Search

Autophagy inducers represent new promising agents for the treatment of a wide range of medical illnesses. However, safe autophagy inducers for clinical applications are lacking. Inhibition of cdc2-like kinase 1 (CLK1) was recently found to efficiently induce autophagy. Unfortunately, most of the known CLK1 inhibitors have unsatisfactory selectivity. Herein, we report the discovery of a series of new CLK1 inhibitors containing the 1H-[1,2,3]triazolo[4,5-c]quinoline scaffold. Among them, compound 25 was the most potent and selective, with an IC50 value of 2 nM against CLK1. The crystal structure of CLK1 complexed with compound 25 was solved, and the potency and kinase selectivity of compound 25 were interpreted. Compound 25 was able to induce autophagy in in vitro assays and displayed significant hepatoprotective effects in the acetaminophen (APAP)-induced liver injury mouse model. Collectively, due to its potency and selectivity, compound 25 could be used as a chemical probe or agent in future mechanism-of...

In cancer cells, kinases of the Clk family control the supply of full-length, functional mRNAs coding for a variety of proteins essential to cell growth and survival. Thus, inhibition of Clks might become a novel anticancer strategy, leading to a selective depletion of cancer-relevant proteins after turnover. On the basis of a Weinreb amide hit compound, we designed and synthesized a diverse set of methoxybenzothiophene-2-carboxamides, of which the N-benzylated derivative showed enhanced Clk1 inhibitory activity. Introduction of a m-fluorine in the benzyl moiety eventually led to the discovery of compound 21b, a potent inhibitor of Clk1 and -4 (IC50 = 7 and 2.3 nM, respectively), exhibiting an unprecedented selectivity over Dyrk1A. 21b triggered the depletion of EGFR, HDAC1, and p70S6 kinase from the cancer cells, with potencies in line with the measured GI50 values. In contrast, the cellular effects of congener 21a, which inhibited Clk1 only weakly, were substantially lower.

The DYRK family contains kinases that are up-regulated in malignancy and control several cancer hallmarks. To assess the anticancer potential of inhibitors targeting DYRK kinases, we developed a series of novel DYRK inhibitors based on the 7-azaindole scaffold. All compounds were tested for their ability to inhibit DYRK1A, DYRK1B, DYRK2, and the structurally related CLK1. The library was screened for anticancer efficacy in established and stem cell-like glioblastoma cell lines. The most potent inhibitors (IC50 ≤ 50 nM) significantly decreased viability, clonogenic survival, migration, and invasion of glioblastoma cells. Target engagement was confirmed with genetic knockdown and the cellular thermal shift assay. We demonstrate that DYRK1A’s thermal stability in cells is increased upon compound treatment, confirming binding in cells. In summary, we present synthesis, structure–activity relationship, and efficacy in glioblastoma-relevant models for a library of novel 7-azaindoles.

International audience; DYRKs (dual specificity, tyrosine phosphorylation regulated kinases) and CLKs (cdc2-like kinases) are implicated in the onset and development of Alzheimer's disease and Down syndrome. The marine sponge alkaloid leucettamine B was recently identified as an inhibitor of DYRKs/CLKs. Synthesis of analogues (leucettines) led to an optimized product, leucettine L41. Leucettines were cocrystallized with DYRK1A, DYRK2, CLK3, PIM1, and GSK-3β. The selectivity of L41 was studied by activity and interaction assays of recombinant kinases and affinity chromatography and competition affinity assays. These approaches revealed unexpected potential secondary targets such as CK2, SLK, and the lipid kinase PIKfyve/Vac14/Fig4. L41 displayed neuroprotective effects on glutamate-induced HT22 cell death. L41 also reduced amyloid precursor protein-induced cell death in cultured rat brain slices. The unusual multitarget selectivity of leucettines may account for their neuroprotective effects. This family of kinase inhibitors deserves further optimization as potential therapeutics against neurodegenerative diseases such as Alzheimer's disease.

The synthesis of new meridianin derivatives is described. The indolic ring system was substituted at the C-4 to C-7 positions either by a bromine atom or by nitro or amino groups. Additionally, an iodine atom or various aryl groups were introduced at the C-5 position of the 2-aminopyrimidine ring. These compounds as well as some of their synthetic intermediates were tested for their kinase inhibitory potencies and for their in vitro antiproliferative activities. We found that this series of compounds is particularly interesting in the development of new inhibitors of DYRK1A and CLK1 kinases. The most effective compounds toward these two kinase families are the 6- and 7-bromo derivatives 30, 33, and 34 that showed more than 45-fold selectivity toward DYRK1A/CLK1 kinases over the other kinases tested. Meridianin derivatives could thus be developed toward potent and selective inhibitors of key RNA splicing regulators and potential therapeutic agents.

Selectivity remains a challenge for ATP-mimetic kinase inhibitors, an issue that may be overcome by targeting unique residues or binding pockets. However, to date only few strategies have been developed. Here we identify that bulky residues located N-terminal to the DFG motif (DFG-1) represent an opportunity for designing highly selective inhibitors with unexpected binding modes. We demonstrate that several diverse inhibitors exerted selective, non-canonical binding modes that exclusively target large hydrophobic DFG-1 residues present in many kinases including PIM, CK1, DAPK and CLK. Using the CLK family as a model, structural and biochemical data revealed that the DFG-1 valine controlled a non-canonical binding mode in CLK1, providing a rational for selectivity over the closely-related CLK3 which harbors a smaller DFG-1 alanine. Our data suggests that targeting the restricted back pocket in the small fraction of kinases that harbor bulky DFG-1 residues offers a versatile selectivity filter for inhibitor design.