Discovery of 5-(2-(Phenylamino)pyrimidin-4-yl)thiazol-2(3H)-one Derivatives as Potent Mnk2 Inhibitors: Synthesis, SAR Analysis and Biological Evaluation

Characterization and Modeling of Marine Bacillus cereus Strain MSS1 Exopolysaccharide and Its Antagonistic Effect on Colon Cancer

Microbial polysaccharides are a significant group of functional phytochemicals. Numerous studies have shown the advantageous pharmacological impacts of polysaccharides, including their effectiveness against cancer. A halophilic bacterial strain obtained from coastal sediments produced exopolysaccharides (EPS). The strain was morphologically recognized and further confirmed as Bacillus cereus strain MSS1 using 16S rDNA analysis, with accession number OR133726. The heteropolysaccharides were purified and fractionated with a DEAE-cellulose column, and the preliminary chemical analysis of the most potent fraction (EPSMSS1) indicated that the four different monosaccharides were mannuronic acid, xylose, fructose, and glucuronic acid, with a molar ratio of 1:1:2:0.5, respectively. The highest production was 12.76 g/l using a Box-Behnken design. It showed antibacterial activity, antioxidant activity, and antibiofilm activity. The 3D architecture of the EPSMSS1 of Bacillus cereus strain MSS1 is being described, predicted, and aligned against other bacterial species. These studies offer valuable insights into optimizing efficiency. Therefore, the EPSMSS1 fraction was shown to have anticancer activity and significant anticancer activities in a dose-dependent manner, with an IC50 value of 20.1 µg/ml. Subsequently, various apoptotic markers, such as cytochrome c, BAX, BCl2, and the BAX/BCL2 ratio, were assessed. Our findings demonstrate that EPSMSS1 triggers the activation of apoptotic protein BAX, enhances the generation of cytochrome c, reduces the expression of antiapoptotic protein BCl2, and distorts the BAX/BCL2 ratio in EPSMSS1-treated HCT-116 cells relative to untreated cells. The anticancer efficacy of EPSMSS1 was verified through the assessment of cell cycle progression using flow cytometry. It has been found that EPSMSS1 pauses the cell cycle in the G1/S phase, causing apoptosis. The main motivation behind this study was EPSMSS1, an innovative marine polysaccharide with remarkable biological activity, especially anti-cancer properties.

Design, synthesis, molecular docking and anticancer activity of benzothiazolecarbohydrazide-sulfonate conjugates: insights into ROS-induced DNA damage and tubulin polymerization inhibition

A series of novel benzothiazolecarbohydrazide-sulfonate conjugates 6a-l were designed, synthesized, and then assessed as potential antiproliferative agents in three distinct human cancer cell lines: MCF-7 (breast cancer), HCT-116 (colon cancer), and PC3 (prostate cancer), along with a normal cell line (BJ-1). The reference standard used was 5-fluorouracil. The results obtained reveal that the newly synthesized analogs demonstrate varying degrees of cytotoxicity against the targeted cell lines; however, compounds 6i and 6e exhibited the highest efficacy against MCF-7, HCT-116, and PC3 cells with IC50 values of 78.8 ± 2.6, 81.4 ± 1.9, and 90.6 ± 2.7 μM, respectively, compared to an IC50 of 78.4 ± 4.2 μM for 5-FU in MCF-7 cells, 29.2 ± 1.7 μM in HCT-116 cells and >200 μM in PC3 cells. Moreover, the most potent compounds demonstrated acceptable safety profiles when evaluated aganist BJ-1 cells. Consequently, compound 6i, which possesses no cytotoxicity towards BJ-1 cells and displays promising anticancer activity, was further investigated for its impact on tubulin polymerization compared to control MCF-7 cells, 210.3 and 632.9 pg ml-1, respectively. Compound 6i was found to significantly elevate the ROS levels in treated cancer cells, resulting in an 8.3-fold increase in DNA fragmentation compared to untreated cells. Additionally, it raised the percentage of accumulated cells in the G2 phase from 6.85% to 18.27% in MCF-7 cells. A molecular docking technique was conducted to elucidate the binding energy, binding pose, and binding interactions of compound 6i, revealing a strong fit within the active sites of the tubulin-colchicine binding site (CBS). This study provides valuable insights into the design and synthesis of novel anticancer agents targeting tubulin polymerization.

The acute and sub-chronic toxicological effects of 3-amino-9-ethylcarbazole (AEC) on zebrafish

INTRODUCTION

In this study, we sought to determine the sub-chronic toxicological effects of AEC on zebrafish embryos.

METHODS

We utilized fish early life stage (FELS) and fish embryo toxicity (FET) tests, vascular, neurological, and renal transgenic zebrafish lines, and gene expression anal-ysis of the zebrafish tissue.

RESULTS

In the FET tests, AEC caused several abnormalities in the larvae, with the LC50 at 24 hpf being 4.076 ± 0.221 mg/L and 3.296 ± 0.127 mg/L at 96 hpf. In the FELS test, AEC was shown to be lethal following 16 days of exposure at 0.5 mg/L, 1 mg/L and 2 mg/L. Some of the transgenic zebrafish lines exhibited slight changes in fluorescent signaling pat-terns after exposure to AEC at 1 mg/L and 2 mg/L. Notable results of the gene expression analysis revealed: gpx4b and got2 were downregulated in the liver; HIF1a was downregulated at 0.25 mg/L and 0.5 mg/L concentrations, NOTCH1a and fli-1 genes were downregulated at all concentrations, and A2b was upregulated in the vasculature; a1T, ngn1, elavl3, syn2a, mbp, gap43 were down-regulated in the nervous system; and wt1b was downregulated in the kidney.

DISCUCCION

Altogether, the results of our study indicate the potential for AEC to cause harm to organisms.

Naturally based pyrazoline derivatives as aminopeptidase N, VEGFR2 and MMP9 inhibitors: design, synthesis and molecular modeling

Aminopeptidase N (APN) is regarded as an attractive target for cancer treatment due to its overexpression in various types of malignancies and its close association with cancer angiogenesis, metastasis and invasion. Herein the authors describe the design, synthesis and biological evaluation of some naturally based pyrazoline derivatives. Among these compounds, the diphenylpyrazole carbothioamide 8 showed significant activity and selectivity index (SI = 4.7) on breast (MCF-7) human cancer cell line and was capable of inhibiting APN with pIC50 value of 4.8, comparable to the reference standard. Further evaluation of derivative 8 against VEGFR2 and MMP9 as biomarkers for angiogenesis and invasion showed that the selected compound had an inhibitory activity on both proteins with pIC50 values of 6.7 and 6.4, respectively. Additionally, the migration ability of cells following treatment with the diphenylpyrazole derivative decreased to record a percentage wound closure of 57.77 for compound 8versus 97.03 for the control. The promising derivative arrested cell growth at the G1 phase inducing early and late apoptosis. Finally, docking and ADMET in silico studies were performed.

Plasma growth factors maintain constitutive translation in platelets to regulate reactivity and thrombotic potential

ABSTRACT

Mechanisms of proteostasis in anucleate circulating platelets are unknown and may regulate platelet function. We investigated the hypothesis that plasma-borne growth factors/hormones (GFHs) maintain constitutive translation in circulating platelets to facilitate reactivity. Bio-orthogonal noncanonical amino acid tagging (BONCAT) coupled with liquid chromatography-tandem mass spectrometry analysis revealed constitutive translation of a broad-spectrum translatome in human platelets dependent upon plasma or GFH exposure, and in murine circulation. Freshly isolated platelets from plasma showed homeostatic activation of translation-initiation signaling pathways: phosphorylation of p38/ERK upstream kinases, essential intermediate MNK1/2, and effectors eIF4E/4E-BP1. Plasma starvation led to loss of pathway phosphorylation, but it was fully restored with 5-minute stimulation by plasma or GFHs. Cycloheximide or puromycin infusion suppressed ex vivo platelet GpIIb/IIIa activation and P-selectin exposure with low thrombin concentrations and low-to-saturating concentrations of adenosine 5'-diphosphate (ADP) or thromboxane analog but not convulxin. ADP-induced thromboxane generation was blunted by translation inhibition, and secondary-wave aggregation was inhibited in a thromboxane-dependent manner. Intravenously administered puromycin reduced injury-induced clot size in cremaster muscle arterioles, and delayed primary hemostasis after tail tip amputation but did not delay neither final hemostasis after subsequent rebleeds, nor final hemostasis after jugular vein puncture. In contrast, these mice were protected from injury-induced arterial thrombosis and thrombin-induced pulmonary thromboembolism (PE), and adoptive transfer of translation-inhibited platelets into untreated mice inhibited arterial thrombosis and PE. Thus, constitutive plasma GFH-driven translation regulates platelet G protein-coupled receptor reactivity to balance hemostasis and thrombotic potential.

Synthesis and evaluation of hybrid sulfonamide-chalcones with potential antileishmanial activity

Leishmaniasis is an emerging tropical infectious disease caused by a protozoan parasite of the genus Leishmania. In this work, the molecular hybridization between a trimethoxy chalcone and a sulfonamide group was used to generate a series of sulfonamide-chalcones. A series of eight sulfonamide-chalcone hybrids were made with good yields (up to 95%). These sulfonamide-chalcones were tested against promastigotes of Leishmania amazonensis and cytotoxicity against mouse macrophages, which showed good antileishmanial activity with IC50  = 1.72-3.19 µM. Three of them (10c, 10g, and 10h) were also highly active against intracellular amastigotes and had a good selectivity index (SI > 9). Thus, those three compounds were docked in the cytosolic tryparedoxin peroxidase (cTXNPx) enzyme of the parasite, and molecular dynamics simulations were carried out. This enzyme was selected as a target protein for the sulfonamide-chalcones due to the fact of the anterior report, which identified a strong and stable interaction between the chalcone NAT22 (6) and the cTXNPx. In addition, a prediction of the drug-likeness, and the pharmacokinetic profile of all compounds were made, demonstrating a good profile of those chalcones.

Regulation of Eukaryotic Translation Initiation Factor 4E as a Potential Anticancer Strategy

Eukaryotic translation initiation factors (eIFs) are highly expressed in cancer cells, especially eIF4E, the central regulatory node driving cancer cell growth and a potential target for anticancer drugs. eIF4E-targeting strategies primarily focus on inhibiting eIF4E synthesis, interfering with eIF4E/eIF4G interactions, and targeting eIF4E phosphorylation and peptide inhibitors. Although some small-molecule inhibitors are in clinical trials, no eIF4E inhibitors are available for clinical use. We provide an overview of the regulatory mechanisms of eIF4E and summarize the progress in developing and discovering eIF4E inhibitor strategies. We propose that interference with eIF4E/eIF4G interactions will provide a new perspective for the design of eIF4E inhibitors and may be a preferred strategy.

Ferrocene modified analogues of imatinib and nilotinib as potent anti-cancer agents

The unique features of ferrocene and the need for development of targeted anticancer drugs inspired the design, synthesis and biological evaluation of ferrocenyl modified tyrosine kinase inhibitors by replacing the pyridyl moiety in imatinib and nilotinib generalized structures with a ferrocenyl group. A series of seven new ferrocene analogues were synthesized and evaluated for their anticancer activity in a panel of bcr-abl positive human malignant cell lines using imatinib as a reference drug. The metallocenes exhibited a dose-dependent inhibition on malignant cell growth with varying antileukemic activity. The most potent analogues were compounds 9 and 15a showing comparable or even superior efficacy to the reference. Their cancer selectivity indices suggest a favorable selectivity profile, indicating a 250 times higher preferential activity of 15a towards malignantly transformed K-562 cells and an even twice greater one (500) of 9 in the LAMA-84 leukemic model as compared to the normal murine fibroblast cell line.

Targeting apoptotic anticancer response with natural glucosinolates from cell suspension culture of Lepidium sativum

BACKGROUND

Finding natural products with anticancer activity is an effective strategy to fight this disease. In this respect, Lepidium sativum or garden cress (family Brassicaceae) has been widely used worldwide for its wide therapeutic application, including anticancer and chemoprotective agents. Plant tissue culture techniques hold great promise for natural product enhancement without any climatic boundaries. In this study, glucosinolates and petroleum ether fractions were isolated from in vitro cell cultures and used against different carcinoma cell lines to investigate their anticancer potential.

METHODS

In this study, callus cultures from leaf and root explants were initiated, cell suspension cultures were established, and cell growth and viability profiles were characterized. Different amino acids were added as precursors to the cell suspension cultures to enhance glucosinolates accumulation. Gas chromatography-mass spectrometric analysis (GC-MS) of glucosinolates and petroleum ether fractions was performed, and all fractions were tested against different carcinoma cell lines.

RESULTS

The findings clarified that the maximum callus initiation percentage was obtained in the medium containing 1.0 mg/l 2,4-dichlorophenoxy acetic acid (2,4-D) + 1.0 mg/l kinetin (Kin) (C1). The viable cell number of cell suspension cultures from leaves and roots increased until it reached the maximum values on day 15. Adding tyrosine and methionine to the cell suspension cultures was the most influential and recorded high glucosinolate percentages. 1H-Cyclopenta (b) pyridine-3-carbonitrile-4,5,6,7-tetrahydro-2-methylthio-4-spirocyclohexane was the main glucosinolate compound found in tyrosine-treated leaf suspension (GLT). Fifteen compounds were detected in the petroleum ether fraction in both cell suspensions initiated from the leaf and root (OL and OR). The major compounds were benzene-1,3,5-trimethyl (12.99%) in root cell suspension (OR), and benzene-2-ethyl-1,4-dimethyl (10.66%) in leaf cell suspension (OL). All glucosinolate extracts demonstrated significant anticancer activity against the prostate (PC3), lung (A-549), colorectal (caco2), and liver (HepG2) cell lines. Glucosinolates extracted from leaf cell suspension (GL) were the most active on the hepatocellular carcinoma cell line (HepG2) among all remaining glucosinolate extracts. Treated hepatocellular carcinoma with an IC₅₀ of GL extract (47.5 ug/ml) upregulates pro-apoptotic BAX and downregulates anti-apoptotic BCL2, which disrupts the BAX/BCL2 ratio, leading to activation of caspase 3 inside treated HepG2 cells.

CONCLUSIONS

The anticancer action of the GL extract was validated by the cell cycle study of its glucosinolates, which successfully promoted apoptosis and reduced hepatocellular growth by causing S-phase arrest.

Discovery of Potent Inhibitors of Cyclin-Dependent Kinases 7 and 9: Design, Synthesis, Structure-Activity Relationship Analysis and Biological Evaluation

Cyclin-dependent kinases (CDKs) 7 and 9 are deregulated in various types of human cancer and are thus viewed as therapeutic targets. Accordingly, small-molecule inhibitors of both CDKs are highly sought-after. Capitalising on our previous discovery of CDKI-73, a potent CDK9 inhibitor, medicinal chemistry optimisation was pursued. A number of N-pyridinylpyrimidin-2-amines were rationally designed, chemically synthesised and biologically assessed. Among them, N-(6-(4-cyclopentylpiperazin-1-yl)pyridin-3-yl)-4-(imidazo[1,2-a]pyrimidin-3-yl)pyrimidin-2-amine was found to be one of the most potent inhibitors of CDKs 7 and 9 as well as the most effective anti-proliferative agent towards multiple human cancer cell lines. The cellular mode of action of this compound was investigated in MV4-11 acute myeloid leukaemia cells, revealing that the compound dampened the kinase activity of cellular CDKs 7 and 9, arrested the cell cycle at sub-G1 phase and induced apoptosis.

MNK Proteins as Therapeutic Targets in Leukemia

In leukemia, resistance to therapy is a major concern for survival. MAPK-interacting kinases (MNKs) have been identified as important activators of oncogenic-related signaling and may be mediators of resistance. Recent studies in leukemia models, especially acute myeloid leukemia (AML), have focused on targeting MNKs together with other inhibitors or treating chemotherapy-resistant cells with MNK inhibitors. The preclinical demonstrations of the efficacy of MNK inhibitors in these combination formats would suggest a promising potential for use in clinical trials. Optimizing MNK inhibitors and testing in leukemia models is actively being pursued and may have important implications for the future. These studies are furthering the understanding of the mechanisms of MNKs in cancer which could translate to clinical studies.

ES-Screen: A Novel Electrostatics-Driven Method for Drug Discovery Virtual Screening

Electrostatic interactions drive biomolecular interactions and associations. Computational modeling of electrostatics in biomolecular systems, such as protein-ligand, protein-protein, and protein-DNA, has provided atomistic insights into the binding process. In drug discovery, finding biologically plausible ligand-protein target interactions is challenging as current virtual screening and adjuvant techniques such as docking methods do not provide optimal treatment of electrostatic interactions. This study describes a novel electrostatics-driven virtual screening method called 'ES-Screen' that performs well across diverse protein target systems. ES-Screen provides a unique treatment of electrostatic interaction energies independent of total electrostatic free energy, typically employed by current software. Importantly, ES-Screen uses initial ligand pose input obtained from a receptor-based pharmacophore, thus independent of molecular docking. ES-Screen integrates individual polar and nonpolar replacement energies, which are the energy costs of replacing the cognate ligand for a target with a query ligand from the screening. This uniquely optimizes thermodynamic stability in electrostatic and nonpolar interactions relative to an experimentally determined stable binding state. ES-Screen also integrates chemometrics through shape and other physicochemical properties to prioritize query ligands with the greatest physicochemical similarities to the cognate ligand. The applicability of ES-Screen is demonstrated with in vitro experiments by identifying novel targets for many drugs. The present version includes a combination of many other descriptor components that, in a future version, will be purely based on electrostatics. Therefore, ES-Screen is a first-in-class unique electrostatics-driven virtual screening method with a unique implementation of replacement electrostatic interaction energies with broad applicability in drug discovery.

Improved Synthesis of the Selected Serine Protease uPA Inhibitor UAMC-00050, a Lead Compound for the Treatment of Dry Eye Disease

The α-aminophosphonate UAMC-00050, a newly developed trypsin-like serine protease inhibitor, is a lead compound for the treatment of dry eye syndrome and ocular inflammation. The medicinal chemistry route developed at the University of Antwerp possessed several problems hampering the scale-up such as poor yields for some of the steps, hazardous reagents, and environmental footprint. Herein, we report an optimized route for the UAMC-00050, in which environmental unfriendly solvents were excluded, hazardous reagents were replaced with safer alternatives, and are more efficient in terms of atom economy. Every reaction step was optimized to reach a higher yield, and design of experiment was used to find the optimum conditions in the last step. Furthermore, all the flash chromatography purifications of intermediates were replaced with plug filtration, slurry purifications, or crystallization. The overall yield was increased from 3% in the medicinal chemistry route to 22% in the process development route.

New 1,2,3-Triazole-Coumarin-Glycoside Hybrids and Their 1,2,4-Triazolyl Thioglycoside Analogs Targeting Mitochondria Apoptotic Pathway: Synthesis, Anticancer Activity and Docking Simulation

Toxicity and resistance to newly synthesized anticancer drugs represent a challenging phenomenon of intensified concern arising from variation in drug targets and consequently the prevalence of the latter concern requires further research. The current research reports the design, synthesis, and anticancer activity of new 1,2,3-triazole-coumarin-glycosyl hybrids and their 1,2,4-triazole thioglycosides as well as acyclic analogs. The cytotoxic activity of the synthesized products was studied against a panel of human cancer cell lines. Compounds 8, 10, 16 and 21 resulted in higher activities against different human cancer cells. The impact of the hybrid derivative 10 upon different apoptotic protein markers, including cytochrome c, Bcl-2, Bax, and caspase-7 along with its effect on the cell cycle was investigated. It revealed a mitochondria-apoptotic effect on MCF-7 cells and had the ability to upregulate pro-apoptotic Bax protein and downregulate anti-apoptotic Bcl-2 protein and thus implies the apoptotic fate of the cells. Furthermore, the inhibitory activities against EGFR, VEGFR-2 and CDK-2/cyclin A2 kinases for 8, 10 and 21 were studied to detect the mechanism of their high potency. The coumarin-triazole-glycosyl hybrids 8 and 10 illustrated excellent broad inhibitory activity (IC₅₀= 0.22 ± 0.01, 0.93 ± 0.42 and 0.24 ± 0.20 μM, respectively, for compound 8), (IC₅₀ = 0.12 ± 0.50, 0.79 ± 0.14 and 0.15± 0. 60 μM, respectively, for compound 10), in comparison with the reference drugs, erlotinib, sorafenib and roscovitine (IC₅₀ = 0.18 ± 0.05, 1.58 ± 0.11 and 0.46 ± 0.30 μM, respectively). In addition, the docking study was simulated to afford better rationalization and put insight into the binding affinity between the promising derivatives and their targeted enzymes and that might be used as an optimum lead for further modification in the anticancer field.

Overcoming Paradoxical Kinase Priming by a Novel MNK1 Inhibitor

Targeting the kinases MNK1 and MNK2 has emerged as a valuable strategy in oncology. However, most of the advanced inhibitors are acting in an adenosine triphosphate (ATP)-competitive mode, precluding the evaluation of different binding modes in preclinical settings. Using rational design, we identified and validated the 4,6-diaryl-pyrazolo[3,4-b]pyridin-3-amine scaffold as the core for MNK inhibitors. Signaling pathway analysis confirmed a direct effect of the hit compound EB1 on MNKs, and in line with the reported function of these kinases, EB1 only affects the growth of tumor but not normal cells. Molecular modeling revealed the binding of EB1 to the inactive conformation of MNK1 and the interaction with the specific DFD motif. This novel mode of action appears to be superior to the ATP-competitive inhibitors, which render the protein in a pseudo-active state. Overcoming this paradoxical activation of MNKs by EB1 represents therefore a promising starting point for the development of a novel generation of MNK inhibitors.

Update on the Development of MNK Inhibitors as Therapeutic Agents

Mitogen-activated protein kinase-interacting kinases 1 and 2 (MNK1/2) represent a central class of enzymes that are activated by extracellular signal-regulated kinase (ERK) or p38 mitogen-activated protein (MAP) kinases. MNK1 and MNK2 coordinate cellular signaling, control production of inflammatory chemokines, and regulate cell proliferation and survival. MNK1/2 are referred to as serine/threonine kinases as they phosphorylate serine or threonine residues on their substrates. Upon activation, MNK1/2 phosphorylate eukaryotic translation initiation factor 4E (eIF4E) at Ser209, which in turn initiates ribosome assembly and protein translation. Deleterious overexpression of MNK1/2 and/or eIF4E have been reported in several diseases including cancers, neurological disorders, autism, and inflammation. Recently, there have been intense efforts toward the development of potent and selective inhibitors of MNK1/2 in both academia and industry. Herein, we review the current understanding of the structural and biological aspects of MNK1/2 and provide an update of pharmacological inhibitors of MNK1/2 including candidates in clinical trials.

New pyridine and chromene scaffolds as potent vasorelaxant and anticancer agents

Based on studies that have reported the association between cancer and cardiovascular diseases, new series of pyridine- (3a–o) and/or chromene- (4a–e) carbonitrile analogous were designed, synthesized and screened for their vasodilation and cytotoxic properties. The majority of the new chemical entities demonstrated significant vasodilation efficacies, compounds 3a, 3h, 3j, 3m, 3o, 4d and 4e exhibited the most promising potency with IC₅₀ = 437.9, 481.0, 484.5, 444.8, 312.1, 427.6 and 417.2 μM, respectively, exceeding prazosin hydrochloride (IC₅₀ = 487.3 μM). Compounds 3b–e, 3k and 3l also, revealed moderate vasodilation activity with IC₅₀ values ranging from 489.7 to 584.5 μM. In addition, the anti-proliferative activity evaluation of the experimental compounds at 10 μM on the MCF-7 and MDA-MB 231 breast cancer cell lines illustrated the excellent anti-proliferative properties of derivatives 3d, 3g and 3i. Compound 3d was the most potent analogue with IC₅₀ = 4.55 ± 0.88 and 9.87 ± 0.89 μM against MCF-7 and MDA-MB 231, respectively. Moreover, compound 3d stimulated apoptosis and cell cycle arrest at the S phase in MCF-7 cells in addition to its capability in accumulation of cells in pre-G1 phase and activating caspase-3. Furthermore, the molecular docking of 3d was performed to discover the binding modes within the active site of caspase-3. 3d, as the only common bi-functional agent among the tested hits, demonstrated that new pyridine-3-carbonitrile derivatives bearing cycloheptyl ring systems offer potential as new therapeutic candidates with combined vasodilation and anticancer properties.

Series of pyridine- (3a–o) and/or chromene- (4a–e) carbonitrile scaffolds have been designed, synthesized and evaluated for their bi-function activities, 3d was the only common derivative having combined vasodilation and anticancer properties.

Progress in developing MNK inhibitors

The MNKs (mitogen-activated protein kinase-interacting protein kinases) phosphorylate eIF4E (eukaryotic initiation factor 4 E) at serine 209; eIF4E plays an important role in the translation of cytoplasmic mRNAs, all of which possess a 5' 'cap' structure to which eIF4E binds. Elevated levels of eIF4E, p-eIF4E and/or the MNK protein kinases have been found in many types of cancer, including solid tumors and leukemia. MNKs also play a role in metabolic disease. Regulation of the activities of MNKs (MNK1 and MNK2), control the phosphorylation of eIF4E, which in turn has a close relationship with the processes of tumor development, cell migration and invasion, and energy metabolism. MNK knock-out mice display no adverse effects on normal cells or phenotypes suggesting that MNK may be a potentially safe targets for the treatment of various cancers. Several MNK inhibitors or 'degraders' have been identified. Initially, some of the inhibitors were developed from natural products or based on other protein kinase inhibitors which inhibit multiple kinases. Subsequently, more potent and selective inhibitors for MNK1/2 have been designed and synthesized. Currently, three inhibitors (BAY1143269, eFT508 and ETC-206) are in various stages of clinical trials for the treatment of solid cancers or leukemia, either alone or combined with inhibitors of other protein kinase. In this review, we summarize the diverse MNK inhibitors that have been reported in patents and other literature, including those with activities in vitro and/or in vivo.

Discovery of a potent, highly selective, and orally bioavailable inhibitor of CDK8 through a structure-based optimisation

CDK8 is deregulated in multiple types of human cancer and is viewed as a therapeutic target for the treatment of the disease. Accordingly, the search for small-molecule inhibitors of CDK8 is being intensified. Capitalising on our initial discovery of AU1-100, a potent CDK8 inhibitor yet with a limited degree of kinase selectivity, a structure-based optimisation was carried out, with a series of new multi-substituted pyridines rationally designed, chemically prepared and biologically evaluated. Such endeavour has culminated in the identification of 42, a more potent CDK8 inhibitor with superior kinomic selectivity and oral bioavailability. The mechanism underlying the anti-proliferative effect of 42 on MV4-11 cells was studied, revealing that the compound arrested the G1 cell cycle and triggered apoptosis. The low risk of hepato- and cardio-toxicity of 42 was estimated. These findings merit further investigation of 42 as a targeted cancer therapeutic.

Mnk inhibitors: a patent review

The alteration of mRNA translation has a crucial role in defining the changes in cellular proteome. The phosphorylation of eukaryotic initiation factor 4E by mitogen-activated protein kinase-interacting kinases (Mnks) leads to the release and translation of mRNAs of specific oncogenic proteins. In recent years, the efforts made by the pharmaceutical industry to develop novel chemical skeletons to create potent and selective Mnk inhibitors have been fruitful. The pyridone-aminal scaffold has been utilized to generate several series of Mnk inhibitors presented in multiple patent applications and research articles. Tomivosertib (eFT508) is one of the molecules with such scaffold. It is one of the first two Mnk inhibitors that entered clinical trials, and has displayed momentous activity against several solid and hematological cancers. The present compilation provides a succinct review of the current state of development of pyridone-aminal-derived Mnk inhibitors through the analysis of relevant patent applications filed in the last 5 years.

Phosphorylation of the mRNA cap-binding protein eIF4E and cancer

Dysregulated protein synthesis is frequently involved in oncogenesis and cancer progression. Translation initiation is thought to be the rate-limiting step in protein synthesis, and the mRNA 5' cap-binding protein eukaryotic translation initiation factor 4E (eIF4E) is a pivotal factor that initiates translation. The activities of eIF4E are regulated at multiple levels, one of which is through its phosphorylation at Serine 209 by the mitogen-activated protein kinase-interacting kinases (MNKs, including MNK1 and MNK2). Benefiting from novel mouse genetic tools and pharmacological MNK inhibitors, our understanding of a role for eIF4E phosphorylation in tumor biology and cancer therapy has greatly evolved in recent years. Importantly, recent studies have found that the level of eIF4E phosphorylation is frequently upregulated in a wide variety of human cancer types, and phosphorylation of eIF4E drives a number of important processes in cancer biology, including cell transformation, proliferation, apoptosis, metastasis and angiogenesis. The MNK-eIF4E axis is being assessed as a therapeutic target either alone or in combination with other therapies in different cancer models. As novel MNK inhibitors are being developed, experimental studies bring new hope to cure human cancers that are not responsive to traditional therapies. Herein we review recent progress on our understanding of a mechanistic role for phosphorylation of eIF4E in cancer biology and therapy.

Synthesis and molecular docking study of new pyrazole derivatives as potent anti-breast cancer agents targeting VEGFR-2 kinase

Based on the previous studies that revealed the valuable role of pyrazole scaffold in cancer management and VEGFR-2 inhibition, a new set of pyrazole conjugated with pyrazoline, triazolopyrimidine and pyrazolone moieties were synthesized and investigated for their anticancer efficiency against human breast cancer MCF-7. The anticancer screening revealed the significant sensitivity of breast carcinoma towards compounds 4b, 5c, 6c, 7b, 7c and 12c with IC₅₀ values ranging from 16.50 - 26.73 µM in comparison with tamoxifen (IC₅₀ = 23.31 µM). Moreover, the new analogues were further examined for their VEGFR-2 inhibitory activity, among the tested derivatives 5c, 6c, 7b, 7c and 12c displayed prominent inhibitory efficiency versus VEGFR-2 kinase with % inhibition ranging from 70 to 79%. Compounds 6c, 7c and 12c revealed inhibitory efficiency in nanomolar level with IC₅₀ (913.51, 225.17 and 828.23 nM, respectively) comparing to sorafenib (IC₅₀ = 186.54 nM). Flow cytometric analysis revealed that the promising compound 12c prompted pre-G1 apoptosis and cell growth cessation at G2/M phase and stimulated apoptosis via activation of caspase-3. Moreover, molecular docking study of the promising derivatives was performed to highlight their binding modes and interactions with the amino acid residues of VEGFR-2 enzyme.

Deeping in the Role of the MAP-Kinases Interacting Kinases (MNKs) in Cancer

The mitogen-activated protein kinase (MAPK)-interacting kinases (MNKs) are involved in oncogenic transformation and can promote metastasis and tumor progression. In human cells, there are four MNKs isoforms (MNK1a/b and MNK2a/b), derived from two genes by alternative splicing. These kinases play an important role controlling the expression of specific proteins involved in cell cycle, cell survival and cell motility via eukaryotic initiation factor 4E (eIF4E) regulation, but also through other substrates such as heterogeneous nuclear ribonucleoprotein A1, polypyrimidine tract-binding protein-associated splicing factor and Sprouty 2. In this review, we provide an overview of the role of MNK in human cancers, describing the studies conducted to date to elucidate the mechanism involved in the action of MNKs, as well as the development of MNK inhibitors in different hematological cancers and solid tumors.

VEGFR-2 inhibiting effect and molecular modeling of newly synthesized coumarin derivatives as anti-breast cancer agents

Twenty five newly synthesized coumarin scaffold based derivatives were assayed for their in vitro anticancer activity against MCF-7 breast and PC-3 prostate cancer cell lines and were further assessed for their in vitro VEGFR-2 kinase inhibitory activity. The in vitro cytotoxic studies revealed that most of the synthesized compounds possessed very promising cytotoxicity against MCF-7, particularly; compounds 4a (IC₅₀ = 1.24 µM) and 3d (IC₅₀ = 1.65 µM) exhibited exceptional activities superior to the positive control staurosporine (IC₅₀ = 8.81 µM). Similarly, the majority of the compounds exhibited higher antiproliferative activities compared to the reference standard with IC₅₀ values ranging from 2.07 to 8.68 µM. The two cytotoxic derivatives 4a and 3d were selected to evaluate their inhibitory potencies against VEGFR-2 kinase. Remarkably, compound 4a, exhibited significant IC₅₀ of 0.36 µM comparable to staurosporine (IC₅₀; 0.33 µM). Moreover, it was capable of inducing preG1 apoptosis, cell growth arrest at G2/M phase and activating caspase-9. On the other hand, insignificant cytotoxic activity was observed for all compounds towards PC-3 cell line. Molecular docking study was carried out for the most active anti-VEGFR-2 derivative 4a, which demonstrated the ability of the tested compound to interact with the key amino acids in the target VEGFR-2 kinase binding site. Additionally, the ADME parameters and physicochemical properties of compound 4a were examined in silico.

Discovery of N-Phenyl-4-(1H-pyrrol-3-yl)pyrimidin-2-amine Derivatives as Potent Mnk2 Inhibitors: Design, Synthesis, SAR Analysis, and Evaluation of in vitro Anti-leukaemic Activity

BACKGROUND

Aberrant expression of eukaryotic translation initiation factor 4E (eIF4E) is common in many types of cancer including acute myeloid leukaemia (AML). Phosphorylation of eIF4E by MAPK-interacting kinases (Mnks) is essential for the eIF4E-mediated oncogenic activity. As such, the pharmacological inhibition of Mnks can be an effective strategy for the treatment of cancer.

METHODS

A series of N-phenyl-4-(1H-pyrrol-3-yl)pyrimidin-2-amine derivatives was designed and synthesised. The Mnk inhibitory activity of these derivatives as well as their anti-proliferative activity against MV4-11 AML cells was determined.

RESULTS

These compounds were identified as potent Mnk2 inhibitors. Most of them demonstrated potent anti-proliferative activity against MV4-11 AML cells. The cellular mechanistic studies of the representative inhibitors revealed that they reduced the level of phosphorylated eIF4E and induced apoptosis by down-regulating the anti-apoptotic protein myeloid cell leukaemia 1 (Mcl-1) and by cleaving poly(ADP-ribose)polymerase (PARP). The lead compound 7k possessed desirable pharmacokinetic properties and oral bioavailability.

CONCLUSION

This work proposes that exploration of the structural diversity in the context of Nphenyl- 4-(1H-pyrrol-3-yl)pyrimidin-2-amine would offer potent and selective Mnk inhibitors.

Discovery of novel Mnk inhibitors using mutation-based induced-fit virtual high-throughput screening

Mnk kinases (Mnk1 and 2) are downstream effectors of Map kinase pathways and regulate phosphorylation of eukaryotic initiation factor 4E. Engagement of the Mnk pathway is critical in acute myeloid leukemia (AML) leukemogenesis and Mnk inhibitors have potent antileukemic properties in vitro and in vivo, suggesting that targeting Mnk kinases may provide a novel approach for treating AML. Here, we report the development and application of a mutation-based induced-fit in silico screen to identify novel Mnk inhibitors. The Mnk1 structure was modeled by temporarily mutating an amino acid that obstructs the ATP-binding site in the Mnk1 crystal structure while carrying out docking simulations of known inhibitors. The hit compounds display activity in Mnk biochemical and cellular assays, including acute myeloid leukemia progenitors. This approach will enable further rational structure-based drug design of new Mnk inhibitors and potentially novel ways of therapeutically targeting this kinase.

New thiazol-hydrazono-coumarin hybrids targeting human cervical cancer cells: Synthesis, CDK2 inhibition, QSAR and molecular docking studies

Motivated by the potential anticancer activity of both coumarin and 2-aminothiazole nuclei, a new set of thiazol-2-yl hydrazono-chromen-2-one analogs were efficiently synthesized aiming to obtain novel hybrids with potential cytotoxic activity. MTT assay investigated the significant potency of all the target compounds against the human cervical cancer cell lines (HeLa cells). Cell cycle analysis showed that the representative compound 8a led to cell cycle cessation at G0/G1 phase indicating that CDK2/E1complex could be the plausible biological target for these newly synthesized compounds. Thus, the most active compounds (7c and 8a-c) were tested for their CDK2 inhibitory activity. The biological results revealed their significant CDK2 inhibitory activity with IC₅₀ range of 0.022-1.629 nM. Moreover, RT-PCR gene expression assay showed that compound 8a increased the levels of the nuclear CDK2 regulators P21 and P27 by 2.30 and 5.7 folds, respectively. ELISA tequnique showed also that compound 8a led to remarkable activation of caspases-9 and -3 inducing cell apoptosis. QSAR study showed that the charge distribution and molecular hydrophobicity are the structural features affecting cytotoxic activity in this series. Molecular docking study for the most potent cytotoxic compounds (7c and 8a-c) rationalized their superior CDK2 inhibitory activity through their hydrogen bonding and hydrophobic interactions with the key amino acids in the CDK2 binding site. Pharmacokinetic properties prediction of the most potent compounds showed that the newly synthesized compounds are not only with promising antitumor activity but also possess promising pharmacokinetic properties.

eIF4E-Dependent Translational Control: A Central Mechanism for Regulation of Pain Plasticity

Translational control of gene expression has emerged as a key mechanism in regulating different forms of long-lasting neuronal plasticity. Maladaptive plastic reorganization of peripheral and spinal nociceptive circuits underlies many chronic pain states and relies on new gene expression. Accordingly, downregulation of mRNA translation in primary afferents and spinal dorsal horn neurons inhibits tissue injury-induced sensitization of nociceptive pathways, supporting a central role for translation dysregulation in the development of persistent pain. Translation is primarily regulated at the initiation stage via the coordinated activity of translation initiation factors. The mRNA cap-binding protein, eukaryotic translation initiation factor 4E (eIF4E), is involved in the recruitment of the ribosome to the mRNA cap structure, playing a central role in the regulation of translation initiation. eIF4E integrates inputs from the mTOR and ERK signaling pathways, both of which are activated in numerous painful conditions to regulate the translation of a subset of mRNAs. Many of these mRNAs are involved in the control of cell growth, proliferation, and neuroplasticity. However, the full repertoire of eIF4E-dependent mRNAs in the nervous system and their translation regulatory mechanisms remain largely unknown. In this review, we summarize the current evidence for the role of eIF4E-dependent translational control in the sensitization of pain circuits and present pharmacological approaches to target these mechanisms. Understanding eIF4E-dependent translational control mechanisms and their roles in aberrant plasticity of nociceptive circuits might reveal novel therapeutic targets to treat persistent pain states.

CDKI-73: an orally bioavailable and highly efficacious CDK9 inhibitor against acute myeloid leukemia

Acute myeloid leukemia (AML) is the most common form of acute leukemia with dismal long-term prognosis with age. The most aggressive subtype of AML is MLL-AML that is characterized by translocations of the mixed-lineage leukemia gene (MLL) and resistance to conventional chemotherapy. Cyclin dependent kinase 9 (CDK9) plays a crucial role in the MLL-driven oncogenic transcription, and hence, inhibiting activity of CDK9 has been proposed as a promising strategy for treatment of AML. We investigated the therapeutic potential of CDKI-73, one of the most potent CDK9 inhibitors, against a panel of AML cell lines and samples derived from 97 patients. CDKI-73 induced cancer cells undergoing apoptosis through transcriptional downregulation of anti-apoptotic proteins Bcl-2, Mcl-1 and XIAP by majorly targeting CDK9. Contrastively, it was relatively low toxic to the bone marrow cells of healthy donors. In MV4-11 xenograft mouse models, oral administration of CDKI-73 resulted in a marked inhibition of tumor growth (p < 0.0001) and prolongation of animal life span (P < 0.001) without causing body weight loss and other overt toxicities. The study suggests that CDKI-73 can be developed as a highly efficacious and orally deliverable therapeutic agent for treatment of AML.

Optimization of Selective Mitogen-Activated Protein Kinase Interacting Kinases 1 and 2 Inhibitors for the Treatment of Blast Crisis Leukemia

Chronic myeloid leukemia (CML) is a myeloproliferative disease caused by bcr-abl1, a constitutively active tyrosine kinase fusion gene responsible for an abnormal proliferation of leukemic stem cells (LSCs). Inhibition of BCR-ABL1 kinase activity offers long-term relief to CML patients. However, for a proportion of them, BCR-ABL1 inhibition will become ineffective at treating the disease, and CML will progress to blast crisis (BC) CML with poor prognosis. BC-CML is often associated with excessive phosphorylated eukaryotic translation initiation factor 4E (eIF4E), which renders LSCs capable of proliferating via self-renewal, oblivious to BCR-ABL1 inhibition. In vivo, eIF4E is exclusively phosphorylated on Ser209 by MNK1/2. Consequently, a selective inhibitor of MNK1/2 should reduce the level of phosphorylated eIF4E and re-sensitize LSCs to BCR-ABL1 inhibition, thus hindering the proliferation of BC LSCs. We report herein the structure-activity relationships and pharmacokinetic properties of a selective MNK1/2 inhibitor clinical candidate, ETC-206, which in combination with dasatinib prevents BC-CML LSC self-renewal in vitro and enhances dasatinib antitumor activity in vivo.

Beyond molecular tumor heterogeneity: protein synthesis takes control

One of the daunting challenges facing modern medicine lies in the understanding and treatment of tumor heterogeneity. Most tumors show intra-tumor heterogeneity at both genomic and proteomic levels, with marked impacts on the responses of therapeutic targets. Therapeutic target-related gene expression pathways are affected by hypoxia and cellular stress. However, the finding that targets such as eukaryotic initiation factor (eIF) 4E (and its phosphorylated form, p-eIF4E) are generally homogenously expressed throughout tumors, regardless of the presence of hypoxia or other cellular stress conditions, opens the exciting possibility that malignancies could be treated with therapies that combine targeting of eIF4E phosphorylation with immune checkpoint inhibitors or chemotherapy.

Translational control of aberrant stress responses as a hallmark of cancer

Altered mRNA translational control is emerging as a critical factor in cancer development and progression. Targeting specific elements of the translational machinery, such as mTORC1 or eIF4E, is emerging as a new strategy for innovative cancer therapy. While translation of most mRNAs takes place through cap-dependent mechanisms, a sub-population of cellular mRNA species, particularly stress-inducible mRNAs with highly structured 5'-UTR regions, are primarily translated through cap-independent mechanisms. Intriguingly, many of these mRNAs encode proteins that are involved in tumour cell adaptation to microenvironmental stress, and thus linked to aggressive behaviour including tumour invasion and metastasis. This necessitates a rigorous search for links between microenvironmental stress and aggressive tumour phenotypes. Under stress, cells block global protein synthesis to preserve energy while maintaining selective synthesis of proteins that support cell survival. One highly conserved mechanism to regulate protein synthesis under cell stress is to sequester mRNAs into cytosolic aggregates called stress granules (SGs), where their translation is silenced. SGs confer survival advantages and chemotherapeutic resistance to tumour cells under stress. Recently, it has been shown that genetically blocking SG formation dramatically reduces tumour invasive and metastatic capacity in vivo. Therefore, targeting SG formation might represent a potential treatment strategy to block cancer metastasis. Here, we present the critical link between selective mRNA translation, stress adaptation, SGs, and tumour progression. Further, we also explain how deciphering mechanisms of selective mRNA translation occurs under cell stress holds great promise for the identification of new targets in the treatment of cancer. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Inhibition of Mnk enhances apoptotic activity of cytarabine in acute myeloid leukemia cells

Cytarabine (Ara-C) is a first line clinical therapeutic agent for treatment of acute myeloid leukemia (AML). However, this therapy is limited due to high rate of resistance and relapse. Recent research has revealed that the poor prognosis and resistance to Ara-C in AML were associated with its abnormally activated MAPK pathways. In this study, we showed a strong synergistic effect of Ara-C with either our Mnk inhibitor (MNKI-8e) or short hairpin RNA (shRNA) mediated knockdown of Mnks in MV4-11 AML cells. We investigated the underlying mechanisms for this synergism. We showed that both MNKI-8e and Mnk shRNAs enhanced the ability of Ara-C to induce apoptosis. We found that Ara-C increased the phosphorylation of Erk1/2, p38 and eIF4E, which correlated with an enhanced level of anti-apoptotic Mcl-1 protein. Inhibition of Mnk activity suppressed the Ara-C-induced MAPK activity, and thus enhanced apoptosis in MV4-11 cells. Taken together, our study suggests that MAPK-Mnk-eIF4E pathway plays a critical role in Ara-C-treated MV4-11 cells and targeting Mnk may be a promising therapeutic strategy for sensitizing leukemic cells to Ara-C therapy.

Synthesis and molecular docking study of new benzofuran and furo[3,2-g]chromone-based cytotoxic agents against breast cancer and p38α MAP kinase inhibitors

This study deals with synthesis of a new set of benzofuran and 5H-furo[3,2-g]chromone linked various heterocyclic functionalities using concise synthetic approaches aiming to gain new antiproliferative candidates against MCF-7 breast cancer cells of p38α MAP kinase inhibiting activity. The biological data proved the significant sensitivity of breast cancer cell lines MCF-7 towards most of the prepared compounds in comparison with doxorubicin. In addition, compounds IIa,b, Va,b, VIa,b, VIIa,b, VIIIa,b, XIc showed significant in vitro p38α MAPK inhibiting potency comparable to the reference standard SB203580. Cell cycle analysis and apoptosis detection data demonstrated that compound VIa induced G2/M phase arrest and apoptosis in MCF-7 cancer cells, in addition to its activation of the caspases-9 and -3. Gold molecular docking studies rationalized the highly acceptable correlation between the calculated docking scores of fitness and the biological data of p38α MAP kinase inhibition. The newly prepared benzofuran and 5H-furo[3,2-g]chromone derivatives might be considered as new promising nuclei in anti-breast cancer chemotherapeutics for further functionalization, optimization and in-depth biological studies.

Dual abrogation of MNK and mTOR: a novel therapeutic approach for the treatment of aggressive cancers

Targeting the translational machinery has emerged as a promising therapeutic option for cancer treatment. Cancer cells require elevated protein synthesis and exhibit augmented activity to meet the increased metabolic demand. Eukaryotic translation initiation factor 4E is necessary for mRNA translation, its availability and phosphorylation are regulated by the PI3K/AKT/mTOR and MNK1/2 pathways. The phosphorylated form of eIF4E drives the expression of oncogenic proteins including those involved in metastasis. In this article, we will review the role of eIF4E in cancer, its regulation and discuss the benefit of dual inhibition of upstream pathways. The discernible interplay between the MNK and mTOR signaling pathways provides a novel therapeutic opportunity to target aggressive migratory cancers through the development of hybrid molecules.

Inhibition of mTOR kinase as a therapeutic target for acute myeloid leukemia

INTRODUCTION

Acute myeloid leukemia (AML), the most common acute leukemia in adults, remains a therapeutic challenge. The phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway is one of the key aberrant intracellular axes involved in AML. Areas covered: mTOR plays a critical role in sensing and responding to environmental determinants such as nutrient availability, stress, and growth factor concentrations; and in modulating key cellular functions such as proliferation, metabolism, and survival. Although abnormalities of mTOR signaling are strongly associated with neoplastic leukemic proliferation, the role of pharmacologic inhibitors of mTOR in the treatment of AML has not been established. Expert opinion: Inhibition of mTOR signaling has in general modest growth-inhibitory effects in preclinical AML models and clinical trials. Yet, combination of allosteric mTOR inhibitors with standard chemotherapy or targeted agents has a greater anti-leukemia efficacy. In turn, dual mTORC1/2 inhibitors, and dual PI3K/mTOR inhibitors show greater activity in pre-clinical AML models. Further, understanding the role of mTOR signaling in stemness of leukemias is important because AML stem cells may become chemoresistant by displaying aberrant signaling molecules, modifying epigenetic mechanisms, and altering the components of the bone marrow microenvironment.

Synthesis and molecular docking studies of new furochromone derivatives as p38α MAPK inhibitors targeting human breast cancer MCF-7 cells

Based on the reported high expression of p38α MAP kinase in invasive breast cancers and the activity of different functionalized chromone derivatives as p38α inhibitors, a new set of 4,9-dimethoxy/4-methoxy-7-methyl-5-oxo-5H-furo[3,2-g]chromone derivatives were efficiently synthesized aiming to introduce new p38α MAP kinase suppressors as new anti-breast cancer tools. Using GOLD program, molecular docking study of the target compounds into p38α MAP kinase binding pocket was performed to highlight their scores, mode of binding and the important interactions to the amino acid residues of the enzyme. MTT assay investigated that fifteen target compounds produced marked cytotoxic potency higher than that obtained by Doxorubicin against MCF-7 cancer cells of IC₅₀ values ranging from 0.007 to 0.17μM vs IC₅₀; 0.62μM of doxorubicin. Eleven selected compounds were evaluated for their inhibitory potency against p38α MAPK kinase. The derivatives IVa, Va,b, VIa, IXb and XIIIa represented significant activity (IC₅₀; 0.19-0.67μM) comparing to the reference drug SB203580 (IC₅₀; 0.50μM). In virtue of its promising cytotoxic and p38α MAP kinase inhibition potency, the furochromone derivative IXb was selected as a representative example to investigate its mechanistic effects on cell cycle progression and induction of apoptosis in MCF-7 cell lines. The results showed that the compound IXb induced cell cycle cessation at G2/M phase preventing its mitotic cycle, alongside its noteworthy activation of caspases-9 and -3 which might mediate the apoptosis of MCF-7 cells.

Dual targeting of eIF4E by blocking MNK and mTOR pathways in leukemia

Dysregulation of mRNA translation leads to aberrant activation of cellular pathways that promote expansion and survival of leukemic clones. A key element of the initiation translation complex is eIF4E (eukaryotic translation initiation factor 4E). The mitogen-activated protein kinase (MAPK) and mammalian target of rapamycin (mTOR) pathways play important roles in the regulation of eIF4E expression and downstream functional outcomes. Mitogen-activated protein kinase interacting protein kinases (Mnks) control translation by phosphorylation of eIF4E, whereas the mTOR kinase phosphorylates/de-activates the eIF4E inhibitor, 4E-BP1, to release translational repression. Both pathways are often abnormally activated in leukemia cells and promote cell survival events by controlling expression of oncogenic proteins. Targeting these pathways may provide approaches to avoid aberrant proliferation and neoplastic transformation.