Tumor progression locus 2 (Tpl2) kinase as a novel therapeutic target for cancer: double-sided effects of Tpl2 on cancer

Functions of MAP3Ks in antiviral immunity

Immune signal transduction is crucial to the body's defense against viral infection. Recognition of pathogen-associated molecular patterns by pattern recognition receptors (PRRs) activates the transcription of interferon regulators and nuclear factor-κB (NF-κB); this promotes the release of interferons and inflammatory factors. Efficient regulation of type I interferon and NF-κB signaling by members of the mitogen-activated protein (MAP) kinase kinase kinase (MAP3K) family plays an important role in antiviral immunity. Elucidating the specific roles of MAP3K activation during viral infection is essential to develop effective antiviral therapies. In this review, we outline the specific regulatory mechanisms of MAP3Ks in antiviral immunity and discuss the feasibility of targeting MAP3Ks for the treatment of virus-induced diseases.

Overexpression of TPL2 may be a predictor of good prognosis in patients with breast invasive ductal carcinoma

The objective of this study was to investigate the clinical significance and roles of tumor progression locus 2 (TPL2) and peptidyl-prolyl cis-trans isomerase 1 (Pin1) in the occurrence and development of breast invasive ductal carcinoma (IDC). Immunohistochemistry was used to detect the expression of TPL2 and Pin1 in human breast tissues, which included normal breast tissues (Normal), tissues with fibrocystic changes (FCC), ductal carcinoma in situ (DCIS), and IDC. The roles of TPL2 and Pin1 in the occurrence and development of IDC, as well as the correlation between their expression levels and clinicopathological parameters, were analyzed. Compared with Normal and FCC groups, the overexpression of TPL2 and Pin1 was significantly increased in DCIS and IDC groups (DCIS vs Normal: P = 0.002/P < 0.001; IDC vs Normal: P = 0.007/P = 0.003; DCIS vs. FCC: P = 0.008/P = 0.004; IDC vs. FCC: P = 0.04/P = 0.043). The expression levels of TPL2 and Pin1 were positively correlated in DCIS and IDC groups (P = 0.001, P = 0.011). In the IDC group, the Ki67 level in the TPL2 overexpression group was significantly lower than that in the TPL2 low expression group (P = 0.02). The TPL2 overexpression rate was significantly higher in IDC with histological grades 1-2 than that in IDC with histological grade 3 (P = 0.029). The TPL2 overexpression rate in IDC with tumor-node-metastasis (TNM) stage I was significantly higher than that in IDC with TNM stages II-III (P = 0.035). We conclude that TPL2 and Pin1 may synergistically promote the occurrence and development of IDC, but TPL2 overexpression may be an early molecular event in IDC development. TPL2 overexpression is significantly related with IDC with lower malignancy or earlier TNM stage, suggesting that the prognosis of IDC patients with TPL2 overexpression may be better and TPL2 overexpression may be a predictor of good prognosis in IDC.

Tumor progression locus 2 (TPL2): A Cot-plicated progression from inflammation to chronic liver disease

The cytoplasmic protein tumor progression locus 2 (TPL2), also known as cancer Osaka thyroid (Cot), or MAP3K8, is thought to have a significant role in a variety of cancers and illnesses and it is a key component in the activation pathway for the expression of inflammatory mediators. Despite the tight connection between inflammation and TPL2, its function has not been extensively studied in chronic liver disease (CLD), a major cause of morbidity and mortality worldwide. Here, we analyze more in detail the significance of TPL2 in CLD to shed light on the pathological and molecular transduction pattern of TPL2 during the progression of CLD. This might result in important advancements and enable progress in the diagnosis and treatment of CLD.

Establishment and characterization of a new activated B-cell-like DLBCL cell line, TMD12

We report the establishment of a novel activated B-cell-like (ABC) diffuse large B-cell lymphoma (DLBCL) cell line, designated as TMD12, from a patient with highly refractory DLBCL. ABC-DLBCL is a subtype with a relatively unfavorable prognosis that was originally categorized using gene expression profiling according to its cell of origin. TMD12 cells were isolated from the pleural effusion of the patient at relapse and passaged continuously in vitro for >4 years. The cells displayed cluster of differentiation (CD)19, CD20, CD22, CD38, human leukocyte antigen-DR isotype, and κ positivity and CD5, CD10, CD23, and λ negativity, as detected using flow cytometric analysis. The chromosomal karyotypic analysis, including the spectral karyotyping method, confirmed t(1;19)(q21:q13.1), del(6q23), gain of chromosome 18, and other abnormalities. Mutation analyses, including whole-exome sequencing, revealed that TMD12 cells harbored mutations in MYD88 and CD79B, indicating an ABC subtype. TMD12 cells exhibited chronic active B-cell receptor signaling and constitutive activation of the nuclear factor κB pathway, which is typically associated with sensitivity to a specific Bruton tyrosine kinase inhibitor, ibrutinib. Intriguingly, TMD12 cells displayed moderate resistance to ibrutinib and lacked activation of Janus kinase/signal transducers and activators of transcription 3 signaling, another hallmark of this DLBCL subtype. Treatment with an inhibitor against tumor progression locus 2 (TPL2), a multifunctional intracellular kinase that is activated particularly downstream of Toll-like receptors or MYD88 and IκB kinase α/β (IKKα/β), suppressed the proliferation of TMD12 cells, implying the possible involvement of the TPL2-p105 pathway in the tumorigenesis of ABC-DLBCL. Because only a limited number of ABC-DLBCL cell lines are currently available, TMD12 cells might provide a useful tool in the search for novel druggable targets for this intractable lymphoma.

IKBKE-driven TPL2 and MEK1 phosphorylations sustain constitutive ERK1/2 activation in tumor cells

IKBKE have been associated with numerous cancers. As a result, IKBKE have emerged as potential target for cancer therapy. Accumulating evidence support that IKBKE orchestrate tumor cell survival in cancers. Here we evaluated the possible link between IKBKE and ERK phosphorylation. The effects of IKBKE silencing on MAPK activation in tumor vs. normal cells were evaluated via WB and RT-PCR. Ectopically expressed IKBKE, TPL2 or MEK1 constructs were used to examine the possible interactions among them via co-IP. In vitro kinase assays were performed to understand nature of the observed interactions. In tumors, IKBKE regulates MEK/ERK constitutive activations in vitro and in vivo. IKBKE and TPL2 physically interact and this interaction leads to TPL2 phosphorylation. We describe here a novel regulatory link between IKBKE and constitutive ERK1/2 activation in tumor cells. This new circuitry may be relevant for tumor cell survival in various malignancies.

MAP3K8 Is a Prognostic Biomarker and Correlated With Immune Response in Glioma

MAP3K8 is a serine/threonine kinase that is widely expressed in immune cells, non-immune cells, and many tumor types. The expression, clinical significance, biological role, and the underlying molecular mechanisms of MAP3K8 in glioma have not been investigated yet. Here, we discovered that MAP3K8 was aberrantly overexpressed in glioma and correlated with poor clinicopathological features of glioma by analysis on different datasets and immunohistochemistry staining. MAP3K8 is an independent prognostic indicator and significantly correlates with the progression of glioma. We also performed the function and pathway enrichment analysis of MAP3K8 in glioma to explore its biological functions and underlying molecular mechanisms in glioma. MAP3K8 co-expressed genes were mainly enriched in immune-related biological processes such as neutrophil activation, leukocyte migration, neutrophil-mediated immunity, lymphocyte-mediated immunity, T-cell activation, leukocyte cell–cell adhesion, regulation of leukocyte cell–cell adhesion, B-cell-mediated immunity, myeloid cell differentiation, and regulation of cell–cell adhesion. Single-cell RNA sequencing data and immunohistochemistry analysis demonstrated that MAP3K8 is expressed in malignant and immune cells and mainly enriched in the microglia/macrophage cells of glioma. The expression of MAP3K8 was positively correlated with immune infiltration, including effector memory CD4⁺ T cells, plasmacytoid dendritic cells, neutrophils, myeloid dendritic cells, mast cells, and macrophage in glioma. Further correlation analysis demonstrated that a series of inhibitory immune checkpoint molecules, chemokines, and chemokine receptors was positively correlated with the expression of MAP3K8. MAP3K8 might play an essential role in tumor immunity, and inhibition of MPA3K8 is a plausible strategy for glioma immunotherapy.

Effect of MAP3K8 on Prognosis and Tumor-Related Inflammation in Renal Clear Cell Carcinoma

Background: MAPK kinase kinase 8 (MAP3K8) is involved in the regulation of MAPK cascades and immune responses. Differential expression of MAP3K8 is closely correlated with tumorigenesis. In this study, we used bioinformatics tools to explore expression level, prognostic values, and interactive networks of MAP3K8 in renal clear cell carcinoma (ccRCC).

Methods: Differential expression of MAP3K8 was determined by TIMER2.0, UALCAN, and Oncomine Platform. For exploration of MAP3K8 mutation profile, TIMER2.0, DriverDBv3, and cBioPortal were used. The survival module of GEPIA, UALCAN, and DriverDBv3 was used to examine the prognostic value of MAP3K8. Immune infiltration was estimated by TIMER, TIDE, CIBERSORT, CIBERSORT-ABS, QUANTISEQ, XCELL, MCPCOUNTER, and EPIC algorithms. PPI networks and functional enrichment analysis were constructed using GeneMANIA, Cytoscape, and Metascape. The co-expression module in cBioPortal was used to find genes that are correlated with MAP3K8 in mRNA expression.

Results: Compared to normal renal samples, ccRCC (3.08-fold change, P = 1.50E-7; 1.10-fold change, P = 3.00E-3), papillary RCC (2.24-fold change, P = 1.86E-4), and hereditary ccRCC (1.98-fold change, P = 1.69E-9) have significantly higher levels of MAP3K8 expression. Compared to Grade 1 ccRCC samples, Grade 2 (P = 1.28E-3) and Grade 3 (P = 7.41E-4) cases have higher levels of MAP3K8 methylation. Percentage of patients harboring MAP3K8 mutation is 0.3% from TIMER2.0 and 0.2 to 11.5% from cBioPortal. High levels of MAP3K8 expression were associated with poorer overall survival (OS) in ccRCC (GEPIA: Log-rank P = 0.60E-2, HR = 1.5; DriverDBv3: Log-rank P = 1.68E-7, HR = 2.21; UALCAN: P = 0.20E-2). MAP3K8 was positively correlated with the presence of T cell regulatory (Tregs) (QUANTISEQ: Rho = 0.33, P = 1.59E-13). PPI network and functional enrichment analyses revealed that MAP3K8 correlated with NFKBIZ, MIAT, PARP15, CHFR, MKNK1, and ERMN, which was mainly involved in I-kappaB kinase/NF-kappaB and toll-like receptor signaling pathways.

Conclusion: MAP3K8 overexpression was correlated with damaged survival in ccRC and may play a crucial role in cancer-related inflammation via I-kappaB kinase/NF-kappaB and toll-like receptor signaling pathways.

Tanshinone IIA Inhibits Osteosarcoma Growth through a Src Kinase-Dependent Mechanism

Introduction

Osteosarcoma is a malignant tumor associated with high mortality rates due to the toxic side effects of current therapeutic methods. Tanshinone IIA can inhibit cell proliferation and promote apoptosis in vitro, but the exact mechanism is still unknown. The aims of this study are to explore the antiosteosarcoma effect of tanshinone IIA via Src kinase and demonstrate the mechanism of this effect.

Materials and Methods

Osteosarcoma MG-63 and U2-OS cell lines were stable transfections with Src-shRNA. Then, the antiosteosarcoma effect of tanshinone IIA was tested in vitro. The protein expression levels of Src, p-Src, p-ERK1/2, and p-AKt were detected by Western blot and RT-PCR. CCK-8 assay and BrdU immunofluorescence assay were used to detect cell proliferation. Transwell assay, cell scratch assay, and flow cytometry were used to detect cell invasion, migration, and cell cycle. Tumor-bearing nude mice with osteosarcoma were constructed. The effect of tanshinone IIA was detected by tumor HE staining, tumor inhibition rate, incidence of lung metastasis, and X-ray.

Results

The oncogene role of Src kinase in osteosarcoma is reflected in promoting cell proliferation, invasion, and migration and in inhibiting apoptosis. However, Src has different effects on cell proliferation, apoptosis, and cell cycle regulation among cell lines. At a cellular level, the antiosteosarcoma effect of tanshinone IIA is mediated by Src downstream of the MAPK/ERK and PI3K/AKt signaling pathways. At the animal level, tanshinone IIA played a role in resisting osteosarcoma formation by Src downstream of the MAPK/ERK and PI3K/AKt signaling pathways.

Conclusion

Tanshinone IIA plays an antiosteosarcoma role in vitro and in vivo and inhibits the progression of osteosarcoma mediated by Src downstream of the MAPK/ERK and PI3K/AKt signaling pathways.

Endothelial Tpl2 regulates vascular barrier function via JNK-mediated degradation of claudin-5 promoting neuroinflammation or tumor metastasis

Increased vascular permeability and leakage are hallmarks of several pathologies and determine disease progression and severity by facilitating inflammatory/metastatic cell infiltration. Using tissue-specific genetic ablation in endothelial cells, we have investigated in vivo the role of Tumor progression locus 2 (Tpl2), a mitogen-activated protein kinase kinase kinase (MAP3K) member with pleiotropic effects in inflammation and cancer. In response to proinflammatory stimuli, endothelial Tpl2 deletion alters tight junction claudin-5 protein expression through inhibition of JNK signaling and lysosomal degradation activation, resulting in reduced vascular permeability and immune cell infiltration. This results in significantly attenuated disease scores in experimental autoimmune encephalomyelitis and fewer tumor nodules in a hematogenic lung cancer metastasis model. Accordingly, pharmacologic inhibition of Tpl2 or small interfering RNA (siRNA)-mediated Tpl2 knockdown recapitulates our findings and reduces lung metastatic tumor invasions. These results establish an endothelial-specific role for Tpl2 and highlight the therapeutic potential of blocking the endothelial-specific Tpl2 pathway in chronic inflammatory and metastatic diseases.

Therapeutic Potential of Tpl2 (Tumor Progression Locus 2) Inhibition on Diabetic Vasculopathy Through the Blockage of the Inflammasome Complex

OBJECTIVE

Diabetic retinopathy, one of retinal vasculopathy, is characterized by retinal inflammation, vascular leakage, blood-retinal barrier breakdown, and neovascularization. However, the molecular mechanisms that contribute to diabetic retinopathy progression remain unclear. Approach and Results: Tpl2 (tumor progression locus 2) is a protein kinase implicated in inflammation and pathological vascular angiogenesis. Nε-carboxymethyllysine (CML) and inflammatory cytokines levels in human sera and in several diabetic murine models were detected by ELISA, whereas liquid chromatography-tandem mass spectrometry analysis was used for whole eye tissues. The CML and p-Tpl2 expressions on the human retinal pigment epithelium (RPE) cells were determined by immunofluorescence. Intravitreal injection of pharmacological inhibitor or NA (neutralizing antibody) was used in a diabetic rat model. Retinal leukostasis, optical coherence tomography, and H&E staining were used to observe pathological features. Sera of diabetic retinopathy patients had significantly increased CML levels that positively correlated with diabetic retinopathy severity and foveal thickness. CML and p-Tpl2 expressions also significantly increased in the RPE of both T1DM and T2DM diabetes animal models. Mechanistic studies on RPE revealed that CML-induced Tpl2 activation and NADPH oxidase, and inflammasome complex activation were all effectively attenuated by Tpl2 inhibition. Tpl2 inhibition by NA also effectively reduced inflammatory/angiogenic factors, retinal leukostasis in streptozotocin-induced diabetic rats, and RPE secretion of inflammatory cytokines. The attenuated release of angiogenic factors led to inhibited vascular abnormalities in the diabetic animal model.

CONCLUSIONS

The inhibition of Tpl2 can block the inflammasome signaling pathway in RPE and has potential clinical and therapeutic implications in diabetes-associated retinal microvascular dysfunction.

JNK3 as Therapeutic Target and Biomarker in Neurodegenerative and Neurodevelopmental Brain Diseases

The c-Jun N-terminal kinase 3 (JNK3) is the JNK isoform mainly expressed in the brain. It is the most responsive to many stress stimuli in the central nervous system from ischemia to Aβ oligomers toxicity. JNK3 activity is spatial and temporal organized by its scaffold protein, in particular JIP-1 and β-arrestin-2, which play a crucial role in regulating different cellular functions in different cellular districts. Extensive evidence has highlighted the possibility of exploiting these adaptors to interfere with JNK3 signaling in order to block its action. JNK plays a key role in the first neurodegenerative event, the perturbation of physiological synapse structure and function, known as synaptic dysfunction. Importantly, this is a common mechanism in many different brain pathologies. Synaptic dysfunction and spine loss have been reported to be pharmacologically reversible, opening new therapeutic directions in brain diseases. Being JNK3-detectable at the peripheral level, it could be used as a disease biomarker with the ultimate aim of allowing an early diagnosis of neurodegenerative and neurodevelopment diseases in a still prodromal phase.

Tumor progression locus 2 (TPL2) in tumor-promoting Inflammation, Tumorigenesis and Tumor Immunity

Over the years, tumor progression locus 2 (TPL2) has been identified as an essential modulator of immune responses that conveys inflammatory signals to downstream effectors, subsequently modulating the generation and function of inflammatory cells. TPL2 is also differentially expressed and activated in several cancers, where it is associated with increased inflammation, malignant transformation, angiogenesis, metastasis, poor prognosis and therapy resistance. However, the relationship between TPL2-driven inflammation, tumorigenesis and tumor immunity has not been addressed. Here, we reconcile the function of TPL2-driven inflammation to oncogenic functions such as inflammation, proliferation, apoptosis resistance, angiogenesis, metastasis, immunosuppression and immune evasion. We also address the controversies reported on TPL2 function in tumor-promoting inflammation and tumorigenesis, and highlight the potential role of the TPL2 adaptor function in regulating the mechanisms leading to pro-tumorigenic inflammation and tumor progression. We discuss the therapeutic implications and limitations of targeting TPL2 for cancer treatment. The ideas presented here provide some new insight into cancer pathophysiology that might contribute to the development of more integrative and specific anti-inflammatory and anti-cancer therapeutics.

Computational modeling reveals MAP3K8 as mediator of resistance to vemurafenib in thyroid cancer stem cells

MOTIVATION

Val600Glu (V600E) mutation is the most common BRAF mutation detected in thyroid cancer. Hence, recent research efforts have been performed trying to explore several inhibitors of the V600E mutation-containing BRAF kinase as potential therapeutic options in thyroid cancer refractory to standard interventions. Among them, vemurafenib is a selective BRAF inhibitor approved by Food and Drug Administration for clinical practice. Unfortunately, vemurafenib often displays limited efficacy in poorly differentiated and anaplastic thyroid carcinomas probably because of intrinsic and/or acquired resistance mechanisms. In this view, cancer stem cells (CSCs) may represent a possible mechanism of resistance to vemurafenib, due to their self-renewal and chemo resistance properties.

RESULTS

We present a computational framework to suggest new potential targets to overcome drug resistance. It has been validated with an in vitro model based upon a spheroid-forming method able to isolate thyroid CSCs that may mimic resistance to vemurafenib. Indeed, vemurafenib did not inhibit cell proliferation of BRAF V600E thyroid CSCs, but rather stimulated cell proliferation along with a paradoxical over-activation of ERK and AKT pathways. The computational model identified a fundamental role of mitogen-activated protein kinase 8 (MAP3K8), a serine/threonine kinase expressed in thyroid CSCs, in mediating this drug resistance. To confirm model prediction, we set a suitable in vitro experiment revealing that the treatment with MAP3K8 inhibitor restored the effect of vemurafenib in terms of both DNA fragmentation and poly (ADP-ribose) polymerase cleavage (apoptosis) in thyroid CSCs. Moreover, MAP3K8 expression levels may be a useful marker to predict the response to vemurafenib.

AVAILABILITY AND IMPLEMENTATION

The model is available in GitHub repository visiting the following URL: https://github.com/francescopappalardo/MAP3K8-Thyroid-Spheres-V-3.0.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

In silico Methods for Design of Kinase Inhibitors as Anticancer Drugs

Rational drug design implies usage of molecular modeling techniques such as pharmacophore modeling, molecular dynamics, virtual screening, and molecular docking to explain the activity of biomolecules, define molecular determinants for interaction with the drug target, and design more efficient drug candidates. Kinases play an essential role in cell function and therefore are extensively studied targets in drug design and discovery. Kinase inhibitors are clinically very important and widely used antineoplastic drugs. In this review, computational methods used in rational drug design of kinase inhibitors are discussed and compared, considering some representative case studies.

Machine Learning Classifiers for Endometriosis Using Transcriptomics and Methylomics Data

Endometriosis is a complex and common gynecological disorder yet a poorly understood disease affecting about 176 million women worldwide and causing significant impact on their quality of life and economic burden. Neither a definitive clinical symptom nor a minimally invasive diagnostic method is available, thus leading to an average of 4 to 11 years of diagnostic latency. Discovery of relevant biological patterns from microarray expression or next generation sequencing (NGS) data has been advanced over the last several decades by applying various machine learning tools. We performed machine learning analysis using 38 RNA-seq and 80 enrichment-based DNA methylation (MBD-seq) datasets. We experimented how well various supervised machine learning methods such as decision tree, partial least squares discriminant analysis (PLSDA), support vector machine, and random forest perform in classifying endometriosis from the control samples trained on both transcriptomics and methylomics data. The assessment was done from two different perspectives for improving classification performances: a) implication of three different normalization techniques and b) implication of differential analysis using the generalized linear model (GLM). Several candidate biomarker genes were identified by multiple machine learning experiments including NOTCH3, SNAPC2, B4GALNT1, SMAP2, DDB2, GTF3C5, and PTOV1 from the transcriptomics data analysis and TRPM6, RASSF2, TNIP2, RP3-522J7.6, FGD3, and MFSD14B from the methylomics data analysis. We concluded that an appropriate machine learning diagnostic pipeline for endometriosis should use TMM normalization for transcriptomics data, and quantile or voom normalization for methylomics data, GLM for feature space reduction and classification performance maximization.

The combination of TPL2 knockdown and TNFα causes synthetic lethality via caspase-8 activation in human carcinoma cell lines

Most normal and tumor cells are protected from tumor necrosis factor α (TNFα)-induced apoptosis. Here, we identify the MAP3 kinase tumor progression locus-2 (TPL2) as a player contributing to the protection of a subset of tumor cell lines. The combination of TPL2 knockdown and TNFα gives rise to a synthetic lethality phenotype via receptor-interacting serine/threonine-protein kinase 1 (RIPK1)-dependent and -independent mechanisms. Whereas wild-type TPL2 rescues the phenotype, its kinase-dead mutant does not. Comparison of the molecular events initiated by small interfering RNA for TPL2 (siTPL2) ± TNFα in treatment-sensitive and -resistant lines revealed that the activation of caspase-8, downstream of miR-21-5p and cFLIP, is the dominant TPL2-dependent event. More important, comparison of the gene expression profiles of all of the tested cell lines results in the clustering of sensitive and resistant lines into distinct groups, providing proof of principle for the feasibility of generating a predictive tool for treatment sensitivity.

Tpl2 is required for VEGF-A-stimulated signal transduction and endothelial cell function

New blood vessel sprouting (angiogenesis) and vascular physiology are fundamental features of metazoan species but we do not fully understand how signal transduction pathways regulate diverse vascular responses. The vascular endothelial growth factor (VEGF) family bind membrane-bound receptor tyrosine kinases (VEGFRs), which trigger multiple signal transduction pathways and diverse cellular responses. We evaluated whether the MAP3K family member and proto-oncoprotein Tpl2 (MAP3K8) regulates basal and VEGF-A-stimulated signal transduction in endothelial cells. Notably, stimulation with exogenous VEGF-A increased Tpl2 mRNA levels and consequently de novo protein synthesis. Depletion of Tpl2 levels reveals a role in both basal and VEGF-A-stimulated endothelial cell responses, including endothelial-leukocyte interactions, monolayer permeability and new blood vessel formation. Under basal conditions, Tpl2 modulates a signal transduction cascade resulting in phosphorylation of a nuclear transcription factor (ATF-2) and altered endothelial gene expression, a pathway previously identified as crucial in VEGF-dependent vascular responses. Loss of Tpl2 expression or activity impairs signal transduction through Akt, eNOS and ATF-2, broadly impacting on endothelial function. Our study now provides a mechanism for Tpl2 as a central component of signal transduction pathways in the endothelium.

Summary: Our study shows that the growth factor VEGF-A stimulates synthesis in endothelial cells of a proto-oncoprotein and protein kinase, Tpl2, and this is required for signal transduction and angiogenesis.

Tumor Progression Locus 2 in Hepatocytes Potentiates Both Liver and Systemic Metabolic Disorders in Mice

Tumor progression locus 2 (TPL2), a serine/threonine kinase, has been regarded as a potentially interesting target for the treatment of various diseases with an inflammatory component. However, the function of TPL2 in regulating hepatocyte metabolism and liver inflammation during the progression of nonalcoholic fatty liver disease (NAFLD) is poorly understood. Here, we report that TPL2 protein expression was significantly increased in fatty liver from diverse species, including humans, monkeys, and mice. Further investigations revealed that compared to wild-type (WT) littermates, hepatocyte-specific TPL2 knockout (HKO) mice exhibited improved lipid and glucose imbalance, reserved insulin sensitivity, and alleviated inflammation in response to high-fat diet (HFD) feeding. Overexpression of TPL2 in hepatocytes led to the opposite phenotype. Regarding the mechanism, we found that mitogen-activated protein kinase kinase 7 (MKK7) was the specific substrate of TPL2 for c-Jun N-terminal kinase (JNK) activation. TPL2-MKK7-JNK signaling in hepatocytes represents a promising drugable target for treating NAFLD and associated metabolic disorders. Conclusion: In hepatocytes, TPL2 acts as a key mediator that promotes both liver and systemic metabolic disturbances by specifically increasing MKK7-JNK activation.

The effect of Ganoderma lucidum extract on immunological function and identify its anti-tumor immunostimulatory activity based on the biological network

Ganoderma lucidum extract (GLE) has shown positive effects for tumor treatment. However, the molecular mechanism of GLE treatment is unknown. In this study, a Hepa1-6-bearing C57 BL/6 mouse model was established to explore the anti-tumor and immunostimulatory activity of GLE treatment. The results showed that GLE effectively inhibited tumor growth without hepatic/renal toxicity and bone marrow suppression, and might enhancing immunological function. Based on the mRNA profiles of GLE treated and untreated mice, 302 differentially expressed (DE) mRNAs were identified and 6 kernel mRNAs were identified from the established protein-protein interaction (PPI) network. Quantitative RT-PCR and western-blot analysis indicated that 6 mRNAs have had statistically significant differences between the GLE treated and untreated mice. Furthermore, four kernel pathways were isolated from the KEGG-Target network, including the Jak-STAT signaling pathway, T cell receptor signaling pathway, PI3K-Akt signaling pathway, and cytokine-cytokine receptor interaction. Western-blot and cytokine detection results demonstrated that GLE suppressed growth and proliferation of tumors by the Jak-STAT signaling pathway, T cell receptor signaling pathway and PI3K-Akt signaling pathway, but also regulated the expression levels of serum immune cytokines and improved the anti-tumor immunostimulatory activity.

Overexpression of Tpl2 is linked to imatinib resistance and activation of MEK-ERK and NF-κB pathways in a model of chronic myeloid leukemia

The introduction of tyrosine kinase inhibitors (TKI) has transformed chronic myeloid leukemia (CML) into a chronic disease with long-term survival exceeding 85%. However, resistance of CML stem cells to TKI may contribute to the 50% relapse rate observed after TKI discontinuation in molecular remission. We previously described a model of resistance to imatinib mesylate (IM), in which K562 cells cultured in high concentrations of imatinib mesylate showed reduced Bcr-Abl1 protein and activity levels while maintaining proliferative potential. Using quantitative phosphoproteomic analysis of these IM-resistant cells, we have now identified significant upregulation of tumor progression locus (Tpl2), also known as cancer Osaka thyroid (COT1) kinase or Map3k8. Overexpression of Tpl2 in IM-resistant cells was accompanied by elevated activities of Src family kinases (SFKs) and NF-κB, MEK-ERK signaling. CD34+ cells isolated from the bone marrow of patients with CML and exposed to IMin vitro showed increased MAP3K8 transcript levels. Dasatinib (SFK inhibitor), U0126 (MEK inhibitor), and PS-1145 (IκB kinase (IKK) inhibitor) used in combination resulted in elimination of 65% of IM-resistant cells and reduction in the colony-forming capacity of CML CD34+ cells in methylcellulose assays by 80%. In addition, CML CD34+ cells cultured with the combination of inhibitors showed reduced MAP3K8 transcript levels. Overall, our data indicate that elevated Tpl2 protein and transcript levels are associated with resistance to IM and that combined inhibition of SFK, MEK, and NF-κB signaling attenuates the survival of IM-resistant CML cells and CML CD34+ cells. Therefore, combination of SFK, MEK, and NF-κB inhibitors may offer a new therapeutic approach to overcome TKI resistance in CML patients.

Map3k8 controls granulocyte colony-stimulating factor production and neutrophil precursor proliferation in lipopolysaccharide-induced emergency granulopoiesis

Map3k8 has been proposed as a useful target for the treatment of inflammatory diseases. We show here that during lipopolysaccharide-induced emergency granulopoiesis, Map3k8 deficiency strongly impairs the increase in circulating mature (Ly6G^highCD11b⁺) and immature (Ly6G^lowCD11b⁺) neutrophils. After chimaeric bone marrow (BM) transplantation into recipient Map3k8^−/− mice, lipopolysaccharide treatment did not increase circulating Ly6G^highCD11b⁺ cells and strongly decreased circulating Ly6G^lowCD11b⁺ cells. Lipopolysaccharide-treated Map3k8^−/− mice showed decreased production of granulocyte colony-stimulating factor (G-CSF), a key factor in neutrophil expansion, and a Map3k8 inhibitor blocked lipopolysaccharide-mediated G-CSF expression in endothelial cell lines. Ly6G^lowCD11b⁺ BM cells from lipopolysaccharide-treated Map3k8^−/− mice displayed impaired expression of CCAAT-enhancer-binding protein β, which depends on G-CSF for expression and is crucial for cell cycle acceleration in this life-threatening condition. Accordingly, lipopolysaccharide-treated Map3k8^−/− mice showed decreased Ly6G^lowCD11b⁺ BM cell proliferation, as evidenced by a decrease in the percentage of the most immature precursors, which have the highest proliferation capacity among this cell population. Thus, Map3k8 expression by non-haematopoietic tissue is required for lipopolysaccharide-induced emergency granulopoiesis. The novel observation that inhibition of Map3k8 activity decreases neutrophilia during life-threatening systemic infection suggests a possible risk in the proposed use of Map3k8 blockade as an anti-inflammatory therapy.

The kinase TPL2 activates ERK and p38 signaling to promote neutrophilic inflammation

Tumor progression locus 2 (TPL2; also known as MAP3K8) is a mitogen-activated protein kinase (MAPK) kinase kinase (MAP3K) that phosphorylates the MAPK kinases MEK1 and MEK2 (MEK1/2), which, in turn, activate the MAPKs extracellular signal-regulated kinase 1 (ERK1) and ERK2 (ERK1/2) in macrophages stimulated through the interleukin-1 receptor (IL-1R), Toll-like receptors (TLRs), or the tumor necrosis factor receptor (TNFR). We describe a conserved and critical role for TPL2 in mediating the effector functions of neutrophils through the activation of the p38 MAPK signaling pathway. Gene expression profiling and functional studies of neutrophils and monocytes revealed a MEK1/2-independent branch point downstream of TPL2 in neutrophils. Biochemical analyses identified the MAPK kinases MEK3 and MEK6 and the MAPKs p38α and p38δ as downstream effectors of TPL2 in these cells. Genetic ablation of the catalytic activity of TPL2 or therapeutic intervention with a TPL2-specific inhibitor reduced the production of inflammatory mediators by neutrophils in response to stimulation with the TLR4 agonist lipopolysaccharide (LPS) in vitro, as well as in rodent models of inflammatory disease. Together, these data suggest that TPL2 is a drug target that activates not only MEK1/2-dependent but also MEK3/6-dependent signaling to promote inflammatory responses.

Cot kinase plays a critical role in Helicobacter pylori-induced IL-8 expression

Helicobacter pylori is a major pathogen causing various gastric diseases including gastric cancer. Infection of H. pylori induces pro-inflammatory cytokine IL-8 expression in gastric epithelial cells in the initial inflammatory process. It has been known that H. pylori can modulate Ras-Raf-Mek-Erk signal pathway for IL-8 induction. Recently, it has been shown that another signal molecule, cancer Osaka thyroid oncogene/tumor progression locus 2 (Cot/Tpl2) kinase, activates Mek and Erk and plays a role in the Erk pathway, similar to MAP3K signal molecule Raf kinase. Therefore, the objective of this study was to determine whether Cot kinase might be involved in IL-8 induction caused by H. pylori infection. AGS gastric epithelial cells were infected by H. pylori strain G27 or its isogenic mutants lacking cagA or type IV secretion system followed by treatment with Cot kinase inhibitor (KI) or siRNA specific for Cot kinase. Activation of Erk was assessed by Western blot analysis and expression of IL-8 was measured by ELISA. Treatment with Cot KI reduced both transient and sustained Erk activation. It also reduced early and late IL-8 secretion in the gastric epithelial cell line. Furthermore, siRNA knockdown of Cot inhibited early and late IL-8 secretion induced by H. pylori infection. Taken together, these results suggest that Cot kinase might play a critical role in H. pylori type IV secretion apparatus-dependent early IL-8 secretion and CagA-dependent late IL-8 secretion as an alternative signaling molecule in the Erk pathway.

miR-589-5p inhibits MAP3K8 and suppresses CD90+ cancer stem cells in hepatocellular carcinoma

BACKGROUND

Cancer stem cells (CSCs) are important in the tumorigenesis and progression of hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) play crucial roles regulating CD133⁺ and EpCAM⁺ CSCs in HCC, although it is unclear whether miRNAs regulate CD90⁺ CSCs in HCC.

METHODS

The miRNA profiles of CD90⁺ and CD90^- HCC cells were analyzed using a miRNA microarray and quantitative real-time PCR (qRT-PCR). CSC characteristics were examined by qRT-PCR and Western blot of pluripotency-associated genes, clone and sphere formation assay, transwell migration assay, and nude mice tumorigenicity assay. miR-589-5p mimic transfection was used to overexpress miR-589-5p in vitro. The CD90 and miR-589-5p expressions of HCC samples were detected by immunohistochemistry and qRT-PCR, respectively.

RESULTS

miR-589-5p and miR-33b-5p were down-regulated in CD90⁺ cells. Overexpression of miR-589-5p suppressed CD90⁺ CSC characteristics such as Oct4, Sox2 and Nanog expression, a high likelihood of forming cell spheres, high invasiveness and high tumorigenicity. Luciferase reporter assays demonstrated that miR-589-5p directly binds to the 3'-untranslated region of mitogen-activated protein kinase kinase kinase 8 (MAP3K8) mRNA, and exogenous miR-589-5p down-regulated MAP3K8 expression. In addition, siRNA inhibition of MAP3K8 also suppressed CD90⁺ CSC characteristics, even in the absence of miR-589-5p overexpression. In HCC tissues, miR-589-5p expression was inversely correlated with CD90 expression, and high CD90 expression and low miR-589-5p expression were positively correlated with vascular invasion and recurrence and significantly decreased disease-free and overall survival by clinical analysis.

CONCLUSION

In HCC, miR-589-5p down-regulates the stemness characteristics of CD90⁺ CSCs in part by silencing MAP3K8. CD90 and miR-589-5p expression predict HCC outcomes and might be novel molecular targets for HCC treatment.

Tumor progression locus 2 ablation suppressed hepatocellular carcinoma development by inhibiting hepatic inflammation and steatosis in mice

Background

Tumor progression locus 2 (TPL2), a serine-threonine kinase, functions as a critical regulator of inflammatory pathways and mediates oncogenic events. The potential role of Tpl2 in nonalcoholic fatty liver disease (NAFLD) associated hepatocellular carcinoma (HCC) development remains unknown.

Methods

Both wild-type and Tpl2 knockout male mice were initiated by a hepatic carcinogen (diethylnitrosamine, i.p. with a single dose of 25 mg.kg⁻¹)at 2 weeks of age, and then were given the high carbohydrate diet feeding to induce hepatic steatosis, inflammation, adenoma and HCC for 24 weeks.

Results

Tpl2 knockout mice had significantly lower incidences of liver tumor and developed hepatocellular adenoma only, which is contrast to wild-type mice where they all developed HCC. Tpl2 knockout mice had significantly down-regulated phosphorylation of JNK and ERK, and levels of mRNA expression of pro-inflammatory cytokines (Il-1β, Il-18, Mcp-1 and Nalp3), which correlated with the reduced incidence and number of hepatic inflammatory foci. Furthermore, Tpl2 ablation resulted in decreased hepatic steatosis and expression of de novo lipogenesis related markers (ACC, SCD1, SREBP1C and AKT phosphorylation), as well as reduction of endoplasmic reticulum stress biomarkers PERK and eIF-2a.

Conclusion

The study revealed for the first time that Tpl2 plays a significant role in promoting HCC development by its pro-inflammatory effect, which suggested that Tpl2 could be a molecular target for HCC prevention.