Endothelial hyperactivation of mutant MAP3K3 induces cerebral cavernous malformation enhanced by PIK3CA GOF mutation.

Cerebral cavernous malformations (CCMs) refer to a common vascular abnormality that affects up to 0.5% of the population. A somatic gain-of-function mutation in MAP3K3 (p.I441M) was recently reported in sporadic CCMs, frequently accompanied by somatic activating PIK3CA mutations in diseased endothelium. However, the molecular mechanisms of these driver genes remain elusive. In this study, we performed whole-exome sequencing and droplet digital polymerase chain reaction to analyze CCM lesions and the matched blood from sporadic patients. 44 of 94 cases harbored mutations in KRIT1/CCM2 or MAP3K3, of which 75% were accompanied by PIK3CA mutations (P = 0.006). AAV-BR1-mediated brain endothelial-specific MAP3K3I441M overexpression induced CCM-like lesions throughout the brain and spinal cord in adolescent mice. Interestingly, over half of lesions disappeared at adulthood. Single-cell RNA sequencing found significant enrichment of the apoptosis pathway in a subset of brain endothelial cells in MAP3K3I441M mice compared to controls. We then demonstrated that MAP3K3I441M overexpression activated p38 signaling that is associated with the apoptosis of endothelial cells in vitro and in vivo. In contrast, the mice simultaneously overexpressing PIK3CA and MAP3K3 mutations had an increased number of CCM-like lesions and maintained these lesions for a longer time compared to those with only MAP3K3I441M. Further in vitro and in vivo experiments showed that activating PI3K signaling increased proliferation and alleviated apoptosis of endothelial cells. By using AAV-BR1, we found that MAP3K3I441M mutation can provoke CCM-like lesions in mice and the activation of PI3K signaling significantly enhances and maintains these lesions, providing a preclinical model for the further mechanistic and therapeutic study of CCMs.

ETV5-mediated upregulation of lncRNA CTBP1-DT as a ceRNA facilitates HGSOC progression by regulating miR-188-5p/MAP3K3 axis.

High-grade serous ovarian cancer (HGSOC) is a common and lethal cancer of the female reproductive system. Long non-coding RNAs (lncRNAs) are aberrantly expressed in various cancers and play crucial roles in tumour progression. However, their function and molecular mechanism in HGSOC remain largely unknown. Based on public databases and bioinformatics analyses, the overexpression of lncRNA CTBP1-DT in HGSOC tissues was detected and validated in a cohort of HGSOC tissues. High expression of lncRNA CTBP1-DT was associated with poor prognosis and was an independent risk factor for survival. Overexpression of lncRNA CTBP1-DT promoted malignant biological behaviour of HGSOC cells, whereas its depletion induced growth arrest of HGSOC cells by vitro and in vivo assays. Mechanistically, lncRNA CTBP1-DT could competitively bind to miR-188-5p to protect MAP3K3 from degradation. Moreover, our results revealed that ETV5 could specifically interact with the promoter of lncRNA CTBP1-DT and activate its transcription. Collectively, these results reveal a novel ETV5/lncRNA CTBP1-DT/miR-188-5p/MAP3K3 pathway for HGSOC progression and suggest that lncRNA CTBP1-DT might be a potential biomarker and therapeutic target for HGSOC.

MEKK3-TGFß crosstalk regulates inward arterial remodeling.

Arterial remodeling is an important adaptive mechanism that maintains normal fluid shear stress in a variety of physiologic and pathologic conditions. Inward remodeling, a process that leads to reduction in arterial diameter, plays a critical role in progression of such common diseases as hypertension and atherosclerosis. Yet, despite its pathogenic importance, molecular mechanisms controlling inward remodeling remain undefined. Mitogen-activated protein kinases (MAPKs) perform a number of functions ranging from control of proliferation to migration and cell-fate transitions. While the MAPK ERK1/2 signaling pathway has been extensively examined in the endothelium, less is known about the role of the MEKK3/ERK5 pathway in vascular remodeling. To better define the role played by this signaling cascade, we studied the effect of endothelial-specific deletion of its key upstream MAP3K, MEKK3, in adult mice. The gene's deletion resulted in a gradual inward remodeling of both pulmonary and systematic arteries, leading to spontaneous hypertension in both vascular circuits and accelerated progression of atherosclerosis in hyperlipidemic mice. Molecular analysis revealed activation of TGFß-signaling both in vitro and in vivo. Endothelial-specific TGFßR1 knockout prevented inward arterial remodeling in MEKK3 endothelial knockout mice. These data point to the unexpected participation of endothelial MEKK3 in regulation of TGFßR1-Smad2/3 signaling and inward arterial remodeling in artery diseases.

A MEKK1 - JNK mitogen activated kinase (MAPK) cascade module is active in Echinococcus multilocularis stem cells.

BACKGROUND: The metacestode larval stage of the fox-tapeworm Echinococcus multilocularis causes alveolar echinococcosis by tumour-like growth within the liver of the intermediate host. Metacestode growth and development is stimulated by host-derived cytokines such as insulin, fibroblast growth factor, and epidermal growth factor via activation of cognate receptor tyrosine kinases expressed by the parasite. Little is known, however, concerning signal transmission to the parasite nucleus and cross-reaction with other parasite signalling systems. METHODOLOGY/PRINCIPAL FINDINGS: Using bioinformatic approaches, cloning, and yeast two-hybrid analyses we identified a novel mitogen-activated kinase (MAPK) cascade module that consists of E. multilocularis orthologs of the tyrosine kinase receptor interactor Growth factor receptor-bound 2, EmGrb2, the MAPK kinase kinase EmMEKK1, a novel MAPK kinase, EmMKK3, and a close homolog to c-Jun N-terminal kinase (JNK), EmMPK3. Whole mount in situ hybridization analyses indicated that EmMEKK1 and EmMPK3 are both expressed in E. multilocularis germinative (stem) cells but also in differentiated or differentiating cells. Treatment with the known JNK inhibitor SP600125 led to a significantly reduced formation of metacestode vesicles from stem cells and to a specific reduction of proliferating stem cells in mature metacestode vesicles. CONCLUSIONS/SIGNIFICANCE: We provide evidence for the expression of a MEKK1-JNK MAPK cascade module which, in mammals, is crucially involved in stress responses, cytoskeletal rearrangements, and apoptosis, in E. multilocularis stem cells. Inhibitor studies indicate an important role of JNK signalling in E. multilocularis stem cell survival and/or maintenance. Our data are relevant for molecular and cellular studies into crosstalk signalling mechanisms that govern Echinococcus stem cell function and introduce the JNK signalling cascade as a possible target of chemotherapeutics against echinococcosis.

CircSETDB1 knockdown inhibits the malignant progression of serous ovarian cancer through miR-129-3p-dependent regulation of MAP3K3.

BACKGROUND: Circular RNA (circRNA) is recently found to participate in the regulation of tumor progression, including ovarian cancer. However, the application of circRNA SET domain bifurcated histone lysine methyltransferase 1 (circSETDB1) as a therapeutic target in serous ovarian cancer (SOC) remains to be elucidated. Herein, circSETDB1 role in SOC malignant progression and underlying mechanism are revealed. METHODS: The expression of circSETDB1, microRNA-129-3p (miR-129-3p) and mitogen-activated protein kinase kinase kinase 3 (MAP3K3) messenger RNA (mRNA) was detected by quantitative real-time polymerase chain reaction. Protein abundance was determined by western blot analysis. Cell proliferation, apoptosis, invasion and migration were demonstrated by cell counting kit-8 and 5-Ethynyl-29-deoxyuridine assays, flow cytometry analysis, transwell invasion assay and wound-healing assay, respectively. The interaction between miR-129-3p and circSETDB1 or MAP3K3 was predicted by online database, and identified by mechanism assays. The effect of circSETDB1 knockdown on tumor formation in vivo was unveiled by mouse model experiment. RESULTS: CircSETDB1 and MAP3K3 expression were apparently upregulated, whereas miR-129-3p expression was downregulated in SOC tissues and cells in comparison with normal fallopian tube tissues or normal ovarian epithelial cells. CircSETDB1 knockdown inhibited cell proliferation, invasion and migration, but induced cell apoptosis in SOC cells. Additionally, miR-129-3p inhibitor impaired circSETDB1 silencing-mediated SOC malignant progression. MiR-129-3p repressed SOC cell processes via binding to MAP3K3. Furthermore, circSETDB1 knockdown suppressed tumor growth in vivo. CONCLUSION: CircSETDB1 silencing repressed SOC malignant progression through miR-129-3p/MAP3K3 pathway. This study supports circSETDB1 as a new therapeutic target for SOC.

1. CircSETDB1 expression was increased in SOC tissues and cells.2. CircSETDB1 silencing repressed the malignancy of SOC cells.3. CircSETDB1 mediated SOC malignant progression by interacting with miR-129-3p.4. MAP3K3 served as a target gene of miR-129-3p.5. CircSETDB1 knockdown inhibited tumor formation in vivo.

Circ_0006988 promotes the proliferation, metastasis and angiogenesis of non-small cell lung cancer cells by modulating miR-491-5p/MAP3K3 axis.

Circular RNAs (circRNAs) are related to the progression of non-small cell lung cancer (NSCLC). However, the roles and mechanism of circ_0006988 are largely unknown. The levels of circ_0006988, Low-Density Lipoprotein Receptor Class A Domain Containing 3 (LDLRAD3), microRNA-491-5p (miR-491-5p), Mitogen-Activated Protein Kinase Kinase Kinase 3 (MAP3K3) were measured using quantitative real-time polymerase-chain reaction (qRT-PCR) and western blot assay. The characteristic of circ_0006988 was analyzed by RNase R assay and Actinomycin D assay. Functional analyses were processed by Cell Counting Kit-8 (CCK-8) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, colony formation assay, flow cytometry analysis, transwell assay, wound-healing assay and tube formation assay. The interactions between circ_0006988 and miR-491-5p as well as miR-491-5p and MAP3K3 were analyzed by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Murine xenograft model assay was processed to verify the function of circ_0006988 in vivo. Immunohistochemistry (IHC) assay was conducted to examine the level of Ki67. Circ_0006988 abundance was increased in NSCLC tissues and cells. Circ_0006988 silencing restrained NSCLC cell proliferation, migration, invasion and angiogenesis, and induced apoptosis. Circ_0006988 sponged miR-491-5p, which directly targeted MAP3K3. MiR-491-5p overexpression repressed NSCLC cell malignant behaviors. MiR-491-5p downregulation or MAP3K3 overexpression reversed the effect of circ_0006988 silencing on NSCLC cell progression. In addition, circ_0006988 knockdown reduced xenograft tumor growth. ssCirc_0006988 contributed to the development of NSCLC by miR-491-5p/MAP3K3 axis.

Somatic MAP3K3 mutation defines a subclass of cerebral cavernous malformation.

Cerebral cavernous malformations (CCMs) are vascular disorders that affect up to 0.5% of the total population. About 20% of CCMs are inherited because of familial mutations in CCM genes, including CCM1/KRIT1, CCM2/MGC4607, and CCM3/PDCD10, whereas the etiology of a majority of simplex CCM-affected individuals remains unclear. Here, we report somatic mutations of MAP3K3, PIK3CA, MAP2K7, and CCM genes in CCM lesions. In particular, somatic hotspot mutations of PIK3CA are found in 11 of 38 individuals with CCMs, and a MAP3K3 somatic mutation (c.1323C>G [p.Ile441Met]) is detected in 37.0% (34 of 92) of the simplex CCM-affected individuals. Strikingly, the MAP3K3 c.1323C>G mutation presents in 95.7% (22 of 23) of the popcorn-like lesions but only 2.5% (1 of 40) of the subacute-bleeding or multifocal lesions that are predominantly attributed to mutations in the CCM1/2/3 signaling complex. Leveraging mini-bulk sequencing, we demonstrate the enrichment of MAP3K3 c.1323C>G mutation in CCM endothelium. Mechanistically, beyond the activation of CCM1/2/3-inhibited ERK5 signaling, MEKK3 p.Ile441Met (MAP3K3 encodes MEKK3) also activates ERK1/2, JNK, and p38 pathways because of mutation-induced MEKK3 kinase activity enhancement. Collectively, we identified several somatic activating mutations in CCM endothelium, and the MAP3K3 c.1323C>G mutation defines a primary CCM subtype with distinct characteristics in signaling activation and magnetic resonance imaging appearance.

Somatic MAP3K3 and PIK3CA mutations in sporadic cerebral and spinal cord cavernous malformations.

Cavernous malformations affecting the CNS occur in ∼0.16-0.4% of the general population. The majority (85%) of cavernous malformations are in a sporadic form, but the genetic background of sporadic cavernous malformations remains enigmatic. Of the 81 patients, 73 (90.1%) patients were detected carrying somatic missense variants in two genes: MAP3K3 and PIK3CA by whole-exome sequencing. The mutation spectrum correlated with lesion size (P = 0.001), anatomical distribution (P < 0.001), MRI appearance (P = 0.004) and haemorrhage events (P = 0.006). PIK3CA mutation was a significant predictor of overt haemorrhage events (P = 0.003, odds ratio = 11.252, 95% confidence interval = 2.275-55.648). Enrichment of endothelial cell population was associated with a higher fractional abundance of the somatic mutations. Overexpression of the MAP3K3 mutation perturbed angiogenesis of endothelial cell models in vitro and zebrafish embryos in vivo. Distinct transcriptional signatures between different genetic subgroups of sporadic cavernous malformations were identified by single cell RNA sequencing and verified by pathological staining. Significant apoptosis in MAP3K3 mutation carriers and overexpression of GDF15 and SERPINA5 in PIK3CA mutation carriers contributed to their phenotype. We identified activating MAP3K3 and PIK3CA somatic mutations in the majority (90.1%) of sporadic cavernous malformations and PIK3CA mutations could confer a higher risk for overt haemorrhage. Our data provide insights into genomic landscapes, propose a mechanistic explanation and underscore the possibility of a molecular classification for sporadic cavernous malformations.

Interplay of microRNAs to genetic, epigenetic, copy number variations of cervical cancer related genes.

This study was to analyses the miRNAs role in cervical cancer and possibilities of microRNA-based markers as diagnostic tools. Genome wide analysis was performed for CNV detection using PennCNV and QuantiSNP. The associated mRNA qRT-PCR detection was used to measure quantities of microRNA gene expression. More than 10 CNV regions has a significant relationship with cervical cancer risk for both CNV detection algorithms. A total of 34 CNVs was detected by QuantiSNP while it was 27 in case of PennCNV, among which 22 CNVs was found to be overlapping between these two algorithms. the mRNA was analyzed for its expression on 36 carvical tumor normal tissue pairs of four targets i.e., MAP3K3, RIPK2, DIRAS3 and GAS7. These infers that there was a significant downregulation of all the four genes cervical tumor. Our results showed that miR-182 can modulate the expression of FAM83H, DIRAS3, RIPK2 and MAP3K3 in cervical cancer. Therefore, indicated that miR-182 can acts through these signaling pathway in proliferation of cervical cancer cells. The expression of tumor modulator miRNAs can be controlled by miRNA replacement therapy. Several miRNAs have been used for this purpose. The modulation of various signaling pathway and proteins in cervical cancer cells by miR-182 needs further clarification.

Cell-substrate adhesion drives Scar/WAVE activation and phosphorylation by a Ste20-family kinase, which controls pseudopod lifetime.

The Scar/WAVE complex is the principal catalyst of pseudopod and lamellipod formation. Here we show that Scar/WAVE's proline-rich domain is polyphosphorylated after the complex is activated. Blocking Scar/WAVE activation stops phosphorylation in both Dictyostelium and mammalian cells, implying that phosphorylation modulates pseudopods after they have been formed, rather than controlling whether they are initiated. Unexpectedly, phosphorylation is not promoted by chemotactic signaling but is greatly stimulated by cell:substrate adhesion and diminished when cells deadhere. Phosphorylation-deficient or phosphomimetic Scar/WAVE mutants are both normally functional and rescue the phenotype of knockout cells, demonstrating that phosphorylation is dispensable for activation and actin regulation. However, pseudopods and patches of phosphorylation-deficient Scar/WAVE last substantially longer in mutants, altering the dynamics and size of pseudopods and lamellipods and thus changing migration speed. Scar/WAVE phosphorylation does not require ERK2 in Dictyostelium or mammalian cells. However, the MAPKKK homologue SepA contributes substantially-sepA mutants have less steady-state phosphorylation, which does not increase in response to adhesion. The mutants also behave similarly to cells expressing phosphorylation-deficient Scar, with longer-lived pseudopods and patches of Scar recruitment. We conclude that pseudopod engagement with substratum is more important than extracellular signals at regulating Scar/WAVE's activity and that phosphorylation acts as a pseudopod timer by promoting Scar/WAVE turnover.

Late-onset multiple venous malformations confined to the upper limb: link to somatic MAP3K3 mutations.

Venous (cavernous) malformations are commonly seen in the upper limb. Almost all venous malformations are congenital. They may be sporadic, familial, or syndromic. Late-onset, multiple venous malformations confined to the upper limb are rare. Lesions present after puberty. All previously reported cases were located subcutaneously and were small in size. The condition is non-hereditary and non-syndromic. We present a unique series of eight patients with this rare condition. Unique features included the presence of large malformations (up to 20 cm in diameter) and the presence of subfascial lesions causing nerve compression. Surgical excision was curative. Mutational analysis in one patient identified a novel somatic MAP3K3 gene mutation (c.1723T > C, p.Tyr 575 His) in the affected veins. The encoded MAP3K3 protein is known to accelerate the RAS pathway of cellular proliferation.Level of evidence: IV.

Long non-coding RNA CDKN2B-AS1 promotes osteosarcoma by increasing the expression of MAP3K3 via sponging miR-4458.

Osteosarcoma (OS) is the most common primary malignant bone tumor worldwide. Recently, several studies have shown that the long non-coding RNA (lncRNA) CDKN2B-AS1 plays a critical role in several cancers. However, the function and underlying mechanism of CDKN2B-AS1 in OS development remains elusive. In this study, we firstly assessed the expression of CDKN2B-AS1 in OS tissues and cells, showing that CDKN2B-AS1 expression were remarkably upregulated in OS tissues and cells. Moreover, CDKN2B-AS1 knockdown suppressed cell proliferation, migration, and EMT progress in OS. Interestingly, we found and proved that CDKN2B-AS1 could sponge miR-4458 in OS cells. Moreover, MAP3K3 was certified as a downstream target of miR-4458 in OS. Besides, MAP3K3 was negatively regulated by miR-4458 and positively regulated by CDKN2B-AS1. More importantly, overexpression of MAP3K3 could partly counteract the effect of CDKN2B-AS1 suppression on the biological behavior of OS cells. Also, the in vivo experiments further testified that CDKN2B-AS1 accelerated tumor growth in OS. Our results suggested that CDKN2B-AS1 facilitated OS progression by sponging miR-4458 to enhance MAP3K3 expression, which provides a novel insight into improving diagnostic and therapeutic strategies for patients with OS.

Cerebral Cavernous Malformation Proteins in Barrier Maintenance and Regulation.

Cerebral cavernous malformation (CCM) is a disease characterized by mulberry shaped clusters of dilated microvessels, primarily in the central nervous system. Such lesions can cause seizures, headaches, and stroke from brain bleeding. Loss-of-function germline and somatic mutations of a group of genes, called CCM genes, have been attributed to disease pathogenesis. In this review, we discuss the impact of CCM gene encoded proteins on cellular signaling, barrier function of endothelium and epithelium, and their contribution to CCM and potentially other diseases.

MicroRNA­9 suppresses human prostate cancer cell viability, invasion and migration via modulation of mitogen­activated protein kinase kinase kinase 3 expression.

MicroRNAs (miRs) are small non­coding RNA molecules that regulate gene expression at the post­transcriptional level. Aberrant expression of miR­9 has been reported to be involved in the tumorigenesis and progression of various malignancies. However, its role in prostate cancer (PC) has not been completely clarified. In the present study, miR­9 expression was examined in different PC cell lines, patient tissues and a mouse model. Cell Counting Kit­8 and BrdU immunofluorescence assays were performed to assess the effect of miR­9 on the viability of PC cells, while Transwell and wound­healing assays were utilized to evaluate the migration and invasion of PC cells expressing miR­9. Furthermore, a dual­luciferase reporter assay was performed to verify whether mitogen­activated protein kinase kinase kinase 3 (MEKK3) was a direct target of miR­9. The results demonstrated significant downregulation of miR­9 expression in different PC cell lines and 31 human PC tissues, as compared with that in a normal prostate cell line and adjacent normal tissues, respectively. By contrast, upregulation of MEKK3 was confirmed in human PC tissue samples, with its level inversely associated with miR­9 expression. Overexpression of miR­9 in six different PC cell lines (DU145, LNCaP, 22Rv1, PC­3, C4­2B and VCaP) reduced the cell viability and migration. Furthermore, it was demonstrated that the 3'­untranslated region of MEKK3 was a target of miR­9, and that MEKK3 overexpression prevented the inhibitory effects of miR­9 on the viability, migration and invasion of PC cells. miR­9 overexpressing tumor cells also exhibited growth delay in comparison with control tumor cells in vivo. Taken together, the current study findings provided novel insights into the underlying molecular mechanisms of PC oncogenesis, which may support the development of new therapeutic approaches for the treatment of PC.

miR­505 inhibits cell growth and EMT by targeting MAP3K3 through the AKT­NFκB pathway in NSCLC cells.

MicroRNAs (miRNAs) are short non­coding RNAs, which generally regulate gene expression at the post­transcriptional level. Dysregulation of miRNAs has been reported in numerous cancer types, including lung cancer. In the present study, the role of miR­505 in non­small cell lung cancer (NSCLC) cells was investigated. miR­505 served a tumor suppressor role in NSCLC cells. By reverse transcriptase­quantitative polymerase chain reaction detection, it was demonstrated that miR­505 was downregulated in NSCLC tissues and cell lines, which is negatively associated with large tumor size, Tumor­Node­Metastasis stage and distant metastasis in patients with NSCLC. Functional studies revealed that miR­505 inhibited cell proliferation, migration, invasion and epithelial­mesenchymal transition progress in vitro and tumor growth in vivo. Mechanically, mitogen­activated protein kinase kinase kinase 3 (MAP3K3) was identified as a direct target of miR­505 by binding to its 3'untranslated region and demonstrated to mediate the tumor suppressor roles of miR­505 in NSCLC cells. The effect of miR­505 on the activation of AKT/nuclear factor­κB (NFκB) pathway, which was downstream targets of MAP3K3, was further analyzed by western blot analysis and immunofluorescence analyses. The data demonstrated the inhibition of the AKT/NFκB pathway upon overexpressing miR­505 and the activation of AKT/NFκB pathway upon silencing miR­505. Collectively, the data revealed the novel role and target of miR­505 in NSCLC cells, which may provide novel insights regarding its role in the carcinogenesis of NSCLC and its potential values for clinical applications.

MiR-194 regulates nasopharyngeal carcinoma progression by modulating MAP3K3 expression.

Despite the recent development of treatment strategies for nasopharyngeal carcinoma, the effective management of this disease remains a challenging clinical problem. A better understanding of the regulatory roles of miR-194 and mitogen-activated protein kinase kinase kinase 3 (MAP3K3) in the nasopharyngeal-carcinoma-related gene network is required to address this issue. Here, we measured relative expression of miR-194 in human nasopharyngeal carcinoma tissues and normal epithelial tissues by quantitative real time PCR. We transfected cultured CNE-1 and C666-1 cells with miR-194 mimics, and then examined the effects on cell proliferation, cell migration and invasion. Luciferase reporter assay was used to validate the putative binding between miR-194 and MAP3K3. We then examined the effect of knockdown and overexpression of MAP3K3 on cell tumorigenesis. Expression of miR-194 is significantly down-regulated in nasopharyngeal carcinoma specimens and tumor cell lines when compared with normal controls. In addition, miR-194 suppressed tumor cell proliferation and viability, as well as migration and invasion of carcinoma cells. We found that miR-194 binds the 3' untranslated region of MAP3K3, and knockdown of miR-194 inhibited nasopharyngeal carcinoma cell proliferation, migration and invasion. In accordance, overexpression of MAP3K3 reversed the inhibitory effects of miR-194 in carcinoma cells. This study suggests that expression of miR-194 is down-regulated in nasopharyngeal carcinoma, and that miR-194 can directly target MAP3K3 to regulate tumor progression. Given the pivotal involvement of MAP3K3 in nasopharyngeal carcinoma development, targeting miR-194 may be a novel strategy for the treatment of nasopharyngeal carcinoma.

MEKK3 Sustains EMT and Stemness in Pancreatic Cancer by Regulating YAP and TAZ Transcriptional Activity.

BACKGROUND/AIM: Pancreatic cancer is one of the most threatening and poorly understood human malignancies. MEKK3 (MAP3K3) is a serine/threonine kinase activated by different signaling pathways. YAP and TAZ are critical oncogenic effectors in pancreatic cancer. We hypothesized that MEKK3 could sustain pancreatic cancer by inducing YAP/TAZ oncogenic activities. MATERIALS AND METHODS: In Panc1 and AsPC1 pancreatic cancer cell lines MEKK3 was knocked-out (KO) by the CRISPR/Cas9 method. These cells were used to evaluate MEKK3 contribution to the expression of YAP/TAZ and their target genes, cell migration, stemness, and in vivo tumor growth. RESULTS: MEKK3 KO reduced both EMT and cell migration, the size of 3D colonies and the percentage of CD44+/CD24+/EpCAM+ CSC, promoter recruitment of YAP/TAZ and the expression of their target genes. It reduced tumor growth and prolonged mice overall survival. CONCLUSION: Silencing of MEKK3 represents a valid approach to revert in vivo the aggressiveness of pancreatic cancer by modulating YAP/TAZ transcriptional activities.

MiroRNA-188 Acts as Tumor Suppressor in Non-Small-Cell Lung Cancer by Targeting MAP3K3.

Non-small cell lung cancer (NSCLC) is the most prevalent form of lung cancer. MicroRNAs have been increasingly implicated in NSCLC and may serve as novel therapeutic targets to combat cancer. Here we investigated the functional implication of miR-188 in NSCLC. We first analyzed miR-188 expression in both NSCLC clinical samples and cancer cell lines. Next we investigated its role in A549 and H2126 cells with cell proliferation, migration, and apoptosis assays. To extend the in vitro study, we employed both xenograft model and LSL- K-ras G12D lung cancer model to examine the role of miR-188 in tumorigenesis. Last we tested MAP3K3 as miR-188 target in NSCLC model. MiR-188 expression was significantly downregulated at the NSCLC tumor sites and lung cancer cells. In vitro transfection of miR-188 reduced cell proliferation and migration potential and promoted cell apoptosis. In xenograft model, miR-188 inhibited tumor growth derived from cancer cells. Intranasal miR-188 administration reduced tumor formation in NSCLC animal model. MAP3K3 was validated as direct target of miR-188. Knocking down MAP3K3 in mice also inhibited tumorigenesis in LSL- K-ras G12D model. Our results demonstrate that miR-188 and its downstream target MAP3K3 could be a potential therapeutic target for NSCLC.

MicroRNA-124 regulates the expression of MEKK3 in the inflammatory pathogenesis of Parkinson's disease.

BACKGROUND: Parkinson's disease (PD) is the most prevalent neurodegenerative disorder that is characterised by selective loss of midbrain dopaminergic (DA) neurons. Chronic inflammation of the central nervous system is mediated by microglial cells and plays a critical role in the pathological progression of PD. Brain-specific microRNA-124 (miR-124) expression is significantly downregulated in lipopolysaccharide (LPS)-treated BV2 cells and in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD. However, whether abnormal miR-124 expression could regulate the activation of microglia remains poorly understood. METHODS: BV2 cells were activated by exposure to LPS, and the expression levels of miR-124, mitogen-activated protein kinase kinase kinase 3 (MEKK3), and the nuclear factor of kappaB (NF-κB) p-p65 were analysed. Over-expression and knockdown studies of miR-124 were performed to observe the effects on MEKK3/NF-κB signalling pathways, and the induction of pro-inflammatory and neurotoxic factors was assessed. In addition, a luciferase reporter assay was conducted to confirm whether MEKK3 is a direct target of miR-124. Meanwhile, production of miR-124, MEKK3, and p-p65; midbrain DA neuronal death; or activation of microglia were analysed when treated with or without miR-124 in the MPTP-induced model of PD. RESULTS: We found that the knockdown of MEKK3 could inhibit the activation of microglia by regulating NF-κB expression. Over-expression of miR-124 could effectively attenuate the LPS-induced expression of pro-inflammatory cytokines and promote the secretion of neuroprotective factors. We also first identified a unique role of miR-124 in mediating the microglial inflammatory response by targeting MEKK3/NF-κB signalling pathways. In the microglial culture supernatant (MCS) transfer model, over-expression of the miR-124 or knockdown of MEKK3 in BV2 cells prevented SH-SY5Y from apoptosis and death. Moreover, MEKK3 and p-p65 were abundantly expressed in the midbrain. Furthermore, their expression levels increased and microglial activation was observed in the MPTP-induced model of PD. In addition, exogenous delivery of miR-124 could suppress MEKK3 and p-p65 expression and attenuate the activation of microglia in the substantia nigra pars compacta of MPTP-treated mice. miR-124 also could prevent MPTP-dependent apoptotic midbrain DA cell death in a MPTP-induced PD model. CONCLUSIONS: Taken together, our data suggest that miR-124 can inhibit neuroinflammation in the development of PD by regulating the MEKK3/NF-κB signalling pathways and implicate miR-124 as a potential therapeutic target for regulating the inflammatory response in PD.

miR-188 promotes senescence of lineage-negative bone marrow cells by targeting MAP3K3 expression.

Lineage-negative bone marrow cells (lin-BMCs) have reparative potential for overcoming endothelial dysfunction and reducing cardiovascular risk. Here, we found that miR-188 is upregulated and mitogen-activated protein kinase kinase kinase 3 (MAP3K3) is downregulated in aged lin-BMCs, whereas their expression is reversed in young lin-BMCs. We identified and confirmed MAP3K3 as a direct target of miR-188. MiR-188 overexpression or MAP3K3 silencing in young lin-BMCs increases p16 and p21 expression, enhances cell senescence, and decreases the ability for cell proliferation, migration, and tube formation. Conversely, miR-188 suppression in aged lin-BMCs yields the opposite results. We further found that MAP3K3 is involved in miR-188-induced promotion of lin-BMC senescence. All data reveal that miR-188 induces lin-BMC senescence by targeting MAP3K3 expression, thus, providing new theoretical basis for the prevention and treatment of cardiovascular diseases.