borderline personality disorder (BPD), especially when severe, and the molecular underpinnings of severe BPD are largely unknown. We hypothesized that MAO-A levels in PFC and ACC would be highest in severe BPD and would correlate with symptom magnitude.

METHODS

[(11)C] Harmine positron emission tomography measured MAO-A total distribution volume (MAO-A VT), an index of MAO-A density, in severe BPD subjects (n = 14), moderate BPD subjects (n = 14), subjects with a major depressive episode (MDE) only (n = 14), and healthy control subjects (n = 14). All subjects were female.

RESULTS

Severe BPD was associated with greater PFC and ACC MAO-A VT compared with moderate BPD, MDE, and healthy control subjects (multivariate analysis of variance group effect: F6,102 = 5.6, p < .001). In BPD, PFC and ACC MAO-A VT were positively correlated with mood symptoms (PFC: r = .52, p = .005; ACC: r = .53, p = .004) and suicidality (PFC: r = .40, p = .037; ACC: r = .38, p = .046), while hippocampus MAO-A VT was negatively correlated with verbal memory (r = -.44, p = .023).

CONCLUSIONS

These results suggest that elevated MAO-A VT is associated with multiple indicators of BPD severity, including BPD symptomatology, mood symptoms, suicidality, and neurocognitive impairment.

Cellular uptake of quercetin and luteolin and their effects on monoamine oxidase-A in human neuroblastoma SH-SY5Y cells

Monoamine oxidase-A (MAO-A) is the main enzyme in the metabolism of the neurotransmitter serotonin (5-hydroxytryptamine). Elevated activity of MAO-A in the brain may contribute to the pathogenesis of depressive disorders. Plant flavonoids, such as flavonol quercetin and flavone luteolin, have been suggested to be potential antidepressant compounds because they exert a suppressive effect on the MAO-A reaction. We evaluated the effects of these flavonoids on MAO-A activity and protein level using SH-SY5Y as model serotoninergic nerve cells. Quercetin and luteolin were incorporated into SH-SY5Y cells rapidly and converted to O-methylated derivatives. Luteolin accumulated in cells after 24-h incubation, whereas quercetin disappeared completely from cell fractions and culture medium. Addition of ascorbic acid prevented the disappearance of quercetin and allowed it to exert its cytotoxicity (similar to luteolin) at >10 μM. Luteolin and quercetin were incorporated into mitochondria fractions within 1-h incubation and attenuated MAO-A activity slightly but significantly. After 24-h incubation, luteolin attenuated MAO-A activity, but quercetin needed ascorbic acid for its attenuation. Neither luteolin nor quercetin significantly affected MAO-A protein level. These data suggest that luteolin and quercetin can be direct inhibitors of MAO-A in nerve cells by targeting mitochondria.