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 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 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 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.

Phosphorylation of Argonaute 2 at serine-387 facilitates its localization to processing bodies

2008 ◽  
Vol 413 (3) ◽  
pp. 429-436 ◽  
Author(s):  
Yan Zeng ◽  
Heidi Sankala ◽  
Xiaoxiao Zhang ◽  
Paul R. Graves
Keyword(s):  
Protein Kinase ◽  
P38 Mapk ◽  
Kinase Inhibitor ◽  
Mapk Pathway ◽  
Phosphorylation Site ◽  
Mitogen Activated Protein Kinase ◽  
Processing Bodies ◽  
Mitogen Activated Protein

Ago (Argonaute) proteins are essential effectors of RNA-mediated gene silencing. To explore potential regulatory mechanisms for Ago proteins, we examined the phosphorylation of human Ago2. We identified serine-387 as the major Ago2 phosphorylation site in vivo. Phosphorylation of Ago2 at serine-387 was significantly induced by treatment with sodium arsenite or anisomycin, and arsenite-induced phosphorylation was inhibited by a p38 MAPK (mitogen-activated protein kinase) inhibitor, but not by inhibitors of JNK (c-Jun N-terminal kinase) or MEK [MAPK/ERK (extracellular-signal-regulated kinase) kinase]. MAPKAPK2 (MAPK-activated protein kinase-2) phosphorylated bacterially expressed full-length human Ago2 at serine-387 in vitro, but not the S387A mutant. Finally, mutation of serine-387 to an alanine residue or treatment of cells with a p38 MAPK inhibitor reduced the localization of Ago2 to processing bodies. These results suggest a potential regulatory mechanism for RNA silencing acting through Ago2 serine-387 phosphorylation mediated by the p38 MAPK pathway.

scholarly journals Enhancing the Therapeutic Efficacy of KRASG12C Inhibitors in Lung Adenocarcinoma Cell Models by Cotargeting the MAPK Pathway or HSP90

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Ying Liu ◽  
Lei Wu ◽  
Hong Lu ◽  
En Wu ◽  
Jun Ni ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Lung Adenocarcinoma ◽  
Tyrosine Kinases ◽  
Tumor Regression ◽  
Mapk Pathway ◽  
Transcriptional Profiling ◽  
Multidrug Resistant ◽  
Mitogen Activated Protein Kinase

Background. KRASG12C inhibitors have shown promising efficacy in early clinical trials, but drug resistance compromises their long-term benefits. Therefore, it is critical to understand the mechanisms of drug resistance and to design appropriate combinatory treatments to improve efficacy. Methods. To understand the comprehensive mechanisms of drug resistance, we treated lung cancer cells with KRASG12C inhibitors for different periods and performed transcriptional profiling and signaling analysis to identify critical factors and pathways that drive drug tolerance and resistance. We also evaluated several drug combinations in vitro and in vivo to identify potentially effective therapeutics. Results. We found that the feedback activation of multiple receptor tyrosine kinases (RTKs) may have cooperatively induced intrinsic and adaptive resistance to KRASG12C inhibitors. Notably, continuous KRAS inhibition induced a multidrug-resistant phenotype, implying that upfront combinatory treatment might be required to treat this group of patients. We also demonstrated that concurrently targeting multiple nodes in the RTK/RAS/RAF/MEK/ERK axis improved the efficacy of KRASG12C inhibitors, mainly by suppressing the reactivation of the mitogen-activated protein kinase (MAPK) pathway. Moreover, the combined use of HSP90 and KRASG12C inhibitors effectively induced tumor regression in lung adenocarcinoma models in vitro and in vivo. Conclusion. Together, our findings revealed mechanisms underlying KRASG12C inhibitors resistance and provided novel candidate combinatory strategies to improve their anticancer activity.

scholarly journals BET Protein Inhibition Evidently Enhances Sensitivity to PI3K/mTOR Dual Inhibition in Intrahepatic Cholangiocarcinoma

2021 ◽  
Author(s):  
Xiaolong Miao ◽  
Weihua Gong
Keyword(s):  
Targeted Therapy ◽  
Combination Therapy ◽  
Intrahepatic Cholangiocarcinoma ◽  
Molecular Targeted Therapy ◽  
Primary Liver Cancer ◽  
Mtor Inhibitors ◽  
Dual Inhibitor ◽  
Hydrodynamic Transfection

Abstract Background & Aims: Intrahepatic cholangiocarcinoma (ICC), the second most common primary liver cancer, is a fatal malignancy with a poor prognosis. Molecular targeted therapy is a promising treatment strategy. However, resistance to molecular-targeted therapy is inevitable and represents a major clinical challenge. Our objective was to provide a novel and efficient therapeutic strategy in treating primary ICC.Approach & Results: We generated an orthotopic ICC mouse model through hydrodynamic transfection of AKT and YAP into mouse liver. Genetic approaches were applied to study the mechanism that mediated resistance to a PI3K/mTOR dual inhibitor in mediating AKT/YapS127A-driven tumorigenesis. Haematoxylin and eosin staining, immunohistochemistry and immunoblotting were applied to assess the efficacy of ICC combination therapy in vitro and in vivo.Conclusions: We confirmed that mTOR signalling is the most significantly affected pathway in ICC. BEZ235, a novel PI3K/mTOR dual inhibitor, can suppress the proliferation, invasion and colony formation abilities of ICC cells in vitro but cannot effectively inhibit ICC progression in vivo. The inhibition of PI3K/mTOR allowed the upregulation of c-Myc and YAP through the suppression of the phosphorylation of LATS1. This is a novel mechanism that mediates resistance to PI3K/mTOR dual inhibitors. However, BET inhibition by JQ1 downregulates c-Myc and YAP transcription, which could enhance the efficacy of PI3K/mTOR inhibitors. The efficacy results of combination therapy exhibited effective treatment of ICC in vitro and in vivo. Our data further confirmed that the combination of a PI3K/mTOR dual inhibitor and BET inhibition induces M1 polarization and suppresses M2 polarization in macrophages by regulating the expression of HIF-1a.

LIF transduces contradictory signals on capillary outgrowth through induction of stat3 and (P41/43)MAP kinase

2000 ◽  
Vol 113 (23) ◽  
pp. 4331-4339 ◽  
Author(s):  
H. Paradis ◽  
R.L. Gendron
Keyword(s):  
Signaling Pathways ◽  
Tyrosine Kinases ◽  
Mapk Pathway ◽  
Present Report ◽  
Binding Activity ◽  
Negative Regulator ◽  
Mapk Cascade ◽  
Mitogen Activated Protein Kinase

The signaling pathways regulating blood vessel growth and development are not well understood. In the present report, an in vitro model was used to identify signaling pathways regulating capillary formation in embryonic endothelial cells. Basic fibroblast growth factor (bFGF) plus leukemia inhibitory factor (LIF) optimally stimulate the formation of capillary-like structures of the embryonic endothelial cell line IEM. LIF stimulation of IEM cells leads to activation of the Stat3 as well as the (P41/43)mitogen-activated protein kinase ((P41/43)MAPK) cascade, while bFGF does not activate Stat3 but does induce the (P41/43)MAPK cascade. Inhibition of Stat3 DNA-binding activity by expression of a dominant inhibitory Stat3 mutant increases the capillary outgrowth of the IEM cells induced by LIF. Increased Stat3 activity by overexpression of the wild-type Stat3 greatly reduced capillary outgrowth. In contrast, inhibition of the (P41/43)MAPK cascade using a MEK-1 inhibitor dramatically inhibits the LIF-induced capillary outgrowth. Moreover, the increased formation of capillary-like structures of the IEM cells mediated by Stat3 inhibition does not overcome the requirement for activation of the (P41/43)MAPK pathway for capillary outgrowth. Stat3 activity correlates with the LIF-induced expression of the negative feedback regulators of the Janus (JAK) family of tyrosine kinases, SOCS-1 and SOCS-3. These results provide evidence that Stat3 acts as a negative regulator of capillary outgrowth, possibly by increasing SOCS-1 or SOCS-3 expression. The contradictory signals stimulated by LIF could be necessary to control the intensity of the response leading to capillary outgrowth in vivo.

scholarly journals MKK3 sustains cell proliferation and survival through p38DELTA MAPK activation in colorectal cancer

2019 ◽  
Vol 10 (11) ◽  
Author(s):  
Lorenzo Stramucci ◽  
Angelina Pranteda ◽  
Arianna Stravato ◽  
Carla Azzurra Amoreo ◽  
Annarita Pennetti ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Map Kinases ◽  
Molecular Mechanisms ◽  
Malignant Tumors ◽  
Mapk Pathway ◽  
Primary Cultures ◽  
Mitogen Activated Protein Kinase ◽  
Antitumor Effects

Abstract Colorectal cancer (CRC) is one of the most common malignant tumors worldwide and understanding its underlying molecular mechanisms is crucial for the development of therapeutic strategies. The mitogen-activated protein kinase-kinase 3 (MKK3) is a specific activator of p38 MAP kinases (p38 MAPKs), which contributes to the regulation of several cellular functions, such as proliferation, differentiation, apoptosis as well as response to drugs. At present, the exact MKK3/p38 MAPK pathway contribution in cancer is heavily debated because of its pleiotropic function. In this work, we retrospectively explored the prognostic and pathobiologic relevance of MKK3 in a cohort of CRC patients and assessed MKK3 molecular functions in a panel of CRC lines and colonocytes primary cultures. We found increased MKK3 levels in late-stage CRC patients which correlated with shorter overall survival. Herein, we report that the MKK3 targeting by inducible RNA interference univocally exerts antitumor effects in CRC lines but not in primary colonocytes. While MKK3 depletion per se affects growth and survival by induction of sustained autophagy and death in some CRC lines, it potentiates response to chemotherapeutic drug 5-fluorouracil (5-FU) in all of the tested CRC lines in vitro. Here, we demonstrate for the first time that in CRC the MKK3 specifically activates p38delta MAPK isoform to sustain prosurvival signaling and that such effect is exacerbated upon 5-FU challenge. Indeed, p38delta MAPK silencing recapitulates MKK3 depletion effects in CRC cells in vitro and in vivo. Overall, our data identified a molecular mechanism through which MKK3 supports proliferation and survival signaling in CRC, further supporting MKK3 as a novel and extremely attractive therapeutic target for the development of promising strategies for the management of CRC patients.

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