-Amyloid peptides (A) that form the senile plaques of Alzheimer disease consist mainly of 40-and 42-amino acid (A 40 and A 42) peptides generated from the cleavage of the amyloid precursor protein (APP). Generation of A involves -secretase and ␥-secretase activities and is regulated by membrane trafficking of the proteins involved in A production. Here we describe a new small molecule, EHT 1864, which blocks the Rac1 signaling pathways. In vitro, EHT 1864 blocks A 40 and A 42 production but does not impact sAPP␣ levels and does not inhibit -secretase. Rather, EHT 1864 modulates APP processing at the level of ␥-secretase to prevent A 40 and A 42 generation. This effect does not result from a direct inhibition of the ␥-secretase activity and is specific for APP cleavage, since EHT 1864 does not affect Notch cleavage. In vivo, EHT 1864 significantly reduces A 40 and A 42 levels in guinea pig brains at a threshold that is compatible with delaying plaque accumulation and/or clearing the existing plaque in brain. EHT 1864 is the first derivative of a new chemical series that consists of candidates for inhibiting A formation in the brain of AD patients. Our findings represent the first pharmacological validation of Rac1 signaling as a target for developing novel therapies for Alzheimer disease. Alzheimer disease (AD)2 is the most common neurodegenerative disorder marked by progressive loss of memory and cognitive ability. The pathology of AD is characterized by the presence of amyloid plaques (1), intracellular neurofibrillary tangles, and pronounced cell death. The -amyloid peptide (A) (2) is the main constituent of senile plaques found in AD brains. Furthermore, extracellular A 42 appears toxic to neurons in vitro and in vivo (reviewed in Ref.3). A is generated by proteolysis of an integral membrane protein, the amyloid precursor protein (APP), via at least two post-translational pathways. The amyloidogenic cleavage of APP is a sequential processing of APP initiated by -secretase (BACE), which cleaves APP within the luminal domain or at the cell surface, generating the N terminus of A (4). This cleavage generates several membrane-bound proteolytic C-terminal fragments (CTFs), such as the 99-residue -CTF (also called C99), as well as the secreted APP ectodomain sAPP. The C terminus of A is subsequently generated by intramembranous cleavage of CTFs by ␥-secretase, producing either A 40 or A 42. The cleavages at residues 40 -42 are referred to as ␥-cleavage, and the cleavages at residues 49 -52 are referred to as ⑀-cleavage (5). The nonamyloidogenic cleavage of APP, which precludes A generation, is mediated by ␣-secretase, a disintegrin and metalloproteinase 10, and a disintegrin and metalloproteinase 17, in a reaction believed to occur primarily on the plasma membrane. This proteolytic cleavage by ␣-secretase occurs within the A region and produces soluble APP (sAPP␣), the dominant processing product, and the residual membrane-bound 10-kDa CTF (CTF␣, also called C83). Like C99, C83 is a subs...
Dual-specificity tyrosine-phosphorylated and regulated kinases (DYRK) is a family of conserved protein kinases which mediate survival and differentiation in normal tissues like skeletal muscle for Mirk/Dyrk1B or neuronal cells for Dyrk1A. Among the five Dyrk proteins, Mirk/Dyrk1B has very low level of expression in most normal cell types but has been found to be upregulated in solid tumors and to mediate cell survival in colon cancer, pancreatic ductal adenocarcinoma, rhabdomyosarcomas, lung and ovarian cancer. Mirk/Dyrk1B expression and abundance varies during the cell cycle with the highest levels found in quiescent G0 phase where it mediates G0 tumor cells prolonged survival (through increasing expression of a cohort of antioxidant genes). Dyrk1A also promotes quiescence and senescence through DREAM complex assembly by phosphorylating the DREAM subunit LIN52. The ability of cells to exit from the cell cycle and enter into the G0 or quiescence state is important for cell differentiation, tissue development, and prevention of tumorigenesis. Tumors may contain a fraction of quiescent cells responsible for resistance to chemotherapy and radiation, serving as a reservoir for tumor repopulation post-therapy. Thus, pharmacological Dyrk inhibition would reduce the ability of cells to enter into quiescence and sensitize cancer cells to conventional chemotherapeutic agents. Exonhit has developed a novel class of DYRK inhibitors. Lead optimization led to the synthesis of new chemical entities with subnanomolar kinase inhibitory activities associated with a high degree of selectivity over 400 kinases. Most active compounds were evaluated in various cellular models, demonstrating good correlation between cellular activity and amplification/expression of Mirk/Dyrk1B. Similarly, in accordance with the expression levels of Mirk/Dyrk1B during the cell cycle, cellular potency of pharmacological inhibitors was improved 3 to 11 fold in SW620 quiescent cultures when compared to cycling cultures. We analyzed the effects of Dyrk inhibitors alone and in combination with gemcitabine in the Panc1 pancreatic cancer cell line multicellular tumor spheroid model described to be largely quiescent and enriched in Mirk/Dyrk1B kinase and confirmed that Dyrk inhibitors sensitize cells to gemcitabine with a synergistic effect of the combination. Among the 120 NCEs from this series, we identified lead compounds having potent in vitro efficacy as Dyrk inhibitors. These compounds are being further characterized in various cellular studies and show promising in vivo activities in patient-derived ovarian cancer ascites spheroids and Panc1 xenografts model without detectable toxicity in mice, establishing the usefulness of these inhibitors for targeting cancer cells with high Dyrk kinase activity. Citation Format: Anne-Sophie Casagrande, Florence Bachelot, Séverine Coutadeur, Bertrand Leblond, Thierry Besson, Matthew P. Pando, Laurent Désiré. Structure activity relationship of a novel chemical class of Dyrk inhibitors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2165. doi:10.1158/1538-7445.AM2013-2165
Background Overall survival (OS) is the gold standard endpoint to assess treatment efficacy in cancer clinical trials. In metastatic breast cancer (mBC), progression-free survival (PFS) is commonly used as an intermediate endpoint. Evidence remains scarce regarding the degree of association between PFS and OS. Our study aimed to describe the individual-level association between real-world PFS (rwPFS) and OS according to first-line treatment in female patients with mBC managed in real-world setting for each BC subtype (defined by status for both hormone-receptor [HR] expression and HER2 protein expression/gene amplification). Methods We extracted data from the ESME mBC database (NCT03275311) which gathers deidentified data from consecutive patients managed in 18 French Comprehensive Cancer Centers. Adult women diagnosed with mBC between 2008 and 2017 were included. Endpoints (PFS, OS) were described using the Kaplan–Meier method. Individual-level associations between rwPFS and OS were estimated using the Spearman’s correlation coefficient. Analyses were conducted by tumor subtype. Results 20,033 women were eligible. Median age was 60.0 years. Median follow-up duration was 62.3 months. Median rwPFS ranged from 6.0 months (95% CI 5.8–6.2) for HR-/HER2 − subtype to 13.3 months (36% CI 12.7–14.3) for HR + /HER2 + subtype. Correlation coefficients were highly variable across subtypes and first-line (L1) treatments. Among patients with HR − /HER2 − mBC, correlation coefficients ranged from 0.73 to 0.81, suggesting a strong rwPFS/OS association. For HR + /HER2 + mBC patients, the individual-level associations were weak to strong with coefficients ranging from 0.33 to 0.43 for monotherapy and from 0.67 to 0.78 for combined therapies. Conclusions Our study provides comprehensive information on individual-level association between rwPFS and OS for L1 treatments in mBC women managed in real-life practice. Our results could be used as a basis for future research dedicated to surrogate endpoint candidates.
Tumor blood vessels are an important emerging target for anticancer therapy. Here, we characterize the in vitro antiproliferative and antiangiogenic properties of the synthetic small molecule, 7-ethoxy-4-(3,4,5-trimethoxybenzyl)isoquinolin-8-amine dihydrochloride, EHT 6706, a novel microtubule-disrupting agent that targets the colchicine-binding site to inhibit tubulin polymerization. At low nM concentrations, EHT 6706 exhibits highly potent antiproliferative activity on more than 60 human tumor cell lines, even those described as being drug resistant. EHT 6706 also shows strong efficacy as a vascular-disrupting agent, since it prevents endothelial cell tube formation and disrupts pre-established vessels, changes the permeability of endothelial cell monolayers and inhibits endothelial cell migration. Genome-wide transcriptomic analysis of EHT 6706 effects on human endothelial cells shows that the antiangiogenic activity elicits gene deregulations of antiangiogenic pathways. These findings indicate that EHT 6706 is a promising tubulin-binding compound with potentially broad clinical antitumor efficacy.
The dual-specificity tyrosine phosphorylated and regulated kinase Mirk/DYRK1B belongs to an evolutionary conserved family of kinases involved in the control of growth and development. DYRK1B has low level of expression in most normal cell types but is amplified or over-expressed in a number of human cancers. DYRK1B regulates the exit of cancer cells from quiescence through regulating cyclin D turnover and p27kip1 stabilization, thus participating as substantial actor in the control of cancer cell cycle progression. Diaxonhit has developed a novel class of DYRK inhibitors with potent in vitro efficacy. Among them, EHT 5372 reduces tumor growth in a PANC-1 xenograft model and reduces ascites spheroids to single cells and induces their apoptosis. Three-dimensional (3D) multicellular spheroids are symmetrical cellular aggregates that model an in vitro system of intermediate complexity between monolayer cultures and tumors in vivo. Here, we have conducted genome-wide analysis of transcriptional changes between normal (monolayer, 2D) and 3D culture conditions of pancreatic PANC-1 cells using Diaxonhit's GWSATM platform to identify tumor-relevant genes and pathways. The PANC-1 multicellular spheroid model was first characterized based on phenotypical and functional properties and we then analyzed the pharmacological response of spheroids to EHT 5372 and other DYRK inhibitors treatment. A strong up-regulation of DYRK1B was evidenced and confirmed at the protein level. Stemness-related markers were investigated and some were also found much higher in the spheroids than within the monolayer cultures and further increased in a culture time-dependent manner. Stem-like cancer cells may be the cause of therapy-resistance and relapse in patients and sphere forming ability is one of properties of this quiescent cancer-initiating cells. As DYRK1B contributes to G0 arrest to maintain the viability of quiescent cancer cells, pharmacological DYRK inhibition would reduce the capacity of cells to enter into quiescence and sensitize cancer cells to conventional chemotherapeutic agents or radiation. Molecular and physiological consequences of inhibiting DYRK1B with EHT 5372 are now being investigated along with genes expression changes in stemness-related markers and in biological pathways involved in tumor cell growth regulation. A molecular characterization of pancreatic cancer cell spheroids is currently undertaken to determine the utility of the 3D assay as a surrogate tool enriched in cancer stem cells. Spheroids also enable the study of quiescence, chemoresistance and metastasis. DYRK1B inhibitors screening in 3D models is a powerful approach that can help focus on compounds active on these crucial mechanisms of cancer cell biology. The most active compounds identified in this program are likely good candidates for in vivo xenograft studies. Citation Format: Anne-Sophie CASAGRANDE, Florence BACHELOT, Emeline THROO, Florence MAHE, Bertrand LEBLOND, Thierry BESSON, Matthew PANDO, Laurent DESIRE. 3D multicellular pancreatic cancer spheroids as drug screening tool for pharmacological evaluation of EHT 5372 and other Mirk/DYRK1B inhibitors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2620. doi:10.1158/1538-7445.AM2014-2620
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.