4 research outputs found
Mechanism and <i>In Vitro</i> Pharmacology of TAK1 Inhibition by (5<i>Z</i>)‑7-Oxozeaenol
Transforming growth factor-β activated kinase-1
(TAK1) is
a member of the mitogen-activated protein kinase kinase kinase (MAP3K)
family that regulates several signaling pathways including NF-κB
signal transduction and p38 activation. TAK1 deregulation has been
implicated in human diseases including cancer and inflammation. Here,
we show that, in addition to its kinase activity, TAK1 has intrinsic
ATPase activity, that (5<i>Z</i>)-7-Oxozeaenol irreversibly
inhibits TAK1, and that sensitivity to (5<i>Z</i>)-7-Oxozeaenol
inhibition in hematological cancer cell lines is NRAS mutation status
and TAK1 pathway dependent. X-ray crystallographic and mass spectrometric
studies showed that (5<i>Z</i>)-7-Oxozeaenol forms a covalent
complex with TAK1. Detailed biochemical characterization revealed
that (5<i>Z</i>)-7-Oxozeaenol inhibited both the kinase
and the ATPase activity of TAK1 following a bi-phase kinetics, consistent
with the irreversible inhibition mechanism. In DoHH2 cells, (5<i>Z</i>)-7-Oxozeaenol potently inhibited the p38 phosphorylation
driven by TAK1, and the inhibition lasted over 6 h after withdrawal
of (5<i>Z</i>)-7-Oxozeaenol. Profiling (5<i>Z</i>)-7-Oxozeaenol in a panel of hematological cancer cells showed that
sensitive cell lines tended to carry NRAS mutations and that genes
in TAK1 regulated pathways were enriched in sensitive cell lines.
Taken together, we have elucidated the molecular mechanism of a TAK1
irreversible inhibitor and laid the foundation for designing next
generation TAK1 irreversible inhibitors. The NRAS-TAK1-Wnt signaling
network discerned in our study may prove to be useful in patient selection
for TAK1 targeted agents in hematological cancers
Potent and Selective Inhibitors of MTH1 Probe Its Role in Cancer Cell Survival
Recent
literature has claimed that inhibition of the enzyme MTH1 can eradicate
cancer. MTH1 is one of the “housekeeping” enzymes that
are responsible for hydrolyzing damaged nucleotides in cells and thus
prevent them from being incorporated into DNA. We have developed orthogonal
and chemically distinct tool compounds to those published in the literature
to allow us to test the hypothesis that inhibition of MTH1 has wide
applicability in the treatment of cancer. Here we present the work
that led to the discovery of three structurally different series of
MTH1 inhibitors with excellent potency, selectivity, and proven target
engagement in cells. None of these compounds elicited the reported
cellular phenotype, and additional siRNA and CRISPR experiments further
support these observations. Critically, the difference between the
responses of our highly selective inhibitors and published tool compounds
suggests that the effect reported for the latter may be due to off-target
cytotoxic effects. As a result, we conclude that the role of MTH1
in carcinogenesis and utility of its inhibition is yet to be established
Structure Guided Lead Generation for <i>M. tuberculosis</i> Thymidylate Kinase (Mtb TMK): Discovery of 3‑Cyanopyridone and 1,6-Naphthyridin-2-one as Potent Inhibitors
<i>M. tuberculosis</i> thymidylate
kinase (Mtb TMK) has
been shown in vitro to be an essential
enzyme in DNA synthesis. In order to identify novel leads for Mtb
TMK, we performed a high throughput biochemical screen and an NMR
based fragment screen through which we discovered two novel classes
of inhibitors, 3-cyanopyridones and 1,6-naphthyridin-2-ones, respectively.
We describe three cyanopyridone subseries that arose during our hit
to lead campaign, along with cocrystal structures of representatives
with Mtb TMK. Structure aided optimization of the cyanopyridones led
to single digit nanomolar inhibitors of Mtb TMK. Fragment based lead
generation, augmented by crystal structures and the SAR from the cyanopyridones,
enabled us to drive the potency of our 1,6-naphthyridin-2-one fragment
hit from 500 μM to 200 nM while simultaneously improving the
ligand efficiency. Cyanopyridone derivatives containing sulfoxides
and sulfones showed cellular activity against <i>M. tuberculosis</i>. To the best of our knowledge, these compounds are the first reports
of non-thymidine-like inhibitors of Mtb TMK
Discovery and Optimization of a Novel Series of Potent Mutant B‑Raf<sup>V600E</sup> Selective Kinase Inhibitors
B-Raf
represents an attractive target for anticancer therapy and
the development of small molecule B-Raf inhibitors has delivered new
therapies for metastatic melanoma patients. We have discovered a novel
class of small molecules that inhibit mutant B-Raf<sup>V600E</sup> kinase activity both in vitro and in vivo. Investigations into the
structure–activity relationships of the series are presented
along with efforts to improve upon the cellular potency, solubility,
and pharmacokinetic profile. Compounds selectively inhibited B-Raf<sup>V600E</sup> in vitro and showed preferential antiproliferative activity
in mutant B-Raf<sup>V600E</sup> cell lines and exhibited selectivity
in a kinase panel against other kinases. Examples from this series
inhibit growth of a B-Raf<sup>V600E</sup> A375 xenograft in vivo at
a well-tolerated dose. In addition, aminoquinazolines described herein
were shown to display pERK elevation in nonmutant B-Raf cell lines
in vitro