6 research outputs found
Discovery and Mechanistic Study of a Small Molecule Inhibitor for Motor Protein KIFC1
Centrosome
amplification is observed in many human cancers and
has been proposed to be a driver of both genetic instability and tumorigenesis.
Cancer cells have evolved mechanisms to bundle multiple centrosomes
into two spindle poles to avoid multipolar mitosis that can lead to
chromosomal segregation defects and eventually cell death. KIFC1,
a kinesin-14 family protein, plays an essential role in centrosomal
bundling in cancer cells, but its function is not required for normal
diploid cell division, suggesting that KIFC1 is an attractive therapeutic
target for human cancers. To this end, we have identified the first
reported small molecule inhibitor AZ82 for KIFC1. AZ82 bound specifically
to the KIFC1/microtubule (MT) binary complex and inhibited the MT-stimulated
KIFC1 enzymatic activity in an ATP-competitive and MT-noncompetitive
manner with a <i>K</i><sub>i</sub> of 0.043 μM. AZ82
effectively engaged with the minus end-directed KIFC1 motor inside
cells to reverse the monopolar spindle phenotype induced by the inhibition
of the plus end-directed kinesin Eg5. Treatment with AZ82 caused centrosome
declustering in BT-549 breast cancer cells with amplified centrosomes.
Consistent with genetic studies, our data confirmed that KIFC1 inhibition
by a small molecule holds promise for targeting cancer cells with
amplified centrosomes and provided evidence that functional suppression
of KIFC1 by inhibiting its enzymatic activity could be an effective
means for developing cancer therapeutics
Discovery of Potent KIFC1 Inhibitors Using a Method of Integrated High-Throughput Synthesis and Screening
KIFC1
(HSET), a member of the kinesin-14 family of motor proteins,
plays an essential role in centrosomal bundling in cancer cells, but
its function is not required for normal diploid cell division. To
explore the potential of KIFC1 as a therapeutic target for human cancers,
a series of potent KIFC1 inhibitors featuring a phenylalanine scaffold
was developed from hits identified through high-throughput screening
(HTS). Optimization of the initial hits combined both design–synthesis–test
cycles and an integrated high-throughput synthesis and biochemical
screening method. An important aspect of this integrated method was
the utilization of DMSO stock solutions of compounds registered in
the corporate compound collection as synthetic reactants. Using this
method, over 1500 compounds selected for structural diversity were
quickly assembled in assay-ready 384-well plates and were directly
tested after the necessary dilutions. Our efforts led to the discovery
of a potent KIFC1 inhibitor, <b>AZ82</b>, which demonstrated
the desired centrosome declustering mode of action in cell studies
Potent and Selective Inhibitors of CK2 Kinase Identified through Structure-Guided Hybridization
In this paper we describe a series of 3-cyano-5-aryl-7-aminopyrazoloÂ[1,5-<i>a</i>]Âpyrimidine hits identified by kinase-focused subset screening
as starting points for the structure-based design of conformationally
constrained 6-acetamido-indole inhibitors of CK2. The synthesis, SAR,
and effects of this novel series on Akt signaling and cell proliferation <i>in vitro</i> are described
Pyrimidinone Nicotinamide Mimetics as Selective Tankyrase and Wnt Pathway Inhibitors Suitable for in Vivo Pharmacology
The canonical Wnt pathway plays an
important role in embryonic
development, adult tissue homeostasis, and cancer. Germline mutations
of several Wnt pathway components, such as Axin, APC, and ß-catenin,
can lead to oncogenesis. Inhibition of the polyÂ(ADP-ribose) polymerase
(PARP) catalytic domain of the tankyrases (TNKS1 and TNKS2) is known
to inhibit the Wnt pathway via increased stabilization of Axin. In
order to explore the consequences of tankyrase and Wnt pathway inhibition
in preclinical models of cancer and its impact on normal tissue, we
sought a small molecule inhibitor of TNKS1/2 with suitable physicochemical
properties and pharmacokinetics for hypothesis testing in vivo. Starting
from a 2-phenyl quinazolinone hit (compound <b>1</b>), we discovered
the pyrrolopyrimidinone compound <b>25</b> (AZ6102), which is
a potent TNKS1/2 inhibitor that has 100-fold selectivity against other
PARP family enzymes and shows 5 nM Wnt pathway inhibition in DLD-1
cells. Moreover, compound <b>25</b> can be formulated well in
a clinically relevant intravenous solution at 20 mg/mL, has demonstrated
good pharmacokinetics in preclinical species, and shows low Caco2
efflux to avoid possible tumor resistance mechanisms
Structure Based Design of Non-Natural Peptidic Macrocyclic Mcl‑1 Inhibitors
Mcl-1 is a pro-apoptotic
BH3 protein family member similar to Bcl-2
and Bcl-xL. Overexpression of Mcl-1 is often seen in various tumors
and allows cancer cells to evade apoptosis. Here we report the discovery
and optimization of a series of non-natural peptide Mcl-1 inhibitors.
Screening of DNA-encoded libraries resulted in hit compound <b>1</b>, a 1.5 μM Mcl-1 inhibitor. A subsequent crystal structure
demonstrated that compound <b>1</b> bound to Mcl-1 in a β-turn
conformation, such that the two ends of the peptide were close together.
This proximity allowed for the linking of the two ends of the peptide
to form a macrocycle. Macrocyclization resulted in an approximately
10-fold improvement in binding potency. Further exploration of a key
hydrophobic interaction with Mcl-1 protein and also with the moiety
that engages Arg256 led to additional potency improvements. The use
of protein–ligand crystal structures and binding kinetics contributed
to the design and understanding of the potency gains. Optimized compound <b>26</b> is a <3 nM Mcl-1 inhibitor, while inhibiting Bcl-2 at
only 5 μM and Bcl-xL at >99 μM, and induces cleaved
caspase-3
in MV4–11 cells with an IC<sub>50</sub> of 3 μM after
6 h
Structure Based Design of Non-Natural Peptidic Macrocyclic Mcl‑1 Inhibitors
Mcl-1 is a pro-apoptotic
BH3 protein family member similar to Bcl-2
and Bcl-xL. Overexpression of Mcl-1 is often seen in various tumors
and allows cancer cells to evade apoptosis. Here we report the discovery
and optimization of a series of non-natural peptide Mcl-1 inhibitors.
Screening of DNA-encoded libraries resulted in hit compound <b>1</b>, a 1.5 μM Mcl-1 inhibitor. A subsequent crystal structure
demonstrated that compound <b>1</b> bound to Mcl-1 in a β-turn
conformation, such that the two ends of the peptide were close together.
This proximity allowed for the linking of the two ends of the peptide
to form a macrocycle. Macrocyclization resulted in an approximately
10-fold improvement in binding potency. Further exploration of a key
hydrophobic interaction with Mcl-1 protein and also with the moiety
that engages Arg256 led to additional potency improvements. The use
of protein–ligand crystal structures and binding kinetics contributed
to the design and understanding of the potency gains. Optimized compound <b>26</b> is a <3 nM Mcl-1 inhibitor, while inhibiting Bcl-2 at
only 5 μM and Bcl-xL at >99 μM, and induces cleaved
caspase-3
in MV4–11 cells with an IC<sub>50</sub> of 3 μM after
6 h