PRMT1 (IC50 = 30 nM); PRMT3 (IC50 = 119 nM); PRMT4 (IC50 = 83 nM); PRMT6 (IC50 = 4 nM); PRMT8 (IC50 = 5 nM)

In MCF7 cells, PRMT1 methyltransferase activity is inhibited by MS023 (1-1000 nM; 48 h) [1]. In HEK293 cells, MS023 (1-1000 nM; 20 h) suppresses PRMT6 methyltransferase activity [1].

When combined with PKC412 (100 mg/kg, ig), MS023 (160 mg/kg, ip) prevents the growth of MLL-r acute lymphoblastic leukemia (ALL) by preventing the maintenance of functional MLL-r ALL initiating cells. disperse[2].

PRMT biochemical assays[1]
A scintillation proximity assay (SPA) was used for assessing the effect of test compounds on inhibiting the methyl transfer reaction catalyzed by PRMTs as described previously.27 In brief, the tritiated S-adenosyl-L-methionine was used as the donor of methyl group. The (3H) methylated biotin labelled peptide was captured in streptavidin/scintillant-coated microplate which brings the incorporated 3H-methyl and the scintillant to close proximity resulting in light emission that is quantified by tracing the radioactivity signal (counts per minute) as measured by a TopCount NXT™ Microplate Scintillation and Luminescence Counter. When necessary, non-tritiated SAM was used to supplement the reactions. The IC50 values were determined under balanced conditions at Km concentrations of both substrate and cofactor by titration of test compounds in the reaction mixture.

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Cellular PRMT1 assay[1]
MCF7 cells were grown in 12-well plates in DMEM supplemented with 10% FBS, penicillin (100 units mL−1) and streptomycin (100 μg mL−1). 40% confluent cells were treated with different concentrations of MS023 and compounds 4 – 6 at indicated concentrations or DMSO control for 48 h. Cells were lysed in 100 μL of total lysis buffer (20 mM Tris-HCl pH 8, 150 mM NaCl, 1 mM EDTA, 10 mM MgCl2, 0.5% TritonX-100, 12.5 U mL−1 benzonase, complete EDTA-free protease inhibitor cocktail). After 3 min incubation at RT, SDS was added to final 1% concentration. Lysates were run on SDS-PAGE and immunoblotting was done as outlined below to determine H4R3me2a, arginine asymmetric dimethylation, arginine symmetric dimethylation and arginine monomethylation in western blot.

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Cellular PRMT6 assay[1]
HEK293 cells were grown in 12-well plates in DMEM supplemented with 10% FBS, penicillin (100 U mL−1) and streptomycin (100 μg mL−1). 50 % confluent cells were transfected with FLAG-tagged PRMT6 or mutant V86K/D88A PRMT6 (1 μg of DNA per well) using jetPRIME® transfection reagent (Polyplus-Transfection), following manufacturer instructions. After 4 h media were removed and cells were treated with MS023 at indicated concentrations or DMSO control. After 20 h, media was removed and cells were lysed in 100 μL of total lysis buffer.

Western Blot Analysis[1]
Cell Types: MCF7 and HEK293 cells
Tested Concentrations: 1.4, 4, 12, 37, 111, 333, and 1000 nM
Incubation Duration: 48 hrs (hours) for MCF7 cells; 20 hrs (hours) for HEK293 cells
Experimental Results: Treatment potently and concentration -dependently decreased cellular levels of H4R3me2a (IC50=9±0.2 nM). Treatment concentration-dependently decreased the H3R2me2a mark (IC50=56±7 nM).

Animal/Disease Models: NOD-scid IL2Rgnull (NSG) mice bearing primary MLL-r ALL cells[2]
Doses: 160 mg/kg
Route of Administration: intraperitoneal (ip)injection; PKC412 (100 mg/kg, ig), MS023 (160 mg/kg, ip ), or a combination for 4 weeks
Experimental Results: Combinatorial treatment extended survival of leukemic mice relative to single treatments.

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In vivo treatment of MLL-r ALL-engrafted mouse model[1]
For studying inducible short hairpin PRMT1 (shPRMT1), SEM cells stably expressing either doxycycline (DOX)-inducible short hairpin control (shCtrl) or PRMT1 short hairpin RNA (shRNA) (shPRMT1) were transplanted into irradiated immunodeficient NOD-scid IL2Rgnull (NSG) mice (1 × 106 cells per mouse). Each group was administered DOX treatment (10 mg/kg) orally for 3 weeks after engraftment. To assess R972/973 function in leukemogeneis, KOCL45 cells transduced with constructs expressing an FLT3 variant were sorted by using red fluorescent protein and injected into mice (1 × 105 cells per mouse), and mouse survival was monitored daily. To assess MS023 effects in vivo, we transplanted primary MLL-r ALL cells into NSG mice (0.5 × 106 cells per mouse). After engraftment, grouped mice were treated with vehicle, PKC412 (100 mg/kg, intragastrically), MS023 (160 mg/kg, intraperitoneally), or a combination for 4 weeks. After treatment, engrafted human cells were identified. Secondary transplantations of whole bone marrow (BM) cells from treated or control mice were then performed. Animal procedures were performed in accordance with federal and state government guidelines and established institutional guidelines and protocols approved by the Institutional Animal Care and Use Committee at City of Hope.

[1]. Eram MS, et al. A Potent, Selective, and Cell-Active Inhibitor of Human Type I Protein Arginine Methyltransferases. ACS Chem Biol. 2016 Mar 18;11(3):772-81.
[2]. Yinghui Zhu, et al. Targeting PRMT1-mediated FLT3 methylation disrupts maintenance of MLL-rearranged acute lymphoblastic leukemia. Blood. 2019 Oct 10;134(15):1257-1268.

Protein arginine methyltransferases (PRMTs) play a crucial role in a variety of biological processes. Overexpression of PRMTs has been implicated in various human diseases including cancer. Consequently, selective small-molecule inhibitors of PRMTs have been pursued by both academia and the pharmaceutical industry as chemical tools for testing biological and therapeutic hypotheses. PRMTs are divided into three categories: type I PRMTs which catalyze mono- and asymmetric dimethylation of arginine residues, type II PRMTs which catalyze mono- and symmetric dimethylation of arginine residues, and type III PRMT which catalyzes only monomethylation of arginine residues. Here, we report the discovery of a potent, selective, and cell-active inhibitor of human type I PRMTs, MS023, and characterization of this inhibitor in a battery of biochemical, biophysical, and cellular assays. MS023 displayed high potency for type I PRMTs including PRMT1, -3, -4, -6, and -8 but was completely inactive against type II and type III PRMTs, protein lysine methyltransferases and DNA methyltransferases. A crystal structure of PRMT6 in complex with MS023 revealed that MS023 binds the substrate binding site. MS023 potently decreased cellular levels of histone arginine asymmetric dimethylation. It also reduced global levels of arginine asymmetric dimethylation and concurrently increased levels of arginine monomethylation and symmetric dimethylation in cells. We also developed MS094, a close analog of MS023, which was inactive in biochemical and cellular assays, as a negative control for chemical biology studies. MS023 and MS094 are useful chemical tools for investigating the role of type I PRMTs in health and disease.[1]

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Relapse remains the main cause of MLL-rearranged (MLL-r) acute lymphoblastic leukemia (ALL) treatment failure resulting from persistence of drug-resistant clones after conventional chemotherapy treatment or targeted therapy. Thus, defining mechanisms underlying MLL-r ALL maintenance is critical for developing effective therapy. PRMT1, which deposits an asymmetric dimethylarginine mark on histone/non-histone proteins, is reportedly overexpressed in various cancers. Here, we demonstrate elevated PRMT1 levels in MLL-r ALL cells and show that inhibition of PRMT1 significantly suppresses leukemic cell growth and survival. Mechanistically, we reveal that PRMT1 methylates Fms-like receptor tyrosine kinase 3 (FLT3) at arginine (R) residues 972 and 973 (R972/973), and its oncogenic function in MLL-r ALL cells is FLT3 methylation dependent. Both biochemistry and computational analysis demonstrate that R972/973 methylation could facilitate recruitment of adaptor proteins to FLT3 in a phospho-tyrosine (Y) residue 969 (Y969) dependent or independent manner. Cells expressing R972/973 methylation-deficient FLT3 exhibited more robust apoptosis and growth inhibition than did Y969 phosphorylation-deficient FLT3-transduced cells. We also show that the capacity of the type I PRMT inhibitor MS023 to inhibit leukemia cell viability parallels baseline FLT3 R972/973 methylation levels. Finally, combining FLT3 tyrosine kinase inhibitor PKC412 with MS023 treatment enhanced elimination of MLL-r ALL cells relative to PKC412 treatment alone in patient-derived mouse xenografts. These results indicate that abolishing FLT3 arginine methylation through PRMT1 inhibition represents a promising strategy to target MLL-r ALL cells.[2]

C17H25N3O

287.4

287.19976

C, 71.04; H, 8.77; N, 14.62; O, 5.57

1831110-54-3

MS023 dihydrochloride;1992047-64-9;MS023 trihydrochloride;2108631-19-0

92136227

Typically exists as white to light yellow solids at room temperature

1.1±0.1 g/cm3

437.8±45.0 °C at 760 mmHg

218.6±28.7 °C

0.0±1.1 mmHg at 25°C

1.567

2

54.3Ų

O(C(C)C)C1C=CC(=CC=1)C1=CNC=C1CN(C)CCN

FMTVWAGUJRUAKE-UHFFFAOYSA-N

InChI=1S/C17H25N3O/c1-13(2)21-16-6-4-14(5-7-16)17-11-19-10-15(17)12-20(3)9-8-18/h4-7,10-11,13,19H,8-9,12,18H2,1-3H3

N1-((4-(4-isopropoxyphenyl)-1H-pyrrol-3-yl)methyl)-N1-methylethane-1,2-diamine

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: 53.33 mg/mL (185.56 mM) in Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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 (Please use freshly prepared in vivo formulations for optimal results.)