Matthieu Desroses

MTH1 inhibition eradicates cancer by preventing sanitation of the dNTP pool.

Cancers have dysfunctional redox regulation resulting in reactive oxygen species production, damaging both DNA and free dNTPs. The MTH1 protein sanitizes oxidized dNTP pools to prevent incorporation of damaged bases during DNA replication. Although MTH1 is non-essential in normal cells, we show that cancer cells require MTH1 activity to avoid incorporation of oxidized dNTPs, resulting in DNA damage and cell death. We validate MTH1 as an anticancer target in vivo and describe small molecules TH287 and TH588 as first-in-class nudix hydrolase family inhibitors that potently and selectively engage and inhibit the MTH1 protein in cells. Protein co-crystal structures demonstrate that the inhibitors bind in the active site of MTH1. The inhibitors cause incorporation of oxidized dNTPs in cancer cells, leading to DNA damage, cytotoxicity and therapeutic responses in patient-derived mouse xenografts. This study exemplifies the non-oncogene addiction concept for anticancer treatment and validates MTH1 as being cancer phenotypic lethal.

Crystal structure, biochemical and cellular activities demonstrate separate functions of MTH1 and MTH2.

Deregulated redox metabolism in cancer leads to oxidative damage to cellular components including deoxyribonucleoside triphosphates (dNTPs). Targeting dNTP pool sanitizing enzymes, such as MTH1, is a highly promising anticancer strategy. The MTH2 protein, known as NUDT15, is described as the second human homologue of bacterial MutT with 8-oxo-dGTPase activity. We present the first NUDT15 crystal structure and demonstrate that NUDT15 prefers other nucleotide substrates over 8-oxo-dGTP. Key structural features are identified that explain different substrate preferences for NUDT15 and MTH1. We find that depletion of NUDT15 has no effect on incorporation of 8-oxo-dGTP into DNA and does not impact cancer cell survival in cell lines tested. NUDT17 and NUDT18 were also profiled and found to have far less activity than MTH1 against oxidized nucleotides. We show that NUDT15 is not a biologically relevant 8-oxo-dGTPase, and that MTH1 is the most prominent sanitizer of the cellular dNTP pool known to date.

A new concise synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives

A new T3P®-assisted, convenient and efficient procedure for the synthesis of dihydroquinazolinones is described. The main advantages of this protocol include its practical simplicity, short reaction times and particularly the ease with which products are isolated.

Vinylic MIDA Boronates: New Building Blocks for the Synthesis of Aza-Heterocycles

A two-step synthesis of structurally diverse pyrrole-containing bicyclic systems is reported. ortho-Nitro-haloarenes coupled with vinylic N-methyliminodiacetic acid (MIDA) boronates generate ortho-vinyl-nitroarenes, which undergo a metal-free nitrene insertion, resulting in a new pyrrole ring. This novel synthetic approach has a wide substrate tolerance and it is applicable in the preparation of more complex drug-like molecules. Interestingly, an ortho-nitro-allylarene derivative furnished a cyclic β-aminophosphonate motif.

Piperazin-1-ylpyridazine Derivatives Are a Novel Class of Human dCTP Pyrophosphatase 1 Inhibitors

The dCTP pyrophosphatase 1 (dCTPase) is a nucleotide pool housekeeping enzyme responsible for the catabolism of canonical and noncanonical nucleoside triphosphates (dNTPs) and has been associated with cancer progression and cancer cell stemness. We have identified a series of piperazin-1-ylpyridazines as a new class of potent dCTPase inhibitors. Lead compounds increase dCTPase thermal and protease stability, display outstanding selectivity over related enzymes and synergize with a cytidine analogue against leukemic cells. This new class of dCTPase inhibitors lays the first stone toward the development of drug-like probes for the dCTPase enzyme.

dUTPase inhibition augments replication defects of 5-Fluorouracil

The antimetabolite 5-Fluorouracil (5-FU) is used in the treatment of various forms of cancer and has a complex mode of action. Despite 6 decades in clinical application the contribution of 5-FdUTP and dUTP [(5-F)dUTP] and 5-FUTP misincorporation into DNA and RNA respectively, for 5-FU-induced toxicity is still under debate. This study investigates DNA replication defects induced by 5-FU treatment and how (5-F)dUTP accumulation contributes to this effect. We reveal that 5-FU treatment leads to extensive problems in DNA replication fork progression, causing accumulation of cells in S-phase, DNA damage and ultimately cell death. Interestingly, these effects can be reinforced by either depletion or inhibition of the deoxyuridine triphosphatase (dUTPase, also known as DUT), highlighting the importance of (5-F)dUTP accumulation for cytotoxicity. With this study, we not only extend the current understanding of the mechanism of action of 5-FU, but also contribute to the characterization of dUTPase inhibitors. We demonstrate that pharmacological inhibition of dUTPase is a promising approach that may improve the efficacy of 5-FU treatment in the clinic.

Corrigendum: MTH1 inhibition eradicates cancer by preventing sanitation of the dNTP pool

Nature 508, 215–221 (2014); doi:10.1038/nature13181 In this Article, the structure of compound TH650 (4) in Fig. 4a was drawn incorrectly; the correct structure is shown as Fig. 1 to this Corrigendum. Preparative, spectroscopic and biological data associated with this compound are as reported in theArticle, and the error does not influence any of the reported data or interpretations.

STAT3 differential scanning fluorimetry and differential scanning light scattering assays: Addressing a missing link in the characterization of STAT3 inhibitor interactions

HIGHLIGHTSTruncated variants of STAT3 allowed the development of conventional STAT3 thermal stability assays.Thermal denaturing of STAT3 can be tracked using Sypro OrangeTM fluorescence, tryptophan fluorescence or light scattering.Novel thermal stability assays confirm that peptide STAT3 inhibitors bind specifically to the STAT3 SH2 domain.Thermal stability assays show that reported small molecule STAT3 inhibitors may not specifically bind the STAT3 SH2 domain.High‐throughput STAT3 thermal stability assays could help to accelerate the development of new STAT3 inhibitors. ABSTRACT STAT3 protein is an established target for the development of new cancer therapeutic agents. Despite lacking a traditional binding site for small molecule inhibitors, many STAT3 inhibitors have been identified and explored for their anti‐cancer activity. Because STAT3 signaling is mediated by protein‐protein interactions, indirect methods are often employed to determine if proposed STAT3 inhibitors bind to STAT3 protein. While established STAT3 inhibition assays (such as the fluorescence polarization assay, electrophoretic mobility shift assay and ELISAs) have been used to identify novel inhibitors of STAT3 signaling, methods that directly assess STAT3 protein‐inhibitor interactions could facilitate the development of novel inhibitors. In this context, we herein report new STAT3 binding assays based on differential scanning fluorimetry (DSF) and differential scanning light scattering (DSLS) to characterize interactions between STAT3 protein and inhibitors. Several peptide and small molecule STAT3 inhibitors have been evaluated, and new insight into how these compounds may interact with STAT3 is provided.

The Next Step Forward in Ubiquitin-Specific Protease 7 Selective Inhibition

Ubiquitin-specific protease 7 is a validated anticancer target; thus, selective USP7 inhibitors are of great interest. In this issue of Cell Chemical Biology, Lamberto etxa0al. (2017) and Pozhidaeva etxa0al. (2017) report important insights into the structural inhibitor-enzyme interplay, lighting the way toward the development of selective inhibitors.