A-196

• CAT Number: R065702
• CAS Number: 1982372-88-2
• Molecular Formula: C18H16Cl2N4
• Molecular Weight: 359.3
• Purity: ≥95%
• Synonyms: 6,7-dichloro-N-cyclopentyl-4-(4-pyridinyl)-1-phthalazinamine
• Storage: -20°C
• IUPAC Name: 6,7-dichloro-N-cyclopentyl-4-pyridin-4-ylphthalazin-1-amine
• InChI: InChI=1S/C18H16Cl2N4/c19-15-9-13-14(10-16(15)20)18(22-12-3-1-2-4-12)24-23-17(13)11-5-7-21-8-6-11/h5-10,12H,1-4H2,(H,22,24)
• InChIKey: ABGOSOMRWSYAOB-UHFFFAOYSA-N
• SMILES: ClC1=C(Cl)C=C(C(C2=CC=NC=C2)=NN=C3NC4CCCC4)C3=C1

A-196(cas 1982372-88-2) is a selective inhibitor of SUV420H1 and SUV420H2 (IC50s = 25 and 144 nM, respectively) that is more than 100-fold selective over other histone methyltransferases and non-epigenetic targets. A-196 has been shown to inhibit the di- and tri-methylation of lysine 20 of histone H4 (H4K20me) in multiple cell lines with IC50 values less than 1 μM. 

Reference

1. Nat Chem Biol. 2017 Mar;13(3):317-324. doi: 10.1038/nchembio.2282. Epub 2017 Jan
23.

The SUV4-20 inhibitor A-196 verifies a role for epigenetics in genomic integrity.

Bromberg KD(1), Mitchell TR(2), Upadhyay AK(1), Jakob CG(1), Jhala MA(1), Comess
KM(1), Lasko LM(1), Li C(3), Tuzon CT(4), Dai Y(1), Li F(2), Eram MS(2), Nuber
A(5), Soni NB(1), Manaves V(1), Algire MA(1), Sweis RF(1), Torrent M(1), Schotta
G(5), Sun C(1), Michaelides MR(1), Shoemaker AR(1), Arrowsmith CH(2), Brown
PJ(2), Santhakumar V(2), Martin A(3), Rice JC(4), Chiang GG(1)(6), Vedadi
M(2)(7), Barsyte-Lovejoy D(2), Pappano WN(1).

Author information:
(1)Discovery, Research and Development, AbbVie, North Chicago, Illinois, USA.
(2)Structural Genomics Consortium, University of Toronto, Toronto, Ontario,
Canada.
(3)Department of Immunology, University of Toronto, Medical Sciences Building,
Toronto, Canada.
(4)Department of Biochemistry and Molecular Biology, Norris Comprehensive Cancer
Center, University of Southern California, Los Angeles, California, USA.
(5)Ludwig-Maximilians-Universität München and Munich Center for Integrated
Protein Science (CiPSM), Biomedical Center, Planegg-Martinsried, Germany.
(6)eFFECTOR Therapeutics, San Diego, California, USA.
(7)Department of Pharmacology and Toxicology, University of Toronto, Toronto,
Ontario, Canada.

Protein lysine methyltransferases (PKMTs) regulate diverse physiological
processes including transcription and the maintenance of genomic integrity.
Genetic studies suggest that the PKMTs SUV420H1 and SUV420H2 facilitate
proficient nonhomologous end-joining (NHEJ)-directed DNA repair by catalyzing the
di- and trimethylation (me2 and me3, respectively) of lysine 20 on histone 4
(H4K20). Here we report the identification of A-196, a potent and selective
inhibitor of SUV420H1 and SUV420H2. Biochemical and co-crystallization analyses
demonstrate that A-196 is a substrate-competitive inhibitor of both SUV4-20
enzymes. In cells, A-196 induced a global decrease in H4K20me2 and H4K20me3 and a
concomitant increase in H4K20me1. A-196 inhibited 53BP1 foci formation upon
ionizing radiation and reduced NHEJ-mediated DNA-break repair but did not affect
homology-directed repair. These results demonstrate the role of SUV4-20 enzymatic
activity in H4K20 methylation and DNA repair. A-196 represents a first-in-class
chemical probe of SUV4-20 to investigate the role of histone methyltransferases
in genomic integrity.