scholarly journals P.022 Myasthenia gravis following dabrafenib and trametinib for metastatic melanoma

2019 ◽  
Vol 46 (s1) ◽  
pp. S19 ◽  
Author(s):  
A Zaloum ◽  
JR Falet ◽  
A Elkrief ◽  
C Chalk
Keyword(s):  
Protein Kinase ◽  
Myasthenia Gravis ◽  
Metastatic Melanoma ◽  
Mapk Pathway ◽  
Braf Inhibitor ◽  
Mek Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Proximal Muscle Weakness ◽  
Proximal Muscle ◽  
Mitogen Activated Protein

Background: Inhibitors of BRAF and MEK, enzymes in the mitogen-activated protein kinase (MAPK) pathway, are now widely used in the treatment of metastatic melanoma. We report a case of acetylcholine receptor (AChR) antibody-positive myasthenia gravis developing after exposure to dabrafenib, a BRAF inhibitor, and trametinib, a MEK inhibitor. Methods: A 68-year-old man presented with dysarthria, dysphagia, cough, dyspnea, and fever. Examination revealed fatigable ptosis and proximal muscle weakness. He had started dabrafenib and trametinib for metastatic melanoma two weeks prior. He was diagnosed with myasthenia gravis and superimposed aspiration pneumonia. AChR antibodies were positive. Dabrafenib and trametinib were stopped. He improved rapidly with pyridostigmine alone, and remained free of myasthenic symptoms for the next two months. Another course of dabrafenib and trametinib was given, and seven weeks later, his myasthenic symptoms recurred. Pyridostigmine produced only partial improvement, and treatment with intravenous immunoglobulin and prednisone was initiated. Results: We are unaware of prior reports of an association between BRAF/MEK inhibitors and seropositive myasthenia gravis. The development of myasthenic symptoms twice after BRAF/MEK inhibitor exposure suggests that the association is more than coincidental. Conclusions: Myasthenia gravis may be a complication of treatment of melanoma with dabrafenib and trametinib. The mechanism by which this occurs is unknown.

scholarly journals Ocular changes in metastatic melanoma patients treated with MEK inhibitor cobimetinib and BRAF inhibitor vemurafenib

2018 ◽  
Vol 52 (2) ◽  
pp. 213-219 ◽  
Author(s):  
Ana Ursula Gavric ◽  
Janja Ocvirk ◽  
Polona Jaki Mekjavic
Keyword(s):  
Metastatic Melanoma ◽  
Braf Inhibitor ◽  
Mek Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Retinal Layers ◽  
Ocular Symptoms ◽  
Ocular Side ◽  
Mitogen Activated Protein ◽  
Melanoma Patients ◽  
Murine Sarcoma

AbstractBackgroundMitogen-activated protein kinase kinase (MEK) inhibitor cobimetinib and V-raf murine sarcoma viral oncogene homolog B1 (BRAF) inhibitor vemurafenib have significantly improved the prognosis of BRAF-mutated metastatic melanoma. Some ocular symptoms and signs were recently recognized to follow this treatment. The study was aimed to investigate ocular toxicity in patients with metastatic melanoma treated with cobimetinib in combination with vemurafenib.Patients and methodsIn the prospective, observational study, patients with BRAF-mutated metastatic melanoma treated with cobimetinib in combination with vemurafenib at the Institute of Oncology Ljubljana were asked to participate. Ophthalmic examination was performed including measurement of visual acuity and intraocular pressure, slit lamp examination, funduscopy (CF), infrared-reflectance (IR) imaging and optical coherence tomography (OCT).ResultsFive out of 7 patients noticed changes in vision few days after starting the therapy with cobimetinib. In all patients, small circular lesions, described as MEKAR lesions, were documented in outer retinal layers demonstrated with OCT, IR, and CF. Changes were in the center and/or scattered over the retina almost symmetrical in both eyes in 6 patients, and asymmetrical in one patient, the latter presented also with unilateral anterior uveitis and cystoid macular edema.ConclusionsMultiple bilateral foveal and extrafoveal small retinal lesions in the outer retinal layers develop in patients treated with MEK inhibitor in combination with BRAF inhibitor. Ophthalmologists and oncologists need to be aware of this common, yet relatively benign and often transient ocular side effect to avoid needless intervention, including the discontinuance of a potentially life-prolonging therapy.

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.

Thrombopoietin-Induced Activation of the Mitogen-Activated Protein Kinase (MAPK) Pathway in Normal Megakaryocytes: Role in Endomitosis

Blood ◽  
1999 ◽  
Vol 94 (4) ◽  
pp. 1273-1282 ◽  
Author(s):  
Ponlapat Rojnuckarin ◽  
Jonathan G. Drachman ◽  
Kenneth Kaushansky
Keyword(s):  
Protein Kinase ◽  
Mapk Pathway ◽  
Geometric Mean ◽  
Critical Role ◽  
Mek Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Mapk Activity ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Signaling Domain

Thrombopoietin (TPO) plays a critical role in megakaryocyte proliferation and differentiation. Using various cultured cell lines, several recent studies have implicated the mitogen-activated protein kinase (MAPK) pathway in megakaryocyte differentiation. In the study reported here, we examined the role played by thrombopoietin-induced MAPK activity in a cytokine-dependent cell line (BAF3/Mpl) and in primary murine megakaryocytes. In both systems, extracellular signal-regulated protein kinase (ERK) 1 and 2 MAPK phosphorylation was rapidly induced by TPO stimulation. To identify the Mpl domain responsible for MAPK activation, BAF3 cells expressing truncated forms of the Mpl receptor were studied. Phosphorylation of ERKs did not require elements of the cytoplasmic signaling domain distal to Box 2 and was not dependent on phosphorylation of the adapter protein Shc. ERK activation in murine megakaryocytes was maximal at 10 minutes and was markedly decreased over the subsequent 3 hours. Next, the physiologic consequences of MAPK inhibition were studied. Using the MAPK kinase (MEK) inhibitor, PD 98059, blockade of MAPK activity substantially reduced TPO-dependent proliferation in BAF3/Mpl cells and markedly decreased mean megakaryocyte ploidy in cultures. To exclude an indirect effect of MAPK inhibition on stromal cells in whole bone marrow, CD41+ cells were selected and then cultured in TPO. The number of polyploid megakaryocytes derived from the CD41-selected cells was also significantly reduced by MEK inhibition, as was their geometric mean ploidy. These studies show an important role for MAPK in TPO-induced endomitosis and underscore the value of primary cells when studying the physiologic effects of signaling pathways.

Thrombopoietin-Induced Activation of the Mitogen-Activated Protein Kinase (MAPK) Pathway in Normal Megakaryocytes: Role in Endomitosis

Blood ◽  
1999 ◽  
Vol 94 (4) ◽  
pp. 1273-1282 ◽  
Author(s):  
Ponlapat Rojnuckarin ◽  
Jonathan G. Drachman ◽  
Kenneth Kaushansky
Keyword(s):  
Protein Kinase ◽  
Mapk Pathway ◽  
Geometric Mean ◽  
Critical Role ◽  
Mek Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Mapk Activity ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Signaling Domain

Abstract Thrombopoietin (TPO) plays a critical role in megakaryocyte proliferation and differentiation. Using various cultured cell lines, several recent studies have implicated the mitogen-activated protein kinase (MAPK) pathway in megakaryocyte differentiation. In the study reported here, we examined the role played by thrombopoietin-induced MAPK activity in a cytokine-dependent cell line (BAF3/Mpl) and in primary murine megakaryocytes. In both systems, extracellular signal-regulated protein kinase (ERK) 1 and 2 MAPK phosphorylation was rapidly induced by TPO stimulation. To identify the Mpl domain responsible for MAPK activation, BAF3 cells expressing truncated forms of the Mpl receptor were studied. Phosphorylation of ERKs did not require elements of the cytoplasmic signaling domain distal to Box 2 and was not dependent on phosphorylation of the adapter protein Shc. ERK activation in murine megakaryocytes was maximal at 10 minutes and was markedly decreased over the subsequent 3 hours. Next, the physiologic consequences of MAPK inhibition were studied. Using the MAPK kinase (MEK) inhibitor, PD 98059, blockade of MAPK activity substantially reduced TPO-dependent proliferation in BAF3/Mpl cells and markedly decreased mean megakaryocyte ploidy in cultures. To exclude an indirect effect of MAPK inhibition on stromal cells in whole bone marrow, CD41+ cells were selected and then cultured in TPO. The number of polyploid megakaryocytes derived from the CD41-selected cells was also significantly reduced by MEK inhibition, as was their geometric mean ploidy. These studies show an important role for MAPK in TPO-induced endomitosis and underscore the value of primary cells when studying the physiologic effects of signaling pathways.

scholarly journals Control of thrombopoietin-induced megakaryocytic differentiation by the mitogen-activated protein kinase pathway.

1997 ◽  
Vol 17 (9) ◽  
pp. 4991-5000 ◽  
Author(s):  
M C Rouyez ◽  
C Boucheron ◽  
S Gisselbrecht ◽  
I Dusanter-Fourt ◽  
F Porteu
Keyword(s):  
Protein Kinase ◽  
Mapk Pathway ◽  
Mek Inhibitor ◽  
Cytoplasmic Domain ◽  
Mitogen Activated Protein Kinase ◽  
Mapk Activation ◽  
Erk Activation ◽  
Megakaryocytic Differentiation ◽  
Mitogen Activated Protein ◽  
Cellular Context

Thrombopoietin (TPO) is the major regulator of both growth and differentiation of megakaryocytes. We previously showed that both functions can be generated by TPO in the megakaryoblastic cell line UT7, in which murine Mpl was introduced, and are independently controlled by distinct regions of the cytoplasmic domain of Mpl. Particularly, residues 71 to 94 of this domain (deleted in the mutant mpl delta3) were found to be required for megakaryocytic maturation but dispensable for proliferation. We show here that TPO-induced differentiation in UT7 cells is tightly dependent on a strong, long-lasting activation of the mitogen-activated protein kinase (MAPK) pathway. Indeed, (i) in UT7-mpl cells, TPO induced a strong activation of extracellular signal-regulated kinases (ERK) which was persistent until at least 4 days in TPO-containing medium; (ii) a specific MAPK kinase (MEK) inhibitor inhibited TPO-induced megakaryocytic gene expression; (iii) the Mpl mutant mpl delta3, which displayed no maturation activity, transduced only a weak and transient ERK activation in UT7 cells; and (iv) TPO-induced megakaryocytic differentiation in UT7-mpl delta3 cells was partially restored by expression of a constitutively activated mutant of MEK. The capacity of TPO to trigger a strong and prolonged MAPK signal depended on the cell in which Mpl was introduced. In BAF3-mpl cells, TPO triggered a weak and transient ERK activation, similar to that induced in UT7-mpl delta3 cells. In these cells, no difference in MAPK activation was found between normal Mpl and mpl delta3. Thus, depending on the cellular context, several distinct regions of the cytoplasmic domain of Mpl and signaling pathways may contribute to generate quantitative variations in MAPK activation.

scholarly journals Expression of transgenes enriched in rare codons is enhanced by the MAPK pathway

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jackson Peterson ◽  
Siqi Li ◽  
Erin Kaltenbrun ◽  
Ozgun Erdogan ◽  
Christopher M. Counter
Keyword(s):  
Amino Acids ◽  
Protein Kinase ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Rare Codons ◽  
Synonymous Codons ◽  
Multiple Components ◽  
Human Genes ◽  
Regulatory Module ◽  
Mitogen Activated Protein

AbstractThe ability to translate three nucleotide sequences, or codons, into amino acids to form proteins is conserved across all organisms. All but two amino acids have multiple codons, and the frequency that such synonymous codons occur in genomes ranges from rare to common. Transcripts enriched in rare codons are typically associated with poor translation, but in certain settings can be robustly expressed, suggestive of codon-dependent regulation. Given this, we screened a gain-of-function library for human genes that increase the expression of a GFPrare reporter encoded by rare codons. This screen identified multiple components of the mitogen activated protein kinase (MAPK) pathway enhancing GFPrare expression. This effect was reversed with inhibitors of this pathway and confirmed to be both codon-dependent and occur with ectopic transcripts naturally coded with rare codons. Finally, this effect was associated, at least in part, with enhanced translation. We thus identify a potential regulatory module that takes advantage of the redundancy in the genetic code to modulate protein expression.

scholarly journals Ghrelin exerts a proliferative effect on a rat pituitary somatotroph cell line via the mitogen-activated protein kinase pathway

2004 ◽  
pp. 233-240 ◽  
Author(s):  
AM Nanzer ◽  
S Khalaf ◽  
AM Mozid ◽  
RC Fowkes ◽  
MV Patel ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Protein Kinase ◽  
Cell Line ◽  
Kinase Inhibitor ◽  
Thymidine Incorporation ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Gh3 Cells ◽  
Rat Pituitary ◽  
Mitogen Activated Protein

OBJECTIVES: Ghrelin is a brain-gut peptide with GH-releasing and appetite-inducing activities and a widespread tissue distribution. Ghrelin is the endogenous ligand of the GH secretagogue receptor type 1a (GHS-R1a), and both ghrelin and the GHS-R1a are expressed in the pituitary. There are conflicting data regarding the effects of ghrelin on cell proliferation. A positive effect on proliferation and activation of the mitogen-activated protein kinase (MAPK) pathway has been found in hepatoma, adipose, cardiomyocyte and prostate cell lines. However, ghrelin has also been shown to have anti-proliferative effects on breast, lung and thyroid cell lines. We therefore examined the effect of ghrelin on the rat pituitary cell line GH3. METHODS: RT-PCR was used for the detection of GHS-R1a and pre-proghrelin mRNA expression in GH3 cells. The effect of ghrelin on cell proliferation was studied using [(3)H]thymidine incorporation; cell counting and the activation of the MAPK pathway were studied using immunoblotting and inhibitors of the extracellular signal-regulated kinase 1 and 2 (ERK 1/2), protein kinase C (PKC) and tyrosine phosphatase pathways. RESULTS: GHS-R1a and ghrelin mRNA expression were detected in GH3 cells. Ghrelin, at 10(-10) to 10(-6) M concentrations, significantly increased [(3)H]thymidine incorporation (at 10(-9) M, 183+/-13% (means+/-s.e.m.) compared with untreated controls), while 12-phorbol 13-myristate acetate (PMA) at 10(-7) M (used as a positive control) caused a 212+/-14% increase. A reproducible stimulatory effect of desoctanoyl ghrelin was also observed on [(3)H]thymidine incorporation (135+/-5%; P<0.01 at 10(-9) M compared with control), as well as on the cell count (control 6.8 x 10(4)+/-8.7 x 10(3) cells/ml vs desoctanoyl ghrelin (10(-9) M) 1.04 x 10(5)+/-7.5 x 10(3) cells/ml; P<0.01). Ghrelin caused a significant increase in phosphorylated ERK 1/2 in immunoblotting, while desoctanoyl ghrelin showed a smaller but also significant stimulatory effect. The positive effect of ghrelin and desoctanoyl ghrelin on [(3)H]thymidine incorporation was abolished by the MAPK kinase inhibitor U0126, the PKC inhibitor GF109203X and the tyrosine kinase inhibitor tyrphostin 23, suggesting that the ghrelin-induced cell proliferation of GH3 cells is mediated both via a PKC-MAPK-dependent pathway and via a tyrosine kinase-dependent pathway. This could also be clearly demonstrated by Western blot analysis, where a transient increase in ERK 1/2 phosphorylation by ghrelin was attenuated by all three inhibitors. CONCLUSION: We have shown a novel role for ghrelin in stimulating the proliferation of a somatotroph pituitary tumour cell line, suggesting that ERK activation is involved in mediating the effects of ghrelin on cell proliferation. Desoctanoyl ghrelin showed a similar effect. As ghrelin has been shown to be expressed in both normal and adenomatous pituitary tissue, locally produced ghrelin may play a role in pituitary tumorigenesis via an autocrine/paracrine pathway.

scholarly journals The vaccinia virus-stimulated mitogen-activated protein kinase (MAPK) pathway is required for virus multiplication

2004 ◽  
Vol 381 (2) ◽  
pp. 437-446 ◽  
Author(s):  
Anderson A. ANDRADE ◽  
Patrícia N. G. SILVA ◽  
Anna C. T. C. PEREIRA ◽  
Lirlândia P. de SOUSA ◽  
Paulo C. P. FERREIRA ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Vaccinia Virus ◽  
Mapk Pathway ◽  
Decisive Role ◽  
Virus Multiplication ◽  
Mitogen Activated Protein Kinase ◽  
Actin Dynamics ◽  
Kinase Activation ◽  
Mitogen Activated Protein

Early events play a decisive role in virus multiplication. We have shown previously that activation of MAPK/ERK1/2 (mitogen-activated protein kinase/extracellular-signal-regulated kinase 1/2) and protein kinase A are pivotal for vaccinia virus (VV) multiplication [de Magalhães, Andrade, Silva, Sousa, Ropert, Ferreira, Kroon, Gazzinelli and Bonjardim (2001) J. Biol. Chem. 276, 38353–38360]. In the present study, we show that VV infection provoked a sustained activation of both ERK1/2 and RSK2 (ribosomal S6 kinase 2). Our results also provide evidence that this pattern of kinase activation depends on virus multiplication and ongoing protein synthesis and is maintained independently of virus DNA synthesis. It is noteworthy that the VGF (VV growth factor), although involved, is not essential for prolonged ERK1/2 activation. Furthermore, our findings suggest that the VV-stimulated ERK1/2 activation also seems to require actin dynamics, microtubule polymerization and tyrosine kinase phosphorylation. The VV-stimulated pathway MEK/ERK1/2/RSK2 (where MEK stands for MAPK/ERK kinase) leads to phosphorylation of the ternary complex factor Elk-1 and expression of the early growth response (egr-1) gene, which kinetically paralleled the kinase activation. The recruitment of this pathway is biologically relevant, since its disruption caused a profound effect on viral thymidine kinase gene expression, viral DNA replication and VV multiplication. This pattern of sustained kinase activation after VV infection is unique. In addition, by connecting upstream signals generated at the cytoskeleton and by tyrosine kinase, the MEK/ERK1/2/RSK2 cascade seems to play a decisive role not only at early stages of the infection, i.e. post-penetration, but is also crucial to define the fate of virus progeny.

scholarly journals APPL1 mediates adiponectin-stimulated p38 MAPK activation by scaffolding the TAK1-MKK3-p38 MAPK pathway

2011 ◽  
Vol 300 (1) ◽  
pp. E103-E110 ◽  
Author(s):  
Xiaoban Xin ◽  
Lijun Zhou ◽  
Caleb M. Reyes ◽  
Feng Liu ◽  
Lily Q. Dong
Keyword(s):  
Protein Kinase ◽  
P38 Mapk ◽  
Mapk Pathway ◽  
Adaptor Protein ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Scaffolding Protein ◽  
Mapk Activation ◽  
P38 Mapk Pathway ◽  
Mitogen Activated Protein

The adaptor protein APPL1 mediates the stimulatory effect of adiponectin on p38 mitogen-activated protein kinase (MAPK) signaling, yet the underlying mechanism remains unclear. Here we show that, in C2C12 cells, overexpression or suppression of APPL1 enhanced or suppressed, respectively, adiponectin-stimulated p38 MAPK upstream kinase cascade, consisting of transforming growth factor-β-activated kinase 1 (TAK1) and mitogen-activated protein kinase kinase 3 (MKK3). In vitro affinity binding and coimmunoprecipitation experiments revealed that TAK1 and MKK3 bind to different regions of APPL1, suggesting that APPL1 functions as a scaffolding protein to facilitate adiponectin-stimulated p38 MAPK activation. Interestingly, suppressing APPL1 had no effect on TNFα-stimulated p38 MAPK phosphorylation in C2C12 myotubes, indicating that the stimulatory effect of APPL1 on p38 MAPK activation is selective. Taken together, our study demonstrated that the TAK1-MKK3 cascade mediates adiponectin signaling and uncovers a scaffolding role of APPL1 in regulating the TAK1-MKK3-p38 MAPK pathway, specifically in response to adiponectin stimulation.

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