Comprehensive Analysis of ERK1/2 Substrates for Potential Combination Immunotherapies

The mechanistic study of codonopsis pilosula on laryngeal squamous cell carcinoma based on network pharmacology and experimental validation

Introduction

Laryngeal squamous cell carcinoma (LSCC) is a common malignant tumor of the head and neck, with poor prognosis for advanced patients, and there is an urgent need to find new treatment strategies. Codonopsis pilosula, a traditional Chinese medicinal herb, possesses various pharmacological activities, but its antitumor effects and mechanisms in LSCC are still unclear. The aim of this study was to systematically investigate the potential antitumor mechanism of Codonopsis pilosula in LSCC.

Methods

In this study, we screened the effective compounds and targets of Codonopsis pilosula by TCMSP, ETCM and BATMAN-TCM databases, and screened targets related to LSCC by combining DisGeNET, GeneCards database and Cytoscape software. KEGG pathway enrichment analysis was utilized to explore the related signaling pathways. The core targets were further screened based on TCGA and GEO database analysis, and molecular docking was carried out to predict their binding ability to effective compounds. The presence of key compounds was verified by LC-MS, the MAPK3 expression was detected by qPCR in LSCC tissues, and the effects of MAPK3 knockdown on proliferation, migration, invasion, cell cycle, and apoptosis of LSCC cells were evaluated by cellular function assays.

Results

In this study, 22 targets of Codonopsis pilosula that might regulate LSCC were screened based on network pharmacology. KEGG pathway enrichment analysis showed that Codonopsis pilosula-LSCC targets were mainly involved in HIF-1, TNF, IL-17 and FoxO signaling pathways. Based on TCGA and GEO database analysis, MAPK3 was identified as the core target of Codonopsis pilosula-LSCC. The molecular docking results showed that a variety of effective compounds from Codonopsis pilosula had strong binding abilities to MAPK3, among them, Caprylic Acid, Emodin and Luteolin have been confirmed by LC-MS. QPCR analysis indicated that MAPK3 was highly expressed in LSCC tissues. MAPK3 knockdown significantly inhibits LSCC cell proliferation, migration and invasion. It also suppresses LSCC cell growth by blocking the cell cycle and inducing apoptosis.

Conclusion

Codonopsis pilosula exerts antitumor effects in LSCC through the regulation of MAPK3 and multiple signaling pathways, providing a theoretical basis for its clinical application.

All intrinsically active Erk1/2 mutants autophosphorylate threonine207/188, a plausible regulator of the TEY motif phosphorylation

The extracellular-activated kinases 1 & 2 (Erk1/2) are catalytically active when dually phosphorylated on a TEY motif located at the activation loop. In human patients with cardiac hypertrophy, Erk1/2 are phosphorylated on yet another activation loop's residue, T207/188. Intrinsically active variants of Erk1/2, mutated at R84/65, are also (auto)phosphorylated on T207/188. It is not known whether T207/188 phosphorylation is restricted to these cases, nor how it affects Erks' activity. We report that T207/188 phosphorylation is not rare, as we found that: 1) All known auto-activated Erk1/2 variants are phosphorylated on T207/188. 2) It occurs in various cell lines and mouse tissues. 3) It is extremely high in patients with skeletal muscle atrophies or myopathies. We propose that T207/188 controls the permissiveness of the TEY motif for phosphorylation because T207/188-mutated Erk1/2 and the yeast Erk/Mpk1 were efficiently dually phosphorylated when expressed in HEK293 or yeast cells, respectively. The T207/188-mutated Mpk1 was not TEY-phosphorylated in cells knocked out for MEKs, suggesting that its enhanced phosphorylation in wild-type cells is MEK-dependent. Thus, as T207/188-mutated Erk1/2 and Mpk1 recruit MEKs, the role of T207/188 is to impede MEKs' ability to phosphorylate Erks. T207/188 also impedes autophosphorylation as recombinant Erk2 mutated at T188 is spontaneously autophosphorylated, although exclusively on Y185. The role of T207/188 in regulating activation loop phosphorylation may be common to most Ser/Thr kinases, as 86% of them (in the human kinome) possess T207/188 orthologs, and 160 of them were already reported to be phosphorylated on this residue.

ERK Allosteric Activation: The Importance of Two Ordered Phosphorylation Events

ERK, a coveted proliferation drug target, is a pivotal kinase in the Ras/ERK signaling cascade. Despite this, crucial questions about its activation have not been fully explored on the foundational, conformational level. Such questions include (i) Why ERK's activation demands dual phosphorylation; (ii) What is the role of each phosphorylation site in the activation loop; and (iii) Exactly how the (ordered) phosphorylation steps affect the conformational ensembles of the activation loop, their propensities and restriction to a narrower range favoring ERK's catalytic action. Here we used explicit molecular dynamics simulations to study ERK's stability and the conformational changes in different stages along the activation process. The initial monophosphorylation event elongates the activation loop to enable successive phosphorylations, which reintroduce stability/compactness through newly formed salt bridges. The interactions formed by monophosphorylation are site-dependent, with threonine's phosphorylation presenting stronger electrostatic interactions compared to tyrosine's. Dual phosphorylated ERKs revealed a compact kinase structure which allows the HRD catalytic motif to stabilize the ATP. We further observe that the hinge and the homodimerization binding site responded to a tri-state signaling code based solely on the phosphorylation degree (unphosphorylated, monophosphorylated, dual phosphorylated) of the activation loop, confirming that the activation loop can allosterically influence distant regions. Last, our findings indicate that threonine phosphorylation as the second step is necessary for ERK to become effectively activated and that activation depends on the phosphorylation order. Collectively, we offer ERK's dual allosteric phosphorylation code in activation and explain why the phosphorylation site order is crucial.

The Role of Connections Between Cellular and Tissue Mechanical Elements and the Importance of Applied Energy in Mechanotransduction in Cancerous Tissue

In the presence of cellular mutations and impaired mechanisms of energy transmission to the attached cells and tissues, excess energy is available to upregulate some of the mechanotransduction pathways that maintain cell and tissue structure and function. The ability to transfer applied energy through integrin-mediated pathways, cell ion channels, cell membrane, cytoskeleton-nucleoskeleton connections, cell junctions, and cell-extracellular matrix attachments provides an equilibrium for energy storage, transmission, and dissipation in tissues. Disruption in energy storage, transmission, or dissipation via genetic mutations blocks mechanical communication between cells and tissues and impairs the mechanical energy equilibrium that exists between cells and tissues. This results in local structural changes through altered regulatory pathways, which produce cell clustering, collagen encapsulation, and an epithelial-mesenchymal transition (EMT), leading to increased cellular motility along newly reorganized collagen fibers (fibrosis). The goal of this review is to postulate how changes in energy transfer between cells and the extracellular matrix may alter local energy equilibrium and mechanotransduction pathways. The changes along with cellular mutations lead to cell and ECM changes reported in cancer, which is postulated to modify mechanical equilibria between cells and their ECM. This leads to uncontrolled cancer cellular proliferation and collagen remodeling.

Disruptions in cellular communication: Molecular interplay between glutamate/NMDA signalling and MAPK pathways in neurological disorders

Neurological disorders significantly impact the central nervous system, contributing to a growing public health crisis globally. The spectrum of these disorders includes neurodevelopmental and neurodegenerative diseases. This manuscript reviews the crucial roles of cellular signalling pathways in the pathophysiology of these conditions, focusing primarily on glutaminase/glutamate/NMDA receptor signalling, alongside the mitogen-activated protein kinase (MAPK) pathways-ERK1/2, C-JNK, and P38 MAPK. Activation of these pathways is often correlated with neuronal excitotoxicity, apoptosis, and inflammation, leading to many other pathological conditions such as traumatic brain injury, stroke, and brain tumor. The interplay between glutamate overstimulation and MAPK signalling exacerbates neurodegenerative processes, underscoring the complexity of cellular communication in maintaining neuronal health. Dysfunctional signalling alters synaptic plasticity and neuronal survival, contributing to cognitive impairments in various neurological diseases. The manuscript emphasizes the potential of targeting these signalling pathways for therapeutic interventions, promoting neuroprotection and reducing neuroinflammation. Incorporating insights from precision medicine and innovative drug delivery systems could enhance treatment efficacy. Overall, understanding the intricate mechanisms of these pathways is essential for developing effective strategies to mitigate the impact of neurological disorders and improve patient outcomes. This review highlights the necessity for further exploration into these signalling cascades to facilitate advancements in therapeutic approaches, ensuring better prognoses for individuals affected by neurological conditions.

Virally mediated expression of a biologically active peptide to restrain the nuclear functions of ERK1/2 attenuates learning extinction but not acquisition

Peptide drug technologies offer powerful approaches to develop potent and selective lead molecules for therapeutic and research applications. However, new and optimized delivery approaches are necessary to overcome current pitfalls including fast degradation in cells and tissue. Extracellular signal-regulated kinases 1/2 (ERK1/2) exemplifies proteins that play crucial and varied roles within distinct cellular compartments. Here, we established an innovative method, based on viral vectors, which utilizes the endogenous biogenesis of neurotrophins to deliver and express a biologically active peptide to attenuate specifically ERK1/2 nuclear functions in specific brain area of the adult forebrain. In contrast to our hypothesis, nuclear functions of ERK1/2 in the forebrain are fundamental for the extinction of associative-aversive memories, but not for acquisition, nor for retrieval of these memories. Our research demonstrates the feasibility and applicability of viral vectors to deliver a peptide of interest to manipulate specific molecular processes and/or protein interactions in specific tissue.

Redox regulation: mechanisms, biology and therapeutic targets in diseases

Redox signaling acts as a critical mediator in the dynamic interactions between organisms and their external environment, profoundly influencing both the onset and progression of various diseases. Under physiological conditions, oxidative free radicals generated by the mitochondrial oxidative respiratory chain, endoplasmic reticulum, and NADPH oxidases can be effectively neutralized by NRF2-mediated antioxidant responses. These responses elevate the synthesis of superoxide dismutase (SOD), catalase, as well as key molecules like nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione (GSH), thereby maintaining cellular redox homeostasis. Disruption of this finely tuned equilibrium is closely linked to the pathogenesis of a wide range of diseases. Recent advances have broadened our understanding of the molecular mechanisms underpinning this dysregulation, highlighting the pivotal roles of genomic instability, epigenetic modifications, protein degradation, and metabolic reprogramming. These findings provide a foundation for exploring redox regulation as a mechanistic basis for improving therapeutic strategies. While antioxidant-based therapies have shown early promise in conditions where oxidative stress plays a primary pathological role, their efficacy in diseases characterized by complex, multifactorial etiologies remains controversial. A deeper, context-specific understanding of redox signaling, particularly the roles of redox-sensitive proteins, is critical for designing targeted therapies aimed at re-establishing redox balance. Emerging small molecule inhibitors that target specific cysteine residues in redox-sensitive proteins have demonstrated promising preclinical outcomes, setting the stage for forthcoming clinical trials. In this review, we summarize our current understanding of the intricate relationship between oxidative stress and disease pathogenesis and also discuss how these insights can be leveraged to optimize therapeutic strategies in clinical practice.

NOTCH, ERK, and SHH signaling respectively control the fate determination of cortical glia and olfactory bulb interneurons

During cortical development, radial glial cells (neural stem cells) initially are neurogenic, generating intermediate progenitor cells that exclusively produce glutamatergic pyramidal neurons. Next, radial glial cells generate tripotential intermediate progenitor cells (Tri-IPCs) that give rise to cortical astrocytes and oligodendrocytes, and olfactory bulb interneurons. The molecular mechanisms underlying the transition from cortical neurogenesis to gliogenesis, and the subsequent fate determination of cortical astrocytes, oligodendrocytes, and olfactory bulb interneurons, remain unclear. Here, we report that extracellular signal-regulated kinase (ERK) signaling plays a fundamental role in promoting cortical gliogenesis and the generation of Tri-IPCs. Additionally, sonic hedgehog-smoothened-glioma-associated oncogene homolog (SHH-SMO-GLI) activator signaling has an auxiliary function to ERK during these processes. We further demonstrate that, from Tri-IPCs, NOTCH signaling is crucial for the fate determination of astrocytes, while ERK signaling plays a prominent role in oligodendrocyte fate specification, and SHH signaling is required for the fate determination of olfactory bulb interneurons. We provide evidence suggesting that this mechanism is conserved in both mice and humans. Finally, we propose a unifying principle of mammalian cortical gliogenesis.

MAPK14/p38α shapes the molecular landscape of endometrial cancer and promotes tumorigenic characteristics

The molecular underpinnings of high-grade endometrial carcinoma (HGEC) metastatic growth and survival are poorly understood. Here, we show that ascites-derived and primary tumor HGEC cell lines in 3D spheroid culture faithfully recapitulate key features of malignant peritoneal effusion and exhibit fundamentally distinct transcriptomic, proteomic, and metabolomic landscapes compared with conventional 2D monolayers. Using a genetic screening platform, we identify MAPK14 (which encodes the protein kinase p38α) as a specific requirement for HGEC in spheroid culture. MAPK14/p38α has broad roles in programming the phosphoproteome, transcriptome, and metabolome of HGEC spheroids, yet has negligible impact on monolayer cultures. MAPK14 promotes tumorigenicity in vivo and is specifically required to sustain a sub-population of spheroid cells that is enriched in cancer stemness markers. Therefore, spheroid growth of HGEC activates unique biological programs, including p38α signaling, that cannot be captured using 2D culture models and are highly relevant to malignant disease pathology.

Mechanistic exploration of Traditional Chinese Medicine regulation on tumor immune microenvironment in the treatment of triple-negative breast cancer: based on CiteSpace and bioinformatics analysis

Background

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer, characterized by frequent recurrence, metastasis, and poor survival outcomes despite chemotherapy-based treatments. This study aims to investigate the mechanisms by which Traditional Chinese Medicine (TCM) modulates the tumor immune microenvironment in TNBC, utilizing CiteSpace and bioinformatics analysis.

Methods

We employed CiteSpace to analyze treatment hotspots and key TCM formulations, followed by bioinformatics analysis to identify the main active components, targets, associated pathways, and their clinical implications in TNBC treatment.

Results

CiteSpace analysis highlighted key TCM formulations, including Sanhuang Decoction. Network pharmacology identified major bioactive components such as Mutatochrome, Physcion diglucoside, Procyanidin B-5,3'-O-gallate, gallic acid-3-O-(6'-O-galloyl)-glucoside, and isomucronulatol-7,2'-di-O-glucosiole, with core targets including Mitogen-Activated Protein Kinase 1 (MAPK1), Janus Kinase 2 (JAK2), and Lymphocyte-specific protein tyrosine kinase (LCK). These targets were found to be involved in immune regulation, particularly the modulation of CD8+ and CD4+ T cells. Additionally, core targets were associated with improved recurrence-free survival (RFS) and overall survival (OS) in TNBC patients.

Conclusion

The therapeutic effects of TCM in TNBC primarily involve immune modulation within the tumor microenvironment, particularly through the regulation of CD8+ and CD4+ T cells.

pH-sensing GPR68 inhibits vascular smooth muscle cell proliferation through Rap1A

Phenotypic transformation of vascular smooth muscle (VSM) from a contractile state to a synthetic, proliferative state is a hallmark of cardiovascular disease (CVD). In CVD, diseased tissue often becomes acidic from altered cellular metabolism secondary to compromised blood flow, yet the contribution of local acid/base imbalance to the disease process has been historically overlooked. In this study, we examined the regulatory impact of the pH-sensing G protein-coupled receptor GPR68 on vascular smooth muscle (VSM) proliferation in vivo and in vitro in wild-type (WT) and GPR68 knockout (KO) male and female mice. Arterial injury reduced GPR68 expression in WT vessels and exaggerated medial wall remodeling in GPR68 KO vessels. In vitro, KO VSM cells showed increased cell-cycle progression and proliferation compared with WT VSM cells, and GPR68-inducing acidic exposure reduced proliferation in WT cells. mRNA and protein expression analyses revealed increased Rap1A in KO cells compared with WT cells, and RNA silencing of Rap1A reduced KO VSM cell proliferation. In sum, these findings support a growth-inhibitory capacity of pH-sensing GPR68 and suggest a mechanistic role for the small GTPase Rap1A in GPR68-mediated VSM growth control. These results shed light on GPR68 and its effector Rap1A as potential targets to combat pathological phenotypic switching and proliferation in VSM.NEW & NOTEWORTHY Extracellular acidosis remains an understudied feature of many pathologies. We examined a potential regulatory role for pH-sensing GPR68 in vascular smooth muscle (VSM) growth in the context of CVD. With in vivo and in vitro growth models with GPR68-deficient mice and GPR68 induction strategies, novel findings revealed capacity of GPR68 to attenuate growth through the small GTPase Rap1A. These observations highlight GPR68 and its effector Rap1A as possible therapeutic targets to combat pathological VSM growth.

ADAM8 promotes alcoholic liver fibrosis through the MAPK signaling pathway

The effect and molecular regulatory mechanism of A Disintegrin and Metalloproteinase 8 (ADAM8) were explored in alcoholic liver fibrosis (ALF). C57BL/6N male mice were randomly divided into control, alcohol, and ADAM8-sgRNA3 plasmid groups. The control group received control liquid diet, while the alcohol and ADAM8-sgRNA3 plasmid groups were given alcohol liquid feed diet combined with ethanol gavage treatment for 8 weeks to induce ALF modeling. In addition, the ADAM8-sgRNA3 plasmid group was injected with the effective ADAM8-sgRNA3 plasmid, while the alcohol and control group mice were injected with an equivalent amount of physiological saline. LX-2 human hepatic stellate cells were divided into control, alcohol, si-ADAM8-2, and si-ADAM8-NC groups and induced for 48 h for model establishment in vitro. Serological detection, pathological staining, Western blotting, qRT-PCR and CCK8 assay were performed for experiments. Compared with the alcohol group, ADAM8 mRNA, protein and, positive area rate, serological indicators, pathological changes, and the expression of liver fibrosis marker and MAPK signaling pathway-related factors in the ADAM8-sgRNA3 plasmid group significantly decreased in vivo. Compared with the alcohol group, ADAM8 mRNA and protein expression, cell viability, and the expression of liver fibrosis markers and MAPK signaling pathway-related factors (p-ERK1/2, PCNA, Bcl-2, p-c-Jun, TGFβ1, p-p38 MAPK and HSP27) reduced significantly in the si-ADAM8-2 group. Therefore, ADAM8 promotes ALF through the MAPK signaling pathway, a promising target for treating ALF.

From Deworming to Cancer Therapy: Benzimidazoles in Hematological Malignancies

Drug repurposing is a strategy to discover new therapeutic uses for existing drugs, which have well-established toxicity profiles and are often more affordable. This approach has gained significant attention in recent years due to the high costs and low success rates associated with traditional drug development. Drug repositioning offers a more time- and cost-effective path for identifying new treatments. Several FDA-approved non-chemotherapy drugs have been investigated for their anticancer potential. Among these, anthelmintic benzimidazoles (such as albendazole, mebendazole, and flubendazole) have garnered interest due to their effects on microtubules and oncogenic signaling pathways. Blood cancers, which frequently develop resistance and have high mortality rates, present a critical need for effective therapies. This review highlights the recent advances in repurposing benzimidazoles for blood malignancies. These compounds induce cell cycle arrest, differentiation, tubulin depolymerization, loss of heterozygosity, proteasomal degradation, and inhibit oncogenic signaling to exert their anticancer effects. We also discuss current limitations and strategies to overcome them, emphasizing the potential of combining benzimidazoles with standard therapies for improved treatment of hematological cancers.

Mechanism of emodin in treating hepatitis B virus-associated hepatocellular carcinoma: network pharmacology and cell experiments

Introduction

Hepatocellular carcinoma (HCC) is a pressing global issue, with Hepatitis B virus (HBV) infection remaining the primary. Emodin, an anthraquinone compound extracted from the natural plant's. This study investigates the molecular targets and possible mechanisms of emodin in treating HBV-related HCC based on network pharmacology and molecular docking and validates the screened molecular targets through in vitro experiments.

Methods

Potential targets related to emodin were obtained through PubChem, CTD, PharmMapper, SuperPred, and TargetNet databases. Potential disease targets for HBV and HCC were identified using the DisGeNET, GeneCards, OMIM, and TTD databases. A Venn diagram was used to determine overlapping genes between the drug and the diseases. Enrichment analysis of these genes was performed using GO and KEGG via bioinformatics websites. The overlapping genes were imported into STRING to construct a protein-protein interaction network. Cytoscape 3.9.1 software was used for visualizing and analyzing the core targets. Molecular docking analysis of the drug and core targets was performed using Schrodinger. The regulatory effects of emodin on these core targets were validate through in vitro experiments.

Results

A total of 43 overlapping genes were identified. GO analysis recognized 926 entries, and KEGG analysis identified 135 entries. The main pathways involved in the KEGG analysis included cancer, human cytomegalovirus infection and prostate cancer. The binding energies of emodin with HSP90AA1, PTGS2, GSTP1, SOD2, MAPK3, and PCNA were all less than -5 kcal/mol. Compared to normal liver tissue, the mRNA levels of XRCC1, MAPK3, and PCNA were significantly elevated in liver cancer tissue. The expression levels of XRCC1, HIF1A, MAPK3, and PCNA genes were closely related to HCC progression. High expressions of HSP90AA1, TGFB1, HIF1A, MAPK3, and PCNA were all closely associated with poor prognosis in HCC. In vitro experiments demonstrated that emodin significantly downregulated the expression of HSP90AA1, MAPK3, XRCC1, PCNA, and SOD2, while significantly upregulating the expression of PTGS2 and GSTP1.

Conclusion

This study, based on network pharmacology and molecular docking validation, suggests that emodin may exert therapeutic effects on HBV-related HCC by downregulating the expression of XRCC1, MAPK3, PCNA, HSP90AA1, and SOD2, and upregulating the expression of PTGS2 and GSTP1.

Targeting ERK-MYD88 interaction leads to ERK dysregulation and immunogenic cancer cell death

The quest for targeted therapies is critical in the battle against cancer. The RAS/MAP kinase pathway is frequently implicated in neoplasia, with ERK playing a crucial role as the most distal kinase in the RAS signaling cascade. Our previous research demonstrated that the interaction between ERK and MYD88, an adaptor protein in innate immunity, is crucial for RAS-dependent transformation and cancer cell survival. In this study, we examine the biological consequences of disrupting the ERK-MYD88 interaction through the ERK D-recruitment site (DRS), while preserving ERK's kinase activity. Our results indicate that EI-52, a small-molecule benzimidazole targeting ERK-MYD88 interaction induces an HRI-mediated integrated stress response (ISR), resulting in immunogenic apoptosis specific to cancer cells. Additionally, EI-52 exhibits anti-tumor efficacy in patient-derived tumors and induces an anti-tumor T cell response in mice in vivo. These findings suggest that inhibiting the ERK-MYD88 interaction may be a promising therapeutic approach in cancer treatment.

IL-1β-activated PI3K/AKT and MEK/ERK pathways coordinately promote induction of partial epithelial-mesenchymal transition

Epithelial-mesenchymal transition (EMT) is a cellular process in embryonic development, wound healing, organ fibrosis, and cancer metastasis. Previously, we and others have reported that proinflammatory cytokine interleukin-1β (IL-1β) induces EMT. However, the exact mechanisms, especially the signal transduction pathways, underlying IL-1β-mediated EMT are not yet completely understood. Here, we found that IL-1β stimulation leads to the partial EMT-like phenotype in human lung epithelial A549 cells, including the gain of mesenchymal marker (vimentin) and high migratory potential, without the complete loss of epithelial marker (E-cadherin). IL-1β-mediated partial EMT induction was repressed by PI3K inhibitor LY294002, indicating that the PI3K/AKT pathway plays a significant role in the induction. In addition, ERK1/2 inhibitor FR180204 markedly inhibited the IL-1β-mediated partial EMT induction, demonstrating that the MEK/ERK pathway was also involved in the induction. Furthermore, we found that the activation of the PI3K/AKT and MEK/ERK pathways occurred downstream of the epidermal growth factor receptor (EGFR) pathway and the IL-1 receptor (IL-1R) pathway, respectively. Our findings suggest that the PI3K/AKT and MEK/ERK pathways coordinately promote the IL-1β-mediated partial EMT induction. The inhibition of not one but both pathways is expected yield clinical benefits by preventing partial EMT-related disorders such as organ fibrosis and cancer metastasis.

A novel chemical genetic approach reveals paralog-specific role of ERK1/2 in mouse embryonic stem cell fate control

Introduction: Mouse embryonic stem cell (ESC) self-renewal can be maintained through dual inhibition of GSK3 and MEK kinases. MEK has two highly homologous downstream kinases, extracellular signal-regulated kinase 1 and 2 (ERK1/2). However, the exact roles of ERK1/2 in mouse ESC self-renewal and differentiation remain unclear. Methods: We selectively deleted or inhibited ERK1, ERK2, or both using genetic and chemical genetic approaches combined with small molecule inhibitors. The effects of ERK paralog-specific inhibition on mouse ESC self-renewal and differentiation were then assessed. Results: ERK1/2 were found to be dispensable for mouse ESC survival and self-renewal. The inhibition of both ERK paralogs, in conjunction with GSK3 inhibition, was sufficient to maintain mouse ESC self-renewal. In contrast, selective deletion or inhibition of only one ERK paralog did not mimic the effect of MEK inhibition in promoting mouse ESC self-renewal. Regarding ESC differentiation, inhibition of ERK1/2 prevented mesendoderm differentiation. Additionally, selective inhibition of ERK1, but not ERK2, promoted mesendoderm differentiation. Discussion: These findings suggest that ERK1 and ERK2 have both overlapping and distinct roles in regulating ESC self-renewal and differentiation. This study provides new insights into the molecular mechanisms of ERK1/2 in governing ESC maintenance and lineage commitment, potentially informing future strategies for controlling stem cell fate in research and therapeutic applications.

MAPK14 /p38α Shapes the Molecular Landscape of Endometrial Cancer and promotes Tumorigenic Characteristics

The molecular underpinnings of H igh G rade E ndometrial C arcinoma (HGEC) metastatic growth and survival are poorly understood. Here we show that ascites-derived and primary tumor HGEC cell lines in 3D spheroid culture faithfully recapitulate key features of malignant peritoneal effusion and exhibit fundamentally distinct transcriptomic, proteomic and metabolomic landscapes when compared with conventional 2D monolayers. Using genetic screening platform we identify MAPK14 (which encodes the protein kinase p38α) as a specific requirement for HGEC in spheroid culture. MAPK14 /p38α has broad roles in programing the phosphoproteome, transcriptome and metabolome of HGEC spheroids, yet has negligible impact on monolayer cultures. MAPK14 promotes tumorigenicity in vivo and is specifically required to sustain a sub-population of spheroid cells that is enriched in cancer stemness markers. Therefore, spheroid growth of HGEC activates unique biological programs, including p38α signaling, that cannot be captured using 2D culture models and are highly relevant to malignant disease pathology.

Progress in the development of ERK1/2 inhibitors for treating cancer and other diseases

The extracellular signal-regulated kinases-1 and 2 (ERK1/2) are ubiquitous regulators of many cellular functions, including proliferation, differentiation, migration, and cell death. ERK1/2 regulate cell functions by phosphorylating a diverse collection of protein substrates consisting of other kinases, transcription factors, structural proteins, and other regulatory proteins. ERK1/2 regulation of cell functions is tightly regulated through the balance between activating phosphorylation by upstream kinases and inactivating dephosphorylation by phosphatases. Disruption of homeostatic ERK1/2 regulation caused by elevated extracellular signals or mutations in upstream regulatory proteins leads to the constitutive activation of ERK1/2 signaling and uncontrolled cell proliferation observed in many types of cancer. Many inhibitors of upstream kinase regulators of ERK1/2 have been developed and are part of targeted therapeutic options to treat a variety of cancers. However, the efficacy of these drugs in providing sustained patient responses is limited by the development of acquired resistance often involving re-activation of ERK1/2. As such, recent drug discovery efforts have focused on the direct targeting of ERK1/2. Several ATP competitive ERK1/2 inhibitors have been identified and are being tested in cancer clinical trials. One drug, Ulixertinib (BVD-523), has received FDA approval for use in the Expanded Access Program for patients with no other therapeutic options. This review provides an update on ERK1/2 inhibitors in clinical trials, their successes and limitations, and new academic drug discovery efforts to modulate ERK1/2 signaling for treating cancer and other diseases.

ERK pathway agonism for cancer therapy: evidence, insights, and a target discovery framework

At least 40% of human cancers are associated with aberrant ERK pathway activity (ERKp). Inhibitors targeting various effectors within the ERKp have been developed and explored for over two decades. Conversely, a substantial body of evidence suggests that both normal human cells and, notably to a greater extent, cancer cells exhibit susceptibility to hyperactivation of ERKp. However, this vulnerability of cancer cells remains relatively unexplored. In this review, we reexamine the evidence on the selective lethality of highly elevated ERKp activity in human cancer cells of varying backgrounds. We synthesize the insights proposed for harnessing this vulnerability of ERK-associated cancers for therapeutical approaches and contextualize these insights within established pharmacological cancer-targeting models. Moreover, we compile the intriguing preclinical findings of ERK pathway agonism in diverse cancer models. Lastly, we present a conceptual framework for target discovery regarding ERKp agonism, emphasizing the utilization of mutual exclusivity among oncogenes to develop novel targeted therapies for precision oncology.

ERK2 Is a Promoter of Cancer Cell Growth and Migration in Colon Adenocarcinoma

ERK1/2 phosphorylation is frequently downregulated in the early phase of colon tumorigenesis with subsequent activation of ERK5. In the current work, we studied the advantages of ERK1/2 downregulation for tumor growth by dissecting the individual functions of ERK1 and ERK2. The patient sample data demonstrated decreased ERK1/2 phosphorylation in the early phase of tumorigenesis followed by increased phosphorylation in late-stage colon adenocarcinomas with intratumoral invasion or metastasis. In vitro results indicated that SOD3-mediated coordination of small GTPase RAS regulatory genes inhibited RAS-ERK1/2 signaling. In vitro and in vivo studies suggested that ERK2 has a more prominent role in chemotactic invasion, collective migration, and cell proliferation than ERK1. Of note, simultaneous ERK1 and ERK2 expression inhibited collective cell migration and proliferation but tended to promote invasion, suggesting that ERK1 controls ERK2 function. According to the present data, phosphorylated ERK1/2 at the early phase of colon adenocarcinoma limits tumor mass expansion, whereas reactivation of the kinases at the later phase of colon carcinogenesis is associated with the initiation of metastasis. Additionally, our results suggest that ERK1 is a regulatory kinase that coordinates ERK2-promoted chemotactic invasion, collective migration, and cell proliferation. Our findings indicate that ROS, especially H2O2, are associated with the regulation of ERK1/2 phosphorylation in colon cancer by either increasing or decreasing kinase activity. These data suggest that ERK2 has a growth-promoting role and ERK1 has a regulatory role in colon tumorigenesis, which could lead to new avenues in the development of cancer therapy.

Snail transcription factors as key regulators of chemoresistance, stemness and metastasis of ovarian cancer cells

Ovarian cancer is one of the deadliest gynecological malignancies among women. The reason for this outcome is the frequent acquisition of cancer cell resistance to platinum-based drugs and unresponsiveness to standard therapy. It has been increasingly recognized that the ability of ovarian cancer cells to adopt more aggressive behavior (mainly through the epithelial-to-mesenchymal transition, EMT), as well as dedifferentiation into cancer stem cells, significantly affects drug resistance acquisition. Transcription factors in the Snail family have been implicated in ovarian cancer chemoresistance and metastasis. In this article, we summarize published data that reveal Snail proteins not only as key inducers of the EMT in ovarian cancer but also as crucial links between the acquisition of ovarian cancer stem properties and spheroid formation. These Snail-related characteristics significantly affect the ovarian cancer cell response to treatment and are related to the acquisition of chemoresistance.

Navigating the ERK1/2 MAPK Cascade

The RAS-ERK pathway is a fundamental signaling cascade crucial for many biological processes including proliferation, cell cycle control, growth, and survival; common across all cell types. Notably, ERK1/2 are implicated in specific processes in a context-dependent manner as in stem cells and pancreatic β-cells. Alterations in the different components of this cascade result in dysregulation of the effector kinases ERK1/2 which communicate with hundreds of substrates. Aberrant activation of the pathway contributes to a range of disorders, including cancer. This review provides an overview of the structure, activation, regulation, and mutational frequency of the different tiers of the cascade; with a particular focus on ERK1/2. We highlight the importance of scaffold proteins that contribute to kinase localization and coordinate interaction dynamics of the kinases with substrates, activators, and inhibitors. Additionally, we explore innovative therapeutic approaches emphasizing promising avenues in this field.

Cinnamic acids as promising bioactive compounds for cancer therapy by targeting MAPK3: a computational simulation study

OBJECTIVES

Mitogen-activated protein kinase-3 (MAPK3) is the upstream regulator in the MAPK cascade and is involved in many critical signaling pathways and biological processes, such as cell proliferation, survival, and apoptosis. MAPK3 overexpression is linked to onset, development, metastasis, and drug resistance in several human cancers. Thus, identifying novel and effective MAPK3 inhibitors is highly demanded. Herein, we aimed to discover organic compounds from cinnamic acid derivatives as potential MAPK3 inhibitors.

METHODS

The binding affinity of 20 cinnamic acids to the MAPK3 active site was tested using the AutoDock 4.0 software. Top-ranked cinnamic acids were ranked based on the ΔG binding values between the ligands and the receptor's active site. Interaction modes between top-ranked cinnamic acids and MAPK3 catalytic site were indicated using the Discovery Studio Visualizer tool. Molecular dynamics (MD) simulation was carried out to study the stability of the docked pose for the most potent MAPK3 inhibitor in this study.

RESULTS

Cynarin, chlorogenic acid, rosmarinic acid, caffeic acid 3-glucoside, and cinnamyl caffeate exhibited a salient binding affinity to the MAPK3 active site with the criteria of ΔG binding <-10 k cal/mol. Further, the inhibition constant value for cynarin was calculated at the picomolar concentration. The docked pose of cynarin within the MAPK3 catalytic domain was stable in 100 ns simulation.

CONCLUSIONS

Cynarin, chlorogenic acid, rosmarinic acid, caffeic acid 3-glucoside, and cinnamyl caffeate might be helpful in cancer therapy by inhibiting MAPK3.

Kinase Suppressor of RAS 1 (KSR1) Maintains the Transformed Phenotype of BRAFV600E Mutant Human Melanoma Cells

Kinase Suppressor of RAS 1 (KSR1) is a scaffolding protein for the RAS-RAF-MEK-ERK pathway, which is one of the most frequently altered pathways in human cancers. Previous results have shown that KSR1 has a critical role in mutant RAS-mediated transformation. Here, we examined the role of KSR1 in mutant BRAF transformation. We used CRISPR/Cas9 to knock out KSR1 in a BRAFV600E-transformed melanoma cell line. KSR1 loss produced a complex phenotype characterised by impaired proliferation, cell cycle defects, decreased transformation, decreased invasive migration, increased cellular senescence, and increased apoptosis. To decipher this phenotype, we used a combination of proteomic ERK substrate profiling, global protein expression profiling, and biochemical validation assays. The results suggest that KSR1 directs ERK to phosphorylate substrates that have a critical role in ensuring cell survival. The results further indicate that KSR1 loss induces the activation of p38 Mitogen-Activated Protein Kinase (MAPK) and subsequent cell cycle aberrations and senescence. In summary, KSR1 function plays a key role in oncogenic BRAF transformation.

IL-6/ERK signaling pathway participates in type I IFN-programmed, unconventional M2-like macrophage polarization

Type I interferons (IFN-Is) have been harnessed for cancer therapies due to their immunostimulatory functions. However, certain tumor-tolerating activities by IFN-Is also exist, and may potentially thwart their therapeutic effects. In this respect, our previous studies have demonstrated a monocyte-orchestrated, IFN-I-to-IL-4 cytokine axis, which can subsequently drive M2-skewed pro-tumoral polarization of macrophages. Whether other IFN-dependent signals may also contribute to such an unconventional circumstance of M2-like macrophage skewing remain unexplored. Herein, we first unveil IL-6 as another ligand that participates in IFN-dependent induction of a typical M2 marker (ARG1) in transitional monocytes. Indeed, IL-6 significantly promotes IL-4-dependent induction of a major group of prominent M2 markers in mouse bone marrow-derived macrophages (BMDMs) and human peripheral blood-derived macrophages, while it alone does not engage marked increases of these markers. Such a pattern of regulation is confirmed globally by RNAseq analyses in BMDMs, which in turn suggests an association of IL-6-amplified subset of M2 genes with the ERK1/2 signaling pathway. Interestingly, pharmacological experiments establish the role of SHP2-ERK cascade in mediating IL-6's enhancement effect on these M2 targets. Similar approaches also validate the involvement of IL-6/ERK signaling in promoting the IFN-dependent, unconventional M2-skewing phenotype in transitional monocytes. Furthermore, an inhibitor of ERK signaling cooperates with an IFN-I inducer to enable a greater antitumor effect, which correlates with suppression of treatment-elicited ARG1. The present work establishes a role of IL-6/ERK signaling in promoting M2-like macrophage polarization, and suggests this axis as a potential therapeutic target for combination with IFN-I-based cancer treatments.

Circular RNA hsa_circ_0023404 promotes the proliferation, migration and invasion in endometrial cancer cells through regulating miR-217/MAPK1 axis

Background

Emerging studies indicated that circular RNA hsa_circ_ 0023404 and its target miR-217/MARK1 axis play a critical role in cancer progression such as non-small cell lung cancer and cervical cancer. However, the role of hsa_circ_0023404/miR-217/MARK1 involved in endometrial cancer (EC) was not investigated yet. The aim of this study is to investigate the functions of hsa_circ_0023404 in endometrial cancer (EC) and the potential molecular mechanism.

Methods

We used RT-qPCR and Western blot approach to detect the expressed levels of related genes in EC cell lines. Transfected siRNAs were applied to knockdown the level of related mRNA in cells. Cell proliferation by CCK-8 assay and colony formation assay were applied to detect cell proliferation. Transwell migration and invasion assay was for detecting the migration and invasion of the cells.

Results

RT-qPCR showed that the levels of hsa_circ_0023404 and MARK1 mRNA were upregulated, but mirR-217 was decreased in three endometrial cancer cell lines. Knockdown of hsa_circ_0023404 by siRNA markedly increased the level of miR-217 and reduced the proliferation of the Ishikawa cells. It also inhibited the cell migration and invasion. Anti-miR-217 can reverse the promoted proliferation, migrations and invasion of Ishikawa cells mediated by si-circ_0023404. si-MARK1 restored the inhibited cell proliferation, migration and invasion of the co-transfected Ishikawa cells with si- circ_0023404 and anti-miR-217.

Conclusion

hsa_circ_0023404 exerts a tumor-promoting role in endometrial cancer by regulating miR-217/MARK1 axis. hsa_circ_0023404 inhibit miR-217 as sponge which inhibit endometrial cancer cell growth and metastasis. MARK1 is downstream target of miR217 and upregulated by hsa_circ_ 0023404/miR-217 axis and involved in the endometrial cancer progression.

Application of shear stress for enhanced osteogenic differentiation of mouse induced pluripotent stem cells

The self-organizing potential of induced pluripotent stem cells (iPSCs) represents a promising tool for bone tissue engineering. Shear stress promotes the osteogenic differentiation of mesenchymal stem cells, leading us to hypothesize that specific shear stress could enhance the osteogenic differentiation of iPSCs. For osteogenesis, embryoid bodies were formed for two days and then maintained in medium supplemented with retinoic acid for three days, followed by adherent culture in osteogenic induction medium for one day. The cells were then subjected to shear loading (0.15, 0.5, or 1.5 Pa) for two days. Among different magnitudes tested, 0.5 Pa induced the highest levels of osteogenic gene expression and greatest mineral deposition, corresponding to upregulated connexin 43 (Cx43) and phosphorylated Erk1/2 expression. Erk1/2 inhibition during shear loading resulted in decreased osteogenic gene expression and the suppression of mineral deposition. These results suggest that shear stress (0.5 Pa) enhances the osteogenic differentiation of iPSCs, partly through Cx43 and Erk1/2 signaling. Our findings shed light on the application of shear-stress technology to improve iPSC-based tissue-engineered bone for regenerative bone therapy.

Rapamycin inhibits oral cancer cell growth by promoting oxidative stress and suppressing ERK1/2, NF-κB and beta-catenin pathways

Treatment of oral cancer is based exclusively on surgery combined with or without chemotherapy. However, it has several side effects. Targeting a new, more effective therapy has become an urgent matter. The purpose of this study was to evaluate the anti-tumor activity of rapamycin in oral cancer and its mechanism of action. Human gingival carcinoma cells were stimulated with different concentrations of rapamycin to assess proliferation, colony formation, cell migration, as well as apoptosis, and autophagy. The expression of proteins involved in the cell cycle (cyclin D1, p15, p21, p27) and autophagy, as well as that of oncogenes and tumor suppressor genes, were determined by quantitative PCR. The signaling pathways were evaluated by Western blotting. Our results show that rapamycin has a selective effect at a low dose on cancer cell growth/survival. This was confirmed by low colony formation and the inhibition of cell migration, while increasing cell apoptosis by activating caspase-9 and -3. Rapamycin promoted cell autophagy and increased mitochondrial oxidative stress by being involved in DNA damage in the exposed cells. Finally, rapamycin exhibits potent anti-oral cancer properties through inhibition of several cancer-promoting pathways (MAPK, NF-κB, and Wnt/beta-catenin). These results indicate that rapamycin could be a potential agent for the treatment of oral cancer and for a prevention strategy.

ERK2 signaling regulates cell-cell adhesion of epithelial cells and enhances growth factor-induced cell scattering

The ERK signaling pathway, consisting of core protein kinases Raf, MEK and effector kinases ERK1/2, regulates various biological outcomes such as cell proliferation, differentiation, apoptosis, or cell migration. Signal transduction through the ERK signaling pathway is tightly controlled at all levels of the pathway. However, it is not well understood whether ERK pathway signaling can be modulated by the abundance of ERK pathway core kinases. In this study, we investigated the effects of low-level overexpression of the ERK2 isoform on the phenotype and scattering of cuboidal MDCK epithelial cells growing in discrete multicellular clusters. We show that ERK2 overexpression reduced the vertical size of lateral membranes that contain cell-cell adhesion complexes. Consequently, ERK2 overexpressing cells were unable to develop cuboidal shape, remained flat with increased spread area and intercellular adhesive contacts were present only on the basal side. Interestingly, ERK2 overexpression was not sufficient to increase phosphorylation of multiple downstream targets including transcription factors and induce global changes in gene expression, namely to increase the expression of pro-migratory transcription factor Fra1. However, ERK2 overexpression enhanced HGF/SF-induced cell scattering as these cells scattered more rapidly and to a greater extent than parental cells. Our results suggest that an increase in ERK2 expression primarily reduces cell-cell cohesion and that weakened intercellular adhesion synergizes with upstream signaling in the conversion of the multicellular epithelium into single migrating cells. This mechanism may be clinically relevant as the analysis of clinical data revealed that in one type of cancer, pancreatic adenocarcinoma, ERK2 overexpression correlates with a worse prognosis.

KinasePhos 3.0: Redesign and Expansion of the Prediction on Kinase-specific Phosphorylation Sites

The purpose of this work is to enhance KinasePhos, a machine learning-based kinase-specific phosphorylation site prediction tool. Experimentally verified kinase-specific phosphorylation data were collected from PhosphoSitePlus, UniProtKB, the Group-based Prediction System 5.0, and Phospho.ELM. In total, 41,421 experimentally verified kinase-specific phosphorylation sites were identified. A total of 1380 unique kinases were identified, including 753 with existing classification information from KinBase and the remaining 627 annotated by building a phylogenetic tree. Based on this kinase classification, a total of 771 predictive models were built at the individual, family, and group levels, using at least 15 experimentally verified substrate sites in positive training datasets. The improved models demonstrated their effectiveness compared with other prediction tools. For example, the prediction of sites phosphorylated by the protein kinase B, casein kinase 2, and protein kinase A families had accuracies of 94.5%, 92.5%, and 90.0%, respectively. The average prediction accuracy for all 771 models was 87.2%. For enhancing interpretability, the SHapley Additive exPlanations (SHAP) method was employed to assess feature importance. The web interface of KinasePhos 3.0 has been redesigned to provide comprehensive annotations of kinase-specific phosphorylation sites on multiple proteins. Additionally, considering the large scale of phosphoproteomic data, a downloadable prediction tool is available at https://awi.cuhk.edu.cn/KinasePhos/download.html or https://github.com/tom-209/KinasePhos-3.0-executable-file.

Harnessing redox signaling to overcome therapeutic-resistant cancer dormancy

Dormancy occurs when cells preserve viability but stop proliferating, which is considered an important cause of tumor relapse, which may occur many years after clinical remission. Since the life cycle of dormant cancer cells is affected by both intracellular and extracellular factors, gene mutation or epigenetic regulation of tumor cells may not fully explain the mechanisms involved. Recent studies have indicated that redox signaling regulates the formation, maintenance, and reactivation of dormant cancer cells by modulating intracellular signaling pathways and the extracellular environment, which provides a molecular explanation for the life cycle of dormant tumor cells. Indeed, redox signaling regulates the onset of dormancy by balancing the intrinsic pathways, the extrinsic environment, and the response to therapy. In addition, redox signaling sustains dormancy by managing stress homeostasis, maintaining stemness and immunogenic equilibrium. However, studies on dormancy reactivation are still limited, partly explained by redox-mediated activation of lipid metabolism and the transition from the tumor microenvironment to inflammation. Encouragingly, several drug combination strategies based on redox biology are currently under clinical evaluation. Continuing to gain an in-depth understanding of redox regulation and develop specific methods targeting redox modification holds the promise to accelerate the development of strategies to treat dormant tumors and benefit cancer patients.

The glucocorticoid receptor associates with RAS complexes to inhibit cell proliferation and tumor growth

Mutations that activate members of the RAS family of GTPases are associated with various cancers and drive tumor growth. The glucocorticoid receptor (GR), a member of the nuclear receptor family, has been proposed to interact with and inhibit the activation of components of the PI3K-AKT and MAPK pathways downstream of RAS. In the absence of activating ligands, we found that GR was present in cytoplasmic KRAS-containing complexes and inhibited the activation of wild-type and oncogenic KRAS in mouse embryonic fibroblasts and human lung cancer A549 cells. The DNA binding domain of GR was involved in the interaction with KRAS, but GR-dependent inhibition of RAS activation did not depend on the nuclear translocation of GR. The addition of ligand released GR-dependent inhibition of RAS, AKT, the MAPK p38, and the MAPKK MEK. CRISPR-Cas9-mediated deletion of GR in A549 cells enhanced tumor growth in xenografts in mice. Patient samples of non-small cell lung carcinomas showed lower expression of NR3C1, the gene encoding GR, compared to adjacent normal tissues and lower NR3C1 expression correlated with a worse disease outcome. These results suggest that glucocorticoids prevent the ability of GR to limit tumor growth by inhibiting RAS activation, which has potential implications for the use of glucocorticoids in patients with cancer.

Analysis of the role and mechanism of EGCG in septic cardiomyopathy based on network pharmacology

Background

Septic cardiomyopathy (SC) is a common complication of sepsis that leads to an increase in mortality. The pathogenesis of septic cardiomyopathy is unclear, and there is currently no effective treatment. EGCG (epigallocatechin gallate) is a polyphenol that has anti-inflammatory, antiapoptotic, and antioxidative stress effects. However, the role of EGCG in septic cardiomyopathy is unknown.

Methods

Network pharmacology was used to predict the potential targets and molecular mechanisms of EGCG in the treatment of septic cardiomyopathy, including the construction and analysis of protein-protein interaction (PPI) network, gene ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and molecular docking. The mouse model of septic cardiomyopathy was established after intraperitoneal injection of LPS (lipopolysaccharide). The myocardial protective effect of EGCG on septic mice is observed by cardiac ultrasound and HE staining. RT-PCR is used to verify the expression level of the EGCG target in the septic cardiomyopathy mouse model.

Results

A total of 128 anti-SC potential targets of EGCGareselected for analysis. The GO enrichment analysis and KEGG pathway analysis results indicated that the anti-SC targets of EGCG mainly participate in inflammatory and apoptosis processes. Molecular docking results suggest that EGCG has a high affinity for the crystal structure of six targets (IL-6 (interleukin-6), TNF (tumor necrosis factor), Caspase3, MAPK3 (Mitogen-activated protein kinase 3), AKT1, and VEGFA (vascular endothelial growth factor)), and the experimental verification result showed levated expression of these 6 hub targets in the LPS group, but there is an obvious decrease in expression in the LPS + EGCG group. The functional and morphological changes found by echocardiography and HE staining show that EGCG can effectively improve the cardiac function that is reduced by LPS.

Conclusion

Our results reveal that EGCG may be a potentially effective drug to improve septic cardiomyopathy. The potential mechanism by which EGCG improves myocardial injury in septic cardiomyopathy is through anti-inflammatory and anti-apoptotic effects. The anti-inflammatory and anti-apoptotic effects of EGCG occur not only through direct binding to six target proteins (IL-6,TNF-α, Caspase3, MAPK3, AKT1, and VEGFA) but also by reducing their expression.

ERK1/2‐RSK regulation of oestrogen homeostasis

The molecular mechanisms regulating oestrogen homeostasis have been primarily studied in the mammary gland, which is the focus of this review. In the non-pregnant adult, the mammary gland undergoes repeated cycles of proliferation and apoptosis in response to the fluctuating levels of oestrogen that occur during the reproductive stage. Oestrogen actions are mediated through the steroid hormone receptors, oestrogen receptor α and β and through a G-protein coupled receptor. In the mammary gland, ERα is of particular importance and thus will be highlighted. Mechanisms regulating oestrogen-induced responses through ERα are necessary to maintain homeostasis given that the signalling pathways that are activated in response to ERα-mediated transcription can also induce transformation. ERK1/2 and its downstream effector, p90 ribosomal S6 kinase (RSK), control homeostasis in the mammary gland by limiting oestrogen-mediated ERα responsiveness. ERK1/2 drives degradation coupled ERα-mediated transcription, whereas RSK2 acts as a negative regulator of ERK1/2 activity to limit oestrogen responsiveness. Moreover, RSK2 acts as a positive regulator of translation. Thus, RSK2 provides both positive and negative signals to maintain oestrogen responsiveness. In addition to transmitting signals through tyrosine kinase receptors, ERK1/2-RSK engages with hedgehog signalling to maintain oestrogen levels and with the HIPPO pathway to regulate ERα-mediated transcription. Additionally, ERK1/2-RSK controls the progenitor populations within the mammary gland to maintain the ERα-positive population. RSK2 is involved in increased breast cancer risk in individuals taking oral contraceptives and in parity-induced protection against breast cancer. RSK2 and ERα may also co-operate in diseases in tissues outside of the mammary gland.

Tumor-Associated Macrophages: Reasons to Be Cheerful, Reasons to Be Fearful

Tumor microenvironment (TME) is a complex and constantly evolving entity that consists not only of cancer cells, but also of resident host cells and immune-infiltrating cells, among which macrophages are significant components, due to their diversity of functions through which they can influence the immune response against tumor cells. Macrophages present in tumor environment are termed as tumor-associated macrophages (TAMs). They are strongly plastic cells, and depending on the TME stimuli (i.e., cytokines, chemokines), TAMs polarize to antitumoral (M1-like TAMs) or protumoral (M2-like TAMs) phenotype. Both types of TAMs differ in the surface receptors' expression, activation of intracellular signaling pathways, and ability of production and various metabolites release. At the early stage of tumor formation, TAMs are M1-like phenotype, and they are able to eliminate tumor cells, i.e., by reactive oxygen species formation or by presentation of cancer antigens to other effector immune cells. However, during tumor progression, TAMs M2-like phenotype is dominating. They mainly contribute to angiogenesis, stromal remodeling, enhancement of tumor cells migration and invasion, and immunosuppression. This wide variety of TAMs' functions makes them an excellent subject for use in developing antitumor therapies which mainly is based on three strategies: TAMs' elimination, reprograming, or recruitment inhibition.

Integration of data from the cell-based ERK1/2 ELISA and the Comparative Toxicogenomics Database deciphers the potential mode of action of bisphenol A and benzo[a]pyrene in lung neoplasm

Chemicals can activate a variety of signaling pathways, initiating changes in gene expression and cellular functions. Here, we combined experimental data on the chemical-induced extracellular signal-regulated kinase 1/2 (ERK1/2) activation with the Comparative Toxicogenomics Database (CTD) to connect signaling, genes, and phenotypes to reveal the potential chemical's mode of action (MOA) responsible for the disease state. Experimental data on ERK1/2 activation were derived from the cell-based phospho-ERK1/2 ELISA on human alveolar epithelial cells A549. A549 cells were exposed to bisphenol A (BPA), benzo[a]pyrene (BaP), tributyltin (TBT), and ibuprofen from 10^-12 M to 10^-5 M. Results show that BPA, BaP, and TBT can activate ERK1/2 in A549 cells. We selected BPA and BaP to elucidate the molecular events connecting chemical exposure, ERK1/2 signaling, phenotypes, and lung neoplasm (LN) using CTD. CTD analysis showed that BPA and BaP share 26 mitogen-activated protein kinase 1/3 (MAPK1/3) signaling genes associated with LN. Phenotype prioritization revealed 37 BPA, 10 BaP, and 11 shared key phenotypes associated with LN. Alignment of MAPK1/3 signaling genes and phenotypes showed that ERK1/2 and oxidative stress, EGFR gene, and positive regulation of cell proliferation and migration could be the shared key events (KE) for BPA and BaP. This analysis also identified protein kinase B and ERK1/2 signaling, FGF9, FGFR1 and FGFR2 genes, positive regulation of cell proliferation and angiogenesis as KE in MOA for BPA, whereas ERK1/2 signaling, IL6 and DAB2IP genes, negative regulation of cell proliferation and inflammatory response were identified as KE in MOA for BaP.

ERK: A Double-Edged Sword in Cancer. ERK-Dependent Apoptosis as a Potential Therapeutic Strategy for Cancer

The RAF/MEK/ERK signaling pathway regulates diverse cellular processes as exemplified by cell proliferation, differentiation, motility, and survival. Activation of ERK1/2 generally promotes cell proliferation, and its deregulated activity is a hallmark of many cancers. Therefore, components and regulators of the ERK pathway are considered potential therapeutic targets for cancer, and inhibitors of this pathway, including some MEK and BRAF inhibitors, are already being used in the clinic. Notably, ERK1/2 kinases also have pro-apoptotic functions under certain conditions and enhanced ERK1/2 signaling can cause tumor cell death. Although the repertoire of the compounds which mediate ERK activation and apoptosis is expanding, and various anti-cancer compounds induce ERK activation while exerting their anti-proliferative effects, the mechanisms underlying ERK1/2-mediated cell death are still vague. Recent studies highlight the importance of dual-specificity phosphatases (DUSPs) in determining the pro- versus anti-apoptotic function of ERK in cancer. In this review, we will summarize the recent major findings in understanding the role of ERK in apoptosis, focusing on the major compounds mediating ERK-dependent apoptosis. Studies that further define the molecular targets of these compounds relevant to cell death will be essential to harnessing these compounds for developing effective cancer treatments.

HOXB8 Counteracts MAPK/ERK Oncogenic Signaling in a Chicken Embryo Model of Neoplasia

HOX transcription factors are members of an evolutionarily conserved family of proteins required for the establishment of the anteroposterior body axis during bilaterian development. Although they are often deregulated in cancers, the molecular mechanisms by which they act as oncogenes or tumor suppressor genes are only partially understood. Since the MAPK/ERK signaling pathway is deregulated in most cancers, we aimed at apprehending if and how the Hox proteins interact with ERK oncogenicity. Using an in vivo neoplasia model in the chicken embryo consisting in the overactivation of the ERK1/2 kinases in the trunk neural tube, we analyzed the consequences of the HOXB8 gain of function at the morphological and transcriptional levels. We found that HOXB8 acts as a tumor suppressor, counteracting ERK-induced neoplasia. The HOXB8 tumor suppressor function relies on a large reversion of the oncogenic transcriptome induced by ERK. In addition to showing that the HOXB8 protein controls the transcriptional responsiveness to ERK oncogenic signaling, our study identified new downstream targets of ERK oncogenic activation in an in vivo context that could provide clues for therapeutic strategies.

NRAS mutant melanoma: Towards better therapies

Genetic alterations affecting RAS proteins are commonly found in human cancers. Roughly a fourth of melanoma patients carry activating NRAS mutations, rendering this malignancy particularly challenging to treat. Although the development of targeted as well as immunotherapies led to a substantial improvement in the overall survival of non-NRAS^mut melanoma patients (e.g. BRAF^mut), patients with NRAS^mut melanomas have an overall poorer prognosis due to the high aggressiveness of RAS^mut tumors, lack of efficient targeted therapies or rapidly emerging resistance to existing treatments. Understanding how NRAS-driven melanomas develop therapy resistance by maintaining cell cycle progression and survival is crucial to develop more effective and specific treatments for this group of melanoma patients. In this review, we provide an updated summary of currently available therapeutic options for NRAS^mut melanoma patients with a focus on combined inhibition of MAPK signaling and CDK4/6-driven cell cycle progression and mechanisms of the inevitably developing resistance to these treatments. We conclude with an outlook on the most promising novel therapeutic approaches for melanoma patients with constitutively active NRAS. STATEMENT OF SIGNIFICANCE: An estimated 75000 patients are affected by NRAS^mut melanoma each year and these patients still have a shorter progression-free survival than BRAF^mut melanomas. Both intrinsic and acquired resistance occur in NRAS-driven melanomas once treated with single or combined targeted therapies involving MAPK and CDK4/6 inhibitors and/or checkpoint inhibiting immunotherapy. Oncolytic viruses, mRNA-based vaccinations, as well as targeted triple-agent therapy are promising alternatives, which could soon contribute to improved progression-free survival of the NRAS^mut melanoma patient group.

Differential expression of phosphorylated MEK and ERK correlates with aggressive BCC subtypes

Basal cell carcinoma (BCC) is associated with aberrant Hedgehog (HH) signalling through mutational inactivation of PTCH1; however, there is conflicting data regarding MEK/ERK signalling in BCC and the signalling pathway interactions in these carcinomas. To address this, expression of active phospho (p) MEK and ERK was examined in a panel of 15 non-aggressive and 14 aggressive BCCs. Although not uniformly expressed, both phospho-proteins were detected in the nuclei and/or cytoplasm of normal and tumour-associated epidermal cells however, whereas phospho-MEK (pMEK) was present in all non-aggressive BCCs (14/14), phospho-ERK (pERK) was rarely expressed (2/14). In contrast pERK expression was more prevalent in aggressive tumours (11/14). Interestingly, pMEK was only localized to the tumour mass whereas pERK was expressed in tumours and stroma of aggressive BCCs. Similarly, pERK (but not pMEK) was absent in mouse BCC-like tumours derived from X-ray irradiated Ptch1+/- mice with stromal pERK observed in myofibroblasts of the aggressive variant as well as in the tumour mass. RNA sequencing analysis of tumour epithelium and stroma of aggressive and non-aggressive BCC revealed the upregulation of epidermal growth factor receptor- and ERK-related pathways. Angiogenesis and immune response pathways were also upregulated in the stroma compared with the tumour. PTCH1 suppressed NEB1 immortalized keratinocytes (shPTCH1) display upregulated pERK that can be independent of MEK expression. Furthermore, epidermal growth factor pathway inhibitors affect the HH pathway by suppressing GLI1. These studies reveal differential expression of pERK between human BCC subtypes that maybe active by a pathway independent of MEK.

Extracellular signal-regulated kinases associate with and phosphorylate DHPS to promote cell proliferation

The ERK1/2 pathway is one of the most commonly dysregulated pathways in human cancers and controls many vital cellular processes. Although many ERK1/2 kinase substrates have been identified, the diversity of ERK1/2 mediated processes suggests the existence of additional targets. Here, we identified Deoxyhypusine synthase (DHPS), an essential hypusination enzyme regulating protein translation, as a major and direct-binding protein of ERK1/2. Further experiments showed that ERK1/2 phosphorylate DHPS at Ser-233 site. The Ser-233 phosphorylation of DHPS by ERK1/2 is important for its function in cell proliferation. Moreover, we found that higher DHPS expression correlated with poor prognosis in lung adenocarcinoma and increased resistance to inhibitors of the ERK1/2 pathway. In summary, our results suggest that ERK1/2-mediated DHPS phosphorylation is an important mechanism that underlies protein translation and that DHPS expression is a potent biomarker of response to therapies targeting ERK1/2-pathway.

Down-regulation of TRIB3 inhibits the progression of ovarian cancer via MEK/ERK signaling pathway

Background

Tribbles pseudokinase 3 (TRIB3) protein is a pseudokinase which plays an important role in cellular stress, metabolism, and tumor progression. However, the expression and function of TRIB3 in ovarian cancer is unknown.

Methods

TRIB3 expression was detected by immunohistochemistry in the ovarian tissue samples. Following down-regulation of TRIB3 by siRNA, multiple aspects of ovarian cancer cells were detected by the MTT assay, flow cytometry, scratch test and Transwell. Additionally, changes in related molecules and the MEK/ERK pathway were detected by western blotting. Finally, many bioinformatic methods, websites and databases, such as gene set enrichment analysis (GSEA), DVAID, Genemania, TISIDB and cBioPortal were used to study the TRIB3.

Results

The expression level of TRIB3 was higher in ovarian epithelial malignant tumors as compared to other groups. Patients with a high expression level of TRIB3 had significantly shorter survival times,which was consistent with the results of analysis of the KM-plot database. Down-regulation of TRIB3 expression significantly inhibited the proliferation, invasion, and migration capabilities of ovarian cancer cells, and induced apoptosis and cell cycle arrest. Following TRIB3 siRNA transfection, expression levels of relative proteins were found to be decreased. Additionally, analysis in DAVID website and GSEA revealed that TRIB3 expression was associated with multiple biological processes. Protein phosphorylation levels of MEK and ERK also decreased following TRIB3-siRNA transfection. The Genemania website was used to analyze the proteins that interact with TRIB3. Analysis of TRIB3 in the TISIDB database and cBioPortal website showed that ovarian cancer patients with high levels of mutation in TRIB3 had poor prognosis, and that the expression of TRIB3 was related to immunomodulation.

Conclusions

The TRIB3 was highly expressed and promoting the malignant behavior of ovarian cancer cells by activating the MEK-ERK signaling pathway. It was also found to be associated with genetic variations and immune modulators.

Growth Inhibitory Signaling of the Raf/MEK/ERK Pathway

In response to extracellular stimuli, the Raf/MEK/extracellular signal-regulated kinase (ERK) pathway regulates diverse cellular processes. While mainly known as a mitogenic signaling pathway, the Raf/MEK/ERK pathway can mediate not only cell proliferation and survival but also cell cycle arrest and death in different cell types. Growing evidence suggests that the cell fate toward these paradoxical physiological outputs may be determined not only at downstream effector levels but also at the pathway level, which involves the magnitude of pathway activity, spatial-temporal regulation, and non-canonical functions of the molecular switches in this pathway. This review discusses recent updates on the molecular mechanisms underlying the pathway-mediated growth inhibitory signaling, with a major focus on the regulation mediated at the pathway level.

Lestaurtinib potentiates TRAIL-induced apoptosis in glioma via CHOP-dependent DR5 induction

Lestaurtinib, also called CEP-701, is an inhibitor of tyrosine kinase, causes haematological remission in patients with AML possessing FLT3-ITD (FLT3 gene) internal tandem duplication and strongly inhibits tyrosine kinase FLT3. Treatment with lestaurtinib modulates various signalling pathways and leads to cell growth arrest and programmed cell death in several tumour types. However, the effect of lestaurtinib on glioma remains unclear. In this study, we examined lestaurtinib and TRAIL interactions in glioma cells and observed their synergistic activity on glioma cell apoptosis. While U87 and U251 cells showed resistance to TRAIL single treatment, they were sensitized to apoptosis induced by TRAIL in the presence of lestaurtinib because of increased death receptor 5 (DR5) levels through CHOP-dependent manner. We also demonstrated using a xenograft model of mouse that the tumour growth was absolutely suppressed because of the combined treatment compared to TRAIL or lestaurtinib treatment carried out singly. Our findings reveal a potential new strategy to improve antitumour activity induced by TRAIL in glioma cells using lestaurtinib through a mechanism dependent on CHOP.

Insulin receptor endocytosis in the pathophysiology of insulin resistance

Insulin signaling controls cell growth and metabolic homeostasis. Dysregulation of this pathway causes metabolic diseases such as diabetes. Insulin signaling pathways have been extensively studied. Upon insulin binding, the insulin receptor (IR) triggers downstream signaling cascades. The active IR is then internalized by clathrin-mediated endocytosis. Despite decades of studies, the mechanism and regulation of clathrin-mediated endocytosis of IR remain incompletely understood. Recent studies have revealed feedback regulation of IR endocytosis through Src homology phosphatase 2 (SHP2) and the mitogen-activated protein kinase (MAPK) pathway. Here we review the molecular mechanism of IR endocytosis and its impact on the pathophysiology of insulin resistance, and discuss the potential of SHP2 as a therapeutic target for type 2 diabetes.

Mutations That Confer Drug-Resistance, Oncogenicity and Intrinsic Activity on the ERK MAP Kinases-Current State of the Art

Unique characteristics distinguish extracellular signal-regulated kinases (Erks) from other eukaryotic protein kinases (ePKs). Unlike most ePKs, Erks do not autoactivate and they manifest no basal activity; they become catalysts only when dually phosphorylated on neighboring Thr and Tyr residues and they possess unique structural motifs. Erks function as the sole targets of the receptor tyrosine kinases (RTKs)-Ras-Raf-MEK signaling cascade, which controls numerous physiological processes and is mutated in most cancers. Erks are therefore the executers of the pathway’s biology and pathology. As oncogenic mutations have not been identified in Erks themselves, combined with the tight regulation of their activity, Erks have been considered immune against mutations that would render them intrinsically active. Nevertheless, several such mutations have been generated on the basis of structure-function analysis, understanding of ePK evolution and, mostly, via genetic screens in lower eukaryotes. One of the mutations conferred oncogenic properties on Erk1. The number of interesting mutations in Erks has dramatically increased following the development of Erk-specific pharmacological inhibitors and identification of mutations that cause resistance to these compounds. Several mutations have been recently identified in cancer patients. Here we summarize the mutations identified in Erks so far, describe their properties and discuss their possible mechanism of action.