Mnk kinase pathway: Cellular functions and biological outcomes

Gene Expression Profile of Cultured Human Coronary Arterial Endothelial Cells Exposed to Serum from Chronic Kidney Disease Patients: Role of MAPK Signaling Pathway

Patients with end-stage renal disease (ESRD) are at increased risk of cardiovascular disease (CVD), such as myocardial infarction (MI). Uremic toxins and endothelial dysfunction are central to this process. In this exploratory study, we used the Affymetrix GeneChip microarray to investigate the gene expression profile in uremic serum-induced human coronary arterial endothelial cells (HCAECs) from ESRD patients with and without MI (UWI and UWOI groups) as an approach to its underlying mechanism. We also explored which pathways are involved in this process. We found 100 differentially expressed genes (DEGs) among the conditions of interest by supervised principal component analysis and hierarchical cluster analysis. The expressions of four major DEGs were validated by quantitative RT-PCR. Pathway analysis and molecular network were used to analyze the interaction and expression patterns. Ten pathways were identified as the main enriched metabolic pathways according to the transcriptome profiling analysis, which were, among others, positive regulation of inflammatory response, positive regulation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) cascade, cardiac muscle cell development, highlighting positive regulation of mitogen-activated protein kinase (MAPK) activity (p = 0.00016). Up- and down-regulation of genes from HCAECs exposed to uremic serum could contribute to increased endothelial dysfunction and CVD in ESRD patients. Our study suggests that inflammation and the ERK-MAPK pathway are highly enriched in kidney disease patients with MI, suggesting their role in ESRD pathology. Further studies and approaches based on MAPK pathway interfering strategies are needed to confirm these data.

Diapause and Anoxia-Induced Quiescence Are Unique States in Embryos of the Annual Killifish, Austrofundulus limnaeus

Diapause is a state of developmental and metabolic dormancy that precedes exposure to environmental stresses. Yet, diapausing embryos are typically stress-tolerant. Evidence suggests that diapausing embryos "prepare" for stress as part of a gene expression program as they enter dormancy. Here, we investigate if diapause II embryos of the annual killifish Austrofundulus limnaeus, which can survive for hundreds of days of anoxia, can mount a transcriptomic response to anoxic insult. Bulk RNAseq was used to characterize the transcriptomes of diapause II embryos exposed to normoxia, 4 h and 24 h anoxia, and 2 h and 24 h normoxic recovery from anoxia. Differential expression and gene ontology analyses were used to probe for pathways that may mitigate survival. Transcriptional factor analysis was used to predict potential mediators of this response. Diapausing embryos exhibited a robust transcriptomic response to anoxia and recovery that returns to near baseline conditions after 24 h. Anoxia induced an upregulation of genes involved in the integrated stress response, lipid metabolism, p38mapk kinase signaling, and apoptosis. Developmental and mitochondrial genes decreased. We conclude that diapause II embryos mount a robust transcriptomic stress response when faced with anoxic insult. This response is consistent with mediating expected challenges to cellular homeostasis in anoxia.

Discovery of Potent and Selective MNK Kinase Inhibitors for the Treatment of Leukemia

MNK activity is regulated by the p38 and Erk MAPK pathways. Phosphorylation of MNK leads to its activation and binding to the eIF4G/eIF4E complex. MNK then phosphorylates eIF4E at Ser209, whose activation is associated with oncogene translation, leading to tumorigenesis. Given this important role for eIF4E in tumorigenesis, MNK inhibition with novel small molecule inhibitors could be a promising strategy to combat AML, which continues to be an area of unmet medical need. Here, we report the medicinal optimization of a series of novel inhibitors and their evaluation of their effects on eIF4E and leukemia cell viability. We discovered a class of ether-containing compounds with a high MNK1/2 selectivity. These MNK inhibitors show good potency in reducing cell viability and colony formation and have desirable pharmacokinetic properties. X-ray cocrystallization was accomplished to confirm the binding mode of our inhibitors and aid in future optimization.

iTRAQ proteomic analysis of the anterior insula in morphine-induced conditioned place preference rats with high-frequency deep brain stimulation intervention

Morphine dependence or addiction is a serious global public health and social problem, and traditional treatments are very limited. Deep brain stimulation (DBS) has emerged as a new potential treatment for drug addiction. Repeated use of morphine leads to neuroadaptive and molecular changes in the addiction-related brain regions. We have previously performed isobaric tags for relative and absolute quantitation (iTRAQ) labelling coupled with 2D-LC MS/MS in anterior insular samples from rats treated with saline control, morphine or morphine plus DBS, and the identified expression of eight proteins are altered by morphine and reversed by high-frequency DBS (HF-DBS). In this study, we analysed the proteomic data in more details. A total of 5575 proteins were identified. Relative to the saline group, the morphine group showed 14 down-regulated and three up-regulated proteins. There were 118 proteins increased and 87 proteins decreased between DBS implanted animals and morphine group. Several differentially expressed proteins were verified with parallel reaction monitoring (PRM) assay. Based on Gene Ontology enrichment an KEGG pathway analyses, the majority of these differentially expressed proteins (DEPs) were involved in protein metabolic process, G-protein coupled receptor signalling pathway, calcium-mediated signalling, neurotransmitter transport, dopaminergic synapse and mTOR signalling pathway. These data offer a comprehensive understanding of the proteomic changes associated with morphine addiction and DBS therapy in addicted animal models, which is important for the development of DBS interventions for drug addiction.

A patent review of mitogen-activated protein kinase-interacting kinases (MNKs) modulators (2019-present)

INTRODUCTION

The mitogen-activated protein kinase interacting kinases (MNKs) modulate protein translation through the phosphorylation of eukaryotic initiation factor 4E (eIF4E) at serine 209, which is crucial for tumorigenesis but dispensable for normal development. MNKs are implicated in various pathological processes, including inflammation, obesity, cancer, etc. Thus, MNKs are considered as potential drug targets and the development of potent and selective MNK inhibitors is a current research focus.

AREAS COVERED

This review covers inhibitors of MNKs reported in patents published in the online databases of the World Intellectual Property Organization and European Patent Office from 2019 to 2024. This review provides a landscape of available inhibitors, including their chemical structures, activity, and stage of development.

EXPERT OPINION

In recent years, highly potent and selective inhibitors have been discovered and many of them show promising results in several preclinical cancer models. The majority of small-molecule inhibitors developed recently, similarly to the structure of eFT508 and ETC-206. Also, some new skeletons were disclosed and showed novel mechanisms, including non-traditional ATP competition and induced protein degradation by proteolysis targeting chimeras. Ongoing preclinical research and clinical trials will provide us more information on these new compounds and MNKs novel functions beyond cancer.

eIF4E orchestrates mRNA processing, RNA export and translation to modify specific protein production

The eukaryotic translation initiation factor eIF4E acts as a multifunctional factor that simultaneously influences mRNA processing, export, and translation in many organisms. Its multifactorial effects are derived from its capacity to bind to the methyl-7-guanosine cap on the 5'end of mRNAs and thus can act as a cap chaperone for transcripts in the nucleus and cytoplasm. In this review, we describe the multifactorial roles of eIF4E in major mRNA-processing events including capping, splicing, cleavage and polyadenylation, nuclear export and translation. We discuss the evidence that eIF4E acts at two levels to generate widescale changes to processing, export and ultimately the protein produced. First, eIF4E alters the production of components of the mRNA processing machinery, supporting a widescale reprogramming of multiple mRNA processing events. In this way, eIF4E can modulate mRNA processing without physically interacting with target transcripts. Second, eIF4E also physically interacts with both capped mRNAs and components of the RNA processing or translation machineries. Further, specific mRNAs are sensitive to eIF4E only in particular mRNA processing events. This selectivity is governed by the presence of cis-acting elements within mRNAs known as USER codes that recruit relevant co-factors engaging the appropriate machinery. In all, we describe the molecular bases for eIF4E's multifactorial function and relevant regulatory pathways, discuss the basis for selectivity, present a compendium of ~80 eIF4E-interacting factors which play roles in these activities and provide an overview of the relevance of its functions to its oncogenic potential. Finally, we summarize early-stage clinical studies targeting eIF4E in cancer.

The effects of miR-217 inhibitor and mimic in the progression of Kirsten rat sarcoma viral oncogene homologue driven cancers

Background

Kirsten rat sarcoma viral oncogene homologue (KRAS) is one of the most frequently mutated proto-oncogenes in approximately 90% of pancreatic ductal carcinoma (PDAC) and 45% of colorectal cancer (CC) cases. Studies in the past have identified microRNA-217 (miR-217) as a potential tumour-suppressing miRNA that is downregulated in various cancers. Using in silico prediction algorithms, several studies have identified miR-217 as a potential regulator of KRAS, and we investigated its role in PDAC and CC progression.

Method

The study was carried out in KRAS-driven cancer (KDC) cell lines PANC-1 (pancreatic cancer) and SW-480 (CC), which have mutant KRAS gene expression. The KDC cells are transfected with specific oligonucleotides for miR-217, anti-miR-217, and a negative control in serum-free media using lipofectamine. After fixing the IC50, using specific primers, gene expression studies were carried out by qPCR for KRAS downstream targets and genes associated with apoptosis and cell cycle. Anti-migration and anti-apoptotic effects were studied using the transwell migration assay and annexin-V/PI staining methods, and mitochondrial morphology was observed using a transmission electron microscope.

Results

The present study demonstrates that overexpression of miR-217 in KDC cells mitigates proliferation and migration and promotes cell cycle arrest and apoptosis of KDC cells via the MAPK/ERK signalling pathway. Besides, decreased miR-217 expression rescues KDC cells from the effects mediated by KRAS downstream signalling.

Conclusion

The outcome of the study indicates miR-217 suppresses tumour growth and promotes apoptosis in KDC and that these effects are associated with down regulation of MAPK/ERK signalling.

Molecular signaling and clinical implications in the human aging-cancer cycle

It is well documented that aging is associated with cancer, and likewise, cancer survivors display accelerated aging. As the number of aging individuals and cancer survivors continues to grow, it raises additional concerns across society. Therefore, unraveling the molecular mechanisms of aging in tissues is essential to developing effective therapies to fight the aging and cancer diseases in cancer survivors and cancer patients. Indeed, cellular senescence is a critical response, or a natural barrier to suppress the transition of normal cells into cancer cells, however, hypoxia which is physiologically required to maintain the stem cell niche, is increased by aging and inhibits senescence in tissues. Interestingly, oxygen restriction or hypoxia increases longevity and slows the aging process in humans, but hypoxia can also drive angiogenesis to facilitate cancer progression. In addition, cancer treatment is considered as one of the major reasons that drive cellular senescence, subsequently followed by accelerated aging. Several clinical trials have recently evaluated inhibitors to eliminate senescent cells. However, some mechanisms of aging typically can also retard cancer cell growth and progression, which might require careful strategy for better clinical outcomes. Here we describe the molecular regulation of aging and cancer in crosstalk with DNA damage and hypoxia signaling pathways in cancer patients and cancer survivors. We also update several therapeutic strategies that might be critical in reversing the cancer treatment-associated aging process.

Structural insights into trypanosomatid Mnk kinase orthologues (kMnks) suggest altered mechanism in the kinase domain

Mitogen-activated protein kinase (MAPK) interacting protein kinases (Mnk1 and Mnk2) mediated phosphorylation of the eukaryotic initiation factor eIF4E is an important translation initiation control, in Mnk-mediated oncogenic activity and other disease conditions. Thus, Mnk kinases are an important target for therapy. Trypanosomatids are a class of kinetoplastids, some of which are protozoan parasites and cause diseases in humans. While protein translation initiation is well understood in eukaryotes and prokaryotes, there is a lack of sufficient structural information of this process in trypanosomatids. Here, we report that trypanosomatids have one orthologue of Mnk kinase with low overall sequence homology but high homology in the kinase domain and an additional C-terminal domain containing putative calmodulin binding site(s). We show that while many of the domains and motifs are conserved, homology modeling/structure prediction, docking analysis and molecular dynamics simulation studies suggest that trypanosomatid kMnk kinases, kinase domains are present in DFG-in conformation as opposed to the auto-inhibited DFD-out conformation of un-phosphorylated human Mnk1. Furthermore, we observed that several regulatory features are different in trypanosomatid kMnk kinases. Our study indicates that mechanism and regulation in the kinase domain of trypanosomatid kMnks are likely to be altered, and that they can be important drug targets.

RIPK1 inhibition mitigates neuroinflammation and rescues depressive-like behaviors in a mouse model of LPS-induced depression

BACKGROUND

Depression is often linked to inflammation in the brain. Researchers have been exploring ways to reduce this inflammation to improve depression symptoms. One potential target is a protein called RIPK1, which is known to contribute to brain inflammation. However, it's unclear how RIPK1 influences depression. Our study aims to determine whether RIPK1 inhibition could alleviate neuroinflammation-associated depression and elucidate its underlying mechanisms.

METHODS

To investigate our research objectives, we established a neuroinflammation mouse model by administering LPS. Behavioral and biochemical assessments were conducted on these mice. The findings were subsequently validated through in vitro experiments.

RESULTS

Using LPS-induced depression models, we investigated RIPK1's role, observing depressive-like behaviors accompanied by elevated cytokines, IBA-1, GFAP levels, and increased inflammatory signaling molecules and NO/H2O2. Remarkably, Necrostatin (Nec-1 S), a RIPK1 inhibitor, mitigated these changes. We further found altered expression and phosphorylation of eIF4E, PI3K/AKT/mTOR, and synaptic proteins in hippocampal tissues, BV2, and N2a cells post-LPS treatment, which Nec-1 S also ameliorated. Importantly, eIF4E inhibition reversed some of the beneficial effects of Nec-1 S, suggesting a complex interaction between RIPK1 and eIF4E in LPS-induced neuroinflammation. Moreover, citronellol, a RIPK1 agonist, significantly altered eIF4E phosphorylation, indicating RIPK1's potential upstream regulatory role in eIF4E and its contribution to neuroinflammation-associated depression.

CONCLUSION

These findings propose RIPK1 as a pivotal mediator in regulating neuroinflammation and neural plasticity, highlighting its significance as a potential therapeutic target for depression.

MNK-driven eIF4E phosphorylation regulates the fibrogenic transformation of mesenchymal cells and chronic lung allograft dysfunction

Tissue fibrosis remains unamenable to meaningful therapeutic interventions and is the primary cause of chronic graft failure after organ transplantation. Eukaryotic translation initiation factor (eIF4E), a key translational regulator, serves as convergent target of multiple upstream profibrotic signaling pathways that contribute to mesenchymal cell (MC) activation. Here, we investigate the role of MAP kinase-interacting serine/threonine kinase-induced (MNK-induced) direct phosphorylation of eIF4E at serine 209 (Ser209) in maintaining fibrotic transformation of MCs and determine the contribution of the MNK/eIF4E pathway to the pathogenesis of chronic lung allograft dysfunction (CLAD). MCs from patients with CLAD demonstrated constitutively higher eIF4E phosphorylation at Ser209, and eIF4E phospho-Ser209 was found to be critical in regulating key fibrogenic protein autotaxin, leading to sustained β-catenin activation and profibrotic functions of CLAD MCs. MNK1 signaling was upregulated in CLAD MCs, and genetic or pharmacologic targeting of MNK1 activity inhibited eIF4E phospho-Ser209 and profibrotic functions of CLAD MCs in vitro. Treatment with an MNK1/2 inhibitor (eFT-508) abrogated allograft fibrosis in an orthotopic murine lung-transplant model. Together these studies identify what we believe is a previously unrecognized MNK/eIF4E/ATX/β-catenin signaling pathway of fibrotic transformation of MCs and present the first evidence, to our knowledge, for the utility of MNK inhibitors in fibrosis.

The role of MNK1-mTORC1 pathway in modulating macrophage responses to Vibrio vulnificus infection

Vibrio vulnificus (Vv) is known to cause life-threatening infections, particularly septicemia. These patients often exhibit elevated levels of pro-inflammatory cytokines. While it is established that mitogen-activated protein kinase (MAPK)-interacting kinase (MNK) contributes to the production of pro-inflammatory cytokines, the role of MNK in macrophages during Vv infection remains unclear. In this study, we investigate the impact of MNK on macrophages. We demonstrate that the inhibition of MNK in J774A.1 cells, when treated with lipopolysaccharide or Vv, resulted in decreased production of tumor necrosis factor alpha and interleukin-6, without affecting their transcription. Interestingly, treatment with MNK inhibitor CGP57380 led to enhanced phosphorylation of MNK1 but decreased phosphorylation of eIF4E. Moreover, MNK1 knockout cells exhibited an increased capacity for phagocytosis and clearance of Vv, with more acidic phagosomes than the parental cells. Notably, CGP57380 did not impact phagocytosis, bacterial clearance, or phagosome acidification in Vv-infected J774A.1 cells. Considering the reported association between MNK and mammalian target of rapamycin complex 1 (mTORC1) activation, we investigated the mTORC1 signaling in MNK1 knockout cells infected with Vv. Our results revealed that attenuation of the mTORC1 signaling in these cells and treatment with the mTORC1 inhibitor rapamycin significantly enhanced bacterial clearance in J774A.1 cells following Vv infection. In summary, our findings suggest that MNK promotes the Vv-induced cytokine production in J774A.1 cells without affecting their transcription levels. MNK1 appears to impair the phagocytosis, bacterial clearance, and phagosome acidification in Vv-infected J774A.1 cells through the MNK1-mTORC1 signaling pathway rather than the MNK1-eIF4E signaling pathway. Our findings highlight the importance of the MNK1-mTORC1 pathway in modulating macrophage responses to Vv infection.

IMPORTANCE

Mitogen-activated protein kinase (MAPK)-interacting kinase (MNK) plays a role in promoting the production of tumor necrosis factor alpha and interleukin-6 in macrophages during Vibrio vulnificus (Vv) infection. Inhibition or knockout of MNK1 in J774A.1 cells resulted in reduced cytokine production without affecting their transcription levels. MNK1 also impairs phagocytosis, bacterial clearance, and phagosome acidification in Vv-infected cells through the MNK1-mammalian target of rapamycin complex 1 (mTORC1) signaling pathway. The findings highlight the importance of the MNK1-mTORC1 pathway in modulating macrophage responses to Vv infection.

Development of an Imidazopyridazine-Based MNK1/2 Inhibitor for the Treatment of Lymphoma

The mitogen-activated protein kinase-interacting protein kinases (MNKs) are the only kinases known to phosphorylate eukaryotic translation initiation factor 4E (eIF4E) at Ser209, which plays a significant role in cap-dependent translation. Dysregulation of the MNK/eIF4E axis has been found in various solid tumors and hematological malignancies, including diffuse large B-cell lymphoma (DLBCL). Herein, structure-activity relationship studies and docking models determined that 20j exhibits excellent MNK1/2 inhibitory activity, stability, and hERG safety. 20j exhibits strong and broad antiproliferative activity against different cancer cell lines, especially GCB-DLBCL DOHH2. 20j suppresses the phosphorylation of eIF4E in Hela cells (IC50 = 90.5 nM) and downregulates the phosphorylation of eIF4E and 4E-BP1 in A549 cells. In vivo studies first revealed that ibrutinib enhances the antitumor effect of 20j without side effects in a DOHH2 xenograft model. This study provided a solid foundation for the future development of a MNK inhibitor for GCB-DLBCL treatment.

Mechanisms of Sepsis-Induced Acute Lung Injury and Advancements of Natural Small Molecules in Its Treatment

Sepsis-induced acute lung injury (ALI), characterized by widespread lung dysfunction, is associated with significant morbidity and mortality due to the lack of effective pharmacological treatments available clinically. Small-molecule compounds derived from natural products represent an innovative source and have demonstrated therapeutic potential against sepsis-induced ALI. These natural small molecules may provide a promising alternative treatment option for sepsis-induced ALI. This review aims to summarize the pathogenesis of sepsis and potential therapeutic targets. It assembles critical updates (from 2014 to 2024) on natural small molecules with therapeutic potential against sepsis-induced ALI, detailing their sources, structures, effects, and mechanisms of action.

Vinorelbine causes a neuropathic pain-like state in mice via STING and MNK1 signaling associated with type I interferon induction

Type I interferons (IFNs) increase the excitability of dorsal root ganglia (DRGs) neurons via MNK-eIF4E signaling to promote pain sensitization in mice. Activation of stimulator of interferon response cGAMP interactor 1 (STING) signaling is pivotal for type I IFN induction. We hypothesized that vinorelbine, a chemotherapeutic and activator of STING, would cause a neuropathic pain-like state in mice via STING signaling in DRG neurons associated with IFN production. Vinorelbine caused tactile allodynia and grimacing in wild-type (WT) mice and increased p-IRF3, type I IFNs, and p-eIF4E in peripheral nerves. Supporting our hypothesis, vinorelbine failed to induce IRF3-IFNs-MNK-eIF4E in StingGt/Gt mice and, subsequently, failed to cause pain. The vinorelbine-elicited increase of p-eIF4E was not observed in Mknk1-/- (MNK1 knockout) mice in peripheral nerves consistent with the attenuated pro-nociceptive effect of vinorelbine in these mice. Our findings show that activation of STING signaling in the periphery causes a neuropathic pain-like state through type I IFN signaling to DRG nociceptors.

A tRF-5a fragment that regulates radiation resistance of colorectal cancer cells by targeting MKNK1

Radiotherapy serves as a crucial strategy in the treatment of colorectal cancer (CRC). However, its efficacy is often hindered by the challenge of radiation resistance. Although the literature suggests that some tRNA-derived small RNAs (tsRNAs) are associated with various cancers, studies reporting the relationship of tsRNAs with cancer cell radiosensitivity have not been published yet. In our study, we utilized tsRNAs sequencing to predict differentially expressed tsRNAs in two CRC cells and their radioresistant cells, and 10 tsRNAs with significant differences in expression were validated by qPCR. The target genes of tRF-16-7X9PN5D were predicted and verified by the bioinformatics, dual-luciferase reporter gene assay and western blotting analyses. Wound healing, colony formation, transwell invasion and CCK-8 assays were performed to detect the effects of tRF-16-7X9PN5D on cell function and radiosensitivity. Western blotting evaluated the relationship between tRF-16-7X9PN5D and the MKNK-eIF4E axis. Our findings demonstrated that tRF-16-7X9PN5D expression was substantially downregulated in radioresistant CRC cells. Furthermore, tRF-16-7X9PN5D could promote CRC cells' ability to proliferate, migrate, invade and obtain radiation resistance by targeting MKNK1. Finally, tRF-16-7X9PN5D could regulate eIF4E phosphorylation via MKNK1. This investigation indicated that tRF-16-7X9PN5D has an essential regulatory role in the radiation resistance of CRC by directly targeting MKNK1, and may be a new pathway for regulating the CRC radiosensitivity.

MNK, mTOR or eIF4E-selecting the best anti-tumor target for blocking translation initiation

Overexpression of eIF4E is common in patients with various solid tumors and hematologic cancers. As a potential anti-cancer target, eIF4E has attracted extensive attention from researchers. At the same time, mTOR kinases inhibitors and MNK kinases inhibitors, which are directly related to regulation of eIF4E, have been rapidly developed. To explore the optimal anti-cancer targets among MNK, mTOR, and eIF4E, this review provides a detailed classification and description of the anti-cancer activities of promising compounds. In addition, the structures and activities of some dual-target inhibitors are briefly described. By analyzing the different characteristics of the inhibitors, it can be concluded that MNK1/2 and eIF4E/eIF4G interaction inhibitors are superior to mTOR inhibitors. Simultaneous inhibition of MNK and eIF4E/eIF4G interaction may be the most promising anti-cancer method for targeting translation initiation.

Molecular targeting of the UDP-glucuronosyltransferase enzymes in high-eukaryotic translation initiation factor 4E refractory/relapsed acute myeloid leukemia patients: a randomized phase II trial of vismodegib, ribavirin with or without decitabine

Drug resistance underpins poor outcomes in many malignancies including refractory and relapsed acute myeloid leukemia (R/R AML). Glucuronidation is a common mechanism of drug inactivation impacting many AML therapies, e.g., cytarabine, decitabine, azacytidine and venetoclax. In AML cells, the capacity for glucuronidation arises from increased production of the UDP-glucuronosyltransferase 1A (UGT1A) enzymes. UGT1A elevation was first observed in AML patients who relapsed after response to ribavirin, a drug used to target the eukaryotic translation initiation factor eIF4E, and subsequently in patients who relapsed on cytarabine. UGT1A elevation resulted from increased expression of the sonic-hedgehog transcription factor GLI1. Vismodegib inhibited GLI1, decreased UGT1A levels, reduced glucuronidation of ribavirin and cytarabine, and re-sensitized cells to these drugs. Here, we examined if UGT1A protein levels, and thus glucuronidation activity, were targetable in humans and if this corresponded to clinical response. We conducted a phase II trial using vismodegib with ribavirin, with or without decitabine, in largely heavily pre-treated patients with high-eIF4E AML. Pre-therapy molecular assessment of patients' blasts indicated highly elevated UGT1A levels relative to healthy volunteers. Among patients with partial response, blast response or prolonged stable disease, vismodegib reduced UGT1A levels, which corresponded to effective targeting of eIF4E by ribavirin. In all, our studies are the first to demonstrate that UGT1A protein, and thus glucuronidation, are targetable in humans. These studies pave the way for the development of therapies that impair glucuronidation, one of the most common drug deactivation modalities. Clinicaltrials.gov: NCT02073838.

From signalling pathways to targeted therapies: unravelling glioblastoma's secrets and harnessing two decades of progress

Glioblastoma, a rare, and highly lethal form of brain cancer, poses significant challenges in terms of therapeutic resistance, and poor survival rates for both adult and paediatric patients alike. Despite advancements in brain cancer research driven by a technological revolution, translating our understanding of glioblastoma pathogenesis into improved clinical outcomes remains a critical unmet need. This review emphasises the intricate role of receptor tyrosine kinase signalling pathways, epigenetic mechanisms, and metabolic functions in glioblastoma tumourigenesis and therapeutic resistance. We also discuss the extensive efforts over the past two decades that have explored targeted therapies against these pathways. Emerging therapeutic approaches, such as antibody-toxin conjugates or CAR T cell therapies, offer potential by specifically targeting proteins on the glioblastoma cell surface. Combination strategies incorporating protein-targeted therapy and immune-based therapies demonstrate great promise for future clinical research. Moreover, gaining insights into the role of cell-of-origin in glioblastoma treatment response holds the potential to advance precision medicine approaches. Addressing these challenges is crucial to improving outcomes for glioblastoma patients and moving towards more effective precision therapies.

Canagliflozin shares common mTOR and MAPK signaling mechanisms with other lifespan extension treatments

Long-lived mouse models and treatments that extend lifespan, such as Rapamycin, acarbose and 17α- -estradiol, lead to reduction in mTORC1 activity, declines in cap-dependent translation and increases in cap-independent translation. In addition, these treatments reduce the MEK-ERK-MNK (ERK1-2) signaling cascade, leading to reduction in eIF4E phosphorylation, which also regulates mRNA translation. Here, we report that Canagliflozin, a drug that extends lifespan only in male mice reduces mTORC1 and ERK1-2 signaling in male mice only. The data suggest reduction in mTORC1 and ERK pathways are common mechanisms shared by both genetic and pharmacological models of slowed aging in mice. Our data also reveal a significant sexual dimorphism in the ERK1-2 signaling pathway which might help to explain why some drugs can extend lifespan in males but have no effects in female mice.

Role of irisin in bone diseases

Bone diseases are common among middle-aged and elderly people, and harm to activities of daily living (ADL) and quality of life (QOL) for patients. It is crucial to search for key regulatory factors associated with the development of bone diseases and explore potential therapeutic targets for bone diseases. Irisin is a novel myokine that has been discovered in recent years. Accumulating evidence indicates that irisin has beneficial effects in the treatment of various diseases such as metabolic, cardiovascular and neurological disorders, especially bone-related diseases. Recent studies had shown that irisin plays the role in various bone diseases such as osteoarthritis, osteoporosis and other bone diseases, suggesting that irisin may be a potential molecule for the prevention and treatment of bone diseases. Therefore, in this review, by consulting the related domestic and international literature of irisin and bone diseases, we summarized the specific regulatory mechanisms of irisin in various bone diseases, and provided a systematic theoretical basis for its application in the diagnosis and treatment of the bone diseases.

Aging Rate Indicators: Speedometers for Aging Research in Mice

A "biomarker of aging" is conceptualized as an index of how far an individual has moved along the path from youth to old age. In contrast, an aging rate indicator (ARI) represents a measure of speed, rather than distance, that is, a measure of how rapidly the individual is moving toward the phenotypic changes typical of old age. This essay presents and reviews recent data suggesting common characteristics of slow-aging mice, whether the slowed aging is caused by a mutant allele, the calorie restriction diet, or drugs that slow aging and extend mean and maximal lifespan. Some of the candidate ARIs, shared by nine varieties of slow-aging mice, are physiological changes seen in fat, fat-associated macrophages, muscle, liver, brain, and plasma. Others are molecular measurements, reflecting activity of mTORC1, selective mRNA translation, or each of six MAP kinases in two distinct MAPK cascades in liver, muscle, or kidney. Changes in ARIs are notable in young adult mice after 8 months of drug or diet exposure, are detectable in mutant mice at least as early as 4-6 months of age, and persist until at least 18-22 months. Many of the candidate ARIs are thought to play an influential role in cognition, inflammation, exercise responses, and control of metabolic rate, and are thus plausible as modulators of age-related physiological and neurological illnesses. In principle, screening for drugs that induce alterations in ARIs in normal young adult mice might facilitate the search for preventive medicines that can retard aging and late-life illnesses in mice or in human populations.

Medicinal chemistry approaches to target the MNK-eIF4E axis in cancer

Aberrant translation of proteins that promote cell proliferation is an essential factor that defines oncogenic processes and cancer. The process for ribosomal translation of proteins from mRNA requires an essential initiation step which is controlled by the protein eIF4E, which binds the RNA 5'-cap and forms the eIF4F complex that subsequently translates protein. Typically, eIF4E is activated by phosphorylation on Ser209 by MNK1 and MNK2 kinases. Substantial work has shown that eIF4E and MNK1/2 are dysregulated in many cancers and this axis has therefore become an active area of interest for developing new cancer therapeutics. This review summarizes and discusses recent work to develop small molecules that target different steps in the MNK-eIF4E axis as potential cancer therapeutics. The aim of this review is to cover the breadth of different molecular approaches being taken and the medicinal chemistry basis for their optimization and testing as new cancer therapeutics.

Vinorelbine causes a neuropathic pain-like state in mice via STING and MNK1 signaling associated with type I interferon induction

Type I interferons (IFNs) increase the excitability of dorsal root ganglion (DRG) neurons via activation of MNK-eIF4E translation signaling to promote pain sensitization in mice. Activation of STING signaling is a key component of type I IFN induction. Manipulation of STING signaling is an active area of investigation in cancer and other therapeutic areas. Vinorelbine is a chemotherapeutic that activates STING and has been shown to cause pain and neuropathy in oncology clinical trials in patients. There are conflicting reports on whether STING signaling promotes or inhibits pain in mice. We hypothesized that vinorelbine would cause a neuropathic pain-like state in mice via STING and signaling pathways in DRG neurons associated with type I IFN induction. Vinorelbine (10 mg/kg, i.v.) induced tactile allodynia and grimacing in WT male and female mice and increased p-IRF3 and type I IFN protein in peripheral nerves. In support of our hypothesis, vinorelbine-mediated pain was absent in male and female StingGt/Gt mice. Vinorelbine also failed to induce IRF3 and type I IFN signaling in these mice. Since type I IFNs engage translational control via MNK1-eIF4E in DRG nociceptors, we assessed vinorelbine-mediated p-eIF4E changes. Vinorelbine increased p-eIF4E in DRG in WT animals but not in StingGt/Gt or Mknk1-/- (MNK1 KO) mice. Consistent with these biochemical findings, vinorelbine had an attenuated pro-nociceptive effect in male and female MNK1 KO mice. Our findings support the conclusion that activation of STING signaling in the peripheral nervous system causes a neuropathic pain-like state that is mediated by type I IFN signaling to DRG nociceptors.

eIF4E phosphorylation recruits β-catenin to mRNA cap and promotes Wnt pathway translation in dentate gyrus LTP maintenance

The mRNA cap-binding protein, eukaryotic initiation factor 4E (eIF4E), is crucial for translation and regulated by Ser209 phosphorylation. However, the biochemical and physiological role of eIF4E phosphorylation in translational control of long-term synaptic plasticity is unknown. We demonstrate that phospho-ablated Eif4e^S209A Knockin mice are profoundly impaired in dentate gyrus LTP maintenance in vivo, whereas basal perforant path-evoked transmission and LTP induction are intact. mRNA cap-pulldown assays show that phosphorylation is required for synaptic activity-induced removal of translational repressors from eIF4E, allowing initiation complex formation. Using ribosome profiling, we identified selective, phospho-eIF4E-dependent translation of the Wnt signaling pathway in LTP. Surprisingly, the canonical Wnt effector, β-catenin, was massively recruited to the eIF4E cap complex following LTP induction in wild-type, but not Eif4e^S209A, mice. These results demonstrate a critical role for activity-evoked eIF4E phosphorylation in dentate gyrus LTP maintenance, remodeling of the mRNA cap-binding complex, and specific translation of the Wnt pathway.

Mnk1/2 kinases regulate memory and autism-related behaviours via Syngap1

MAPK interacting protein kinases 1 and 2 (Mnk1/2) regulate a plethora of functions, presumably via phosphorylation of their best characterized substrate, eukaryotic translation initiation factor 4E (eIF4E) on Ser209. Here, we show that, whereas deletion of Mnk1/2 (Mnk double knockout) impairs synaptic plasticity and memory in mice, ablation of phospho-eIF4E (Ser209) does not affect these processes, suggesting that Mnk1/2 possess additional downstream effectors in the brain. Translational profiling revealed only a small overlap between the Mnk1/2- and phospho-eIF4E(Ser209)-regulated translatome. We identified the synaptic Ras GTPase activating protein 1 (Syngap1), encoded by a syndromic autism gene, as a downstream target of Mnk1 because Syngap1 immunoprecipitated with Mnk1 and showed reduced phosphorylation (S788) in Mnk double knockout mice. Knockdown of Syngap1 reversed memory deficits in Mnk double knockout mice and pharmacological inhibition of Mnks rescued autism-related phenotypes in Syngap1+/- mice. Thus, Syngap1 is a downstream effector of Mnk1, and the Mnks-Syngap1 axis regulates memory formation and autism-related behaviours.

MNK1 and MNK2 Expression in the Human Dorsal Root and Trigeminal Ganglion

Mitogen activated protein kinase interacting kinases (MNK) 1 and 2 are serine/threonine protein kinases that play an important role in translation of mRNAs through their phosphorylation of the RNA 5'-cap binding protein, eukaryotic translation initiation factor (eIF) 4E. These kinases are downstream targets for mitogen activated protein kinases (MAPKs), extracellular activity regulated protein kinase (ERK) and p38. MNKs have been implicated in the sensitization of peripheral nociceptors of the dorsal root and trigeminal ganglion (DRG and TG) using transgenic mouse lines and through the use of specific inhibitors of MNK1 and MNK2. While specific knockout of the Mknk1 gene suggests that it is the key isoform for regulation of nociceptor excitability and nociceptive behaviors in mice, both MKNK1 and MKNK2 genes are expressed in the DRG and TG of mice and humans based on RNA sequencing experiments. Single cell sequencing in mice suggests that Mknk1 and Mknk2 may be expressed in different populations of nociceptors. We sought to characterize mRNA expression in human DRG and TG (N = 3 ganglia for both DRG and TG) for both MNK1 and MNK2. Our results show that both genes are expressed by nearly all neurons in both human ganglia with expression in other cell types as well. Our findings provide evidence that MNK1 and MNK2 are expressed by human nociceptors of males and females and suggest that efforts to pharmacologically target MNKs for pain would likely be translatable due its conserved expression in both species.

Computational and Functional Analysis of Structural Features in the ZAKα Kinase

The kinase ZAKα acts as the proximal sensor of translational impairment and ribotoxic stress, which results in the activation of the MAP kinases p38 and JNK. Despite recent insights into the functions and binding partners of individual protein domains in ZAKα, the mechanisms by which ZAKα binds ribosomes and becomes activated have remained elusive. Here, we highlight a short, thrice-repeated, and positively charged peptide motif as critical for the ribotoxic stress-sensing function of the Sensor (S) domain of ZAKα. We use this insight to demonstrate that the mutation of the SAM domain uncouples ZAKα activity from ribosome binding. Finally, we use 3D structural comparison to identify and functionally characterize an additional folded domain in ZAKα with structural homology to YEATS domains. These insights allow us to formulate a model for ribosome-templated ZAKα activation based on the re-organization of interactions between modular protein domains. In sum, our work both advances our understanding of the protein domains and 3D architecture of the ZAKα kinase and furthers our understanding of how the ribotoxic stress response is activated.

Regulation of germline proteostasis by HSF1 and insulin/IGF-1 signaling

Protein homeostasis (proteostasis) is essential for cellular function and organismal health and requires the concerted actions of protein synthesis, folding, transport, and turnover. In sexually reproducing organisms, the immortal germline lineage passes genetic information across generations. Accumulating evidence indicates the importance of proteome integrity for germ cells as genome stability. As gametogenesis involves very active protein synthesis and is highly energy-demanding, it has unique requirements for proteostasis regulation and is sensitive to stress and nutrient availability. The heat shock factor 1 (HSF1), a key transcriptional regulator of cellular response to cytosolic and nuclear protein misfolding has evolutionarily conserved roles in germline development. Similarly, insulin/insulin-like growth factor-1 (IGF-1) signaling, a major nutrient-sensing pathway, impacts many aspects of gametogenesis. Here, we focus on HSF1 and IIS to review insights into their roles in germline proteostasis and discuss the implications on gamete quality control during stress and aging.

Proteome diversification by mRNA translation in cancer

mRNA translation is a highly conserved and tightly controlled mechanism for protein synthesis and is well known to be altered by oncogenes to promote cancer development. This distorted mRNA translation is accompanied by the vulnerability of cancer to inhibitors of key mRNA translation components. Novel studies also suggest that these alternations could be utilized for immunotherapy. Ribosome heterogeneity and alternative responses to nutrient shortages, which aid cancer growth and spread, are proposed to elicit aberrant protein production but may also result in previously unidentified therapeutic targets, such as the presentation of cancer-specific peptides at the surface of cancer cells (neoepitopes). This review will assess the driving forces in tRNA and ribosome function that underlie proteome diversification due to alterations in mRNA translation in cancer cells.

Finnish-specific AKT2 gene variant leads to impaired insulin signalling in myotubes

Finnish-specific gene variant p.P50T/AKT2 (minor allele frequency (MAF) = 1.1%) is associated with insulin resistance and increased predisposition to type 2 diabetes. Here, we have investigated in vitro the impact of the gene variant on glucose metabolism and intracellular signalling in human primary skeletal muscle cells, which were established from 14 male p.P50T/AKT2 variant carriers and 14 controls. Insulin-stimulated glucose uptake and glucose incorporation into glycogen were detected with 2-[1,2-3H]-deoxy-D-glucose and D-[14C]-glucose, respectively, and the rate of glycolysis was measured with a Seahorse XFe96 analyzer. Insulin signalling was investigated with Western blotting. The binding of variant and control AKT2-PH domains to phosphatidylinositol (3,4,5)-trisphosphate (PI(3,4,5)P3) was assayed using PIP StripsTM Membranes. Protein tyrosine kinase and serine-threonine kinase assays were performed using the PamGene® kinome profiling system. Insulin-stimulated glucose uptake and glycogen synthesis in myotubes in vitro were not significantly affected by the genotype. However, the insulin-stimulated glycolytic rate was impaired in variant myotubes. Western blot analysis showed that insulin-stimulated phosphorylation of AKT-Thr308, AS160-Thr642 and GSK3β-Ser9 was reduced in variant myotubes compared to controls. The binding of variant AKT2-PH domain to PI(3,4,5)P3 was reduced as compared to the control protein. PamGene® kinome profiling revealed multiple differentially phosphorylated kinase substrates, e.g. calmodulin, between the genotypes. Further in silico upstream kinase analysis predicted a large-scale impairment in activities of kinases participating, for example, in intracellular signal transduction, protein translation and cell cycle events. In conclusion, myotubes from p.P50T/AKT2 variant carriers show multiple signalling alterations which may contribute to predisposition to insulin resistance and T2D in the carriers of this signalling variant.

MNK1 and MNK2 expression in the human dorsal root and trigeminal ganglion

Mitogen activated protein kinase interacting kinases (MNK) 1 and 2 are serine/threonine protein kinases that play an important role in translation of mRNAs through their phosphorylation of the RNA 5’-cap binding protein, eukaryotic translation initiation factor (eIF) 4E. These kinases are downstream targets for mitogen activated protein kinases (MAPKs), extracellular activity regulated protein kinase (ERK) and p38. MNKs have been implicated in the sensitization of peripheral nociceptors of the dorsal root and trigeminal ganglion (DRG and TG) using transgenic mouse lines and through the use of specific inhibitors of MNK1 and MNK2. While specific knockout of the Mknk1 gene suggests that it is the key isoform for regulation of nociceptor excitability and nociceptive behaviors in mice, both MKNK1 and MKNK2 genes are expressed in the DRG and TG of mice and humans based on RNA sequencing experiments. Single cell sequencing in mice suggests that Mknk1 and Mknk2 may be expressed in different populations of nociceptors. We sought to characterize mRNA expression in human DRG and TG for both MNK1 and MNK2. Our results show that both genes are expressed by nearly all neurons in both human ganglia with expression in other cell types as well. Our findings provide evidence that MNK1 and MNK2 are expressed by human nociceptors and suggest that efforts to pharmacologically target MNKs for pain would likely be translatable due its conserved expression in both species.

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.

Immune-related pulmonary toxicities of checkpoint inhibitors in non-small cell lung cancer: Diagnosis, mechanism, and treatment strategies

Immune checkpoint inhibitors (ICI) therapy based on programmed cell death-1 (PD-1) and programmed cell death ligand 1 (PD-L1) has changed the treatment paradigm of advanced non-small cell lung cancer (NSCLC) and improved the survival expectancy of patients. However, it also leads to immune-related adverse events (iRAEs), which result in multiple organ damage. Among them, the most common one with the highest mortality in NSCLC patients treated with ICI is checkpoint inhibitor pneumonitis (CIP). The respiratory signs of CIP are highly coincident and overlap with those in primary lung cancer, which causes difficulties in detecting, diagnosing, managing, and treating. In clinical management, patients with serious CIP should receive immunosuppressive treatment and even discontinue immunotherapy, which impairs the clinical benefits of ICIs and potentially results in tumor recrudesce. Therefore, accurate diagnosis, detailedly dissecting the pathogenesis, and developing reasonable treatment strategies for CIP are essential to prolong patient survival and expand the application of ICI. Herein, we first summarized the diagnosis strategies of CIP in NSCLC, including the classical radiology examination and the rising serological test, pathology test, and artificial intelligence aids. Then, we dissected the potential pathogenic mechanisms of CIP, including disordered T cell subsets, the increase of autoantibodies, cross-antigens reactivity, and the potential role of other immune cells. Moreover, we explored therapeutic approaches beyond first-line steroid therapy and future direction based on targeted signaling pathways. Finally, we discussed the current impediments, future trends, and challenges in fighting ICI-related pneumonitis.

13-Acetoxysarcocrassolide induces apoptosis in human hepatocellular carcinoma cells through mitochondrial dysfunction and suppression of the PI3K/AKT/mTOR/p70S6K signalling pathway

CONTEXT

13-Acetoxysarcocrasside, isolated from the Taiwanese soft coral Sarcophyton crassocaule Moser (Alcyoniidae), has biological activity and induces apoptosis in hepatocellular carcinoma cells.

OBJECTIVE

To elucidate the mechanisms underlying apoptosis induced by 13-acetoxysarcocrasside in HA22T and HepG2 hepatocellular carcinoma cells.

MATERIAL AND METHODS

MTT and morphology assays were employed to assess the anti-proliferative effects of 13-acetoxysarcocrasside (1-5 μM). TUNEL/DAPI staining and annexin V-fluorescein isothiocyanate/propidium iodide staining were used to detect apoptosis. Cells were treated with13-acetoxysarcocrassolide (0, 1, 2, and 4 μM) for 24 h, and the mechanism of cells apoptotic was detected by western blotting. Cells treated with DMSO were the control.

RESULTS

Survival of the cells decreased with the addition of 13-acetoxysarcocrassolide, and at 4 μM cell survival was inhibited by approximately 40%. After treatment of cells with 13-acetoxysarcocrassolide, the incidence of early/late apoptosis to be 0.3%/0.5%∼5.4%/22.7% for HA22T cells, in the HePG2 cells were 0.6%/0.2%∼14.4%/23.7%. Western blotting analysis showed that the expression of Bax, Bad, cleaved caspase 3, cleaved caspase 9, cleaved-PARP-1, cytochrome c, and p-4EBP1 increased with an increasing concentration of 13-acetoxysarcocrasside (0, 1, 2, and 4 μM), whereas that of Bcl-2, Bcl-xL, Mcl-1, p-Bad, p-PI3K, p-AKT, p-mTOR, p-70S6K, p-S6, p-eIF4E, and p-eIF4B decreased.

DISCUSSION AND CONCLUSIONS

Apoptosis induced by 13-acetoxysarcocrassolide in HA22T and HepG2 cells is mediated by mitochondrial dysfunction and inactivation of the PI3K/AKT/mTOR/p70S6K pathway. The potential of 13-acetoxysarcocrassolide as a chemotherapeutic agent should be further assessed for use in human hepatocellular carcinoma treatment.

The role of immune checkpoints in cardiovascular disease

Immune checkpoint inhibitors (ICI) are monoclonal antibodies which bind to immune checkpoints (IC) and their ligands to prevent inhibition of T-cell activation by tumor cells. Currently, multiple ICI are approved targeting Cytotoxic T-lymphocyte antigen 4 (CTLA-4), Programmed Death Protein 1 (PD-1) and its ligand PD-L1, and Lymphocyte-activation gene 3 (LAG-3). This therapy has provided potent anti-tumor effects and improved prognosis for many cancer patients. However, due to systemic effects, patients can develop immune related adverse events (irAE), including possible life threatening cardiovascular irAE, like atherosclerosis, myocarditis and cardiomyopathy. Inhibition of vascular IC is associated with increased atherosclerotic burden and plaque instability. IC protect against atherosclerosis by inhibiting T-cell activity and cytokine production, promoting regulatory T-cell differentiation and inducing T-cell exhaustion. In addition, PD-L1 on endothelial cells might promote plaque stability by reducing apoptosis and increasing expression of tight junction molecules. In the heart, IC downregulate the immune response to protect against cardiac injury by reducing T-cell activity and migration. Here, inhibition of IC could induce life-threatening T-cell-mediated-myocarditis. One proposed purpose behind lymphocyte infiltration is reaction to cardiac antigens, caused by decreased self-tolerance, and thereby increased autoimmunity because of IC inhibition. In addition, there are several reports of ICI-mediated cardiomyopathy with immunoglobulin G expression on cardiomyocytes, indicating an autoimmune response. IC are mostly known due to their cardiotoxicity. However, t his review compiles current knowledge on mechanisms behind IC function in cardiovascular disease with the aim of providing an overview of possible therapeutic targets in prevention or treatment of cardiovascular irAEs.

Design, Synthesis and Evaluation of Novel Phorbazole C Derivatives as MNK Inhibitors through Virtual High-Throughput Screening

MNKs (mitogen-activated protein kinase-interacting protein kinases) phosphorylate eIF4E at Ser209 to control the translation of certain mRNAs and regulate the process of cell proliferation, cell migration and invasion, etc. Development of MNK inhibitors would be an effective treatment for related diseases. We used the MarineChem3D database to identify hit compounds targeting the protein MNK1 and MNK2 through high-throughput screening. Compounds from the phorbazole family showed good interactions with MNK1, and phorbazole C was selected as our hit compound. By analyzing the binding mode, we designed and synthesized 29 derivatives and evaluated their activity against MNKs, of which, six compounds showed good inhibition to MNKs. We also confirmed three interactions between this kind of compound and MNK1, which are vital for the activity. In conclusion, we report series of novel MNK inhibitors inspired from marine natural products and their relative structure–activity relationship. This will provide important information for further developing MNK inhibitors based on this kind of structure.

Towards Kinase Inhibitor Therapies for Fragile X Syndrome: Tweaking Twists in the Autism Spectrum Kinase Signaling Network

Absence of the Fragile X Mental Retardation Protein (FMRP) causes autism spectrum disorders and intellectual disability, commonly referred to as the Fragile X syndrome. FMRP is a negative regulator of protein translation and is essential for neuronal development and synapse formation. FMRP is a target for several post-translational modifications (PTMs) such as phosphorylation and methylation, which tightly regulate its cellular functions. Studies have indicated the involvement of FMRP in a multitude of cellular pathways, and an absence of FMRP was shown to affect several neurotransmitter receptors, for example, the GABA receptor and intracellular signaling molecules such as Akt, ERK, mTOR, and GSK3. Interestingly, many of these molecules function as protein kinases or phosphatases and thus are potentially amendable by pharmacological treatment. Several treatments acting on these kinase-phosphatase systems have been shown to be successful in preclinical models; however, they have failed to convincingly show any improvements in clinical trials. In this review, we highlight the different protein kinase and phosphatase studies that have been performed in the Fragile X syndrome. In our opinion, some of the paradoxical study conclusions are potentially due to the lack of insight into integrative kinase signaling networks in the disease. Quantitative proteome analyses have been performed in several models for the FXS to determine global molecular processes in FXS. However, only one phosphoproteomics study has been carried out in Fmr1 knock-out mouse embryonic fibroblasts, and it showed dysfunctional protein kinase and phosphatase signaling hubs in the brain. This suggests that the further use of phosphoproteomics approaches in Fragile X syndrome holds promise for identifying novel targets for kinase inhibitor therapies.

The Candida albicans toxin candidalysin mediates distinct epithelial inflammatory responses through p38 and EGFR-ERK pathways

The fungal pathogen Candida albicans secretes the peptide toxin candidalysin, which damages epithelial cells and drives an innate inflammatory response mediated by the epidermal growth factor receptor (EGFR) and mitogen-activated protein kinase (MAPK) pathways and the transcription factor c-Fos. In cultured oral epithelial cells, candidalysin activated the MAPK p38, which resulted in heat shock protein 27 (Hsp27) activation, IL-6 release, and EGFR phosphorylation without affecting the induction of c-Fos. p38 activation was not triggered by EGFR but by two nonredundant pathways involving MAPK kinases (MKKs) and the kinase Src, which differentially controlled p38 signaling outputs. Whereas MKKs mainly promoted p38-dependent release of IL-6, Src promoted p38-mediated phosphorylation of EGFR in a ligand-independent fashion. In parallel, candidalysin also activated the EGFR-ERK pathway in a ligand-dependent manner, resulting in c-Fos activation and release of the neutrophil-activating chemokines G-CSF and GM-CSF. In mice, early clearance events of oral C. albicans infection required p38 but not c-Fos. These findings delineate how candidalysin activates the pathways downstream of the MAPKs p38 and ERK that differentially contribute to immune activation during C. albicans infection.

Inhibiting MNK kinases promotes macrophage immunosuppressive phenotype to limit CD8+ T cell anti-tumor immunity

To elicit effective anti-tumor responses, CD8+ T cells need to infiltrate tumors and sustain their effector function within the immunosuppressive tumor microenvironment. Here we evaluate the role of MNK kinase activity in regulating CD8+ T cell infiltration and anti-tumor activity in pancreatic and thyroid tumors. We first show that human pancreatic and thyroid tumors with increased MNK kinase activity are associated with decreased infiltration by CD8+ T cells. We then show that while MNK inhibitors increase CD8+ T cells in these tumors, they induce a T cell exhaustion phenotype in the tumor microenvironment. Mechanistically, we show that the exhaustion phenotype is not caused by upregulation of PD-L1 but by tumor-associated macrophages (TAMs) becoming more immunosuppressive following MNK inhibitor treatment. Reversal of CD8+ T cell exhaustion by an anti-PD-1 antibody or TAM depletion synergizes with MNK inhibitors to control tumor growth and prolong animal survival. Importantly, we show in ex vivo human pancreatic tumor slice cultures that MNK inhibitors increase the expression of markers associated with immunosuppressive TAMs. Together, these findings demonstrate a previously unknown role of MNK kinases in modulating a pro-tumoral phenotype in macrophages and identify combination regimens involving MNK inhibitors to enhance anti-tumor immune responses.

The Sphingolipid Inhibitors Ceranib-2 and SKI-II Reduce Measles Virus Replication in Primary Human Lymphocytes: Effects on mTORC1 Downstream Signaling

The bioactive sphingolipids ceramide and sphingosine-1-phosphate (S1P) are involved in the regulation of cell homeostasis and activity ranging from apoptosis to proliferation. We recently described that the two compounds ceranib-2 (inhibiting acid ceramidase) and SKI-II [inhibiting the sphingosine kinases 1 and − 2 (SphK1/2)] reduce mTORC1 activity and measles virus (MV) replication in human primary peripheral blood lymphocytes (PBL) by about one log step. We now further investigated whether mTORC1 downstream signaling and viral protein expression may be affected by ceranib-2 and/or SKI-II. Western blot analyses showed that in uninfected cells the phosphorylation of the eukaryotic initiation factor 4E (eIF4E) was reduced by both inhibitors. Interestingly, MV infection led to an increase of rpS6 protein levels and phosphorylation of eIF4E. Treatment with both inhibitors reduced the rpS6 protein expression, and in addition, SKI-II reduced rpS6 phosphorylation. The phosphorylation of eIF4E was slightly reduced by both inhibitors. In addition, SKI-II led to reduced levels of IKK in MV-infected cells. Both inhibitors reduced the expression of viral proteins and the titers of newly synthesized MV by approximately one log step. As expected, SKI-II and rapamycin reduced also the virally encoded GFP expression; however, ceranib-2 astonishingly led to increased levels of GFP fluorescence. Our findings suggest that the inhibitors ceranib-2 and SKI-II act via differential mechanisms on MV replication. The observed effects on mTORC1 downstream signaling, predominantly the reduction of rpS6 levels by both inhibitors, may affect the translational capacity of the cells and contribute to the antiviral effect in human primary PBL.

Specific mesoderm subset derived from human pluripotent stem cells ameliorates microvascular pathology in type 2 diabetic mice

Human induced pluripotent stem cells (hiPSCs) were differentiated into a specific mesoderm subset characterized by KDR+CD56+APLNR+ (KNA+) expression. KNA+ cells had high clonal proliferative potential and specification into endothelial colony-forming cell (ECFCs) phenotype. KNA+ cells differentiated into perfused blood vessels when implanted subcutaneously into the flank of nonobese diabetic/severe combined immunodeficient mice and when injected into the vitreous of type 2 diabetic mice (db/db mice). Transcriptomic analysis showed that differentiation of hiPSCs derived from diabetics into KNA+ cells was sufficient to change baseline differences in gene expression caused by the diabetic status and reprogram diabetic cells to a pattern similar to KNA+ cells derived from nondiabetic hiPSCs. Proteomic array studies performed on retinas of db/db mice injected with either control or diabetic donor-derived KNA+ cells showed correction of aberrant signaling in db/db retinas toward normal healthy retina. These data provide "proof of principle" that KNA+ cells restore perfusion and correct vascular dysfunction in db/db mice.

Recent development of BTK-based dual inhibitors in the treatment of cancers

Bruton's tyrosine kinase (BTK) is a promising target in the treatment of various cancers. Despite the early success of BTK inhibitors in the clinic, these single-target drug therapies have limitations in their clinical applications, such as drug resistance. Several alternative strategies have been developed, including the use of dual inhibitors, to maximize the therapeutic potential of anticancer drugs. In this review, we highlight the scientific background and theoretical basis for developing BTK-based dual inhibitors, as well as the status of these agents in preclinical and clinical studies, and discuss further options in this field. We posit that these advances in BTK-based dual inhibitors confirm their feasibility for the treatment of refractory tumors, including those with drug resistance, and provide a framework for future drug design in this field. Accordingly, we anticipate increasingly rapid progress in the development of novel potent dual inhibitors and advanced clinical research on BTK-based dual inhibitors.

A multiscale cell-based model of tumor growth for chemotherapy assessment and tumor-targeted therapy through a 3D computational approach

OBJECTIVES

Computational modeling of biological systems is a powerful tool to clarify diverse processes contributing to cancer. The aim is to clarify the complex biochemical and mechanical interactions between cells, the relevance of intracellular signaling pathways in tumor progression and related events to the cancer treatments, which are largely ignored in previous studies.

MATERIALS AND METHODS

A three-dimensional multiscale cell-based model is developed, covering multiple time and spatial scales, including intracellular, cellular, and extracellular processes. The model generates a realistic representation of the processes involved from an implementation of the signaling transduction network.

RESULTS

Considering a benign tumor development, results are in good agreement with the experimental ones, which identify three different phases in tumor growth. Simulating tumor vascular growth, results predict a highly vascularized tumor morphology in a lobulated form, a consequence of cells' motile behavior. A novel systematic study of chemotherapy intervention, in combination with targeted therapy, is presented to address the capability of the model to evaluate typical clinical protocols. The model also performs a dose comparison study in order to optimize treatment efficacy and surveys the effect of chemotherapy initiation delays and different regimens.

CONCLUSIONS

Results not only provide detailed insights into tumor progression, but also support suggestions for clinical implementation. This is a major step toward the goal of predicting the effects of not only traditional chemotherapy but also tumor-targeted therapies.

Rapamycin, Acarbose and 17α-estradiol share common mechanisms regulating the MAPK pathways involved in intracellular signaling and inflammation

BACKGROUND

Rapamycin (Rapa), acarbose (ACA), and 17α-estradiol (17aE2, males only) have health benefits that increase lifespan of mice. Little is known about how these three agents alter the network of pathways downstream of insulin/IGF1 signals as well as inflammatory/stress responses.

RESULTS

ACA, Rapa, and 17aE2 (in males, but not in females) oppose age-related increases in the MEK1- ERK1/2-MNK1/2 cascade, and thus reduce phosphorylation of eIF4E, a key component of cap-dependent translation. In parallel, these treatments (in both sexes) reduce age-related increases in the MEK3-p38MAPK-MK2 pathway, to decrease levels of the acute phase response proteins involved in inflammation.

CONCLUSION

Each of three drugs converges on the regulation of both the ERK1/2 signaling pathway and the p38-MAPK pathway. The changes induced by treatments in ERK1/2 signaling are seen in both sexes, but the 17aE2 effects are male-specific, consistent with the effects on lifespan. However, the inhibition of age-dependent p38MAPK pathways and acute phase responses is triggered in both sexes by all three drugs, suggesting new approaches to prevention or reversal of age-related inflammatory changes in a clinical setting independent of lifespan effects.

Potential therapies for immune-related adverse events associated with immune checkpoint inhibition: from monoclonal antibodies to kinase inhibition

The therapeutic benefits of immune checkpoint inhibitors (ICIs), which enable antitumor immune responses, can be tempered by unwanted immune-related adverse events (irAEs). Treatment recommendations stratified by irAE phenotype and immunohistopathological findings have only recently been proposed and are often based on those used in primary autoimmune diseases, including targeting of specific proinflammatory cytokines with monoclonal antibodies. Increasing evidence supports the use of such antibody-based strategies as effective steroid-sparing treatments, although the therapies themselves may be associated with additional drug toxicities and reduced ICI efficacy. Kinases are key contributors to the adaptive and innate responses that drive primary autoimmune diseases and irAEs. The janus kinase/signal transducer and activator of transcription, Bruton’s tyrosine kinase, and mitogen-activated protein kinase-interacting serine/threonine protein kinases 1 and 2 pathways are also critical to tumor progression and have important roles in cells of the tumor microenvironment. Herein, we review the histopathological, biological, and clinical evidence to support specific monoclonal antibodies and kinase inhibition as management strategies for irAEs.

JAK2 inhibitor persistence in MPN: uncovering a central role of ERK activation

The Philadelphia chromosome negative myeloproliferative neoplasms, including polycythemia vera, essential thrombocytosis, and myelofibrosis, are driven by hyper activation of the JAK2 tyrosine kinase, the result of mutations in three MPN driving genes: JAK2, MPL, and CALR. While the anti-inflammatory effects of JAK2 inhibitors can provide improved quality of life for many MPN patients, the upfront and persistent survival of disease-driving cells in MPN patients undergoing JAK2 inhibitor therapy thwarts potential for remission. Early studies indicated JAK2 inhibitor therapy induces heterodimeric complex formation of JAK2 with other JAK family members leading to sustained JAK2-dependent signaling. Recent work has described novel cell intrinsic details as well as cell extrinsic mechanisms that may contribute to why JAK2 inhibition may be ineffective at targeting MPN driving cells. Diverse experimental strategies aimed at uncovering mechanistic details that contribute to JAK2 inhibitor persistence have each highlighted the role of MEK/ERK activation. These approaches include, among others, phosphoproteomic analyses of JAK2 signaling as well as detailed assessment of JAK2 inhibition in mouse models of MPN. In this focused review, we highlight these and other studies that collectively suggest targeting MEK/ERK in combination with JAK2 inhibition has the potential to improve the efficacy of JAK2 inhibitors in MPN patients. As MPN patients patiently wait for improved therapies, such studies should further strengthen optimism that pre-clinical research is continuing to uncover mechanistic insights regarding the ineffectiveness of JAK2 inhibitors, which may lead to development of improved therapeutic strategies.

The Cap-Binding Complex CBC and the Eukaryotic Translation Factor eIF4E: Co-Conspirators in Cap-Dependent RNA Maturation and Translation

The translation of RNA into protein is a dynamic process which is heavily regulated during normal cell physiology and can be dysregulated in human malignancies. Its dysregulation can impact selected groups of RNAs, modifying protein levels independently of transcription. Integral to their suitability for translation, RNAs undergo a series of maturation steps including the addition of the m7G cap on the 5' end of RNAs, splicing, as well as cleavage and polyadenylation (CPA). Importantly, each of these steps can be coopted to modify the transcript signal. Factors that bind the m7G cap escort these RNAs through different steps of maturation and thus govern the physical nature of the final transcript product presented to the translation machinery. Here, we describe these steps and how the major m7G cap-binding factors in mammalian cells, the cap binding complex (CBC) and the eukaryotic translation initiation factor eIF4E, are positioned to chaperone transcripts through RNA maturation, nuclear export, and translation in a transcript-specific manner. To conceptualize a framework for the flow and integration of this genetic information, we discuss RNA maturation models and how these integrate with translation. Finally, we discuss how these processes can be coopted by cancer cells and means to target these in malignancy.