acids B–E, did not significantly improve the potency against SETD8 [127]. The
quinazoline-based SETD8 selective substrate-competitive inhibitor UNC0379 (75,
Fig. 9) (IC 50 : 7.3 Æ 1.0 μM) was reported in 2014 by Ma et al. [128, 129]. The novel
quinazoline-based inhibitor proved selective for SETD8 over 15 other methyltransferases. Recently, it was proved that pharmacological inhibition of SETD8 by
compound 75 phenocopied the effects of SETD8 knockdown and inhibited the
proliferation of neuroblastoma cells [130]. In 2016, among various substitutions
on the scaffold compound 75, the insertion of an aminoethyl chain to the 7-position
yielded MS2177 (76, Fig. 9) as a more potent SETD8 inhibitor (IC 50 : 1.9 μM)
[131]. ITC confirmed the target binding (K D : 1.3 μM), while kinetic studies showed
that compound 76 is a substrate-competitive inhibitor. Thanks to the resolution of
the co-crystal structure of SETD8 in complex with compound 76, Cys311 was
identified as a possible site to target with covalent inhibitors. Indeed, MS453 (77,
Fig. 9) was developed as covalent analogue of compound 76, containing an acrylamide that could specifically react with Cys311. The authors, using MS techniques
in presence of WT and mutant SETD8, demonstrated that compound 77 specifically
links to Cys311, displaying an IC 50 of 0.8 μM and a time-dependent inhibition
activity. Additionally, the novel covalent inhibitor proved selective for SETD8 over
29 other methyltransferases in biochemical assays. Despite its nice biochemical
Cl
Cl
N
N
N
NH
80, A-196
SUV420H1 IC 50 : 25 nM
SUV420H2 IC 50 : 144 nM
OH NH 2
HO 3 S
SO 3 H
68, H acid
SETD8 IC 50 : 3.8 M
EZH2 IC 50 : 3.0 M
O
O
HO
OH
69, Timolphtalein
SETD8 IC 50 : 9.0 M
EZH2 IC 50 : 25.2 M
O
Br
H 3 CO
R
Br
OCH 3
R
O
Br
H 3 CO
R
Br
OCH 3
R
72, MC1948 (R= Br) SETD8 IC 50 : 2.6 M
73, MC2569 (R= H) SETD8 IC 50 : 10.2 M
70, MC1946 (R= Br) SETD8 IC 50 : 3.3 M
71, MC1947 (R= H) SETD8 IC 50 : 9.0 M
H
OH
OH OH
HO
OH
COOH
74, Nahuoic acid A
SETD8 IC 50 : 6.5 M
N
N
H 3 CO
RO
HN
N
N
75, UNC0379 (R= CH 3 ) SETD8 IC 50 : 7.3 M
76, MS2177 (R= CH 2 CH 2 NH 2 ) SETD8 IC 50 : 1.9 M
N
N
H 3 CO
H 3 CO
HN
N
H
N
O
77, MS453
SETD8 IC 50 : 0.804 M
79
SETD8 IC 50 : 0.33 M
N
O
O
N
H
N
O
Cl
78, NSC663284
SETD8 IC 50 <0.25 M
N
H
N
N
H
NH
N
H
NH
N
H
H
N
NH
NH 2
HO O
O
O
O
O
O
O
H
N
NH
NH 2
O
HN
O
N
H
NH 2
NH 2
O
H
N
NH
H 2 N
Fig. 9 H4K20 methyltransferases SETD8, SUV420H1, and SUV420H2 inhibitors
Lysine Methyltransferases and Their Inhibitors
145
quinazoline-based SETD8 selective substrate-competitive inhibitor UNC0379 (75,
Fig. 9) (IC 50 : 7.3 Æ 1.0 μM) was reported in 2014 by Ma et al. [128, 129]. The novel
quinazoline-based inhibitor proved selective for SETD8 over 15 other methyltransferases. Recently, it was proved that pharmacological inhibition of SETD8 by
compound 75 phenocopied the effects of SETD8 knockdown and inhibited the
proliferation of neuroblastoma cells [130]. In 2016, among various substitutions
on the scaffold compound 75, the insertion of an aminoethyl chain to the 7-position
yielded MS2177 (76, Fig. 9) as a more potent SETD8 inhibitor (IC 50 : 1.9 μM)
[131]. ITC confirmed the target binding (K D : 1.3 μM), while kinetic studies showed
that compound 76 is a substrate-competitive inhibitor. Thanks to the resolution of
the co-crystal structure of SETD8 in complex with compound 76, Cys311 was
identified as a possible site to target with covalent inhibitors. Indeed, MS453 (77,
Fig. 9) was developed as covalent analogue of compound 76, containing an acrylamide that could specifically react with Cys311. The authors, using MS techniques
in presence of WT and mutant SETD8, demonstrated that compound 77 specifically
links to Cys311, displaying an IC 50 of 0.8 μM and a time-dependent inhibition
activity. Additionally, the novel covalent inhibitor proved selective for SETD8 over
29 other methyltransferases in biochemical assays. Despite its nice biochemical
Cl
Cl
N
N
N
NH
80, A-196
SUV420H1 IC 50 : 25 nM
SUV420H2 IC 50 : 144 nM
OH NH 2
HO 3 S
SO 3 H
68, H acid
SETD8 IC 50 : 3.8 M
EZH2 IC 50 : 3.0 M
O
O
HO
OH
69, Timolphtalein
SETD8 IC 50 : 9.0 M
EZH2 IC 50 : 25.2 M
O
Br
H 3 CO
R
Br
OCH 3
R
O
Br
H 3 CO
R
Br
OCH 3
R
72, MC1948 (R= Br) SETD8 IC 50 : 2.6 M
73, MC2569 (R= H) SETD8 IC 50 : 10.2 M
70, MC1946 (R= Br) SETD8 IC 50 : 3.3 M
71, MC1947 (R= H) SETD8 IC 50 : 9.0 M
H
OH
OH OH
HO
OH
COOH
74, Nahuoic acid A
SETD8 IC 50 : 6.5 M
N
N
H 3 CO
RO
HN
N
N
75, UNC0379 (R= CH 3 ) SETD8 IC 50 : 7.3 M
76, MS2177 (R= CH 2 CH 2 NH 2 ) SETD8 IC 50 : 1.9 M
N
N
H 3 CO
H 3 CO
HN
N
H
N
O
77, MS453
SETD8 IC 50 : 0.804 M
79
SETD8 IC 50 : 0.33 M
N
O
O
N
H
N
O
Cl
78, NSC663284
SETD8 IC 50 <0.25 M
N
H
N
N
H
NH
N
H
NH
N
H
H
N
NH
NH 2
HO O
O
O
O
O
O
O
H
N
NH
NH 2
O
HN
O
N
H
NH 2
NH 2
O
H
N
NH
H 2 N
Fig. 9 H4K20 methyltransferases SETD8, SUV420H1, and SUV420H2 inhibitors
Lysine Methyltransferases and Their Inhibitors
145