scholarly journals Mutant SETBP1 enhances NRAS-driven MAPK pathway activation to promote aggressive leukemia

2021 ◽  
Author(s):  
Sarah A. Carratt ◽  
Theodore P. Braun ◽  
Cody Coblentz ◽  
Zachary Schonrock ◽  
Rowan Callahan ◽  
...  
Keyword(s):  
Mapk Pathway ◽  
Gene Expression Signature ◽  
Mek Inhibitor ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Juvenile Myelomonocytic Leukemia ◽  
Murine Bone Marrow ◽  
Relapsed Disease

AbstractMutations in SET binding protein 1 (SETBP1) are associated with poor outcomes in myeloid leukemias. In the Ras-driven leukemia, juvenile myelomonocytic leukemia, SETBP1 mutations are enriched in relapsed disease. While some mechanisms for SETBP1-driven oncogenesis have been established, it remains unclear how SETBP1 specifically modulates the biology of Ras-driven leukemias. In this study, we found that when co-expressed with Ras pathway mutations, SETBP1 promoted oncogenic transformation of murine bone marrow in vitro and aggressive myeloid leukemia in vivo. We demonstrate that SETBP1 enhances the NRAS gene expression signature, driving upregulation of mitogen-activated protein kinase (MAPK) signaling and downregulation of differentiation pathways. SETBP1 also enhances NRAS-driven phosphorylation of MAPK proteins. Cells expressing NRAS and SETBP1 are sensitive to inhibitors of the MAPK pathway, and treatment with the MEK inhibitor trametinib conferred a survival benefit in a mouse model of NRAS/SETBP1-mutant disease. Our data demonstrate that despite driving enhanced MAPK signaling, SETBP1-mutant cells remain susceptible to trametinib in vitro and in vivo, providing encouraging pre-clinical data for the use of trametinib in SETBP1-mutant disease.

scholarly journals MEK-inhibitor-mediated rescue of skeletal myopathy caused by activating Hras mutation in a Costello syndrome mouse model

2021 ◽  
Author(s):  
William E. Tidyman ◽  
Alice F. Goodwin ◽  
Yoshiko Maeda ◽  
Ophir D. Klein ◽  
Katherine A. Rauen
Keyword(s):  
Mouse Model ◽  
Mapk Pathway ◽  
Mek Inhibitor ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Costello Syndrome ◽  
Skeletal Myopathy ◽  
Mitogen Activated Protein

Costello syndrome (CS) is a congenital disorder caused by heterozygous activating germline HRAS mutations in the canonical Ras/mitogen-activated protein kinase (Ras/MAPK) pathway. CS is one of the RASopathies, a large group of syndromes due to mutations within various components of the Ras/MAPK pathway. An important part of the phenotype that greatly impacts quality of life is hypotonia. To gain a better understanding of the mechanisms underlying hypotonia in CS, a mouse model with an activating HrasG12V allele was utilized. We identified a skeletal myopathy that was due in part to an inhibition of embryonic myogenesis and myofiber formation, resulting in a reduction of myofiber size and number that led to reduced muscle mass and strength. In addition to hyperactivation of the Ras/MAPK and PI3K/AKT pathways, there was a significant reduction of p38 signaling, as well as global transcriptional alterations consistent with the myopathic phenotype. Inhibition of Ras/MAPK pathway signaling using a MEK inhibitor rescued the HrasG12V myopathy phenotype both in vitro and in vivo, demonstrating that increased MAPK signaling is the main cause of the muscle phenotype in CS.

scholarly journals Combined VEGFR and MAPK pathway inhibition in angiosarcoma

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michael J. Wagner ◽  
Yasmin A. Lyons ◽  
Jean H. Siedel ◽  
Robert Dood ◽  
Archana S. Nagaraja ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Mapk Pathway ◽  
Combined Treatment ◽  
Mek Inhibitor ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
In Vivo Model ◽  
Mitogen Activated Protein

AbstractAngiosarcoma is an aggressive malignancy of endothelial cells that carries a high mortality rate. Cytotoxic chemotherapy can elicit clinical responses, but the duration of response is limited. Sequencing reveals multiple mutations in angiogenesis pathways in angiosarcomas, particularly in vascular endothelial growth factor (VEGFR) and mitogen-activated protein kinase (MAPK) signaling. We aimed to determine the biological relevance of these pathways in angiosarcoma. Tissue microarray consisting of clinical formalin-fixed paraffin embedded tissue archival samples were stained for phospho- extracellular signal-regulated kinase (p-ERK) with immunohistochemistry. Angiosarcoma cell lines were treated with the mitogen-activated protein kinase kinase (MEK) inhibitor trametinib, pan-VEGFR inhibitor cediranib, or combined trametinib and cediranib and viability was assessed. Reverse phase protein array (RPPA) was performed to assess multiple oncogenic protein pathways. SVR angiosarcoma cells were grown in vivo and gene expression effects of treatment were assessed with whole exome RNA sequencing. MAPK signaling was found active in over half of clinical angiosarcoma samples. Inhibition of MAPK signaling with the MEK inhibitor trametinib decreased the viability of angiosarcoma cells. Combined inhibition of the VEGF and MAPK pathways with cediranib and trametinib had an additive effect in in vitro models, and a combinatorial effect in an in vivo model. Combined treatment led to smaller tumors than treatment with either agent alone. RNA-seq demonstrated distinct expression signatures between the trametinib treated tumors and those treated with both trametinib and cediranib. These results indicate a clinical study of combined VEGFR and MEK inhibition in angiosarcoma is warranted.

scholarly journals SPDR-1 HSP90 inhibition overcomes resistant to molecular targeted therapy in BRAFV600E mutant glioblastoma

2021 ◽  
Vol 3 (Supplement_6) ◽  
pp. vi3-vi3
Author(s):  
Jo Sasame ◽  
Naoki Ikegaya ◽  
Yohei Miyake ◽  
Takahiro Hayashi ◽  
Akito Oshima ◽  
...  
Keyword(s):  
Targeted Therapy ◽  
Molecular Targeted Therapy ◽  
Mapk Pathway ◽  
Mek Inhibitor ◽  
Mtor Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Hsp90 Inhibition ◽  
Pdx Models

Abstract The BRAFV600E mutation results in the constitutive activation of downstream mitogen activated protein kinase (MAPK) pathway that promotes tumor growth. Recently, molecular targeted therapy using BRAF/MEK inhibitor has been reported for BRAFV600E mutant high-grade glioma, but the therapeutic effect is limited by the emergence of drug resistance. Herein, we established paired BRAFV600E mutant glioblastoma (GBM) patient-derived xenograft (PDX) models, which were derived from tumors at prior to and recurrence after molecular targeted therapy. These PDX models were found to extensively recapitulate the histology, genetic abnormalities, and even the clinical course of the patients. Furthermore, BRAF/MEK inhibitor gradually caused resistance in cell lines derived from specimens that initially responded to molecular targeted therapy. In this study, genomic and epigenomic changes had little effect on the resistance mechanism. On the other hand, we found that hyperactivation of the MAPK pathway through c-Raf and the AKT/mTOR pathway primarily caused resistance to molecular targeted therapy in BRAFV600E mutant GBM. Through a high throughput drug screening, we find that HSP90 inhibitor with BRAF/MEK inhibitor coordinately deactivates MAPK pathway and AKT/mTOR pathway, and mediates potent toxicity in vitro and in vivo in refractory and acquired resistant models. These findings support that this therapeutic approach can overcome the limitation of current molecular targeted therapy in BRAFV600E mutant GBM.

scholarly journals Triple blockade of EGFR, MEK and PD-L1 has antitumor activity in colorectal cancer models with constitutive activation of MAPK signaling and PD-L1 overexpression

2019 ◽  
Vol 38 (1) ◽  
Author(s):  
S. Napolitano ◽  
N. Matrone ◽  
A. L. Muddassir ◽  
G. Martini ◽  
A. Sorokin ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Molecular Mechanisms ◽  
Mapk Pathway ◽  
Combined Treatment ◽  
Acquired Resistance ◽  
Mek Inhibitor ◽  
Gene Signature ◽  
Mapk Signaling

Abstract Background Molecular mechanisms driving acquired resistance to anti-EGFR therapies in metastatic colorectal cancer (mCRC) are complex but generally involve the activation of the downstream RAS-RAF-MEK-MAPK pathway. Nevertheless, even if inhibition of EGFR and MEK could be a strategy for overcoming anti-EGFR resistance, its use is limited by the development of MEK inhibitor (MEKi) resistance. Methods We have generated in vitro and in vivo different CRC models in order to underline the mechanisms of MEKi resistance. Results The three different in vitro MEKi resistant models, two generated by human CRC cells quadruple wild type for KRAS, NRAS, BRAF, PI3KCA genes (SW48-MR and LIM1215-MR) and one by human CRC cells harboring KRAS mutation (HCT116-MR) showed features related to the gene signature of colorectal cancer CMS4 with up-regulation of immune pathway as confirmed by microarray and western blot analysis. In particular, the MEKi phenotype was associated with the loss of epithelial features and acquisition of mesenchymal markers and morphology. The change in morphology was accompanied by up-regulation of PD-L1 expression and activation of EGFR and its downstream pathway, independently to RAS mutation status. To extend these in vitro findings, we have obtained mouse colon cancer MC38- and CT26-MEKi resistant syngeneic models (MC38-MR and CT26-MR). Combined treatment with MEKi, EGFR inhibitor (EGFRi) and PD-L1 inhibitor (PD-L1i) resulted in a marked inhibition of tumor growth in both models. Conclusions These results suggest a strategy to potentially improve the efficacy of MEK inhibition by co-treatment with EGFR and PD-L1 inhibitors via modulation of host immune responses.

scholarly journals Resveratrol Rescue Indoxyl Sulfate-Induced Deterioration of Osteoblastogenesis via the Aryl Hydrocarbon Receptor /MAPK Pathway

2020 ◽  
Vol 21 (20) ◽  
pp. 7483 ◽  
Author(s):  
Wen-Chih Liu ◽  
Jia-Fwu Shyu ◽  
Yuh-Feng Lin ◽  
Hui-Wen Chiu ◽  
Paik Seong Lim ◽  
...  
Keyword(s):  
Aryl Hydrocarbon Receptor ◽  
Mapk Pathway ◽  
Mapk Signaling ◽  
Indoxyl Sulfate ◽  
Mitogen Activated Protein Kinase ◽  
Uremic Toxin ◽  
Aryl Hydrocarbon ◽  
The Impact

Indoxyl sulfate (IS), a uremic toxin derived from dietary tryptophan metabolism by the gut microbiota, is an endogenous aryl hydrocarbon receptor (AhR) agonist and a key player in bone remodeling. Resveratrol (RSV), an AhR antagonist, plays a protective role in shielding against AhR ligands. Our study explored the impact of IS on osteoblast differentiation and examined the possible mechanism of IS in controlling the expression of osteoblastogenesis markers through an in-depth investigation of AhR signaling. In vivo, we found histological architectural disruption of the femoral bones in 5/6 nephrectomies of young adult IS exposed mice, including reduced Runx2 antigen expression. RSV improved the diaphysis architecture, Runx2 expression, and trabecular quality. In vitro data suggest that IS at 500 and 1000 μM disturbed osteoblastogenesis through suppression of the ERK and p38 mitogen-activated protein kinase (MAPK) pathways, which were found to be downstream of AhR. RSV proved to ameliorate the anti-osteoblastogenic effects of IS through the inhibition of AhR and downstream signaling. Taken together, we demonstrated that the IS/AhR/MAPK signaling pathway plays a crucial role in the inhibition of osteoblastogenesis, and RSV has a potential therapeutic role in reversing the IS-induced decline in osteoblast development and suppressing abnormal bone turnover in chronic kidney disease patients.

Dual-specificity phosphatases are targets of the Wnt/β-catenin pathway and candidate mediators of β-catenin/Ras signaling interactions

2012 ◽  
Vol 393 (10) ◽  
pp. 1183-1191 ◽  
Author(s):  
Eva Zeller ◽  
Katharina Mock ◽  
Moritz Horn ◽  
Sabine Colnot ◽  
Michael Schwarz ◽  
...  
Keyword(s):  
Mapk Pathway ◽  
Growth Factor Receptor ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Ras Signaling ◽  
Dual Specificity ◽  
Murine Liver ◽  
Dual Specificity Phosphatases

Abstract The Wnt/β-catenin and the Ras/mitogen-activated protein kinase (MAPK) pathways play important roles in cancer development. Both pathways have been studied discretely, but the mechanisms of possible crosstalk are still not fully understood. We have previously shown that β-catenin and MAPK signaling interfere with each other in murine liver in vivo and in vitro. Here, we show that dual specificity phosphatases (Dusps) 6 and 14, known to play an essential role in regulating MAPK pathway activity via feedback mechanisms, are up-regulated by activation of β-catenin in murine liver cells, whereas the epidermal growth factor receptor, an upstream effector in the Ras/MAPK cascade, is down-regulated by β-catenin. In addition, we identified a β-catenin-binding site within the Dusp6 promoter, which is responsible for the activation of the promoter by β-catenin signaling, and demonstrated reduced inducibility of MAPK signaling in cultured mouse hepatoma cells following β-catenin activation. Thus, β-catenin is able to inhibit activation of the Egfr/Ras/MAPK signaling cascade, both at the receptor level and by interfering with MAPK activity via Dusps.

scholarly journals Thymoquinone, a Dietary Bioactive Compound, Exerts Anti-Inflammatory Effects in Colitis by Stimulating Expression of the Colonic Epithelial PPAR-γ Transcription Factor

Nutrients ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 1343
Author(s):  
Balaji Venkataraman ◽  
Saeeda Almarzooqi ◽  
Vishnu Raj ◽  
Abdullah T. Alhassani ◽  
Ahmad S. Alhassani ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Activity Index ◽  
Nigella Sativa ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Ppar Γ ◽  
Anti Inflammatory ◽  
Ht 29

Inflammatory bowel diseases (IBD) are chronic inflammatory disorders with increasing incidence and prevalence worldwide. Here, we investigated thymoquinone (TQ), a naturally occurring phytochemical present in Nigella sativa, for anti-inflammatory effects in colonic inflammation. To address this, we used in vivo (mice) and in vitro (HT-29 cells) models in this investigation. Our results showed that TQ treatment significantly reduced the disease activity index (DAI), myeloperoxidase (MPO) activity, and protected colon microscopic architecture. In addition, TQ also reduced the expression of proinflammatory cytokines and mediators at both the mRNA and protein levels. Further, TQ decreased phosphorylation of the activated mitogen-activated protein kinase (MAPK) signaling pathway and nuclear factor kappa B (NF-κB) proteins and enhanced colon epithelial PPAR-γ transcription factor expression. TQ significantly decreased proinflammatory chemokines (CXCL-1 and IL-8), and mediator (COX-2) mRNA expression in HT-29 cells treated with TNF-α. TQ also increased HT-29 PPAR-γ mRNA, PPAR-γ protein expression, and PPAR-γ promoter activity. These results indicate that TQ inhibits MAPK and NF-κB signaling pathways and transcriptionally regulates PPAR-γ expression to induce potent anti-inflammatory activity in vivo and in vitro models of colon inflammation.

scholarly journals DDRE-07. DIPG HARBOUR ALTERATIONS TARGETABLE BY MEK INHIBITORS, WITH ACQUIRED RESISTANCE MECHANISMS OVERCOME BY COMBINATORIAL INHIBITION

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii62-ii62
Author(s):  
Elisa Izquierdo ◽  
Diana Carvalho ◽  
Alan Mackay ◽  
Sara Temelso ◽  
Jessica K R Boult ◽  
...  
Keyword(s):  
Drug Exposure ◽  
Mapk Pathway ◽  
Synergistic Effects ◽  
Acquired Resistance ◽  
Mek Inhibitor ◽  
Resistance Mechanisms ◽  
Genetic Alterations ◽  
Mesenchymal Transition

Abstract The survival of children with diffuse intrinsic pontine glioma (DIPG) remains dismal, with new treatments desperately needed. In the era of precision medicine, targeted therapies represent an exciting treatment opportunity, yet resistance can rapidly emerge, playing an important role in treatment failure. In a prospective biopsy-stratified clinical trial, we combined detailed molecular profiling (methylation BeadArray, exome, RNAseq, phospho-proteomics) linked to drug screening in newly-established patient-derived models of DIPG in vitro and in vivo. We identified a high degree of in vitro sensitivity to the MEK inhibitor trametinib (GI50 16-50nM) in samples, which harboured genetic alterations targeting the MAPK pathway, including the non-canonical BRAF_G469V mutation, and those affecting PIK3R1 and NF1. However, treatment of PDX models and of a patient with trametinib at relapse failed to elicit a significant response. We generated trametinib-resistant clones (62-188-fold, GI50 2.4–5.2µM) in the BRAF_G469V model through continuous drug exposure, and identified acquired mutations in MEK1/2 (MEK1_K57N, MEK1_I141S and MEK2_I115N) with sustained pathway up-regulation. These cells showed the hallmarks of mesenchymal transition, and expression signatures overlapping with inherently trametinib-insensitive primary patient-derived cells that predicted an observed sensitivity to dasatinib. Combinations of trametinib with dasatinib and the downstream ERK inhibitor ulixertinib showed highly synergistic effects in vitro. These data highlight the MAPK pathway as a therapeutic target in DIPG, and show the importance of parallel resistance modelling and rational combinatorial treatments likely to be required for meaningful clinical translation.

scholarly journals Critical role of the extracellular signal–regulated kinase–MAPK pathway in osteoblast differentiation and skeletal development

2007 ◽  
Vol 176 (5) ◽  
pp. 709-718 ◽  
Author(s):  
Chunxi Ge ◽  
Guozhi Xiao ◽  
Di Jiang ◽  
Renny T. Franceschi
Keyword(s):  
Transcriptional Activity ◽  
Mapk Pathway ◽  
Skeletal Development ◽  
Critical Role ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal

The extracellular signal–regulated kinase (ERK)–mitogen-activated protein kinase (MAPK) pathway provides a major link between the cell surface and nucleus to control proliferation and differentiation. However, its in vivo role in skeletal development is unknown. A transgenic approach was used to establish a role for this pathway in bone. MAPK stimulation achieved by selective expression of constitutively active MAPK/ERK1 (MEK-SP) in osteoblasts accelerated in vitro differentiation of calvarial cells, as well as in vivo bone development, whereas dominant-negative MEK1 was inhibitory. The involvement of the RUNX2 transcription factor in this response was established in two ways: (a) RUNX2 phosphorylation and transcriptional activity were elevated in calvarial osteoblasts from TgMek-sp mice and reduced in cells from TgMek-dn mice, and (b) crossing TgMek-sp mice with Runx2+/− animals partially rescued the hypomorphic clavicles and undemineralized calvaria associated with Runx2 haploinsufficiency, whereas TgMek-dn; Runx2+/− mice had a more severe skeletal phenotype. This work establishes an important in vivo function for the ERK–MAPK pathway in bone that involves stimulation of RUNX2 phosphorylation and transcriptional activity.

LncRNA MALAT1 exhibits positive effects on nucleus pulposus cell biology in vivo and in vitro by sponging miR-503

2020 ◽  
Author(s):  
Hongyu Zheng ◽  
Tingting Wang ◽  
Xiangmin Li ◽  
Wei He ◽  
Zhiqiang Gong ◽  
...  
Keyword(s):  
Nucleus Pulposus ◽  
Disc Degeneration ◽  
Cell Biology ◽  
Mapk Pathway ◽  
Critical Role ◽  
Mapk Signaling ◽  
Positive Effects ◽  
Lncrna Malat1

Abstract Background: Intervertebral disc degeneration (IDD) is characterized by the loss of nucleus pulposus cells (NPCs) and phenotypic abnormalities. Accumulating evidence suggests that long noncoding RNAs (lncRNAs) are involved in the pathogenesis of IDD. In this study, we aimed to investigate the functional effects of lncRNA MALAT1 on NPCs in IDD and the possible mechanism governing these effects. Results: We validated the decreased expression of MALAT1 in the IDD tissues, which was associated with decreased Collagen II and Aggrecan expression. In vitro, overexpressed MALAT1 could attenuate the effect of IL-1β on NPC proliferation, apoptosis, and Aggrecan degradation. In vivo, MALAT1 overexpression attenuated the severity of disc degeneration in IDD model rats. Our molecular study further demonstrated that MALAT1 could sponge miR-503, modulate the expression of miR-503, and activate downstream MAPK signaling pathways. The effects of MALAT1 on NPCs were partially reversed/aggregated by miR-503 mimics/inhibitor treatment. Conclusion: Our data suggested that the MALAT1-miR-503-MAPK pathway plays a critical role in NPCs, which may be a potential strategy for alleviating IDD.

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