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A rhodium(III)-based inhibitor of lysine-specific histone demethylase 1 as an epigenetic modulator in prostate cancer cells Chao Yang, Wanhe Wang, Jiaxin Liang, Guodong Li, Kasipandi Vellaisamy, Chun-Yuen Wong, Dik-Lung Ma, and Chung-Hang Leung J. Med. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jmedchem.7b00133 • Publication Date (Web): 20 Feb 2017 Downloaded from http://pubs.acs.org on February 22, 2017

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Journal of Medicinal Chemistry

A rhodium(III)-based inhibitor of lysine-specific histone demethylase 1 as an epigenetic modulator in prostate cancer cells Chao Yang,a† Wanhe Wang,b† Jiaxin Liang,a† Guodong Li,a Kasipandi Vellaisamy,b Chun-Yuen Wong,c Dik-Lung Ma,*b and Chung-Hang Leung*a a

State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau (China) b Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong (China) c

Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR (China) †

These authors contributed equally to this work.

ABSTRACT: We report herein a novel rhodium(III) complex 1 as a new LSD1 targeting agent and epigenetic modulator. Complex 1 disrupted the interaction of LSD1-H3K4me2 in human prostate carcinoma cells, and enhanced the amplification of p21, FOXA2 and BMP2 gene promoters. Complex 1 was selective for LSD1 over other histone demethylases, such as KDM2b, KDM7 and MAO activities, and also showed anti-proliferative activity towards human cancer cells. To date, complex 1 is the first metal-based inhibitor of LSD1 activity.

KEYWORDS: inhibitor, metal complex, LSD1, epigenetic modulator Introduction The post-translational modification of histones to regulate gene expression via the modeling of nucleosome structure is a central theme in epigenetics.1, 2 This "histone code" includes methylation, acetylation, phosphorylation, and ubiquitination.3, 4 The presence of histone lysine demethylases suggests that histone lysine methylation is a reversible epigenetic modification.4, 5 Lysine-specific demethylase 1 (LSD1) catalyzes the demethylation of di- and mono-methylated Lys4 of histone H3, but not tri-methylated H3K4.6, 7 LSD1 activity is central to the development and maintenance of acute myeloid leukemia (AML),8, 9 as well as prostate carcinoma, colon carcinoma cancer and breast cancer.10, 11 Aberrant activity of LSD1 is linked with tumor suppressor gene silencing, promoting tumorigenesis.12, 13 Thus, considerable effort has been devoted to developing LSD1 inhibitors for the treatment of cancer, despite a lack of precise mechanistic insight.14 Several types of LSD1 inhibitors have been presented in the literature, including peptides, natural products and their derivatives, and polyamines.15-19 Wang and co-workers have reported CBB1007 (6),20 a known potent, reversible and substrate-competitive LSD1 inhibitor in F9 cells. ORY-1001 (9),21 a potent and selective inhibitor of LSD1, has entered phase I clinical trials for the treatment of AML, while 4-[[4-[[[(1R,2S)-2phenylcyclopropyl]amino]methyl]piperidin-1-

yl]methyl]benzoic acid (GSK2879552),22 an orally available, irreversible, inhibitor of LSD1, has also recently entered phase I trials for AML and small-cell lung cancer therapy. Inhibition of LSD1 offers an attractive route to new therapies for various cancers, and research into new LSD1 inhibitors is an active area of research. Metal complexes have attracted considerable attention as anticancer agents in recent decades.23, 24 Although metal complexes tend not be readily orally available, they possess other benefits compared to purely organic molecules, making them appealing alternatives for therapeutic agent development.25, 26 Metal complexes can exhibit various shapes depending on the coordination number of the metal complex and the type of ligands.27 Recent interest has focused on the discovery of molecularly-targeted metal against specific enzymes or protein-protein interactions.28-32 In particular, rhodium(III) complexes have been discovered to inhibit STAT3, β-amyloid fibrillation and JAK2.33-35 Moreover, metal-based epigenetic modulators have been very recently discovered.25, 36 However, there are no metal-based inhibitors of LSD1 reported to date. We report herein a novel rhodium(III) complex 1 as the first metal-based inhibitor of LSD1 activity and which shows promise for the treatment of prostate cancer. Results and discussion

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Synthesis and characterization of metal-based complexes

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Figure 3. Top view of complex 1 bound to the LSD1 generated by molecular docking. LSD1 (PDB: 2V1D) is depicted in ribbon form and is colored purple. Complex 1 is depicted as a space-filling representation showing carbon (yellow), oxygen (red), nitrogen (blue), and chloride (green) atoms. The binding pocket of the LSD1 is represented as a translucent green surface. Figure 1. Chemical structures of rhodium(III) complexes 1-5, 6, 7 (4-Chloro-2-phenylquinoline), 8 (4,4'-dimethoxy2,2'-bipyridine) and 9 evaluated in this study.

Figure 2. (A) Complexes 1–6 inhibit the activity of LSD1 as determined using a fluorimetric assay. (B) Complex 1 dose inhibits LSD1 activity as determined by a fluorimetric assay. Error bars represent the standard deviations of results obtained from three independent experiments.

We screened racemic complexes 1–5 for their ability to modulate LSD1 activity using a fluorescence-based assay. Complexes 1–5 have no intrinsic fluorescence (Figure S1). From those results, the rhodium(III) complex 1 showed the greatest inhibition of LSD1, as it reduced LSD1 activity by a fluorescence-based method at 10 µM (Figure 2A). Compound 6 reduced LSD1 activity by nearly 74.7% at the same concentration.20 Complexes 2, 4 and 5 showed moderate inhibitory activity in this assay, while complex 3 was nearly inactive. A dose-response experiment was then performed to determine the efficacy of complex 1 against LSD1 demethylase activity. Complex 1 inhibited LSD1 activity in a dose-dependent manner, with an IC50 value of 0.04 ± 0.008 µM (Figure 2B). Furthermore, we performed a kinetic assay to determine the kinetics of inhibition. A kinetic assay showed that like the competitive inhibitor compound 6,31 complex 1 acts as a competitive inhibitor of LSD1 with Ki value of 0.57 µM (Figure S2). Structure-activity relationships

To develop potential metal-based scaffolds as LSD1 inhibitors, rhodium(III) complexes 1–5 were synthesized (Figure 1) bearing structurally diverse C^N and N^N ligands. Complex 1 bears the 4-chloro-2-phenylquinoline C^N ligand, while complex 2 carries the related 2-phenylquinoline ligand. Complexes 3 and 5 bear the relatively small 2-phenylpyridine C^N ligand, while complex 4 has the 1-phenyl-1H-pyrazole C^N ligand. With regards to the N^N ligand, complexes 1 and 5 carries a 2,2ʹ-bipyridine scaffold substituted with methoxy groups, respectively, while complex 2 carries the unsubstituted 2,2ʹ-bipyridine ligand. Finally, complex 4 bears the 2,9dimethyl-1,10-phenanthroline N^N ligand, while complex 3 contains the same scaffold substituted with pendant phenyl groups. Complex 3 has been previously investigated for its anticancer and antibacterial activity, whereas complexes 4 and 5 have been studied for their ability to inhibit BRD4, an epigenetic “reader” protein.31, 37 Complexes 1 and 2 are novel and are reported for the first time in this work.

To further investigate the mechanism of action of 1, we evaluated the activity of its isolated ligands 7 and 8 (Figure 1). The results showed that neither 7 or 8 had any effect on the activity of LSD1 (Figure S3). This indicates that the isolated ligands are not effective against LSD1 activity on their own. Additionally, a preliminary structure-activity relationship analysis can be performed by considering the biological potency of complexes 1–5. Complex 2 was the second-most active member of this series, which could be possibly accounted for by the observation that the 2-phenylquinoline C^N ligand of 2 is simply the dechlorinated derivative the 4-chloro-2phenylquinoline C^N ligand of 1. This indicates that C^N ligands of that approximate size might have higher complementarity with the binding site of LSD1 compared to C^N ligands of other sizes. Finally, the weakest activity of complex 5 indicates that the combination of the 2-phenylpyridine C^N ligand and the 4,4ʹ-dimethoxy-2,2ʹ-bipyridine N^N ligand is undesirable for biological activity.

Inhibition of LSD1 activity in vitro Molecular docking analysis


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Figure 4. Effect of complex 1 on the level of H3K4me2 at the p21, FOXA2, BMP2 and GAPDH genes in PC3 cells. ChIP-qPCR assays were performed with primary antibody against H3K4me2. Error bars represent the standard deviations of results obtained from three independent experiments. To further investigate the mechanism of action of complex 1, we evaluated the binding mode of complex 1 to LSD1 via molecular docking. Docking was performed using the Molsoft ICM method (ICM-Pro 3.6-1d molecular docking software). A peptide substrate-like H3K4M, which resembles the natural histone H3 peptide except where lysine 4 (K4) is replaced by methionine, is predicted to bind across the entire LSD1 (PDB: 2V1D) binding site, forming H-bonding interactions to Asp375 and Asp 556 (Figure S4A). This peptide inspired the design of compound 6, which is also predicted to bind across most of the site (Figure S4B). In contrast, compound 9 is predicted to locate only on the lower half of the binding site (Figure S4C). In this respect, the predicted binding mode of complex 1 resembles compound 9 more than compound 6 or the substrate-like peptide, as complex 1 occupies only part of the LSD1 binding site, contacting the residues around Asp556 (Figures 3 and S4D). Selective inhibition of the LSD1 in human prostate carcinoma cells Previous studies have revealed that LSD1 is most likely responsible for the gene inactivation of p21.38, 39 Moreover, inactivation of LSD1 significantly induced the expression of differentiation genes such as FOXA2, BMP2.40, 41 Chromatin immunoprecipitation (ChIP)-qPCR assays were performed to test whether complex 1 could block the binding of LSD1 to chromatin in human prostate cancer PC3 cells and human prostate carcinoma epithelial 22RV1 cells, thereby relieving the suppression of downstream genes. Cells were treated with the indicated concentration of complex 1, and cell lysates were collected and immunoprecipitated with anti-H3K4me2 antibody. ChIP-qPCR analysis showed that complex 1 could increase the amplification of the p21, FOXA2 and BMP2 gene promoters (Figures 4 and S5). This result suggested that complex 1 could suppress the demethylation of H3K4me2 on these promoters in PC3 cells or 22RV1 cells, thus leading to increased gene expression. Complex 1 induced the accumulation of H3K4me2 in treated PC3 cells in a dose-dependent manner (Figure S6), which we presume is due to its effect on LSD1 activity. To further eval-

Figure 5. Effect of 1 on the interaction between LSD1 and other proteins in PC3 cells studied by coimmunoprecipitation. PC3 cells were treated with the indicated concentrations of 1 or 6 for 24 h. Protein lysates were incubated with anti-LSD1 magnetic beads, and precipitated proteins were analysed by Western blotting with the indicated antibodies. uate the mechanism of action of complex 1, coimmunoprecipitation experiments were performed. Cell lysates were immunoprecipitated with LSD1 antibody and immunoblotted with the appropriate antibodies. Notably, complex 1 interrupted the LSD1-H3K4me2 interaction in both PC3 (Figure 5) and 22RV1 (Figure S7) cells, which could account for its ability to induce H3K4me2 accumulation as described previously. However, complex 1 had no effect on the binding between LSD1 and H3K4, H3K4me3, REST and CoREST in PC3 cells (Figure 5). As REST and CoREST form part of the LSD1-containing epigenetic complex,42, 43 this suggests that complex 1 does not act by disrupting the interactions between LSD1 and REST or CoREST. In view of the promising activity of complex 1 at binding to and inhibiting the activity of LSD as described above, the specific mechanism of complex 1 was further investigated using an enzyme-linked immunosorbent assay. In this assay, PC3 cells were treated with different concentration of complex 1 for 24 h, and cell lysates were harvested. In this assay, active LSD1 in the cell lysates binds to and demethylates a unique di-methylated histone H3K4 substrate. Then, remaining nondemethylated substrate is recognized with a high affinity antimethylated histone H3K4 antibody. The results showed that complex 1 decreased H3K4me2 demethylation with an IC50 value of 0.23 µM (Figure 6A), while the IC50 value of compound 6 in the same assay was 7.23 µM. These results suggest that complex 1 could inhibit the activity of LSD1 in vitro with stronger potency compared to compound 6, and is consistent with the results of the previous experiments. To further investigate the specificity of complex 1 for LSD1, we examined the activity of complex 1 against the demethylation of other histone demethylases targeting di- or monomethylated histone H3. KDM2b, highly expressed in human leukemia cells, not only catalyzes the demethylation of monoand dimethylated H3K26, but also demethylates tri- and dimethylated H3K4.44 Another JmjC domain containing protein, KDM7, catalyzes demethylation of both mono- and dimethylated H3K9 and H3K27.45 Thus, PC3 cells were incubated with various concentrations of complex 1 for 24 h, and the demethylase activities of the cell lysates were investigated using ELISA. Complex 1 showed only weak potency against the activities of the other demethylases, with only 10% inhibition



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Figure 7. Effect of complex 1 on GLUT1 protein expression in PC3 cells. PC3 cells were treated with the indicated concentrations of complex 1 for 24 h, and then GLUT1 levels were analysed by Western blotting.

Figure 6. The selectivity of complex 1 for histone demethylases in vitro. PC3 cell lysates were collected after treatment of cells with complex 1 for 24 h. Complexes 1 and 6 dose dependently inhibit LSD1 (A) activity in PC3 cells as determined by ELISA. Effect of complex 1 on KDM2b (B), KDM7 (C), MAO (D) activity in PC3 cells as determined by ELISA. Error bars represent the standard deviations of results obtained from three independent experiments. at the highest concentration (10 µM) tested (Figure 6B, 6C). This indicates that complex 1 is selective for LSD1 over other demethylase enzymes, which could be expected since these demethylases have a different mechanism and are not flavindependent. LSD1 belongs to the flavin adenine dinucleotide (FAD)dependent amine oxidases superfamily, while the monoamine oxidases (MAOs) belong to the same superfamily and share the same enzymatic mechanism of LSD1 demethylase.46 Therefore, the enzyme activity observed activity of complex 1 against MAO was measured on the same cell treatment as before by monitoring the fluorescence at excitation of 530 nm and emission of 585 nm. In brief, MAO reacts with p-tyramine, a substrate for both MAOA and MAOB, resulting in the formation of H2O2, which is determined by a fluorimetric method. Complex 1 exhibited little or no inhibition of MAOA/B in PC3 cells (Figure 6D). Taken together, these results together indicate that complex 1 is selective for LSD1 over other related enzymes, including KDM2b, KDM7, and MAO. Inhibition of GLUT1 expression in human prostate carcinoma cells Glucose transporter 1 (GLUT1) is a uniporter carrier protein that exhibits variable expression in various tumor types.47 Recent studies have suggested that LSD1 is linked with the increased expression of GLUT1 in human cancer cells.48 Therefore, the effect of complex 1 on the expression of GLUT1 was further explored. PC3 cells were treated with the indicated concentration of complex 1 for 24 h, and GLUT1 levels were analyzed by Western blotting. The results showed that complex 1 could decrease GLUT1 expression and have no effect on the expression of LSD1 and GAPDH in PC3 cells (Figure 7).

A previous study has reported that GLUT1 expression was reduced in knockdown MAOA cells under hypoxia.49 Therefore, we performed a quantitative PCR experiment to study the impact of complex 1 on LSD1 or MAOA knockdown cells (Figure S8A). Knockdown of LSD1 and MAOA resulted in a decrease of GLUT1 mRNA levels by 40% and 20%, respectively (Figure S8B). However, cells were more resistant to 1 in LSD1 knockdown cells when compared with knockdown cells with control or MAOA siRNA (Figure S8C). Taken together, these data suggest that 1 suppresses GLUT1 at the transcriptional level in a manner that is, at least in part, LSD1 dependent. Complex 1 inhibits cellular proliferation and induces cell cycle arrest The anti-proliferative activity of 1 and 6 against 22RV1 cells, human prostate cancer DU145 cells, human breast adenocarcinoma MCF-7 cells, PC3 cells, human epithelial colorectal adenocarcinoma Caco2 cells, human embryonic kidney 293 cells and human liver LO2 cells were assessed by the XTT assay. Cell viability was measured after 72 h of treatment with complex 1. IC50 values of complex 1 were greater than 100 µM against PC3 cells, 22RV1 cells or LO2 cells (Figure S9). By comparison, complex 1 was most potent against human prostate cancer PC3 cells, with an IC50 value of 2.83 µM (Figure S10). Moreover, the toxicity of 1 was significantly reduced in LSD1-knockdown PC3 cells (Figure S10). This indicates that complex 1 could be considered as a potential scaffold for the development of anti-prostate cancer drugs. To evaluate the nature of cell death induced by complex 1, we evaluated the levels of proteins related to apoptosis, including cleaved caspase 3 and cleaved PARP, in the presence of 1. Complex 1 had no effect on the expression level of apoptosis markers in both PC3 cancer cells and LO2 normal cells (Figure S11A). In flow cytometry analysis, a minor population of complex 1-treated cells were observed in the Q1-LR quarter (early apoptosis: FITC Annexin V Positive and PI negative) (Figure S11B), indicating that complex 1 below 3 µM, as well as compound 6 at 1 µM, had no effects on early apoptosis in both PC3 and LO2 cells. Moreover, the expression of cyclin D1, a protein related to G0/G1 cell cycle arrest, was downregulated after complex 1 treatment (Figure S11A). Furthermore, complex 1 increased cells in the G0/G1 phase and reduced cell counts in the S phase in a dose-dependent manner, indicating that complex 1 could induce G0/G1 arrest in both PC3 and LO2 cell lines (Figures S11C and D). Taken together, apoptosis and cell cycle arrest analysis suggested that complex


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1 could induce G0/G1 arrest, but not apoptosis, in both PC3 cancer and LO2 normal cell lines. Conclusions In summary, we have described a novel rhodium(III) complex 1 as the first metal-based inhibitor of LSD1 activity. Complex 1 exhibited superior inhibitory activity against LSD1 in a fluorescence-based assay and an ELISA assay compared to the known LSD1 inhibitor, compound 6. Moreover, complex 1 reduced the proliferation of human prostate cancer PC3 cells at low micromolar concentrations. Additionally, complex 1 enhanced the amplification of LSD1-regulated promoters and decreased the LSD1−H3K4me2 interaction in PC3 cells. Complex 1 also selectively inhibited LSD1 activity without inhibiting the activity of other related enzymes, KDM2b, KDM7, and MAO. Finally, complex 1 inhibited the expression of GLUT1 in PC3 cells, presumably due to its ability to inhibit LSD1 activity. We anticipate that complex 1 could be considered as a useful scaffold for the further development of more selective and potent epigenetic modulators to treat different types of cancer, including prostate cancer.

148.32, 146.52, 145.72, 136.13, 132.50, 131.45, 128.88, 128.41, 126.61, 125.96, 124.85, 119.45, 119.43, 114.62, 110.96, 57.03; MALDI-TOF-HRMS: Calcd. For C42H30Cl2N4O2Rh [M–PF6]+: 795.0801 Found: 794.9014; Anal.: (C42H30Cl2F6N4O2PRh+H2O) C, H, N: calcd. 52.57, 3.36, 5.84; found 52.66, 3.23, 5.98. Complex 2. Yield: 35%. HPLC purity: >95%. 1H NMR (400 MHz, Acetone-d6) δ 8.64 – 8.51 (m, 4H), 8.45 (d, J = 5.2 Hz, 2H), 8.40 – 8.27 (m, 4H), 8.10 (t, J = 7.9 Hz, 2H), 7.94 (d, J = 8.1 Hz, 2H), 7.64 (t, J = 7.6 Hz, 2H), 7.57 (d, J = 8.9 Hz, 2H), 7.44 (t, J = 8.0 Hz, 2H), 7.25 (t, J = 8.0 Hz, 2H), 7.15 (t, J = 8.7 Hz, 2H), 6.92 (t, J = 7.5 Hz, 2H), 6.61 (d, J = 7.8 Hz, 2H); 13 C NMR (101 MHz, Acetone) δ 167.35, 155.37, 149.10, 147.67, 146.59, 140.82, 140.68, 136.03, 131.46, 131.09, 130.00, 129.10, 128.51, 128.06, 127.76, 125.86, 124.82, 124.52, 119.16. MALDI-TOF-HRMS: Calcd. For C40H28N4Rh [M–PF6]+: 667.1369 Found: 667.1373; Anal.: (C40H28F6N4PRh+2H2O) C, H, N: calcd. 56.62, 3.80, 6.60; found 56.40, 3.52, 6.61. Complex 3. HPLC purity: >95%. (Reported)37

EXPERIMENTAL SECTION

Complex 4. HPLC purity: >95%. (Reported)31

General synthesis of [Rh2(C^N)4Cl2] complexes Cyclometalated dichloro-bridged dimers of the general formula [Rh2(C^N)4Cl2] were synthesized according to a literature method.50 In brief, RhCl3•xH2O was heated to 140 °C with 2.1 equivalents of cyclometallated C^N ligands in 3:1 methoxymethanol and deionized water under a nitrogen atmosphere overnight. The reaction was cooled to room temperature, and the product was filtered and washed with three portions of deionized water and then three portions of ether to yield the corresponding dimer.

Complex 5. HPLC purity: >95%. (Reported)31

ASSOCIATED CONTENT Supporting Information Experimental methods, and supplemental data (PDF) Molecular formula strings (CSV) were supplied as Supporting Information. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION General synthesis of [Rh(C^N)2(N^N)]PF6 complexes These complexes were synthesized using a modified literature method.50 Briefly, a suspension of [Rh2(C^N)4Cl2] (0.1 mmol) and corresponding N^N (0.21 mmol) ligands in a mixture of dichloromethane:methanol (1:1, 6 mL) was refluxed overnight under a nitrogen atmosphere. The resulting solution was allowed to cool to room temperature, and was filtered to remove unreacted cyclometallated dimer. To the filtrate, an aqueous solution of ammonium hexafluorophosphate (excess) was added and the filtrate was reduced in volume by rotary evaporation until precipitation of the crude product occurred. The precipitate was then filtered and washed with several portions of water (2 × 30 mL) followed by diethyl ether (2 × 30 mL). The solid was dissolved into acetone, and then the product was precipitated by adding diethyl ether, and filtered to yield. The purity of all complexes was determined by an Agilent 1200 high-performance liquid chromatography (HPLC) system. The results showed that the purity of all complexes was over 95% (Figure S12). Complex 1. Yield: 49%. HPLC purity: >95%. 1H NMR (400 MHz, Acetone-d6) δ 8.72 (s, 2H), 8.38 (d, J = 7.9 Hz, 2H), 8.26 – 8.15 (m, 4H), 7.89 (d, J = 2.6 Hz, 2H), 7.72 (d, J = 8.8 Hz, 2H), 7.60 (t, J = 8.2 Hz, 2H), 7.31 (t, J = 8.7 Hz, 2H), 7.26 (t, J = 8.0 Hz, 2H), 7.20 (dd, J = 6.3, 2.6 Hz, 2H), 6.94 (t, J = 7.8 Hz, 2H), 6.64 (d, J = 7.6 Hz, 2H), 3.94 (s, 6H); 13C NMR (101 MHz, Acetone) δ 169.56, 169.07, 167.16, 156.79, 149.97,

Corresponding Author *For C.H.L.: E-mail: [email protected], Tel: +853 88224688 *For D.L.M.: E-mail: [email protected], Tel: +852 92510870 ORCID Chung-Hang Leung: 0000-0003-2988-3786 Dik-Lung Ma: 0000-0002-9515-340X

Author Contributions C.Y., W.H.W., J.X.L. and G.D.L. carried out all the experiments. C.Y., W.H.W. and K.V. wrote the manuscript. D.L.M., C.Y.W. and C.H.L analyzed the results. C.H.L. and D.L.M. designed the experiments.

Notes The authors declare no competing financial interests.

ACKNOWLEDGMENT This work is supported by Hong Kong Baptist University (FRG2/15-16/002), the Health and Medical Research Fund (HMRF/14130522), the Research Grants Council (HKBU/12301115, HKBU/204612 and HKBU/201913), the French National Research Agency/Research Grants Council Joint Research Scheme (A-HKBU201/12 − Oligoswitch), National Natural Science Foundation of China (21575121),



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Guangdong Province Natural Science Foundation (2015A030313816), Hong Kong Baptist University Century Club Sponsorship Scheme 2016, Interdisciplinary Research Matching Scheme (RC-IRMS/15-16/03), the Science and Technology Development Fund, Macao SAR (098/2014/A2), the University of Macau (MYRG2015-00137-ICMS-QRCM, MYRG2016-00151-ICMS-QRCM and MRG044/LCH/2015/ICMS), and National Natural Science Foundation of China (21628502). ABBREVIATIONS LSD1, lysine-specific histone demethylase 1; AML, acute myeloid leukemia; H3K4me2, Histone H3 dimethyl Lys4; MAO, Monoamine oxidase; MAOA, Monoamine oxidase A; MAOB Monoamine oxidase B; ELISA, Enzyme-linked immunosorbent assay; DMEM, Dulbecco's modified eagle medium; FBS, Fetal bovine serum; PBS, Phosphate buffered saline; PC3 cells, Human prostate carcinoma cell; Caco2 cells, Human epithelial colorectal adenocarcinoma cells; LO2 cells, human liver cells; 293 cells, human embryonic kidney cells; 22RV1 cells, human prostate carcinoma epithelial cells; DU145 cells, human prostate cancer cells; KDM2b, Lysine-specific histone demethylase 2b; KDM7, Lysine-specific histone demethylase 7; XTT, Cell Proliferation Kit II; H3K26me2, Histone H3 dimethyl Lys26; H3K27me2, Histone H3 di methyl K27.

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