Negative feedback regulation of the ERK1/2 MAPK pathway

Unlocking the multifaceted roles of GLP-1: Physiological functions and therapeutic potential

Glucagon (GCG) like peptide 1 (GLP-1) has emerged as a powerful player in regulating metabolism and a promising therapeutic target for various chronic diseases. This review delves into the physiological roles of GLP-1, exploring its impact on glucose homeostasis, insulin secretion, and satiety. We examine the compelling evidence supporting GLP-1 receptor agonists (GLP-1RAs) in managing type 2 diabetes (T2D), obesity, and other diseases. The intricate molecular mechanisms underlying GLP-1RAs are explored, including their interactions with pathways like extracellular signal-regulated kinase 1/2 (ERK1/2), activated protein kinase (AMPK), cyclic adenine monophosphate (cAMP), mitogen-activated protein kinase (MAPK), and protein kinase C (PKC). Expanding our understanding, the review investigates the potential role of GLP-1 in cancers. Also, microribonucleic acid (RNA) (miRNAs), critical regulators of gene expression, are introduced as potential modulators of GLP-1 signaling. We delve into the link between miRNAs and T2D obesity and explore specific miRNA examples influencing GLP-1R function. Finally, the review explores the rationale for seeking alternatives to GLP-1RAs and highlights natural products with promising GLP-1 modulatory effects.

miR-486-3p Suppresses Osteosarcoma Proliferation and Migration by Targeting the SPRED1-MAPK/ERK Pathway

Osteosarcoma (OS) is a common malignancy of the bone that originates from stromal cell lines. One of the key cellular pathways extensively studied in OS is the mitogen-activated protein kinase (MAPK) pathway, particularly ERK1/2, whose activation is closely associated with tumor growth and metastasis. MicroRNA (miRNA)-based detection and targeted therapies offer promising new strategies for the treatment of OS. In this study, we investigated the role of miR‑486‑3p in the regulation of the ERK1/2 pathway in OS. We examined the expression level of miR‑486‑3p in the GEO dataset (GSE65071) and clinical samples, and analyzed its regulation of the target gene SPRED1 in OS cells and tumor-bearing mice. Downregulation of miR‑486‑3p was confirmed in OS tissues, with its expression decreasing in line with the progression of clinical stages. Furthermore, the exogenous introduction of a miR-486-3p mimic attenuated the malignant behavior of OS cells, inhibiting their proliferation, migration, and invasion. Bioinformatic analysis revealed that miR‑486‑3p directly targets SPRED1 in OS, leading to alterations in epithelial-to-mesenchymal transition (EMT) markers, including E-cadherin, N-cadherin, and Vimentin. Functional loss- and gain-of-function experiments confirmed that miR‑486‑3p directly targets SPRED1 and inactivates the ERK1/2 pathway in both OS cells and tumor-bearing mice. This review demonstrates that downregulation of miR-486-3p leads to increased SPRED1 expression, which activates the ERK1/2 pathway in OS. Targeting miR-486-3p and SPRED1 could offer potential therapeutic benefits.

The network response to Egf is tissue-specific

Epidermal growth factor receptor (Egfr)-driven signaling regulates fundamental homeostatic processes. Dysregulated signaling via Egfr is implicated in numerous disease pathologies and distinct Egfr-associated disease etiologies are known to be tissue-specific. The molecular basis of this tissue-specificity remains poorly understood. Most studies of Egfr signaling to date have been performed in vitro or in tissue-specific mouse models of disease, which has limited insight into Egfr signaling patterns in healthy tissues. Here, we carried out integrated phosphoproteomic, proteomic, and transcriptomic analyses of signaling changes across various mouse tissues in response to short-term stimulation with the Egfr ligand Egf. We show how both baseline and Egf-stimulated signaling dynamics differ between tissues. Moreover, we propose how baseline phosphorylation and total protein levels may be associated with clinically relevant tissue-specific Egfr-associated phenotypes. Altogether, our analyses illustrate tissue-specific effects of Egf stimulation and highlight potential links between underlying tissue biology and Egfr signaling output.

Ultradeep Phosphoproteomics for Assessing Protein Kinase Inhibitor Selectivity on a Proteome Scale

The selectivity of protein kinase inhibitors (PKIs) remains a major challenge in drug discovery. In this study, we present an ultradeep phosphoproteomics approach for assessing PKI selectivity and elucidating mechanisms of action using Zanubrutinib as a model. Two complementary phosphoproteomics strategies were employed: phosphopeptides enriched with Zr4+-IMAC in combination with TiO2 beads were analyzed using data-independent acquisition (DIA), while tyrosine phosphopeptides enriched with SH2-Superbinder were analyzed via data-dependent acquisition (DDA). The comprehensive phosphoproteomic analysis identified that 97 and 316 phosphosites were significantly altered upon Zanubrutinib stimulation in the DDA and DIA data sets, respectively. Bioinformatics analysis of these phosphoproteins provided a detailed selectivity profile of Zanubrutinib, offering insights into its mechanism of action at the molecular level. Compared to existing methods, our approach is more comprehensive, has higher throughput, and is more precise─not only for PKI selectivity assessment but also for broader cell signaling research.

TRIM21-mediated ubiquitination and phosphorylation of ERK1/2 promotes cell proliferation and drug resistance in pituitary adenomas

BACKGROUND

Pituitary adenomas (PAs) are common intracranial tumors and the TRIM family plays a crucial role in cell proliferation and therapeutic resistance of tumors. However, the role of the TRIM family in PAs is not well recognized.

METHODS

CRISPR screening explored the role of the TRIM family in cell proliferation and drug resistance in PAs. In vitro and in vivo experiments were performed to evaluate the effects of Tripartite Motif Containing 21 (TRIM21). RNA-sequencing, mass spectrometry, immunoprecipitation, and ubiquitination experiments were performed to explore the molecular mechanism. NanoBiT assays were used to screen the drugs reducing TRIM21 expression.

RESULTS

CRISPR-Cas9 screens identified that TRIM21 facilitated cell proliferation and drug resistance in PAs. Mechanistically, TRIM21 interacted with ERK1/2 through PRY-SPRY domain, leading to ERK1/2 K27-linked ubiquitination. The ERK1/2 ubiquitination promotes the interaction between ERK1/2 and MEK1/2, thereby facilitating the phosphorylation of ERK1/2. However, an excess presence of TRIM21 suppressed the phosphorylation of ERK1/2 and cell proliferation via activating ERK1/2 negative feedback pathways. Importantly, TRIM21 was upregulated in dopamine-resistant prolactinomas and cabergoline-resistant MMQ cells. Furthermore, drug screening identified that Fimepinostat and Quisinostat, can reduce the protein levels of TRIM21, inhibit tumor progression, and increase drug sensitivity.

CONCLUSIONS

TRIM21 may represent a therapeutic target for tumors, and inhibiting TRIM21 could be a potential strategy for tumor treatment.

Evaluation of information flows in the RAS-MAPK system using transfer entropy measurements

The RAS-MAPK system plays an important role in regulating various cellular processes, including growth, differentiation, apoptosis, and transformation. Dysregulation of this system has been implicated in genetic diseases and cancers affecting diverse tissues. To better understand the regulation of this system, we employed information flow analysis based on transfer entropy (TE) between the activation dynamics of two key elements in cells stimulated with EGF: SOS, a guanine nucleotide exchanger for the small GTPase RAS, and RAF, a RAS effector serine/threonine kinase. TE analysis allows for model-free assessment of the timing, direction, and strength of the information flow regulating the system response. We detected significant amounts of TE in both directions between SOS and RAF, indicating feedback regulation. Importantly, the amount of TE did not simply follow the input dose or the intensity of the causal reaction, demonstrating the uniqueness of TE. TE analysis proposed regulatory networks containing multiple tracks and feedback loops and revealed temporal switching in the reaction pathway primarily responsible for reaction control. This proposal was confirmed by the effects of an MEK inhibitor on TE. Furthermore, TE analysis identified the functional disorder of a SOS mutation associated with Noonan syndrome, a human genetic disease, of which the pathogenic mechanism has not been precisely known yet. TE assessment holds significant promise as a model-free analysis method of reaction networks in molecular pharmacology and pathology.

Immediate early splicing controls translation in activated T-cells and is mediated by hnRNPC2 phosphorylation

The fast and transient induction of immediate early genes orchestrates the cellular response to various stimuli. These stimuli trigger phosphorylation cascades that promote immediate early gene transcription independent of de novo protein synthesis. Here we show that the same phosphorylation cascades also target the splicing machinery, inducing an analogous splicing switch that we call immediate early splicing (IES). We characterize hnRNPC2-controlled IES, which depends on the MEK-ERK pathway and the T cell-specific kinase PKCθ. This splicing switch mainly targets components of the translation machinery, such as mRNAs encoding ribosomal proteins and eIF5A. Inducing the eIF5A IES protein variant is by itself sufficient to reduce global translation, and consistently, we observe reduced de novo protein synthesis early after T cell activation. We suggest that immediate early splicing and the ensuing transient decrease in translation efficiency help to coordinate the extensive changes in gene expression during T cell activation. Together, these findings set a paradigm for fast and transient alternative splicing in the immediate cellular response to activation, and provide evidence for its functional relevance during T-cell stimulation.

Matrix stiffening induces hepatocyte functional impairment and DNA damage via the Piezo1‒ERK1/2 signaling pathway

Hepatocytes are the primary functional cells in the liver, and the malignant transformation of hepatocytes significantly contributes to hepatocellular carcinoma (HCC) progression. Liver fibrosis and cirrhosis caused by extracellular matrix (ECM) remodeling during liver lesions is a pivotal driver of HCC. However, the impact of matrix stiffness on hepatocytes and the underlying molecular mechanisms are not fully understood. Herein, using gelatin/sodium alginate hydrogels with different stiffnesses to simulate the change of matrix stiffness during liver lesions, we found that matrix stiffening leads to a notable decrease in the expression of hepatocyte nuclear factor 4α (HNF4α) and functional hepatocyte genes and a significant increase in the expression of interleukin 6 (IL‒6) in human hepatocyte line L‒02 cells, indicating obvious damage of hepatocyte function. In addition, matrix stiffening causes extensive DNA damage to L‒02 cells. Mechanistically, matrix stiffening upregulates piezo‒type mechanosensitive ion channel component 1 (Piezo1) expression and activates extracellular signal‒regulated kinase 1/2 (ERK1/2) signaling. Piezo1 knockdown suppresses matrix stiffening‒induced functional impairment and DNA damage in L‒02 cells. Moreover, Piezo1 knockdown blocks matrix stiffening‒activated ERK1/2 signaling in L‒02 cells. U0126 (a selective inhibitor of ERK1/2 activation) treatment could rescue matrix stiffening‒induced functional impairment and DNA damage. Taken together, these findings demonstrate that matrix stiffening induces functional impairment and DNA damage in L‒02 cells via the Piezo1‒ERK1/2 signaling pathway, which provides evidence for a better understanding of the hepatocyte function damage caused by tissue mechanical microenvironment change in liver diseases and the mechanotransduction in this process.

From bench to bedside: murine models of inherited and sporadic brain arteriovenous malformations

Brain arteriovenous malformations are abnormal vascular structures in which an artery shunts high pressure blood directly to a vein without an intervening capillary bed. These lesions become highly remodeled over time and are prone to rupture. Historically, brain arteriovenous malformations have been challenging to treat, using primarily surgical approaches. Over the past few decades, the genetic causes of these malformations have been uncovered. These can be divided into (1) familial forms, such as loss of function mutations in TGF-β (BMP9/10) components in hereditary hemorrhagic telangiectasia, or (2) sporadic forms, resulting from somatic gain of function mutations in genes involved in the RAS-MAPK signaling pathway. Leveraging these genetic discoveries, preclinical mouse models have been developed to uncover the mechanisms underlying abnormal vessel formation, and thus revealing potential therapeutic targets. Impressively, initial preclinical studies suggest that pharmacological treatments disrupting these aberrant pathways may ameliorate the abnormal pathologic vessel remodeling and inflammatory and hemorrhagic nature of these high-flow vascular anomalies. Intriguingly, these studies also suggest uncontrolled angiogenic signaling may be a major driver in bAVM pathogenesis. This comprehensive review describes the genetics underlying both inherited and sporadic bAVM and details the state of the field regarding murine models of bAVM, highlighting emerging therapeutic targets that may transform our approach to treating these devastating lesions.

Second-generation BRAF inhibitor Encorafenib resistance is regulated by NCOA4-mediated iron trafficking in the drug-resistant malignant melanoma cells

The current study established the first in vitro Encorafenib resistance protocol in BRAF-mutated malignant melanoma (MM) cells and investigated the resistance-related mechanisms. After establishing Encorafenib-resistant A375-MM cells, resistant-related mechanisms were investigated using WST-1, Annexin V, cell cycle, morphological analysis, live-cell, Western blot, RNA-Seq, transmission electron microscopy-(TEM), oxidative stress and iron colorimetric assay. The most resistant group, called A375-R, was determined in the cells treated with a constant dose of 10 nM over 3 months. The viability, apoptosis, and G0/G1 arrest reflected the acquired chemoresistance. Autophagic Beclin and LC3 proteins, and AKT signaling increased in the A375-R. RNA-Seq results also exhibited altered epigenetic regulation of resistance; particularly ferritin family members, ion transport pathways. Then, increased NCOA4, FTH1, and iron levels detected in A375-R suggest that the iron metabolism-related mechanism, such as ferritinophagy, might be triggered, which was supported by TEM and oxidative stress analysis. Iron storage, transport, and ferritinophagy have the promising potential to be targeted for combining with BRAF-targeted therapy to reverse Encorafenib resistance in MM. Moreover, this is the first study evaluating in vitro Encorafenib resistance mechanisms, and we suggest that our findings contribute to improving new drug combinations targeting BRAF and iron metabolism in different MM cells.

"Undruggable KRAS": druggable after all

The three RAS genes (HRAS, KRAS, and NRAS) comprise the most frequently mutated oncogene family in cancer. KRAS is the predominant isoform mutated in cancer and is most prevalently mutated in major causes of cancer deaths including lung, colorectal, and pancreatic cancers. Despite extensive academic and industry efforts to target KRAS, it would take nearly four decades before approval of the first clinically effective KRAS inhibitors for the treatment of KRAS mutant lung cancer. We revisit past anti-KRAS strategies and painful lessons learned and then focus on the rapidly evolving landscape of direct RAS inhibitors, resistance mechanisms, and potential combination treatments.

Combination of HSP90 Inhibitors and HSP70 Inducers Prevent Hydrochloric Acid-Induced Pulmonary Fibrosis in Rabbits

Combined therapies with Heat Shock Protein 90 (HSP90) inhibitors and Heat Shock Protein 70 (HSP70) inducers are gaining significant interest in cancer and cardiovascular research. Here, we tested the hypothesis that HSP90 inhibitors and HSP70 inducers, together, can block the development of pulmonary fibrosis. We exposed New Zealand White Rabbits to hydrochloric acid (HCl, 0.1 N, 1.5 mL/kg), one of the top five chemicals most commonly involved in accidental exposures and inhalation injuries worldwide, and treated animals with either the orally available HSP90 inhibitor TAS-116 (1.7 mg/kg 5x/week) or TAS-116 combined with the HSP70 inducer, geranylgeranyl acetone (GGA, 50 mg/kg, 3x/week). At 60 days post-HCl instillation, TAS and GGA treatment markedly reduced the degree of pulmonary fibrosis, lung dysfunction, and activation of profibrotic pathways. The use of HSP70 inducers may be a helpful tool to improve the profile of HSP90 inhibitors and reduce their minimal effective dose and side effects. Further investigation is required to explore the exact synergistic mechanism behind the antifibrotic profile of HSP90 inhibitors and HSP70 inducers.

The effects of Aurora Kinase inhibition on thyroid cancer growth and sensitivity to MAPK-directed therapies

Thyroid cancer is one of the deadliest endocrine cancers, and its incidence has been increasing. While mutations in BRAF are common in thyroid cancer, advanced PTC patients currently lack therapeutic options targeting the MAPK pathway, and despite the approved combination of BRAF and MEK1/2 inhibition for BRAF-mutant ATC, resistance often occurs. Here, we assess growth and signaling responses to combined BRAF and MEK1/2 inhibition in a panel of BRAF-mutant thyroid cancer cell lines. We first showed that combined BRAF and MEK1/2 inhibition synergistically inhibits cell growth in four out of six of the -BRAF-mutant thyroid cancer cell lines tested. Western blotting showed that the MAPK pathway was robustly inhibited in all cell lines. Therefore, to identify potential mechanisms of resistance, we performed RNA-sequencing in cells sensitive or resistant to MEK1/2 inhibition. In response to MEK1/2 inhibition, we identified a downregulation of Aurora Kinase B (AURKB) in sensitive but not resistant cells. We further demonstrated that combined MEK1/2 and AURKB inhibition slowed cell growth, which was phenocopied by inhibiting AURKB and ERK1/2. Finally, we show that combined AURKB and ERK1/2 inhibition induces apoptosis in BRAF-mutant thyroid cancer cell lines, together suggesting a potential combination therapy for BRAF-mutant thyroid cancer patients.

Topical delivery of bioactive compounds from Cortex Dictamni alleviates atopic dermatitis-like lesion by inhibiting the activation of keratinocytes, macrophages, and basophils: Dictamnine versus fraxinellone

Dictamnine and fraxinellone constitute the primary alkaloid and limonoid components in Cortex Dictamni, respectively. Both compounds exhibit anti-inflammatory properties. This study aims to assess the ability of dictamnine and fraxinellone in treating atopic dermatitis (AD) through in silico-, cell-, and animal-based experiments. The effects of these compounds on the coordinated activation of keratinocytes, macrophages, and basophils in AD development were investigated. A dinitrochlorobenzene (DNCB)-sensitized AD model in mice was employed to examine the in vivo anti-AD effects. Dictamnine and fraxinellone effectively reduced the release of proinflammatory effectors, including interleukin (IL)-4, IL-13, chemokine (C-C motif) ligand (CCL)5, and CCL17, by suppressing extracellular signal-regulated kinase (ERK) signaling in activated keratinocytes. The conditioned medium from dictamnine-treated macrophages reduced signal transducer and activator of transcription (STAT)3 in keratinocytes by 39 %, indicating the inhibition of keratinocytes-immune cell interaction. Both compounds comparably suppressed RBL-2H3 cell degranulation by decreasing histamine production. In vitro permeation test (IVPT) demonstrated three-fold greater skin absorption of topically applied dictamnine than fraxinellone. The in silico molecular docking manifested a preferable ceramide interaction with dictamnine over fraxinellone. Topical application of dictamnine decreased the mouse skin lesion development and the overexpressed cytokines/chemokines. This attenuation is comparable to the activity of tacrolimus ointment, a standard clinical treatment. Histological analysis revealed that dictamnine inhibited epidermal proliferation, reducing thickness from 220 to 97 μm. However, dictamnine did not restore the barrier function, as evidenced by the results of filaggrin and loricrin expression and in vivo transepidermal water loss (TEWL). The findings suggest that topical dictamnine can be a promising agent for alleviating AD inflammation.

ASCL1 Restrains ERK1/2 to Promote Survival of a Subset of Neuroendocrine Lung Cancers

The transcription factor achaete-scute complexhomolog 1 (ASCL1) is a lineage oncogene that is central in growth and survival of the majority of small cell lung cancers and neuroendocrine (NE) non-small cell lung cancers (NSCLC) that express it. Targeting ASCL1, or its downstream pathways, remains a challenge. Small cell lung cancers and NSCLC-NE that express ASCL1 exhibit relatively low ERK1/2 activity, in dramatic contrast to NSCLCs in which the ERK pathway plays a major role in pathogenesis. ERK1/2 inhibition in ASCL1-expressing lung tumor cells revealed downregulation of ERK1/2 pathway suppressors SPRY4, SPRED1, DUSP6, and the transcription factor ETV5, which regulates DUSP6. Chromatin immunoprecipitation sequencing demonstrated that these genes are bound by ASCL1. Availability of a pharmacologic inhibitor directed mechanistic studies toward DUSP6, an ERK1/2-selective phosphatase, in a subset of ASCL1-high NE lung tumors. Inhibition of DUSP6 increased active ERK1/2, which accumulated in the nucleus. Pharmacologic and genetic inhibition of DUSP6 reduced proliferation and survival of these cancers. Resistance developed in DUSP6-knockout cells, indicating a bypass mechanism. Although targeting ASCL1 remains a challenge, our findings suggest that expression of ASCL1, DUSP6, and low phospho-ERK1/2 identifies NE lung cancers for which DUSP6 may be a therapeutic target.

IFRD2, a target of miR-2400, regulates myogenic differentiation of bovine skeletal muscle satellite cells via decreased phosphorylation of ERK1/2 proteins

The proliferation and differentiation of skeletal muscle satellite cells is a complex physiological process involving various transcription factors and small RNA molecules. This study aimed to understand the regulatory mechanisms underlying these processes, focusing on interferon-related development factor 2 (IFRD2) as a target gene of miRNA-2400 in bovine skeletal MuSCs (MuSCs). IFRD2 was identified as a target gene of miRNA-2400 involved in regulating the proliferation and differentiation of bovine skeletal MuSCs. Our results indicate that miR-2400 can target binding the 3'UTR of IFRD2 and inhibit its translation. mRNA and protein expression levels of IFRD2 increased significantly with increasing days of differentiation. Moreover, overexpression of the IFRD2 gene inhibited proliferation and promoted differentiation of bovine MuSCs. Conversely, the knockdown of the gene had the opposite effect. Overexpression of IFRD2 resulted in the inhibition of ERK1/2 phosphorylation levels in bovine MuSCs, which in turn promoted differentiation. In summary, IFRD2, as a target gene of miR-2400, crucially affects bovine skeletal muscle proliferation and differentiation by precisely regulating ERK1/2 phosphorylation.

An updated patent review of SOS1 inhibitors (2022-present)

INTRODUCTION

SOS1 is a crucial guanine nucleotide exchange factor for KRAS. It facilitates the transition of KRAS from inactive GDP-bound state to active GTP-bound state. The activation of KRAS triggers downstream signaling pathways, promoting tumor initiation and progression. Inhibiting SOS1 to prevent KRAS activation is an effective strategy for treating tumors driven by KRAS.

AREAS COVERED

This review identified patents claiming to be SOS1 inhibitors or SOS1-KRAS interaction modulators published between January 2022 and June 2024 using Cortellis Drug Discovery Intelligence. A total of 15 patent applications from 5 different applicants were assessed.

EXPERT OPINIONS

In KRAS-driven tumors, inhibiting SOS1 significantly affect cell proliferation and migration by modulating the RAS/MAPK and PI3K/AKT/mTOR signaling pathways. Since 2022, numerous patents for SOS1 inhibitors have been published. The majority of SOS1 inhibitors are currently in the preclinical phase of development, with only a few progressing to clinical trials. However, these inhibitors face significant challenges in clinical studies, including limited efficacy of monotherapies, safety concerns, and the necessity to enhance PK properties. Despite their excellent in vitro performance, SOS1 inhibitors must address issues related to safety, pharmacokinetics, and pharmacodynamics in clinical applications.

Design, synthesis, and evaluation of dual son of sevenless 1 (SOS1) and epidermal growth factor receptor (EGFR) inhibitors for the treatment of cancers

The treatment of KRAS mutant tumors remains challenging and dual-targeted small-molecule drugs are considered to be innovative therapeutic alternatives. Herein, we discovered a series of SOS1 and EGFR dual inhibitors by employing a fused pharmacophore strategy and structural optimization. Notably, compound 4 exhibited potent SOS1 (IC50 = 8.3 nM) and EGFR (IC50 = 14.6 nM) inhibitory activities and markedly inhibited the proliferation of other KRAS-mutant cancer cell lines. Furthermore, Western blot analysis confirmed that compound 4 effectively reduced the level of downstream p-ERK. These results indicated that compound 4 could serve as a potential compound for treating KRAS mutant tumors.

Alternative isoforms and phase separation of Ref1 repress morphogenesis in Cryptococcus

Cryptococcus neoformans, the causative agent of cryptococcosis and a representative of the Basidiomycota phylum of Fungi, is a valuable model for our understanding of eukaryotic/fungal biology. Negative feedback is a well-documented mechanism across Eukarya to regulate developmental transitions. Here, we describe a repressor of the yeast-to-hypha transition, Ref1, which completes a negative feedback loop driven by the master regulator of hyphal morphogenesis, Znf2, during sexual development. Alternative transcription of Ref1, driven by Znf2, produces a functionally distinct Ref1 isoform. Isoform-specific capacity for phase separation imparts this functional distinction, making Ref1 a stronger repressor and more vulnerable to proteolytic degradation. The multimodal nature of Ref1 provides versatility that allows cells to fine-tune Ref1 activity to suit developmental context. This work reveals a mechanism by which phase separation allows a transcriptional program to tailor its own repression to guide an organism through morphological transition.

The evolution of BRAF-targeted therapies in melanoma: overcoming hurdles and unleashing novel strategies

Melanoma, a highly aggressive form of skin cancer, poses a significant global health burden, with 331,647 new cases and 58,645 deaths reported in 2022. The development of melanoma is influenced by various factors, including sunlight exposure and BRAFV600 mutations that activate the MAPK/ERK pathway. The introduction of BRAF and MEK inhibitors has revolutionized the treatment landscape for melanoma patients. However, innate and acquired therapeutic resistance remains a significant challenge. This review provides a comprehensive overview of the current state of BRAF-targeted therapies in melanoma, highlighting the efficacy and limitations of FDA-approved combinations of BRAF and MEK inhibitors such as vemurafenib, dabrafenib, trametinib, and cobimetinib. The review also explores the off-target effects of BRAF inhibitors on endothelial cells, emphasizing the need for more selective therapies to minimize vascular complications and metastatic potential. The article also discusses potential druggable targets, including ERK5, CD73, ALDH1A1, PLA1A, and DMKN, which are promising in addressing diagnostic hurdles and guiding personalized therapeutic decisions. Recent studies on regorafenib, ERK5 signaling, and CD73 inhibition are highlighted as novel strategies to overcome resistance and improve treatment outcomes. The review also delves into the role of advanced therapeutic tools, such as mRNA vaccines and CRISPR-Cas9, in revolutionizing personalized oncology by targeting specific genetic mutations and enhancing immune responses against melanoma. The ongoing synergy between advancing research, targeted interventions, strategic treatment combinations, and cost-effectiveness evaluations offers a promising pathway to elevate patient outcomes in the persistent battle against melanoma significantly.

Activation of MEK-ERK-c-MYC signaling pathway promotes splenic M2-like macrophage polarization to inhibit PHcH-liver cirrhosis

INTRODUCTION

Portal hypertension combined with hypersplenism (PHcH) is the main cause of hypocytosis and esophagogastric variceal hemorrhage in patients with liver cirrhosis. Activated macrophages that destroy excess blood cells are the main cause of hypersplenism, but the activating pathway is not very clear. This study aims to investigate the activation types of splenic macrophages and their activation mechanisms, to provide experimental evidence for the biological treatment of splenomegaly, and to find a strategy to improve liver fibrosis and inflammation by intervening in splenic immune cells. This study revealed the occurrence of M2-like polarization of macrophages and upregulation of c-Myc gene expression in the PH spleen.

METHODS

RNAseq, protein chip, western blot, and chip-seq were performed on macrophages and the in vitro MEK inhibitor rafametinib was used. Carbon tetrachloride and thioacetamide induced mouse cirrhosis models were separately constructed.

RESULTS

c-Myc gene knockout in splenic macrophages reduced M2-like polarization and exacerbated liver fibrosis inflammation. c-Myc activated the MAPK signaling pathway and upregulated the expression of IL-4 and M2-like related genes in PH hypersplenism through the MEK-ERK-c-Myc axis. In addition, the c-Myc gene exerted anti-inflammatory effects by upregulating IL-4-mediated signal transduction to promote M2-like differentiation and anti-inflammatory cytokine secretion.

CONCLUSIONS

Activation of MEK-ERK-c-MYC signaling pathway promotes splenic M2-like macrophage polarization to inhibit PHcH-liver cirrhosis. Therefore, the induction of macrophage depolarization might represent a new therapeutic approach in the cure of PH hypersplenism, making c-Myc a potential candidate for macrophage polarization therapy.

MAP2K1 dampens cigarette smoke-induced inflammation via suppression of type I interferon pathway activation

Chronic obstructive pulmonary disease (COPD), comprised of chronic bronchitis and emphysema, is a leading cause of morbidity and mortality worldwide. Mitogen-activated protein 2 kinase (MAP2K) pathway activation is present in COPD lung tissue and a genetic polymorphism in Map2k1 associates with FEV1 decline in COPD, suggesting it may contribute to disease pathogenesis. To test the functional contribution of Map2k1 in cigarette smoke (CS)-induced lung inflammation, we used a short-term CS exposure model in mice deficient in myeloid Map2k1 (LysmCre+Mek1fl) and wild-type mice (Mek1fl). Mice deficient in myeloid Map2k1 had enhanced CS-induced lung inflammation characterized by increased neutrophil recruitment, vascular leak, augmented expression of elastolytic matrix metalloproteinases, and increased type I interferon-stimulated gene expression. The augmented neutrophilic inflammatory response could be abrogated by IFNAR1 blockade. These findings indicate that myeloid Map2k1 regulates the immune response to CS via inhibition of the type I interferon pathway. Overall, these results suggest that Map2k1 is a critical determinant in modulating the severity of CS-induced lung inflammation and its expression is protective.NEW & NOTEWORTHY Activation of the mitogen-activated protein kinases (MAPK)-ERK1/2 pathway is present in COPD lung tissue compared with healthy lungs. Our study using mice deficient in myeloid Map2k1 reveals that Map2k1 is a critical determinant in modulating the severity of CS-induced lung inflammation via suppression of type I interferon responses, and its expression is protective.

How the Structure of Signaling Regulation Evolves: Insights from an Evolutionary Model

To remain responsive to environmental changes, signaling pathways attenuate their activity with negative feedback loops (NFLs), where proteins produced upon stimulation downregulate the response. NFLs function both upstream of signaling to reduce input and downstream to reduce output. Unlike upstream NFLs, downstream NFLs directly regulate gene expression without the involvement of intermediate proteins. Thus, we hypothesized that downstream NFLs evolve under more stringent selection than upstream NFLs. Indeed, genes encoding downstream NFLs exhibit a slower evolutionary rate than upstream genes. Such differences in selective pressures could result in the robust evolution of downstream NFLs while making the evolution of upstream NFLs more sensitive to changes in signaling proteins and stimuli. Here, we test these assumptions within the context of immune signaling. Our minimal model of immune signaling predicts robust evolution of downstream NFLs to changes in model parameters. This is consistent with their critical role in regulating signaling and the conservative rate of evolution. Furthermore, we show that the number of signaling steps needed to activate a downstream NFL is influenced by the cost of signaling. Our model predicts that upstream NFLs are more likely to evolve under a shorter half-life of signaling proteins, absence of host-pathogen co-evolution, and a high infection rate. Although it has been proposed that NFLs evolve to reduce the cost of signaling, we show that a high cost does not necessarily predict the evolution of upstream NFLs. The insights from our model have broad implications for understanding the evolution of regulatory mechanisms across signaling pathways.

MEK inhibition prevents CAR-T cell exhaustion and differentiation via downregulation of c-Fos and JunB

Clinical evidence supports the notion that T cell exhaustion and terminal differentiation pose challenges to the persistence and effectiveness of chimeric antigen receptor-T (CAR-T) cells. MEK1/2 inhibitors (MEKIs), widely used in cancer treatment due to their ability to inhibit aberrant MAPK signaling, have shown potential synergistic effects when combined with immunotherapy. However, the impact and mechanisms of MEKIs on CAR-T cells remain uncertain and controversial. To address this, we conducted a comprehensive investigation to determine whether MEKIs enhance or impair the efficacy of CAR-T cells. Our findings revealed that MEKIs attenuated CAR-T cell exhaustion and terminal differentiation induced by tonic signaling and antigen stimulation, thereby improving CAR-T cell efficacy against hematological and solid tumors. Remarkably, these effects were independent of the specific scFvs and costimulatory domains utilized in CARs. Mechanistically, analysis of bulk and single-cell transcriptional profiles demonstrates that the effect of MEK inhibition was related to diminish anabolic metabolism and downregulation of c-Fos and JunB. Additionally, the overexpression of c-Fos or JunB in CAR-T cells counteracted the effects of MEK inhibition. Furthermore, our Cut-and-Tag assay revealed that MEK inhibition downregulated the JunB-driven gene profiles associated with exhaustion, differentiation, anergy, glycolysis, and apoptosis. In summary, our research unveil the critical role of the MAPK-c-Fos-JunB axis in driving CAR-T cell exhaustion and terminal differentiation. These mechanistic insights significantly broaden the potential application of MEKIs to enhance the effectiveness of CAR-T therapy.

SPROUTY2, a Negative Feedback Regulator of Receptor Tyrosine Kinase Signaling, Associated with Neurodevelopmental Disorders: Current Knowledge and Future Perspectives

Growth-factor-induced cell signaling plays a crucial role in development; however, negative regulation of this signaling pathway is important for sustaining homeostasis and preventing diseases. SPROUTY2 (SPRY2) is a potent negative regulator of receptor tyrosine kinase (RTK) signaling that binds to GRB2 during RTK activation and inhibits the GRB2-SOS complex, which inhibits RAS activation and attenuates the downstream RAS/ERK signaling cascade. SPRY was formerly discovered in Drosophila but was later discovered in higher eukaryotes and was found to be connected to many developmental abnormalities. In several experimental scenarios, increased SPRY2 protein levels have been observed to be involved in both peripheral and central nervous system neuronal regeneration and degeneration. SPRY2 is a desirable pharmaceutical target for improving intracellular signaling activity, particularly in the RAS/ERK pathway, in targeted cells because of its increased expression under pathological conditions. However, the role of SPRY2 in brain-derived neurotrophic factor (BDNF) signaling, a major signaling pathway involved in nervous system development, has not been well studied yet. Recent research using a variety of small-animal models suggests that SPRY2 has substantial therapeutic promise for treating a range of neurological conditions. This is explained by its function as an intracellular ERK signaling pathway inhibitor, which is connected to a variety of neuronal activities. By modifying this route, SPRY2 may open the door to novel therapeutic approaches for these difficult-to-treat illnesses. This review integrates an in-depth analysis of the structure of SPRY2, the role of its major interactive partners in RTK signaling cascades, and their possible mechanisms of action. Furthermore, this review highlights the possible role of SPRY2 in neurodevelopmental disorders, as well as its future therapeutic implications.

Cell-specific models reveal conformation-specific RAF inhibitor combinations that synergistically inhibit ERK signaling in pancreatic cancer cells

Pancreatic ductal adenocarcinoma (PDAC) presents significant challenges for targeted clinical interventions due to prevalent KRAS mutations, rendering PDAC resistant to RAF and MEK inhibitors (RAFi and MEKi). In addition, responses to targeted therapies vary between patients. Here, we explored the differential sensitivities of PDAC cell lines to RAFi and MEKi and developed an isogenic pair comprising the most sensitive and resistant PDAC cells. To simulate patient- or tumor-specific variations, we constructed cell-line-specific mechanistic models based on protein expression profiling and differential properties of KRAS mutants. These models predicted synergy between two RAFi with different conformation specificity (type I½ and type II RAFi) in inhibiting phospho-ERK (ppERK) and reducing PDAC cell viability. This synergy was experimentally validated across all four studied PDAC cell lines. Our findings underscore the need for combination approaches to inhibit the ERK pathway in PDAC.

Mathematical Modeling and Inference of Epidermal Growth Factor-Induced Mitogen-Activated Protein Kinase Cell Signaling Pathways

The mitogen-activated protein kinase (MAPK) pathway is an important intracellular signaling cascade that plays a key role in various cellular processes. Understanding the regulatory mechanisms of this pathway is essential for developing effective interventions and targeted therapies for related diseases. Recent advances in single-cell proteomic technologies have provided unprecedented opportunities to investigate the heterogeneity and noise within complex, multi-signaling networks across diverse cells and cell types. Mathematical modeling has become a powerful interdisciplinary tool that bridges mathematics and experimental biology, providing valuable insights into these intricate cellular processes. In addition, statistical methods have been developed to infer pathway topologies and estimate unknown parameters within dynamic models. This review presents a comprehensive analysis of how mathematical modeling of the MAPK pathway deepens our understanding of its regulatory mechanisms, enhances the prediction of system behavior, and informs experimental research, with a particular focus on recent advances in modeling and inference using single-cell proteomic data.

The role of polyphenols in modulating mitophagy: Implications for therapeutic interventions

This review rigorously assesses the burgeoning research into the role of polyphenols in modulating mitophagy, an essential cellular mechanism for the targeted removal of impaired mitochondria. These natural compounds, known for their low toxicity, are underscored for their potential in therapeutic strategies against a diverse array of diseases, such as neurodegenerative, cardiovascular, and musculoskeletal disorders. The analysis penetrates deeply into the molecular mechanisms whereby polyphenols promote mitophagy, particularly by influencing crucial signaling pathways and transcriptional regulators, including the phosphatase and tensin homolog (PTEN) induced putative kinase 1 (PINK1)/parkin and forkhead box O3 (FOXO3a) pathways. Noteworthy discoveries include the neuroprotective properties of resveratrol and curcumin, which affect both autophagic pathways and mitochondrial dynamics, and the pioneering integration of polyphenols with other natural substances to amplify therapeutic effectiveness. Furthermore, the review confronts the issue of polyphenol bioavailability and emphasizes the imperative for clinical trials to corroborate their therapeutic viability. By delivering an exhaustive synthesis of contemporary insights and recent advancements in polyphenol and mitophagy research, this review endeavors to catalyze additional research and foster the creation of innovative therapeutic modalities that exploit the distinctive attributes of polyphenols to manage and prevent disease.

BRAFV600E-Mutant Metastatic Colorectal Cancer: Current Evidence, Future Directions, and Research Priorities

BRAFV600E-mutant metastatic colorectal cancer represents a distinct molecular phenotype known for its aggressive biological behavior, resistance to standard therapies, and poor survival rates. Improved understanding of the biology of the BRAF oncogene has led to the development of targeted therapies that have paved the way for a paradigm shift in managing this disease. However, despite significant recent advancements, responses to targeted therapies are short-lived, and several challenges remain. In this review, we discuss how progress in treating BRAFV600E-mutant metastatic colorectal cancer has been made through a better understanding of its unique biological and clinical features. We provide an overview of the evidence to support current treatment approaches and discuss critical areas of need and future research strategies that hold the potential to refine clinical practice further. We also discuss some challenging aspects of managing this disease, particularly the complexity of acquired resistance mechanisms that develop under the selective pressure of targeted therapies and rational strategies being investigated to overcome them.

Ethanol enhances selenoprotein P expression via ERK-FoxO3a axis in HepG2 cells

Drinking alcohol is considered one of the risk factors for development of diabetes mellitus. Recently, it was reported that selenoprotein P levels in blood are increased by ethanol intake. However, the mechanism by which ethanol increases selenoprotein P has not been elucidated. The expression of selenoprotein P protein and its mRNA were increased in a concentration- and time-dependent manner when human liver-derived HepG2 cells were treated with ethanol. Levels of AMPK and JNK proteins, which have been known to regulate selenoprotein P transcription, were unchanged by ethanol treatment. However, the amount of nuclear FoxO3a, a transcription factor of SeP, was increased. This was associated with dephosphorylation of ERK1 but not ERK2. It was found that ERK1 was dephosphorylated by activation of dual-specific phosphatase 5 and dual-specific phosphatase 6. However, the phosphorylation of MEK by ERK phosphokinase was not affected by ethanol treatment. These results suggest that the ethanol-induced increase in SeP levels occurs by enhanced transcription of SeP mRNA via the DUSP5/6-ERK1-FoxO3a pathway.

Pharmacological control of angiogenesis by regulating phosphorylation of myosin light chain 2

BACKGROUND

Control of angiogenesis is widely considered a therapeutic strategy, but reliable control methods are still under development. Phosphorylation of myosin light chain 2 (MLC2), which regulates actin-myosin interaction, is critical to the behavior of vascular endothelial cells (ECs) during angiogenesis. MLC2 is phosphorylated by MLC kinase (MLCK) and dephosphorylated by MLC phosphatase (MLCP) containing a catalytic subunit PP1. We investigated the potential role of MLC2 in the pharmacological control of angiogenesis.

METHODS AND RESULTS

We exposed transgenic zebrafish Tg(fli1a:Myr-mCherry)ncv1 embryos to chemical inhibitors and observed vascular development. PP1 inhibition by tautomycetin increased length of intersegmental vessels (ISVs), whereas MLCK inhibition by ML7 decreased it; these effects were not accompanied by structural dysplasia. ROCK inhibition by Y-27632 also decreased vessel length. An in vitro angiogenesis model of human umbilical vein endothelial cells (HUVECs) showed that tautomycetin increased vascular cord formation, whereas ML7 and Y-27632 decreased it. These effects appear to be influenced by regulation of cell morphology rather than cell viability or motility. Actin co-localized with phosphorylated MLC2 (pMLC2) was abundant in vascular-like elongated-shaped ECs, but poor in non-elongated ECs. pMLC2 was associated with tightly arranged actin, but not with loosely arranged actin. Moreover, knockdown of MYL9 gene encoding MLC2 reduced total MLC2 and pMLC2 protein and inhibited angiogenesis in HUVECs.

CONCLUSION

The present study found that MLC2 is a pivotal regulator of angiogenesis. MLC2 phosphorylation may be involved in the regulation of of cell morphogenesis and cell elongation. The functionally opposite inhibitors positively or negatively control angiogenesis, probably through the regulating EC morphology. These findings may provide a unique therapeutic target for angiogenesis.

Current perspectives of KRAS in non-small cell lung cancer

NSCLC has a diverse genomic background with mutations in key proto-oncogenic drivers including Kirsten rat sarcoma (KRAS) and epidermal growth factor receptor (EGFR). Roughly 40% of adenocarcinoma harbor Kras activating mutations regardless of smoking history. Most KRAS mutations are located at G12, which include G12C (roughly 40%), G12V (roughly 20%), and G12D (roughly 15%). KRAS mutated NSCLC have higher tumor mutational burden and some have increased PD-1 expression, which has resulted in better responses to immunotherapy than other oncogenes. While initial treatment for metastatic NSCLC still relies on chemo-immunotherapy, directly targeting KRAS has proven to be efficacious in treating patients with KRAS mutated metastatic NSCLC. To date, two G12C inhibitors have been FDA-approved, namely sotorasib and adagrasib. In this review, we summarize the different drug combinations used to target KRAS G12c, upcoming G12D inhibitors and novel therapies targeting KRAS.

Targeting guanine nucleotide exchange factors for novel cancer drug discovery

INTRODUCTION

Guanine nucleotide exchange factors (GEFs) regulate the activation of small GTPases (G proteins) of the Ras superfamily proteins controlling cellular functions. Ras superfamily proteins act as 'molecular switches' that are turned 'ON' by guanine exchange. There are five major groups of Ras family GTPases: Ras, Ran, Rho, Rab and Arf, with a variety of different GEFs regulating their GTP loading. GEFs have been implicated in various diseases including cancer. This makes GEFs attractive targets to modulate signaling networks controlled by small GTPases.

AREAS COVERED

In this review, the roles and mechanisms of GEFs in malignancy are outlined. The mechanism of guanine exchange activity by GEFs on a small GTPase is illustrated. Then, some examples of GEFs that are significant in cancer are presented with a discussion on recent progress in therapeutic targeting efforts using a variety of approaches.

EXPERT OPINION

Recently, GEFs have emerged as potential therapeutic targets for novel cancer drug development. Targeting small GTPases is challenging; thus, targeting their activation by GEFs is a promising strategy. Most GEF-targeted drugs are still in preclinical development. A deeper biological understanding of the underlying mechanisms of GEF activity and utilizing advanced technology are necessary to enhance drug discovery for GEFs in cancer.

Investigating underlying molecular mechanisms, signaling pathways, emerging therapeutic approaches in pancreatic cancer

Pancreatic adenocarcinoma, a clinically challenging malignancy constitutes a significant contributor to cancer-related mortality, characterized by an inherently poor prognosis. This review aims to provide a comprehensive understanding of pancreatic adenocarcinoma by examining its multifaceted etiologies, including genetic mutations and environmental factors. The review explains the complex molecular mechanisms underlying its pathogenesis and summarizes current therapeutic strategies, including surgery, chemotherapy, and emerging modalities such as immunotherapy. Critical molecular pathways driving pancreatic cancer development, including KRAS, Notch, and Hedgehog, are discussed. Current therapeutic strategies, including surgery, chemotherapy, and radiation, are discussed, with an emphasis on their limitations, particularly in terms of postoperative relapse. Promising research areas, including liquid biopsies, personalized medicine, and gene editing, are explored, demonstrating the significant potential for enhancing diagnosis and treatment. While immunotherapy presents promising prospects, it faces challenges related to immune evasion mechanisms. Emerging research directions, encompassing liquid biopsies, personalized medicine, CRISPR/Cas9 genome editing, and computational intelligence applications, hold promise for refining diagnostic approaches and therapeutic interventions. By integrating insights from genetic, molecular, and clinical research, innovative strategies that improve patient outcomes can be developed. Ongoing research in these emerging fields holds significant promise for advancing the diagnosis and treatment of this formidable malignancy.

Epithelial-mesenchymal transition status is a remarkable biomarker for the combination treatment with avutometinib and defactinib in KRAS-mutated non-small cell lung cancer

BACKGROUND

Recent therapeutic strategies for KRAS-mutated cancers that inhibit the MAPK pathway have attracted considerable attention. The RAF/MEK clamp avutometinib (VS-6766/CH5126766/RO5126766/CKI27) is promising for patients with KRAS-mutated cancers. Although avutometinib monotherapy has shown clinical activity in patients with KRAS-mutated cancers, effective combination strategies will be important to develop.

METHODS

Using a phosphorylation kinase array kit, we explored the feedback mechanism of avutometinib in KRAS-mutated NSCLC cells, and investigated the efficacy of combining avutometinib with inhibitors of the feedback signal using in vitro and in vivo experiments. Moreover, we searched for a biomarker for the efficacy of combination therapy through an in vitro study and analysis using the The Cancer Genome Atlas Programme dataset.

RESULTS

Focal adhesion kinase (FAK) phosphorylation/activation was increased after avutometinib treatment and synergy between avutometinib and FAK inhibitor, defactinib, was observed in KRAS-mutated NSCLC cells with an epithelial rather than mesenchymal phenotype. Combination therapy with avutometinib and defactinib induced apoptosis with upregulation of Bim in cancer cells with an epithelial phenotype in an in vitro and in vivo study.

CONCLUSIONS

These results demonstrate that the epithelial-mesenchymal transition status may be a promising biomarker for the efficacy of combination therapy with avutometinib and defactinib in KRAS-mutated NSCLC.

FAK loss reduces BRAFV600E-induced ERK phosphorylation to promote intestinal stemness and cecal tumor formation

BRAFV600E mutation is a driver mutation in the serrated pathway to colorectal cancers. BRAFV600E drives tumorigenesis through constitutive downstream extracellular signal-regulated kinase (ERK) activation, but high-intensity ERK activation can also trigger tumor suppression. Whether and how oncogenic ERK signaling can be intrinsically adjusted to a 'just-right' level optimal for tumorigenesis remains undetermined. In this study, we found that FAK (Focal adhesion kinase) expression was reduced in BRAFV600E-mutant adenomas/polyps in mice and patients. In Vil1-Cre;BRAFLSL-V600E/+;Ptk2fl/fl mice, Fak deletion maximized BRAFV600E's oncogenic activity and increased cecal tumor incidence to 100%. Mechanistically, our results showed that Fak loss, without jeopardizing BRAFV600E-induced ERK pathway transcriptional output, reduced EGFR (epidermal growth factor receptor)-dependent ERK phosphorylation. Reduction in ERK phosphorylation increased the level of Lgr4, promoting intestinal stemness and cecal tumor formation. Our findings show that a 'just-right' ERK signaling optimal for BRAFV600E-induced cecal tumor formation can be achieved via Fak loss-mediated downregulation of ERK phosphorylation.

Enhanced MAPK signaling induced by CSF3R mutants confers dependence to DUSP1 for leukemic transformation

ABSTRACT

Elevated MAPK and the JAK-STAT signaling play pivotal roles in the pathogenesis of chronic neutrophilic leukemia and atypical chronic myeloid leukemia. Although inhibitors targeting these pathways effectively suppress the diseases, they fall short in providing enduring remission, largely attributed to the cytostatic nature of these drugs. Even combinations of these drugs are ineffective in achieving sustained remission. Enhanced MAPK signaling besides promoting proliferation and survival triggers a proapoptotic response. Consequently, malignancies reliant on elevated MAPK signaling use MAPK feedback regulators to intricately modulate the signaling output, prioritizing proliferation and survival while dampening the apoptotic stimuli. Herein, we demonstrate that enhanced MAPK signaling in granulocyte colony-stimulating factor 3 receptor (CSF3R)-driven leukemia upregulates the expression of dual specificity phosphatase 1 (DUSP1) to suppress the apoptotic stimuli crucial for leukemogenesis. Consequently, genetic deletion of Dusp1 in mice conferred synthetic lethality to CSF3R-induced leukemia. Mechanistically, DUSP1 depletion in leukemic context causes activation of JNK1/2 that results in induced expression of BIM and P53 while suppressing the expression of BCL2 that selectively triggers apoptotic response in leukemic cells. Pharmacological inhibition of DUSP1 by BCI (a DUSP1 inhibitor) alone lacked antileukemic activity due to ERK1/2 rebound caused by off-target inhibition of DUSP6. Consequently, a combination of BCI with a MEK inhibitor successfully cured CSF3R-induced leukemia in a preclinical mouse model. Our findings underscore the pivotal role of DUSP1 in leukemic transformation driven by enhanced MAPK signaling and advocate for the development of a selective DUSP1 inhibitor for curative treatment outcomes.

Multiomic ALS signatures highlight subclusters and sex differences suggesting the MAPK pathway as therapeutic target

Amyotrophic lateral sclerosis (ALS) is a debilitating motor neuron disease and lacks effective disease-modifying treatments. This study utilizes a comprehensive multiomic approach to investigate the early and sex-specific molecular mechanisms underlying ALS. By analyzing the prefrontal cortex of 51 patients with sporadic ALS and 50 control subjects, alongside four transgenic mouse models (C9orf72-, SOD1-, TDP-43-, and FUS-ALS), we have uncovered significant molecular alterations associated with the disease. Here, we show that males exhibit more pronounced changes in molecular pathways compared to females. Our integrated analysis of transcriptomes, (phospho)proteomes, and miRNAomes also identified distinct ALS subclusters in humans, characterized by variations in immune response, extracellular matrix composition, mitochondrial function, and RNA processing. The molecular signatures of human subclusters were reflected in specific mouse models. Our study highlighted the mitogen-activated protein kinase (MAPK) pathway as an early disease mechanism. We further demonstrate that trametinib, a MAPK inhibitor, has potential therapeutic benefits in vitro and in vivo, particularly in females, suggesting a direction for developing targeted ALS treatments.

RASopathies - what they reveal about RAS/MAPK signaling in skeletal muscle development

RASopathies are rare developmental genetic syndromes caused by germline pathogenic variants in genes that encode components of the RAS/mitogen-activated protein kinase (MAPK) signal transduction pathway. Although the incidence of each RASopathy syndrome is rare, collectively, they represent one of the largest groups of multiple congenital anomaly syndromes and have severe developmental consequences. Here, we review our understanding of how RAS/MAPK dysregulation in RASopathies impacts skeletal muscle development and the importance of RAS/MAPK pathway regulation for embryonic myogenesis. We also discuss the complex interactions of this pathway with other intracellular signaling pathways in the regulation of skeletal muscle development and growth, and the opportunities that RASopathy animal models provide for exploring the use of pathway inhibitors, typically used for cancer treatment, to correct the unique skeletal myopathy caused by the dysregulation of this pathway.

Lapatinib combined with doxorubicin causes dose-dependent cardiotoxicity partially through activating the p38MAPK signaling pathway in zebrafish embryos

Because of its enhanced antitumor efficacy, lapatinib (LAP) is commonly used clinically in combination with the anthracycline drug doxorubicin (DOX) to treat metastatic breast cancer. While it is well recognized that this combination chemotherapy can lead to an increased risk of cardiotoxicity in adult women, its potential cardiotoxicity in the fetus during pregnancy remains understudied. Here, we aimed to examine the combination of LAP chemotherapy and DOX-induced cardiotoxicity in the fetus using a zebrafish embryonic system and investigate the underlying pathologic mechanisms. First, we examined the dose-dependent cardiotoxicity of combined LAP and DOX exposure in zebrafish embryos, which mostly manifested as pericardial edema, bradycardia, cardiac function decline and reduced survival. Second, we revealed that a significant increase in oxidative stress concurrent with activated MAPK signaling, as indicated by increased protein expression of phosphorylated p38 and Jnk, was a notable pathophysiological event after combined LAP and DOX exposure. Third, we showed that inhibiting MAPK signaling by pharmacological treatment with the p38MAPK inhibitor SB203580 or genetic ablation of the map2k6 gene could significantly alleviate combined LAP and DOX exposure-induced cardiotoxicity. Thus, we provided both pharmacologic and genetic evidence to suggest that inhibiting MAPK signaling could exert cardioprotective effects. These findings have implications for understanding the potential cardiotoxicity induced by LAP and DOX combinational chemotherapy in the fetus during pregnancy, which could be leveraged for the development of new therapeutic strategies.

Signaling pathways in liver cancer: pathogenesis and targeted therapy

Liver cancer remains one of the most prevalent malignancies worldwide with high incidence and mortality rates. Due to its subtle onset, liver cancer is commonly diagnosed at a late stage when surgical interventions are no longer feasible. This situation highlights the critical role of systemic treatments, including targeted therapies, in bettering patient outcomes. Despite numerous studies on the mechanisms underlying liver cancer, tyrosine kinase inhibitors (TKIs) are the only widely used clinical inhibitors, represented by sorafenib, whose clinical application is greatly limited by the phenomenon of drug resistance. Here we show an in-depth discussion of the signaling pathways frequently implicated in liver cancer pathogenesis and the inhibitors targeting these pathways under investigation or already in use in the management of advanced liver cancer. We elucidate the oncogenic roles of these pathways in liver cancer especially hepatocellular carcinoma (HCC), as well as the current state of research on inhibitors respectively. Given that TKIs represent the sole class of targeted therapeutics for liver cancer employed in clinical practice, we have particularly focused on TKIs and the mechanisms of the commonly encountered phenomena of its resistance during HCC treatment. This necessitates the imperative development of innovative targeted strategies and the urgency of overcoming the existing limitations. This review endeavors to shed light on the utilization of targeted therapy in advanced liver cancer, with a vision to improve the unsatisfactory prognostic outlook for those patients.

Long Non-Coding RNAs in Drug Resistance of Gastric Cancer: Complex Mechanisms and Potential Clinical Applications

Gastric cancer (GC) ranks as the third most prevalent malignancy and a leading cause of cancer-related mortality worldwide. However, the majority of patients with GC are diagnosed at an advanced stage, highlighting the urgent need for effective perioperative and postoperative chemotherapy to prevent relapse and metastasis. The current treatment strategies have limited overall efficacy because of intrinsic or acquired drug resistance. Recent evidence suggests that dysregulated long non-coding RNAs (lncRNAs) play a significant role in mediating drug resistance in GC. Therefore, there is an imperative to explore novel molecular mechanisms underlying drug resistance in order to overcome this challenging issue. With advancements in deep transcriptome sequencing technology, lncRNAs-once considered transcriptional noise-have garnered widespread attention as potential regulators of carcinogenesis, including tumor cell proliferation, metastasis, and sensitivity to chemo- or radiotherapy through multiple regulatory mechanisms. In light of these findings, we aim to review the mechanisms by which lncRNAs contribute to drug therapy resistance in GC with the goal of providing new insights and breakthroughs toward overcoming this formidable obstacle.

DeKinomics pulse-chases kinase functions in living cells

Cellular context is crucial for understanding the complex and dynamic kinase functions in health and disease. Systematic dissection of kinase-mediated cellular processes requires rapid and precise stimulation ('pulse') of a kinase of interest, as well as global and in-depth characterization ('chase') of the perturbed proteome under living conditions. Here we developed an optogenetic 'pulse-chase' strategy, termed decaging kinase coupled proteomics (DeKinomics), for proteome-wide profiling of kinase-driven phosphorylation at second-timescale in living cells. We took advantage of the 'gain-of-function' feature of DeKinomics to identify direct kinase substrates and further portrayed the global phosphorylation of understudied receptor tyrosine kinases under native cellular settings. DeKinomics offered a general activation-based strategy to study kinase functions with high specificity and temporal resolution under living conditions.

MEK Inhibition for RASopathy-Associated Hypertrophic Cardiomyopathy: Clinical Application of a Basic Concept

The term "RASopathies" designates a group of developmental syndromes that are caused by activating variants of the rat sarcoma virus protein (RAS)/mitogen-activated protein kinase (MAPK) cascade. The most prevalent clinical diagnosis is Noonan syndrome, and other, less prevalent conditions include Noonan syndrome with multiple lentigines, Costello syndrome, cardiofaciocutaneous syndrome, and others. Hypertrophic cardiomyopathy occurs in 10% of these patients and can be severe and life-threating. Recently, repurposing of medications inhibiting the RAS/MAPK on a compassionate use basis has emerged as a promising concept to improve the outcome of these patients. Herein, we specifically review the role of the RAS/MAPK pathway in RASopathy-associated cardiomyopathy, and discuss the role of small-molecule inhibition in the treatment of this condition. We describe how drug repurposing of trametinib (mitogen-activated protein/extracellular signal-regulated kinase inhibition) and sirolimus/everolimus (mammalian target of rapamycin inhibition) was performed, how genotype-specific therapies are chosen and followed, as well as initial outcomes from early case series. Finally, we lay out the challenges and opportunities for trials that aim to quantify the benefits of this approach.

The role of the master cancer regulator Pin1 in the development and treatment of cancer

This review examines the complex role of Pin1 in the development and treatment of cancer. Pin1 is the only peptidyl-prolyl isomerase (PPIase) that can recognize and isomerize phosphorylated Ser/Thr-Pro peptide bonds. Pin1 catalyzes a structural change in phosphorylated Ser/Thr-Pro motifs that can modulate protein function and thereby impact cell cycle regulation and tumorigenesis. The molecular mechanisms by which Pin1 contributes to oncogenesis are reviewed, including Pin1 overexpression and its correlation with poor cancer prognosis, and the contribution of Pin1 to aggressive tumor phenotypes involved in therapeutic resistance is discussed, with an emphasis on cancer stem cells, the epithelial-to-mesenchymal transition (EMT), and immunosuppression. The therapeutic potential of Pin1 inhibition in cancer is discussed, along with the promise and the difficulties in identifying potent, drug-like, small-molecule Pin1 inhibitors. The available evidence supports the efficacy of targeting Pin1 as a novel cancer therapeutic by analyzing the role of Pin1 in a complex network of cancer-driving pathways and illustrating the potential of synergistic drug combinations with Pin1 inhibitors for treating aggressive and drug-resistant tumors.

The Legionella pneumophila effector DenR hijacks the host NRas proto-oncoprotein to downregulate MAPK signaling

Small GTPases of the Ras subfamily are best known for their role as proto-oncoproteins, while their function during microbial infection has remained elusive. Here, we show that Legionella pneumophila hijacks the small GTPase NRas to the Legionella-containing vacuole (LCV) surface. A CRISPR interference screen identifies a single L. pneumophila effector, DenR (Lpg1909), required for this process. Recruitment is specific for NRas, while its homologs KRas and HRas are excluded from LCVs. The C-terminal hypervariable tail of NRas is sufficient for recruitment, and interference with either NRas farnesylation or S-acylation sites abrogates recruitment. Intriguingly, we detect markers of active NRas signaling on the LCV, suggesting it acts as a signaling platform. Subsequent phosphoproteomics analyses show that DenR rewires the host NRas signaling landscape, including dampening of the canonical mitogen-activated protein kinase pathway. These results provide evidence for L. pneumophila targeting NRas and suggest a link between NRas GTPase signaling and microbial infection.

Uncovering the pharmacological mechanism of Shou Tai Wan on recurrent spontaneous abortion: A integrated pharmacology strategy-based research

ETHNOPHARMACOLOGICAL RELEVANCE

Shou Tai Wan (STW), a traditional Chinese medicine formula, has been historically used for the treatment of recurrent spontaneous abortion (RSA). Despite its long-standing usage, the exact mechanism underlying the therapeutic effects of STW remains unclear in the existing literature.

AIMS OF THIS STUDY

To explore the Pharmacological Mechanism of STW on RSA.

METHODS

A network pharmacological methodology was utilized to predict the active compounds and potential targets of STW, collect the RSA targets and other human proteins of STW, and analyze the STW related networks. The animal experiments were also performed to validate the effect of STW on RSA.

RESULTS

The results of network analysis showed that STW may regulate PI3K/AKT, MAPK, FoxO signaling pathways and so on. Animal experiment established the RSA model with CBA/J × DBA/2 mice. It was found that STW can reduce the embryo absorption rate of RSA group (p < 0.05) and balance the expression of Th 1/Th2 type cytokines compared with the model group. After 14 days of administration, the decidual and placental tissues were taken and the CD4+ T cells were isolated, and the phosphorylation level of signaling pathway was detected by Springbio720 antibody microarray. This experiment found that STW can significantly up-regulate the phosphorylation levels of STAT3 and STAT6 proteins in the STAT signaling pathway, and down-regulating the phosphorylation level of STAT1 protein. STW also significantly up-regulated the phosphorylation levels of Raf1, A-Raf, Ask1, Mek1, Mek2, JKK1, ERK1, ERK2, c-fos, c-Jun and CREB proteins in the MAPK signaling pathway, and down-regulate the phosphorylation levels of MEK6 and IKKb proteins. Compared with the RSA group, the STW group increased the expression levels of ERK1/2 mRNA and proteins and p-ERK1/2 proteins, and there was a statistical difference (p < 0.05). This is consistent with the chip results.

CONCLUSION

STW may achieve therapeutic effects by interfering with the signaling pathways, biological processes and targets discovered in this study. It provides a new perspective for revealing the immunological mechanism of STW in the treatment of RSA, and also provides a theoretical basis for the clinical use of STW in the treatment of RSA.

KRAS: Biology, Inhibition, and Mechanisms of Inhibitor Resistance

KRAS is a small GTPase that is among the most commonly mutated oncogenes in cancer. Here, we discuss KRAS biology, therapeutic avenues to target it, and mechanisms of resistance that tumors employ in response to KRAS inhibition. Several strategies are under investigation for inhibiting oncogenic KRAS, including small molecule compounds targeting specific KRAS mutations, pan-KRAS inhibitors, PROTACs, siRNAs, PNAs, and mutant KRAS-specific immunostimulatory strategies. A central challenge to therapeutic effectiveness is the frequent development of resistance to these treatments. Direct resistance mechanisms can involve KRAS mutations that reduce drug efficacy or copy number alterations that increase the expression of mutant KRAS. Indirect resistance mechanisms arise from mutations that can rescue mutant KRAS-dependent cells either by reactivating the same signaling or via alternative pathways. Further, non-mutational forms of resistance can take the form of epigenetic marks, transcriptional reprogramming, or alterations within the tumor microenvironment. As the possible strategies to inhibit KRAS expand, understanding the nuances of resistance mechanisms is paramount to the development of both enhanced therapeutics and innovative drug combinations.

Integrated analyses for identification of a three-gene signature associated with Chaihu Shugan San formula for hepatocellular carcinoma treatment

Chaihu Shugan San (CSS) is a well-known traditional herbal formula that has the potential to ameliorate hepatocellular carcinoma (HCC); however, its mechanism of action remains unknown. Here, we identified the key targets of CSS against HCC and developed a prognostic model to predict the survival of patients with HCC. The effect of CSS plus sorafenib on HCC cell proliferation was evaluated using the MTT assay. LASSO-Cox regression was used to establish a three-gene signature model targeting CSS. Correlations between immune cells, immune checkpoints and risk score were determined to evaluate the immune-related effects of CSS. The interactions between the components and targets were validated using molecular docking and Surface Plasmon Resonance (SPR) assays. CSS and sorafenib synergistically inhibited HCC cell proliferation. Ten core compounds and 224 targets were identified using a drug compound-target network. The prognostic model of the three CSS targets (AKT1, MAPK3 and CASP3) showed predictive ability. Risk scores positively correlated with cancer-promoting immune cells and high expression of immune checkpoint proteins. Molecular docking and SPR analyses confirmed the strong binding affinities of the active components and the target genes. Western blot analysis confirmed the synergistic effect of CSS and sorafenib in inhibiting the expression of these three targets. In conclusion, CSS may regulate the activity of immune-related factors in the tumour microenvironment, reverse immune escape, enhance immune responses through AKT1, MAPK3, and CASP3, and synergistically alleviate HCC. The co-administration of sorafenib with CSS has a strong clinical outlook against HCC.

Tonic ErbB signaling underlies TGFβ-induced activation of ERK and is required for lens cell epithelial to myofibroblast transition

Fibrosis is a major, but incompletely understood, component of many diseases. The most common vision-disrupting complication of cataract surgery involves differentiation of residual lens cells into myofibroblasts. In serum-free primary cultures of lens epithelial cells (DCDMLs), inhibitors of either ERK or of ErbB signaling prevent TGFβ from upregulating both early (fibronectin) and late (αSMA) markers of myofibroblast differentiation. TGFβ stimulates ERK in DCDMLs within 1.5 h. Kinase inhibitors of ErbBs, but not of several other growth factor receptors in lens cells, reduce phospho ERK to below basal levels in the absence or presence of TGFβ. This effect is attributable to constitutive ErbB activity playing a major role in regulating the basal levels pERK. Additional studies support a model in which TGFβ-generated reactive oxygen species serve to indirectly amplify ERK signaling downstream of tonically active ErbBs to mediate myofibroblast differentiation. ERK activity is in turn essential for expression of ErbB1 and ErbB2, major inducers of ERK signaling. By mechanistically linking TGFβ, ErbB, and ERK signaling to myofibroblast differentiation, our data elucidate a new role for ErbBs in fibrosis and reveal a novel mode by which TGFβ directs lens cell fate.