MPS1 kinase is a key regulator of the spindle assembly checkpoint (SAC), a mitotic mechanism specifically required for proper chromosomal alignment and segregation. It has been found aberrantly ...overexpressed in a wide range of human tumors and is necessary for tumoral cell proliferation. Here we report the identification and characterization of NMS-P715, a selective and orally bioavailable MPS1 small-molecule inhibitor, which selectively reduces cancer cell proliferation, leaving normal cells almost unaffected. NMS-P715 accelerates mitosis and affects kinetochore components localization causing massive aneuploidy and cell death in a variety of tumoral cell lines and inhibits tumor growth in preclinical cancer models. Inhibiting the SAC could represent a promising new approach to selectively target cancer cells.
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In this article we describe the identification of unprecedented ATP-competitive ChoKα inhibitors starting from initial hit NMS-P830 that binds to ChoKα in an ATP ...concentration-dependent manner. This result is confirmed by the co-crystal structure of NMS-P830 in complex with Δ75-ChoKα. NMS-P830 is able to inhibit ChoKα in cells resulting in the reduction of intracellular phosphocholine formation. A structure-based medicinal chemistry program resulted in the identification of selective compounds that have good biochemical activity, solubility and metabolic stability and are suitable for further optimization. The ChoKα inhibitors disclosed in this article demonstrate for the first time the possibility to inhibit ChoKα with ATP-competitive compounds.
Poly(ADP‐ribose) polymerase‐2 (PARP2) belongs to the ADP‐ribosyltransferase family of enzymes that catalyze the addition of ADP‐ribose units to acceptor proteins, thus affecting many diverse cellular ...processes. In particular, PARP2 shares with PARP1 and, as recently highlighted, PARP3 the sole property of being catalytically activated by DNA‐strand breaks, implying key downstream functions in the cellular response to DNA damage for both enzymes. However, evidence from several studies suggests unique functions for PARP2 in additional processes, possibly mediated through its basal, DNA‐damage unstimulated ADP‐ribosylating activity. Here, we describe the development and application of a protein microarray‐based approach tailored to identify proteins that are ADP‐ribosylated by PARP2 in the absence of DNA damage mimetics and might thus represent useful entry points to the exploration of novel PARP2 functions. Several candidate substrates for PARP2 were identified and global hit enrichment analysis showed a clear enrichment in translation initiation and RNA helicase molecular functions. In addition, the top scoring candidates FK506‐binding protein 3 and SH3 and cysteine‐rich domain‐containing protein 1 were selected and confirmed in a complementary assay format as substrates for unstimulated PARP2.
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A list of the large number of protein‐protein interactions described in this article is available via the MINT article ID MINT‐8201796
PARP2 ADP‐ribosyltransferase activity is stimulated by DNA damage to participate in the DNA repair process, but there is also evidence for unique functions mediated through basal, DNA‐damage independent enzyme activity. We describe a protein microarray approach tailored to identify PARP2 substrates in the absence of DNA damage mimetics as potential exploratory entry points and report FKBP3 and STAC1 as top‐scoring candidates.
As part of our drug discovery effort, we identified and developed 4,5-dihydro-1H-pyrazolo4,3-hquinazoline derivatives as PLK1 inhibitors. We now report the optimization of this class that led to the ...identification of NMS-P937, a potent, selective and orally available PLK1 inhibitor. Also, in order to understand the source of PLK1 selectivity, we determined the crystal structure of PLK1 with NMS-P937. The compound was active in vivo in HCT116 xenograft model after oral administration and is presently in Phase I clinical trials evaluation.
Maternal embryonic leucine zipper kinase (MELK) is upregulated in several types of tumor, including breast, prostate, and brain tumors. Its expression is generally associated with cell survival, cell ...proliferation, and resistance to apoptosis. Therefore, the potential of MELK inhibitors as therapeutic agents is recently attracting considerable interest. Here we report the first structures of MELK in complex with AMP–PNP and with nanomolar inhibitors. Our studies shed light on the role of the MELK UBA domain, provide a characterization of the kinase active site, and identify key residues for achieving high potency, laying the groundwork for structure-based drug design efforts.
Abstract
Maternal Embryonic Leucine zipper Kinase (MELK) is a serine-threonine kinase implicated in stem cell renewal, override of cell cycle checkpoints, pre-mRNA splicing and resistance to ...apoptosis, while MELK gene expression levels correlate inversely with poor prognosis in breast cancer, prostate cancer and glioblastoma patients. Moreover, recent findings underlie the oncogenic role of this kinase in triple negative breast cancer (TNBC), a category of high-grade, invasive tumors which lack expression of estrogen receptor (ER) and progesterone receptor (PR) and HER2 amplification and which is resistant to current cytotoxic and targeted therapies. Furthermore, they are highly heterogeneous with respect to genomic alterations, and common therapeutic targets are lacking, although substantial evidence implicates dysregulated kinase signaling.
Here, we describe the preclinical characterization of novel, potent and selective ATP-competitive MELK kinase inhibitors identified by means of high-throughput screening of the NMS proprietary compound collection. Leading compounds possess biochemical activity against MELK in the nanomolar range with high selectivity against a panel of 60 further kinases representative of the human kinome. Amongst human tumor cell lines tested in 2-dimensional colony outgrowth assays, marked sensitivity was observed in breast cancer cell lines, with sub-micromolar anti-proliferative activity. This effect was accompanied by dose-dependent induction of apoptosis and by modulation of cellular biomarkers, consistent with a MELK-dependent mechanism of action.
Overall, these data provide further evidence that MELK is a promising biological target for the development of novel anticancer therapies.
Citation Format: Patrizia Carpinelli, Marisa Montemartini, Nadia Amboldi, Dario Ballinari, Sabrina Cribioli, Marina Ciomei, Riccardo Colombo, Stefania Re Depaolini, Nilla Avanzi, Giulia Canevari, Walter Ceccarelli, Helena Posteri, Maria Gabriella Brasca, Daniele Donati, Eduard Rudolf Felder, Antonella Isacchi, Arturo Galvani, Alessia Montagnoli. Novel and selective MELK kinase inhibitors active in breast cancer cell lines. abstract. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3795.
Abstract
PERK (PKR-like endoplasmic reticulum kinase) is a serine-threonine kinase associated to endoplasmic reticulum membrane. Together with ATF6 and IRE1, PERK is a key effector of the Unfolded ...Protein Response (UPR), a network of signaling pathways that ensures protein homeostasis in the endoplasmic reticulum. Multiple Myeloma (MM) and other protein-secreting tumors are highly dependent on UPR for survival, and inhibition of PERK may be an effective strategy to inhibit growth of these tumors. Here we describe the in vitro and in vivo properties of NMS-E194, a novel potent and selective ATP-competitive PERK inhibitor belonging to the arylsulfonamide chemical class. NMS-E194 inhibits PERK kinase with a Ki of ca 1.5 nM in biochemical assay and possesses high selectivity towards a panel of 54 kinases. When tested in cell proliferation assays, NMS-E194 is preferentially active on multiple myeloma (MM) and diffuse large B cell lymphoma cell lines. In mechanism of action studies, NMS-E194 shows a bi-phasic behaviour: at low nanomolar doses it activates PERK, causing ATF4 accumulation, while at >200 nM it inhibits PERK and downstream pathway, inducing apoptosis. NMS-E194 possesses a favourable in vitro ADME profile and has promising PK properties in the mouse. NMS-E194 demonstrated strong anti-tumor activity following oral administration at 25 mg/kg daily to mice harbouring luciferized KMS-11 cells in a disseminated growth model of MM, with no overt toxicity. Overall, the data available so far warrant further development of NMS-E194 and support PERK inhibition as a novel therapeutic approach in MM and other PERK-dependent tumors.
Citation Format: Claudia Perrera, Maurizio Pulici, Davide Carenzi, Ilaria Motto, Marina Fasolini, Elena Casale, Stefania Re Depaolini, Simona Rizzi, Daniela Asa, Fulvia Roletto, Simona Bindi, Daniele Casero, Patrizia Banfi, Elena Ardini, Nadia Amboldi, Dario Ballinari, Fabio Gasparri, Sabrina Cribioli, Laura Mancini, Marina Ciomei, Daniele Donati, Eduard Felder, Arturo Galvani, Antonella Isacchi, Barbara Valsasina. Characterization of NMS-E194, a selective and potent PERK inhibitor with efficacy in the KMS-11 multiple myeloma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5163. doi:10.1158/1538-7445.AM2017-5163
Lead optimization work on the 4,5-dihydro-1
H-pyrazolo4,3-
hquinazoline series led to identification of NMS-P937. Crystal structure of NMS-P937 with PLK1 was obtained and discussed. NMS-P937 is a ...potent, selective and orally available PLK1 inhibitor that is presently in Phase I clinical trials.
As part of our drug discovery effort, we identified and developed 4,5-dihydro-1
H-pyrazolo4,3-
hquinazoline derivatives as PLK1 inhibitors. We now report the optimization of this class that led to the identification of NMS-P937, a potent, selective and orally available PLK1 inhibitor. Also, in order to understand the source of PLK1 selectivity, we determined the crystal structure of PLK1 with NMS-P937. The compound was active in vivo in HCT116 xenograft model after oral administration and is presently in Phase I clinical trials evaluation.
Abstract
The Spindle Assembly Checkpoint (SAC) is a mitotic mechanism specifically required for proper chromosomal segregation ensuring that cells do not divide until all sister chromatids correctly ...align to the metaphase plate. MPS1 kinase, (also known as TTK) is a key regulator of SAC functions and it has been found to be up-regulated in a number of tumors of different origins. The hypothesis is that SAC activity could be highly required to sustain aneuploid tumor growth and MPS1 inhibitors may have a therapeutic benefit in the treatment of certain cancers.
We have identified NMS-P715, a potent and selective oral bioavailable small-molecule MPS1 kinase inhibitor with an ATP-competitive bindingmode. Treatment of cells with NMS-P715 accelerates mitotic exit with an IC50 of 53 nM. This is accompanied by reduction of the mitotic length, MPS1 dephosphorylation, chromosomal mis-alignment, delocalization of kinetochore components and massive aneuploidization, which ultimately leads to cell death.
Proliferation data performed on a large panel of 126 cell lines shows a wide range of activity and indicates selective activity against tumoral cells compared to normal cells. Oral administration of NMS-P715 in tumor xenografted mice resulted in potent tumor growth inhibition in an ovarian cancer xenograft model and was accompanied by biomarker modulation, confirming the expected MOA.
Our data provide evidence that inhibition of MPS1 kinase and SAC abrogation could represent a new promising approach to cancer therapy.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C202.
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