MAPK/ERK Dotaz Zobrazit nápovědu
Úvod: Klinické výstupy histiocytózy Langerhansových buněk (Langerhans cell histiocytosis – LCH) jsou vysoce variabilní. Bylo navrženo, že u pacientů s LCH může být aktivována signální dráha proteinkinázy aktivované mitogenem (MAPK) /extracelulární signální regulační kinázy (ERK). Materiál a metody: Vyšetřili jsme mutace KRAS, BRAF a NRAS u pacientů s LCH pomocí metody kvantitativní polymerázové řetězové reakce. Výsledky: Osm dospělých pacientů s LCH bylo léčeno v Národním onkologickém institutu v Kyjevě na Ukrajině. Pět pacientů dostalo chemoterapii plus radiační terapii a tři pacienti dostali pouze chemoterapii (p < 0,05). Všichni pacienti dostávali studijní protokol LCH-I, v průměru šest cyklů. BRAF c.1799T >A, mutace V600E byla detekována u 25 % (2/8) případů – jeden pacient měl časný relaps po 6 měsících a jeden pacient stabilní onemocnění. U tří pacientů s pozdními relapsy (v 15, 24 a 46 měsících) jsme nenašli mutace BRAF, KRAS ani NRAS. Je zajímavé, že mutace KRAS nebyly odhaleny u žádných vzorků LCH. NRAS c.182A > G, mutace Q61R byla nalezena ve dvou případech – jeden pacient měl LCH transformovaný na Hodgkinův lymfom, jeden pacient měl refrakterní onemocnění. Doba relapsu (time to relapse rate – TTR) u pacientů s mutací genu BRAF V600E a bez mutace byla 13 oproti 28 měsícům, resp. p < 0,05. TTR byl 31,3 oproti 6,41 měsícům u pacientů s absencí a přítomností mutace NRAS, p < 0,05. Multivariační analýza ukázala, že přítomnost NRAS Q61R mutace byla spojena se špatným přežíváním bez příhody u pacientů s LCH s HR 6,1 (95% CI 0,2–12,6; p = 0,008). Závěr: Mutace BRAF a NRAS u LCH naznačují možnost, že onemocnění je řízeno aktivací cesty MAPK/ERK. Tyto onkogenní mutace poskytují nové možnosti v porozumění patogenezi LCH a mohou se stát potenciální cílovou terapií.
Background: Clinical outcomes of Langerhans cell histiocytosis (LCH) are highly variable. It has been suggested that mitogen-activated protein kinase (MAPK) /extracellular signal-regulated kinases (ERK) signaling pathway might be activated in LCH patients. Materials and Methods: We investigated KRAS, BRAF and NRAS mutations in patients with LCH by qPCR. Results: Eight adult patients with LCH were treated at the National Cancer Institute, Kiev, Ukraine. Five patients received chemo plus radiation therapy and three patients received only chemotherapy, resp. (p < 0.05). All patients received LCH–I study protocol, six cycles in average. A BRAF c.1799T > A, p. V600E mutation was detected in 25% (2/8) of cases – 1 patient had an early relapse in 6 months, and 1 patient – stable disease. We did not find any BRAF, KRAS or NRAS mutations in three patients with late relapses (in 15, 24 and 46 months). Notably, KRAS mutations were not revealed in any LCH samples. The NRAS c.182A > G, p. Q61R mutation was found in two cases – one patient had LCH transformed to Hodgkin’s lymphoma, one patient had a refractory disease. Time to relapse rate (TTR) in patients with and without BRAF V600E gene mutation was 13 vs. 28 months, resp. (p < 0.05). TTR was 31.3 vs. 6.41 months in patients with absence and presence of NRAS mutation, p < 0.05. Multivariate analysis showed the presence of NRAS Q61R mutation was associated with poor event-free survival in LCH patients with HR of 6.1 (95% CI 0.2–12.6; p = 0.008). Conclusion: BRAF and NRAS mutations in LCH suggest a possibility of the disease being driven by the activation of the MAPK/ERK pathway. These oncogenic mutations provide new opportunities in understanding LCH pathogenesis and may be a potential target of therapy.
- MeSH
- analýza přežití MeSH
- dospělí MeSH
- genetické testování metody MeSH
- histiocytóza z Langerhansových buněk * genetika MeSH
- kvantitativní polymerázová řetězová reakce metody MeSH
- lidé středního věku MeSH
- lidé MeSH
- mutace * genetika MeSH
- prognóza MeSH
- recidiva MeSH
- retrospektivní studie MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
Hypoxia is involved in the regulation of stem cell fate, and hypoxia-inducible factor 1 (HIF-1) is the master regulator of hypoxic response. Here, we focus on the effect of hypoxia on intracellular signaling pathways responsible for mouse embryonic stem (ES) cell maintenance. We employed wild-type and HIF-1α-deficient ES cells to investigate hypoxic response in the ERK, Akt, and STAT3 pathways. Cultivation in 1% O2 for 24 h resulted in the strong dephosphorylation of ERK and its upstream kinases and to a lesser extent of Akt in an HIF-1-independent manner, while STAT3 phosphorylation remained unaffected. Downregulation of ERK could not be mimicked either by pharmacologically induced hypoxia or by the overexpression. Dual-specificity phosphatases (DUSP) 1, 5, and 6 are hypoxia-sensitive MAPK-specific phosphatases involved in ERK downregulation, and protein phosphatase 2A (PP2A) regulates both ERK and Akt. However, combining multiple approaches, we revealed the limited significance of DUSPs and PP2A in the hypoxia-mediated attenuation of ERK signaling. Interestingly, we observed a decreased reactive oxygen species (ROS) level in hypoxia and a similar phosphorylation pattern for ERK when the cells were supplemented with glutathione. Therefore, we suggest a potential role for the ROS-dependent attenuation of ERK signaling in hypoxia, without the involvement of HIF-1.
- MeSH
- down regulace MeSH
- faktor 1 indukovatelný hypoxií - podjednotka alfa metabolismus MeSH
- mitogenem aktivované proteinkinasy kinas metabolismus MeSH
- myší embryonální kmenové buňky metabolismus MeSH
- myši MeSH
- reaktivní formy kyslíku metabolismus MeSH
- signální transdukce MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The spreading of adhering cells is a morphogenetic process during which cells break spherical or radial symmetry and adopt migratory polarity with spatially segregated protruding cell front and non-protruding cell rear. The organization and regulation of these symmetry-breaking events, which are both complex and stochastic, are not fully understood. Here we show that in radially spreading cells, symmetry breaking commences with the development of discrete non-protruding regions characterized by large but sparse focal adhesions and long peripheral actin bundles. Establishment of this non-protruding static region specifies the distally oriented protruding cell front and thus determines the polarity axis and the direction of cell migration. The development of non-protruding regions requires ERK2 and the ERK pathway scaffold protein RACK1. RACK1 promotes adhesion-mediated activation of ERK2 that in turn inhibits p190A-RhoGAP signaling by reducing the peripheral localization of p190A-RhoGAP. We propose that sustained ERK signaling at the prospective cell rear induces p190A-RhoGAP depletion from the cell periphery resulting in peripheral actin bundles and cell rear formation. Since cell adhesion activates both ERK and p190A-RhoGAP signaling this constitutes a spatially confined incoherent feed-forward signaling circuit.
- MeSH
- aktiny metabolismus MeSH
- biologické modely MeSH
- buněčná adheze MeSH
- fenotyp MeSH
- fibroblasty cytologie enzymologie metabolismus MeSH
- fokální adhezní tyrosinkinasy metabolismus MeSH
- genový knockdown MeSH
- krysa rodu rattus MeSH
- MAP kinasový signální systém * MeSH
- mitogenem aktivovaná proteinkinasa 1 metabolismus MeSH
- pohyb buněk MeSH
- proteiny vázající GTP nedostatek metabolismus MeSH
- represorové proteiny metabolismus MeSH
- tvar buňky MeSH
- umlčování genů MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The eIF4F translation initiation complex plays a critical role in melanoma resistance to clinical BRAF and MEK inhibitors. In this study, we uncover a function of eIF4F in the negative regulation of the rat sarcoma (RAS)/rapidly accelerated fibrosarcoma (RAF)/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) signaling pathway. We demonstrate that eIF4F is essential for controlling ERK signaling intensity in treatment-naïve melanoma cells harboring BRAF or NRAS mutations. Specifically, the dual-specificity phosphatase DUSP6/MKP3, which acts as a negative feedback regulator of ERK activity, requires continuous production in an eIF4F-dependent manner to limit excessive ERK signaling driven by oncogenic RAF/RAS mutations. Treatment with small-molecule eIF4F inhibitors disrupts the negative feedback control of MAPK signaling, leading to ERK hyperactivation and EGR1 overexpression in melanoma cells in vitro and in vivo. Furthermore, our quantitative analyses reveal a high spare signaling capacity in the ERK pathway, suggesting that eIF4F-dependent feedback keeps the majority of ERK molecules inactive under normal conditions. Overall, our findings highlight the crucial role of eIF4F in regulating ERK signaling flux and suggest that pharmacological eIF4F inhibitors can disrupt the negative feedback control of MAPK activity in melanomas with BRAF and NRAS activating mutations.
- MeSH
- eukaryotický iniciační faktor 4F * metabolismus genetika MeSH
- extracelulárním signálem regulované MAP kinasy metabolismus MeSH
- fosfatasa 6 s dvojí specificitou metabolismus genetika MeSH
- GTP-fosfohydrolasy * metabolismus genetika MeSH
- lidé MeSH
- MAP kinasový signální systém * genetika MeSH
- melanom * genetika metabolismus patologie MeSH
- membránové proteiny * metabolismus genetika MeSH
- mutace * MeSH
- myši MeSH
- nádorové buněčné linie MeSH
- protoonkogenní proteiny B-Raf * genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: MAPK/ERK signaling is a well-known mediator of extracellular stimuli controlling intracellular responses to growth factors and mechanical cues. The critical requirement of MAPK/ERK signaling for embryonic stem cell maintenance is demonstrated, but specific functions in progenitor regulation during embryonic development, and in particular kidney development remain largely unexplored. We previously demonstrated MAPK/ERK signaling as a key regulator of kidney growth through branching morphogenesis and normal nephrogenesis where it also regulates progenitor expansion. Here, we performed RNA sequencing-based whole-genome expression analysis to identify transcriptional MAPK/ERK targets in two distinct renal populations: the ureteric bud epithelium and the nephron progenitors. RESULTS: Our analysis revealed a large number (5053) of differentially expressed genes (DEGs) in nephron progenitors and significantly less (1004) in ureteric bud epithelium, reflecting likely heterogenicity of cell types. The data analysis identified high tissue-specificity, as only a fraction (362) of MAPK/ERK targets are shared between the two tissues. Tissue-specific MAPK/ERK targets participate in the regulation of mitochondrial energy metabolism in nephron progenitors, which fail to maintain normal mitochondria numbers in the MAPK/ERK-deficient tissue. In the ureteric bud epithelium, a dramatic decline in progenitor-specific gene expression was detected with a simultaneous increase in differentiation-associated genes, which was not observed in nephron progenitors. Our experiments in the genetic model of MAPK/ERK deficiency provide evidence that MAPK/ERK signaling in the ureteric bud maintains epithelial cells in an undifferentiated state. Interestingly, the transcriptional targets shared between the two tissues studied are over-represented by histone genes, suggesting that MAPK/ERK signaling regulates cell cycle progression and stem cell maintenance through chromosome condensation and nucleosome assembly. CONCLUSIONS: Using tissue-specific MAPK/ERK inactivation and RNA sequencing in combination with experimentation in embryonic kidneys, we demonstrate here that MAPK/ERK signaling maintains ureteric bud tip cells, suggesting a regulatory role in collecting duct progenitors. We additionally deliver new mechanistic information on how MAPK/ERK signaling regulates progenitor maintenance through its effects on chromatin accessibility and energy metabolism.
Excess intracellular zinc has been demonstrated to be responsible for cell injury and cell death in various experimental as well as clinical models. While the cells possess a system of mechanisms regulating intracellular zinc homeostasis, their saturation by acutely increased zinc levels or by a sustained exposure to elevated zinc levels results in liberation of free zinc stores within the cells and ultimate cell damage and cell death. Here we report that in Hep-2 malignant cells enhanced uptake of zinc causes activation of mitogen-activated protein kinase (MAPK) signaling with resulting p53-dependent cell injury which can be significantly prevented by specific p53 inhibition and by prevention of oxidative stress. Our observations are consistent with the view that subacutely increased intracellular free zinc levels stimulate via oxidative stress p53-dependent pathways which are responsible for the final cell damage in tumor cells.
Reactive oxygen species (ROS) are important regulators of cellular functions. In embryonic stem cells, ROS are suggested to influence differentiation status. Regulated ROS formation is catalyzed primarily by NADPH-dependent oxidases (NOXs). Apocynin and diphenyleneiodonium are frequently used inhibitors of NOXs; however, both exhibit uncharacterized effects not related to NOXs inhibition. Interestingly, in our model of mouse embryonic stem cells we demonstrate low expression of NOXs. Therefore we aimed to clarify potential side effects of these drugs. Both apocynin and diphenyleneiodonium impaired proliferation of cells. Surprisingly, we observed prooxidant activity of these drugs determined by hydroethidine. Further, we revealed that apocynin inhibits PI3K/Akt pathway with its downstream transcriptional factor Nanog. Opposite to this, apocynin augmented activity of canonical Wnt signaling. On the contrary, diphenyleneiodonium activated both PI3K/Akt and Erk signaling pathways without affecting Wnt. Our data indicates limits and possible unexpected interactions of NOXs inhibitors with intracellular signaling pathways.
- MeSH
- acetofenony farmakologie MeSH
- extracelulárním signálem regulované MAP kinasy metabolismus MeSH
- fosfatidylinositol-3-kinasy metabolismus MeSH
- fosforylace účinky léků MeSH
- myší embryonální kmenové buňky účinky léků metabolismus MeSH
- myši MeSH
- NADPH-oxidasy genetika metabolismus MeSH
- oniové sloučeniny farmakologie MeSH
- oxidační stres účinky léků MeSH
- proliferace buněk účinky léků MeSH
- proteiny Wnt metabolismus MeSH
- protoonkogenní proteiny c-akt metabolismus MeSH
- reaktivní formy kyslíku metabolismus MeSH
- synergismus léků MeSH
- transkripční faktor STAT3 metabolismus MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
