Functional Recovery Associated with Dendrite Regeneration in PVD Neuron of Caenorhabditis elegans

PVD neuron of Caenorhabditis elegans is a highly polarized cell with well-defined axonal, and dendritic compartments. PVD neuron operates in multiple sensory modalities including the control of both nociceptive touch sensation and body posture. Although both the axon and dendrites of this neuron show a regeneration response following laser-assisted injury, it is rather unclear how the behavior associated with this neuron is affected by the loss of these structures. It is also unclear whether neurite regrowth would lead to functional restoration in these neurons. Upon axotomy, using a femtosecond laser, we saw that harsh touch response was specifically affected leaving the body posture unperturbed. Subsequently, recovery in the touch response is highly correlated to the axon regrowth, which was dependent on DLK-1/MLK-1 MAP Kinase. Dendrotomy of both major and minor primary dendrites affected the wavelength and amplitude of sinusoidal movement without any apparent effect on harsh touch response. We further correlated the recovery in posture behavior to the type of dendrite regeneration events. We found that dendrite regeneration through the fusion and reconnection between the proximal and distal branches of the injured dendrite corresponded to improved recovery in posture. Our data revealed that the axons and dendrites of PVD neurons regulate the nociception and proprioception in worms, respectively. It also revealed that dendrite and axon regeneration lead to the restoration of these differential sensory modalities.

Ciliogenesis-associated Kinase 1 Promotes Breast Cancer Cell Proliferation and Chemoresistance via Phosphorylating ERK1

Ciliogenesis-associated kinase 1 (CILK1) plays a key role in the ciliogenesis and ciliopathies. It remains totally unclear whether CILK1 is involved in tumor progression and therapy resistance. Here, we report that the aberrant high-expression of CILK1 in breast cancer is required for tumor cell proliferation and chemoresistance. Two compounds, CILK1-C30 and CILK1-C28, were identified with selective inhibitory effects towards the Tyr-159/Thr-157 dual-phosphorylation of CILK1, pharmacological inhibition of CILK1 significantly suppressed tumor cell proliferation and overcame chemoresistance in multiple experimental models. Large-scale screen of CILK1 substrates confirmed that the kinase directly phosphorylates ERK1, which is responsible for CILK1-mediated oncogenic function. CILK1 is also indicated to be responsible for the chemoresistance of small-cell lung cancer cells. Our data highlight the importance of CILK1 in cancer, implicating that targeting CILK1/ERK1 might offer therapeutic benefit to cancer patients.

Structural Insights on the Role of Halogen Bonding in Protein MEK Kinase-Inhibitor Complexes

Kinases are enzymes that play a critical role in governing essential biological processes. Due to their pivotal involvement in cancer cell signaling, they have become key targets in the development of anti-cancer drugs. Among these drugs, those containing the 2,4-dihalophenyl moiety demonstrated significant potential. Here we show how this moiety, particularly the 2-fluoro-4-iodophenyl one, is crucial for the structural stability of the formed drug-enzyme complexes. Crystallographic analysis of reported kinase-inhibitor complex structures highlights the role of the halogen bonding that this moiety forms with specific residues of the kinase binding site. This interaction is not limited to FDA-approved MEK inhibitors, but it is also relevant for other kinase inhibitors, indicating its broad relevance in the design of this class of drugs.

Response to Dabrafenib Plus Trametinib in a Patient With an Uncommon Activating BRAF Mutation: A First in Non-Small Cell Lung Cancer

Mutations in BRAF are present in 4% of non-small cell lung cancer (NSCLC), of which half are well-characterized activating variants affecting codon 600 (classified as class I). These mutations, most commonly BRAF V600E, have been associated with response to BRAF/MEK-directed small molecule kinase inhibitors. NSCLC with kinase-activating BRAF mutations occurring at other codons (class II variants) represent a substantial portion of BRAF-mutated NSCLC, but use of targeted therapy in these tumors is still under investigation. Class II mutations have been described in other tumor types and have been associated with response to BRAF/MEK-targeted agents, although optimal treatment strategies for these patients are lacking. This report presents a case of a woman with metastatic NSCLC harboring a class II BRAF p.N486_P490del variant who had a sustained clinical response to combination therapy with dabrafenib and trametinib. This first report of the use of BRAF/MEK-targeted therapy for this variant in NSCLC supports consideration of such treatment for tumors with class II BRAF variants.

Circ_SIPA1L1 Promotes Osteosarcoma Progression Via miR-379-5p/MAP3K9 Axis

Background: Osteosarcoma (OS) is a common malignant bone tumor. Circular RNAs (circRNAs) exert important roles in the pathogenesis of human cancers, including OS. In this study, the authors focused on the role and mechanism of circRNA signal-induced proliferation-associated 1 like 1 (circ_SIPA1L1) in OS. Methods: The enrichment of SIPA1L1, circ_SIPA1L1, microRNA-379-5p (miR-379-5p), and mitogen-activated protein kinase kinase kinase 9 (MAP3K9) was assessed by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The colony formation capacity was assessed through colony formation assay. Transwell assays were used to detect the migration and invasion abilities. Western blot assay was used to measure the expression of metastasis-related proteins and MAP3K9. The target interactions between the genes in circ_SIPA1L1/miR-379-5p/MAP3K9 axis were predicted by StarBase and confirmed by dual-luciferase reporter assay. The in vivo role of circ_SIPA1L1 was verified by murine xenograft assay. Results: Circ_SIPA1L1 abundance was aberrantly elevated in OS tissues and cell lines. Circ_SIPA1L1 accelerated the proliferation and metastasis abilities of OS cells. Circ_SIPA1L1 promoted the malignant behaviors of OS cells through elevating MAP3K9 level. MiR-379-5p directly bound to circ_SIPA1L1 and MAP3K9. MiR-379-5p interference rescued the abilities of proliferation and metastasis in OS cells, which were suppressed by the silencing of circ_SIPA1L1. Circ_SIPA1L1 promoted the development of OS via miR-379-5p/MAP3K9 in vivo. Conclusion: Circ_SIPA1L1 promoted the progression of OS via miR-379-5p/MAP3K9 axis.

An intraflagellar transport dependent negative feedback regulates the MAPKKK DLK-1 to protect cilia from degeneration

Primary cilia are specialized organelles supporting the development and function of cells and organisms. Intraflagellar transport (IFT) is essential for cilia formation, maintenance, and function. In C. elegans ciliated sensory neurons, IFT interacts with signaling molecules to generate distinct morphological and function features and also to maintain the integrity of cilia. Here, we report an IFT-dependent feedback control on the conserved MAPKKK DLK-1 in the ciliated sensory neurons. DLK proteins are widely known to act in synapse formation, axon regeneration, and degeneration, but their roles in other neuronal compartments are understudied. By forward genetic screening for altered expression of the endogenously tagged DLK-1 we identified multiple ift mutants showing increased DLK-1 accumulation in the defective sensory endings. We show that in response to acute IFT disruption, DLK-1 accumulates rapidly and reversibly. The expression levels of the transcription factor CEBP-1, known to act downstream of DLK-1 in the development and maintenance of synapses and axons, are also increased in the ciliated sensory neurons of ift mutants. Interestingly, the regulation of CEBP-1 expression shows sensory neuron-type dependency on DLK-1. Moreover, in the sensory neuron AWC, which has elaborate cilia morphology, up-regulated CEBP-1 represses DLK-1 at the transcription level, thereby dampening DLK-1 accumulation. Last, the IFT-dependent regulatory loop of DLK-1 and CEBP-1 offers neuroprotection in a cilia degeneration model. These findings uncover a surveillance mechanism in which tight control on the DLK-1 signaling protects cilia integrity in a context-specific manner.

Multiple p38/JNK mitogen-activated protein kinase (MAPK) signaling pathways mediate salt chemotaxis learning in C. elegans

Animals are able to adapt their behaviors to the environment. In order to achieve this, the nervous system plays integrative roles, such as perception of external signals, sensory processing, and behavioral regulations via various signal transduction pathways. Here genetic analyses of Caenorhabditis elegans (C. elegans) found that mutants of components of JNK and p38 mitogen-activated protein kinase (MAPK) signaling pathways, also known as stress-activated protein kinase (SAPK) signaling pathways, exhibit various types of defects in the learning of salt chemotaxis. C. elegans homologs of JNK MAPKKK and MAPKK, MLK-1 and MEK-1, respectively, are required for avoidance of salt concentrations experienced during starvation. In contrast, homologs of p38 MAPKKK and MAPKK, NSY-1 and SEK-1, respectively, are required for high-salt chemotaxis after conditioning. Genetic interaction analyses suggest that a JNK family MAPK, KGB-1, functions downstream of both signaling pathways to regulate salt chemotaxis learning. Furthermore, we found that the NSY-1/SEK-1 pathway functions in sensory neurons, ASH, ADF, and ASER, to regulate the learned high-salt chemotaxis. A neuropeptide, NLP-3, expressed in ASH, ADF, and ASER neurons, and a neuropeptide receptor, NPR-15, expressed in AIA interneurons that receive synaptic input from these sensory neurons, function in the same genetic pathway as NSY-1/SEK-1 signaling. These findings suggest that this MAPK pathway may affect neuropeptide signaling between sensory neurons and interneurons, thus promoting high-salt chemotaxis after conditioning.

Femtosecond laser microdissection for isolation of regenerating C. elegans neurons for single-cell RNA sequencing

Our understanding of nerve regeneration can be enhanced by delineating its underlying molecular activities at single-neuron resolution in model organisms such as Caenorhabditis elegans. Existing cell isolation techniques cannot isolate neurons with specific regeneration phenotypes from C. elegans. We present femtosecond laser microdissection (fs-LM), a single-cell isolation method that dissects specific cells directly from living tissue by leveraging the micrometer-scale precision of fs-laser ablation. We show that fs-LM facilitates sensitive and specific gene expression profiling by single-cell RNA sequencing (scRNA-seq), while mitigating the stress-related transcriptional artifacts induced by tissue dissociation. scRNA-seq of fs-LM isolated regenerating neurons revealed transcriptional programs that are correlated with either successful or failed regeneration in wild-type and dlk-1 (0) animals, respectively. This method also allowed studying heterogeneity displayed by the same type of neuron and found gene modules with expression patterns correlated with axon regrowth rate. Our results establish fs-LM as a spatially resolved single-cell isolation method for phenotype-to-genotype mapping.

Inhibition of MEK signaling prevents SARS-CoV2-induced lung damage and improves the survival of infected mice

Coronavirus disease 2019 (COVID-19) is the illness caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Over 500 million confirmed cases of COVID-19 have been recorded, with six million deaths. Thus, reducing the COVID-19-related medical burden is an unmet need. Despite a vaccine that is successful in preventing COVID-19-caused death, effective medication to relieve COVID-19-associated symptoms and alleviate disease progression is still in high demand. In particular, one in three COVID-19 patients have signs of long COVID syndrome and are termed, long haulers. At present, there are no effective ways to treat long haulers. In this study, we determine the effectiveness of inhibiting mitogen-activated protein kinase (MEK) signaling in preventing SARS-CoV-2-induced lung damage in mice. We showed that phosphorylation of extracellular signal-regulated kinase, a marker for MEK activation, is high in SARS-CoV-2-infected lung tissues of mice and humans. We also showed that selumetinib, a specific inhibitor of the upstream MEK kinases, reduces cell proliferation, reduces lung damage following SARS-CoV-2 infection, and prolongs the survival of the infected mice. Selumetinib has been approved by the US Food and Drug Administration to treat cancer. Further analysis indicates that amphiregulin, an essential upstream molecule, was upregulated following SARS-CoV-2 infection. Our data suggest that MEK signaling activation represents a target for therapeutic intervention strategies against SARS-CoV-2-induced lung damage and that selumetinib may be repurposed to treat COVID-19.

A Prognostic Risk Model of a Novel Oxidative Stress-Related Signature Predicts Clinical Prognosis and Demonstrates Immune Relevancy in Lung Adenocarcinoma

Lung adenocarcinoma (LUAD) is among the most prevalent malignant lung cancers with a poor prognosis due to high invasiveness and lethality despite multiple treatments. Since the lung is an important organ associated with oxidative stress, and it has been confirmed that oxidative stress represents a potential cancer-specific depletion, it is of important significance to investigate and evaluate the clinical value of oxidative stress mechanisms regulating tumor cell apoptosis. Furthermore, there are few studies on the impact of the microenvironment on reaction to immune-checkpoint inhibitors (ICIs) in patients with LUAD. Based on the TCGA-LUAD dataset, which is stratified into a training set as well as a validation set in a ratio of 2 : 1, this investigation constructs and validates a prognostic predictive power of a gene signature model of oxidative stress-related prognostic signatures. To ascertain the differences between the high-risk score group and the low-risk score group in tumor-infiltrating lymphocytes and patients' response to ICI therapy. This oxidative stress-related prognostic gene signature is composed of MAP3K19 and NTSR1 and is an independent prognosis-related factor in the LUAD group. The outcome of patients having a low risk score is better, and the difference was statistically significant, and individuals with a low risk score had a larger number of infiltrating immune cell distribution in the tumor microenvironment, which was closely related to clinical outcome. Our study suggests that the synergistic effect of oxidative stress-related prognostic gene markers-MAP3K19 and NTSR1 has clinical significance in the prognosis identification and immunotherapy of LUAD patients. Thus, the results may help to better intersect the oxidative stress-related mechanisms in clinical value in LUAD but requires prospective validation.

Shexiang Baoxin Pill attenuates myocardial ischemia/reperfusion injury by activating autophagy via modulating the ceRNA-Map3k8 pathway

BACKGROUND

The pathogenesis of myocardial ischemia/reperfusion is complex, involving multiple regulatory genes and environmental factors, and requiring the simultaneous regulation of multiple targets. Meanwhile, Traditional Chinese Medicine (TCM) has certain advantages in the comprehensive treatment of multi-site, multi-target conditions and overall regulation of this condition. This study explores the effect of the well-known TCM, the Shexiang Baoxin Pill (SBP) on myocardial ischemia/reperfusion injury in mice.

MATERIALS AND METHODS

In vivo, 20 mg/kg/day SBP was administered by gavage for 28 days. In vitro, cardiomyocytes were pretreated with 25 μg/ml SBP for 24 h. Evans blue/TTC double-staining was employed to determine the infarct size. Markers of myocardial injury were detected in the serum and cell supernatants. The changes of pyroptosis and autophagy proteins were detected by western blot. Immunofluorescence, immunohistochemistry and PCR were performed to further illustrate the results.

RESULTS

SBP significantly reduced the myocardial infarct size, decreased the myocardial injury markers, inhibited cardiomyocyte pyroptosis and oxidative stress, and promoted autophagy in vivo. In vitro, SBP alleviated cardiomyocyte pyroptosis, inhibited oxidative stress, reduced IL-1β and IL-18 secretion, and unblocked autophagy flux. Myocardial injury is mitigated by SBP via the rapid degradation of autophagosomes, and SBP promotes the accumulation of autophagosomes by downregulating mmu_circ_0005874, Map3k8 and upregulating mmu-miR-543-3p.

CONCLUSION

We found for the first time that SBP can inhibit pyroptosis and oxidative stress, and protect from myocardial I/R injury. In addition, it inhibits pyroptosis and improves H/R injury by promoting autophagosome generation and accelerating autophagic flux. SBP interferes with autophagy through the interaction between mmu_circ_0005874/mmu-miR-543-3p/Map3k8.

Arabidopsis MAPKK kinases YODA, MAPKKK3, and MAPKKK5 are functionally redundant in development and immunity

Three MAPK cascade components in Arabidopsis, YDA (MAPKKK4) and MAPKKK3/5, function redundantly in multiple developmental processes and immunity and regulate floral organ abscission.

Loss of Tpl2 activates compensatory signaling and resistance to EGFR/MET dual inhibition in v-RAS transduced keratinocytes

Cutaneous squamous cell carcinoma (cSCC) is the second most common form of skin cancer in the United States, affecting one million people per year. Patients with aggressive disease have limited treatment options and high mortality, highlighting the need to identify new biomarkers linked to poor clinical outcome. HRAS mutations are found in skin papillomas and cSCCs and increase in frequency when MAP3K family members are inhibited, suggesting a link between blockade of mitogen-activated protein kinase (MAPK) signaling and initiation of RAS-primed cells. Tpl2, a MAP3K gene, can serve as a tumor suppressor gene in cSCC. We have previously shown that upon Tpl2 ablation, mice have heightened sensitivity to aberrant RAS signaling. Tpl2-/- mice display significantly higher numbers of papillomas and cSCCs in two-stage chemical carcinogenesis studies and increased tumorigenicity of keratinocytes expressing oncogenic v-rasHa in nude mouse skin grafts. In part, this is mediated through increased mesenchymal-epithelial transition factor (MET) receptor activity. Epidermal Growth Factor Receptor (EGFR) is reported to be an essential factor for MET-driven carcinogenesis and MET activation may confer resistance to EGFR therapies, suggesting that the concurrent use of both an EGFR inhibitor and a MET inhibitor may show promise in advanced cSCCs. In this study we assessed whether normal or Ras-transformed Tpl2-/- keratinocytes have aberrant EGFR signaling and whether concomitant treatment with EGFR/MET tyrosine kinase inhibitors was more effective than single agents in reducing growth and angiogenic potential of Ras-transformed keratinocytes. Tpl2-/- keratinocytes exhibited increased HER-2 and STAT-3 under basal conditions and elevated p-MET and p-EGFR when transduced with oncogenic RAS. Inhibition of MET by Capmatinib increased p-EGFR in Tpl2-/- keratinocytes and papillomas, and inhibition of EGFR by Gefitinib increased HER2 and HER3 signaling in both genotypes. Treatment of keratinocytes with EGFR and MET inhibitors, in combination, significantly enhanced endothelial tube formation, MMP-9 activity and activation of other RTKs, with more pronounced effects when Tpl2 was ablated. These data indicate that Tpl2 cross-talks with both EGFR and MET signaling pathways. Upon inhibition of EGFR/MET signaling, a myriad of escape mechanisms exists in keratinocytes to overcome targeted drug effects.

Histiocytosis

Histiocytoses constitute a heterogeneous group of rare disorders, characterised by infiltration of almost any organ by myeloid cells with diverse macrophage or dendritic cell phenotypes. Histiocytoses can start at any age. Diagnosis is based on histology in combination with appropriate clinical and radiological findings. The low incidence and broad spectrum of clinical manifestations often leads to diagnostic delay, especially for adults. In most cases, biopsy specimens infiltrated by histiocytes have somatic mutations in genes activating the MAP kinase cell-signalling pathway. These mutations might also be present in blood cells and haematopoietic progenitors of patients with multisystem disease. A comprehensive range of investigations and molecular typing are essential to accurately predict prognosis, which can vary from spontaneous resolution to life-threatening disseminated disease. Targeted therapies with BRAF or MEK inhibitors have revolutionised salvage treatment. However, the type and duration of treatment are still debated, and the prevention of neurological sequelae remains a crucial issue.

Ras/Raf/MEK/ERK pathway axis mediated neurotoxicity induced by high-risk pesticide residue-Avermectin

Pesticide residues have become a healthy threaten of human beings. Among the pesticides, many of them have neurotoxicity. Extracellular Regulated Protein Kinases (ERK) pathway is an important signaling pathway that regulates a variety of downstream progress. In this work, peach (PRUNUS persica) and cherry (PRUNUS cerasus) were sampled from over 300 plantations in China and assessed for the residue risk. In mechanism studies, high-risk pesticide Avermectin showed a high activity inhibiting three neurotoxicity models, SH-SY5Y, PC-12 and SK-N-SH cells. At protein levels, ERK pathway proteins and their downstream proteins were obviously down-regulated. Moreover, the effects of low-dose Avermectin can be accumulated at protein levels in the low-dose long-term chronic toxicology detection.

The regulatory function of mixed lineage kinase 3 in tumor and host immunity

Protein kinases are the second most sought-after G-protein coupled receptors as drug targets because of their overexpression, mutations, and dysregulated catalytic activities in various pathological conditions. Till 2019, 48 protein kinase inhibitors have received FDA approval for the treatment of multiple illnesses, of which the majority of them are indicated for different malignancies. One of the attractive sub-group of protein kinases that has attracted attention for drug development is the family members of MAPKs that are recognized to play significant roles in different cancers. Several inhibitors have been developed against various MAPK members; however, none of them as monotherapy has shown sustainable efficacy. One of the MAPK members, called Mixed Lineage Kinase 3 (MLK3), has attracted considerable attention due to its role in inflammation and neurodegenerative diseases; however, its role in cancer is an emerging area that needs more investigation. Recent advances have shown that MLK3 plays a role in cancer cell survival, migration, drug resistance, cell death, and tumor immunity. This review describes how MLK3 regulates different MAPK pathways, cancer cell growth and survival, apoptosis, and host's immunity. We also discuss how MLK3 inhibitors can potentially be used along with immunotherapy for different malignancies.

Nuclear Factor-κB Signaling Mediates Antimony-induced Astrocyte Activation

OBJECTIVE

Antimony (Sb) has recently been identified as a novel nerve poison, although the cellular and molecular mechanisms underlying its neurotoxicity remain unclear. This study aimed to assess the effects of the nuclear factor kappa B (NF-κB) signaling pathway on antimony-induced astrocyte activation.

METHODS

Protein expression levels were detected by Western blotting. Immunofluorescence, cytoplasmic and nuclear fractions separation were used to assess the distribution of p65. The expression of protein in brain tissue sections was detected by immunohistochemistry. The levels of mRNAs were detected by Quantitative real-time polymerase chain reaction (qRT-PCR) and reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Antimony exposure triggered astrocyte proliferation and increased the expression of two critical protein markers of reactive astrogliosis, inducible nitric oxide synthase (iNOS) and glial fibrillary acidic protein (GFAP), indicating that antimony induced astrocyte activation in vivo and in vitro. Antimony exposure consistently upregulated the expression of inflammatory factors. Moreover, it induced the NF-κB signaling, indicated by increased p65 phosphorylation and translocation to the nucleus. NF-κB inhibition effectively attenuated antimony-induced astrocyte activation. Furthermore, antimony phosphorylated TGF-β-activated kinase 1 (TAK1), while TAK1 inhibition alleviated antimony-induced p65 phosphorylation and subsequent astrocyte activation.

CONCLUSION

Antimony activated astrocytes by activating the NF-κB signaling pathway.

Plant Osmotic Stress Signaling: MAPKKKs Meet SnRK2s

Osmotic stress signaling in higher plants is crucial to cope with abiotic stress. RAF-like MAPKKKs are activated by hyperosmotic stress and activate downstream ABA-unresponsive and ABA-activated SnRK2s, integrating early osmotic stress and ABA signaling cascades. The connection of B2/B3/B4 RAF-like MAPKKKs with SnRK2s is a new paradigm in signal transduction.

Arabidopsis MAPKKK δ-1 is required for full immunity against bacterial and fungal infection

The genome of Arabidopsis encodes more than 60 mitogen-activated protein kinase kinase (MAPKK) kinases (MAPKKKs); however, the functions of most MAPKKKs and their downstream MAPKKs are largely unknown. Here, MAPKKK δ-1 (MKD1), a novel Raf-like MAPKKK, was isolated from Arabidopsis as a subunit of a complex including the transcription factor AtNFXL1, which is involved in the trichothecene phytotoxin response and in disease resistance against the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 (PstDC3000). A MKD1-dependent cascade positively regulates disease resistance against PstDC3000 and the trichothecene mycotoxin-producing fungal pathogen Fusarium sporotrichioides. MKD1 expression was induced by trichothecenes derived from Fusarium species. MKD1 directly interacted with MKK1 and MKK5 in vivo, and phosphorylated MKK1 and MKK5 in vitro. Correspondingly, mkk1 mutants and MKK5RNAi transgenic plants showed enhanced susceptibility to F. sporotrichioides. MKD1 was required for full activation of two MAPKs (MPK3 and MPK6) by the T-2 toxin and flg22. Finally, quantitative phosphoproteomics suggested that an MKD1-dependent cascade controlled phosphorylation of a disease resistance protein, SUMO, and a mycotoxin-detoxifying enzyme. Our findings suggest that the MKD1-MKK1/MKK5-MPK3/MPK6-dependent signaling cascade is involved in the full immune responses against both bacterial and fungal infection.

Fisetin activates Hippo pathway and JNK/ERK/AP-1 signaling to inhibit proliferation and induce apoptosis of human osteosarcoma cells via ZAK overexpression

Osteosarcoma (OS) is a tumor entity that can cause a large number of cancer-related deaths. Although chemotherapy can decrease proliferation and increase apoptosis of human OS cells, the clinical prognosis remains poor. Fisetin is a flavonol found in fruits and vegetables and is reported to inhibit cell growth in numerous cancers. But the molecular mechanism underlying fisetin in human OS cells is not clear. It is known that sterile-alpha motif and leucine zipper containing kinase (ZAK), a kinase in the MAP3K family, is involved in various cell processes, including proliferation and apoptosis. In our lab, we have demonstrated that overexpression of ZAK can induce apoptosis in human OS cells. In the previous studies, MAP4K, the upstream of MAP3K, can act in parallel to MST1/2 to activate LATS1/2 in the Hippo pathway. Turning on the Hippo pathway can decrease proliferation and otherwise cause cell apoptosis in cancer cells. In this study, we found that fisetin can upregulate ZAK expression to induce the Hippo pathway and mediate the activation of JNK/ERK, the downstream of ZAK, to trigger cell apoptosis via AP-1 dependent manner in human OS cells. These findings reveal a novel molecular mechanism underlying fisetin effect on human OS cells.

Endothelial Cell Killing by TAK1 Inhibition: A Novel Anti-angiogenic Strategy in Cancer Therapy

TAK1 is a key mediator of proinflammatory signals. In this issue of Developmental Cell, Naito et al. (2019) report that TAK1 loss from endothelial cells in adult mice results in intestinal and hepatic vascular destruction due to TNF-induced death of endothelial cells. Additionally, endothelial TAK1 deletion reduces tumor burden.

[Correlation of K-ras Gene Mutations with the Protein Expressions of TAK1 and MAP4K2 in Colorectal Cancer]

OBJECTIVE

To analyze the correlation of K-ras gene mutations with the protein expressions of transforming growth factor-β activating kinase 1 (TAK1) protein and mitogen-activated protein kinase kinase kinase kinase 2 (MAP4K2) protein in colorectal cancer.

METHODS

K-ras gene mutations were detected by DNA sequencing analysis, and the expressions of TAK1 protein and MAP4K2 protein were detected by immunohistochemical method in 76 cases of colorectal cancer tissues.

RESULTS

In 76 cases of colorectal cancer tissues, the mutation rate of K-ras gene was 32.89% (25 cases), and K-ras gene mutations were correlated with the degrees of cell differentiation ( P<0.05). The positive rates of TAK1 protein and MAP4K2 protein were 48.68% and 46.05%, respectively. The protein expressions of TAK1 and MAP4K2 were positively correlated with the degrees of cell differentiation and lymph node metastases, respectively ( P<0.05). There was no correlation between K-ras gene mutation and either TAK1 protein or MAP4K2 protein expression ( P>0.05). In 25 cases of colorectal cancer with K-ras mutation, the expression of TAK1 protein was positively correlated with the expression of MAP4K2 protein ( P<0.05).

CONCLUSION

K-ras gene mutation, TAK1 and MAP4K2 protein expressions were related to the degree of differentiation of colorectal cancer, but not to the depth of invasion. In colorectal cancer with K-ras gene mutation, the expression of TAK1 protein was positively correlated with the expression of MAP4K2 protein.

Novel genetic variants in the P38MAPK pathway gene ZAK and susceptibility to lung cancer

The P38MAPK pathway participates in regulating cell cycle, inflammation, development, cell death, cell differentiation, and tumorigenesis. Genetic variants of some genes in the P38MAPK pathway are reportedly associated with lung cancer risk. To substantiate this finding, we used six genome-wide association studies (GWASs) to comprehensively investigate the associations of 14 904 single nucleotide polymorphisms (SNPs) in 108 genes of this pathway with lung cancer risk. We identified six significant lung cancer risk-associated SNPs in two genes (CSNK2B and ZAK) after correction for multiple comparisons by a false discovery rate (FDR) <0.20. After removal of three CSNK2B SNPs that are located in the same locus previously reported by GWAS, we performed the LD analysis and found that rs3769201 and rs7604288 were in high LD. We then chose two independent representative SNPs of rs3769201 and rs722864 in ZAK for further analysis. We also expanded the analysis by including these two SNPs from additional GWAS datasets of Harvard University (984 cases and 970 controls) and deCODE (1319 cases and 26 380 controls). The overall effects of these two SNPs were assessed using all eight GWAS datasets (OR = 0.92, 95%CI = 0.89-0.95, and P = 1.03 × 10-5 for rs3769201; OR = 0.91, 95%CI = 0.88-0.95, and P = 2.03 × 10-6 for rs722864). Finally, we performed an expression quantitative trait loci (eQTL) analysis and found that these two SNPs were significantly associated with ZAK mRNA expression levels in lymphoblastoid cell lines. In conclusion, the ZAK rs3769201 and rs722864 may be functional susceptibility loci for lung cancer risk.

Doxorubicin induces ZAKα overexpression with a subsequent enhancement of apoptosis and attenuation of survivability in human osteosarcoma cells

Human osteosarcoma (OS) is a malignant cancer of the bone. It exhibits a characteristic malignant osteoblastic transformation and produces a diseased osteoid. A previous study demonstrated that doxorubicin (DOX) chemotherapy decreases human OS cell proliferation and might enhance the relative RNA expression of ZAK. However, the impact of ZAKα overexpression on the OS cell proliferation that is inhibited by DOX and the molecular mechanism underlying this effect are not yet known. ZAK is a protein kinase of the MAPKKK family and functions to promote apoptosis. In our study, we found that ZAKα overexpression induced an apoptotic effect in human OS cells. Treatment of human OS cells with DOX enhanced ZAKα expression and decreased cancer cell viability while increasing apoptosis of human OS cells. In the meantime, suppression of ZAKα expression using shRNA and inhibitor D1771 both suppressed the DOX therapeutic effect. These findings reveal a novel molecular mechanism underlying the DOX effect on human OS cells. Taken together, our findings demonstrate that ZAKα enhances the apoptotic effect and decreases cell viability in DOX-treated human OS cells.