The Nitro Group Reshapes the Effects of Pyrido[3,4-g]quinazoline Derivatives on DYRK/CLK Activity and RNA Splicing in Glioblastoma Cells.

Serine-threonine protein kinases of the DYRK and CLK families regulate a variety of vital cellular functions. In particular, these enzymes phosphorylate proteins involved in pre-mRNA splicing. Targeting splicing with pharmacological DYRK/CLK inhibitors emerged as a promising anticancer strategy. Investigation of the pyrido[3,4-g]quinazoline scaffold led to the discovery of DYRK/CLK binders with differential potency against individual enzyme isoforms. Exploring the structure-activity relationship within this chemotype, we demonstrated that two structurally close compounds, pyrido[3,4-g]quinazoline-2,10-diamine 1 and 10-nitro pyrido[3,4-g]quinazoline-2-amine 2, differentially inhibited DYRK1-4 and CLK1-3 protein kinases in vitro. Unlike compound 1, compound 2 efficiently inhibited DYRK3 and CLK4 isoenzymes at nanomolar concentrations. Quantum chemical calculations, docking and molecular dynamic simulations of complexes of 1 and 2 with DYRK3 and CLK4 identified a dramatic difference in electron donor-acceptor properties critical for preferential interaction of 2 with these targets. Subsequent transcriptome and proteome analyses of patient-derived glioblastoma (GBM) neurospheres treated with 2 revealed that this compound impaired CLK4 interactions with spliceosomal proteins, thereby altering RNA splicing. Importantly, 2 affected the genes that perform critical functions for cancer cells including DNA damage response, p53 signaling and transcription. Altogether, these results provide a mechanistic basis for the therapeutic efficacy of 2 previously demonstrated in in vivo GBM models.

Synthesis and biological evaluation of Haspin inhibitors: Kinase inhibitory potency and cellular activity.

Haspin (haploid germ cell-specific nuclear protein kinase) offers a potential target for the development of new anticancer drugs. Thus, the identification of new inhibitors targeting this protein kinase is of high interest. However, Haspin inhibitors developed to date show a poor selectivity profile over other protein kinases of the human kinome. Here, we identified a new pyridoquinazoline based inhibitor (4), with excellent inhibitory activity and selectivity for Haspin (IC50 of 50 nM). We describe the structure-activity relationship study including the evaluation of this inhibitor on a large panel of 486 kinases as well as on immortalized or cancer cell lines. In addition, we determined the binding mode of analog 2a in complex with Haspin using X-ray crystallography.

Kinase inhibitions in pyrido[4,3-h] and [3,4-g]quinazolines: Synthesis, SAR and molecular modeling studies.

New pyrido[3,4-g]quinazoline derivatives were prepared and evaluated for their inhibitory potency toward 5 protein kinases (CLK1, DYRK1A, GSK3, CDK5, CK1). A related pyrido[4,3-h]quinazoline scaffold with an angular structure was also synthesized and its potency against the same protein kinase panel was compared to the analogous pyrido[3,4-g]quinazoline. Best results were obtained for 10-nitropyrido[3,4-g]quinazoline 4 toward CLK1 with nanomolar activities.

New pyrido[3,4-g]quinazoline derivatives as CLK1 and DYRK1A inhibitors: synthesis, biological evaluation and binding mode analysis.

Cdc2-like kinase 1 (CLK1) and dual specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) are involved in the regulation of alternative pre-mRNA splicing. Dysregulation of this process has been linked to cancer progression and neurodegenerative diseases, making CLK1 and DYRK1A important therapeutic targets. Here we describe the synthesis of new pyrido[3,4-g]quinazoline derivatives and the evaluation of the inhibitory potencies of these compounds toward CDK5, CK1, GSK3, CLK1 and DYRK1A. Introduction of aminoalkylamino groups at the 2-position resulted in several compounds with low nanomolar affinity and selective inhibition of CLK1 and/or DYRK1A. Their evaluation on several immortalized or cancerous cell lines showed varying degree of cell viability reduction. Co-crystal structures of CLK1 with two of the most potent compounds revealed two alternative binding modes of the pyrido[3,4-g]quinazoline scaffold that can be exploited for future inhibitor design.

Regioselective cycloaddition of potassium alkynyltrifluoroborates with 3-azetidinones and 3-oxetanone by nickel-catalysed C-C bond activation.

In the presence of a nickel catalyst, the intermolecular (4+2) cycloaddition of potassium alkynyltrifluoroborates with 3-azetidinones and 3-oxetanone leads to the formation of borylated dihydropyridinones and dihydropyranones without unwanted carbon-boron bond cleavage. The regioselectivity is influenced only by the trifluoroborate group, and only one regioisomer is obtained, whether the other alkyne substituent is an alkyl, vinyl, or (hetero)aryl group.

Synthesis and preliminary in vitro kinase inhibition evaluation of new diversely substituted pyrido[3,4-g]quinazoline derivatives.

The synthesis of new diversely substituted pyrido[3,4-g]quinazolines is described. The inhibitory potencies of prepared compounds toward a panel of five CMGC protein kinases (CDK5, CLK1, DYRK1A, CK1, GSK3), that are known to play a potential role in Alzheimer's disease, were evaluated. The best overall kinase inhibition profile was found for nitro compound 4 bearing an ethyl group at the 5-position.

Synthesis and biological activity of pyrazole analogues of the staurosporine aglycon K252c.

A derivative of the staurosporine aglycon (K252c), in which the lactam ring was replaced by a pyrazole moiety, was synthesized. The resulting indolopyrazolocarbazole (3) inhibited Pim isoforms 1-3 whereas it did not impair the activity of two known targets of K252c, protein kinase C isoforms α and γ. Compound 3 exhibited moderate cytotoxic activity toward human leukemia and colon carcinoma cell lines (K562 and HCT116), strongly suggesting that this new scaffold deserves further investigations for treatment of malignancies associated with Pim activity.

Heteroaromatic Pim Kinase Inhibitors Containing a Pyrazole Moiety.

This review, of the literature published between 2010 and 2015 reports that molecules containing a non-fused and/or fused pyrazole moiety could exhibit very potent activity toward Pim kinases, including the inhibition of cellular Bad phosphorylation as well as antiproliferative activity against various cancer cells. Even if Pim kinase inhibitors currently in clinical trial do not exhibit a pyrazole moiety, heteroaromatic kinase inhibitors containing an indazole part such as Axitinib and Pazopanib already reached the market. Therefore, one can imagine that in the future, heteroaromatic derivatives inhibiting Pim kinases including pyrazoles could be identified and used for their diagnostic and/or therapeutic potential alone or in combination with other drugs for the diseases in which Pim kinases are involved.

Discovery of pyrido[3,4-g]quinazoline derivatives as CMGC family protein kinase inhibitors: Design, synthesis, inhibitory potency and X-ray co-crystal structure.

The design and synthesis of new pyrido[3,4-g]quinazoline derivatives is described as well as their protein kinase inhibitory potencies toward five CMGC family members (CDK5, CK1, GSK3, CLK1 and DYRK1A). The interest for this original tricyclic heteroaromatic scaffold as modulators of CLK1/DYRK1A activity was validated by nanomolar potencies (compounds 12 and 13). CLK1 co-crystal structures with two inhibitors revealed the binding mode of these compounds within the ATP-binding pocket.