RESUMO
Schwannoma tumours typically arise on the eighth cranial nerve and are mostly caused by loss of the tumour suppressor Merlin (NF2). There are no approved chemotherapies for these tumours and the surgical removal of the tumour carries a high risk of damage to the eighth or other close cranial nerve tissue. New treatments for schwannoma and other NF2-null tumours such as meningioma are urgently required. Using a combination of human primary tumour cells and mouse models of schwannoma, we have examined the role of the Hippo signalling pathway in driving tumour cell growth. Using both genetic ablation of the Hippo effectors YAP and TAZ as well as novel TEAD palmitoylation inhibitors, we show that Hippo signalling may be successfully targeted in vitro and in vivo to both block and, remarkably, regress schwannoma tumour growth. In particular, successful use of TEAD palmitoylation inhibitors in a preclinical mouse model of schwannoma points to their potential future clinical use. We also identify the cancer stem cell marker aldehyde dehydrogenase 1A1 (ALDH1A1) as a Hippo signalling target, driven by the TAZ protein in human and mouse NF2-null schwannoma cells, as well as in NF2-null meningioma cells, and examine the potential future role of this new target in halting schwannoma and meningioma tumour growth.
Assuntos
Neoplasias Meníngeas , Meningioma , Neurilemoma , Animais , Humanos , Camundongos , Proliferação de Células , Neurilemoma/genética , Neurilemoma/patologia , Neurofibromina 2/genética , Neurofibromina 2/metabolismo , Proteínas de Sinalização YAP/metabolismo , Proteínas com Motivo de Ligação a PDZ com Coativador Transcricional/metabolismo , Fatores de Transcrição de Domínio TEA/metabolismoRESUMO
There is an unmet need for the identification of biomarkers to aid in the diagnosis, clinical management, prognosis and follow-up of meningiomas. There is currently no consensus on the optimum management of WHO grade II meningiomas. In this study, we identified the calcium binding extracellular matrix glycoprotein, Fibulin-2, via mass-spectrometry-based proteomics, assessed its expression in grade I and II meningiomas and explored its potential as a grade II biomarker. A total of 87 grade I and 91 grade II different meningioma cells, tissue and plasma samples were used for the various experimental techniques employed to assess Fibulin-2 expression. The tumours were reviewed and classified according to the 2016 edition of the Classification of the Tumours of the central nervous system (CNS). Mass spectrometry proteomic analysis identified Fibulin-2 as a differentially expressed protein between grade I and II meningioma cell cultures. Fibulin-2 levels were further evaluated in meningioma cells using Western blotting and Real-time Quantitative Polymerase Chain Reaction (RT-qPCR); in meningioma tissues via immunohistochemistry and RT-qPCR; and in plasma via Enzyme-Linked Immunosorbent Assay (ELISA). Proteomic analyses (p < 0.05), Western blotting (p < 0.05) and RT-qPCR (p < 0.01) confirmed significantly higher Fibulin-2 (FBLN2) expression levels in grade II meningiomas compared to grade I. Fibulin-2 blood plasma levels were also significantly higher in grade II meningioma patients compared to grade I patients. This study suggests that elevated Fibulin-2 might be a novel grade II meningioma biomarker, when differentiating them from the grade I tumours. The trend of Fibulin-2 expression observed in plasma may serve as a useful non-invasive biomarker.
Assuntos
Biomarcadores Tumorais/sangue , Proteínas de Ligação ao Cálcio/sangue , Proteínas da Matriz Extracelular/sangue , Neoplasias Meníngeas/sangue , Meningioma/sangue , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Masculino , Neoplasias Meníngeas/genética , Neoplasias Meníngeas/patologia , Meningioma/genética , Meningioma/patologia , Pessoa de Meia-Idade , Gradação de Tumores , Prognóstico , ProteômicaRESUMO
The majority of meningiomas are grade I, but some grade I tumours are clinically more aggressive. Recent advances in the genetic study of meningiomas has allowed investigation into the influence of genetics on the tumour microenvironment, which is important for tumorigenesis. We have established that the endpoint genotyping method Kompetitive Allele Specific PCR (KASP™) is a fast, reliable method for the screening of meningioma samples into different non-NF2 mutational groups using a standard real-time PCR instrument. This genotyping method and four-colour flow cytometry has enabled us to assess the variability in the largest immune cell infiltrate population, M2 macrophages (CD45+HLA-DR+CD14+CD163+) in 42 meningioma samples, and to suggest that underlying genetics is relevant. Further immunohistochemistry analysis comparing AKT1 E17K mutants to WHO grade I NF2-negative samples showed significantly lower levels of CD163-positive activated M2 macrophages in meningiomas with mutated AKT1 E17K, signifying a more immunosuppressive tumour microenvironment in NF2 meningiomas. Our data suggested that underlying tumour genetics play a part in the development of the immune composition of the tumour microenvironment. Stratifying meningiomas by mutational status and correlating this with their cellular composition will aid in the development of new immunotherapies for patients.
Assuntos
Macrófagos/metabolismo , Meningioma/genética , Proteínas Proto-Oncogênicas c-akt/genética , Microambiente Tumoral/genética , Alelos , Antígenos CD/genética , Antígenos de Diferenciação Mielomonocítica/genética , Linhagem da Célula/genética , Feminino , Genótipo , Antígenos HLA-DR/genética , Humanos , Antígenos Comuns de Leucócito/genética , Receptores de Lipopolissacarídeos/genética , Macrófagos/classificação , Macrófagos/patologia , Masculino , Meningioma/classificação , Meningioma/patologia , Pessoa de Meia-Idade , Mutação/genética , Neurofibromina 2/genética , Receptores de Superfície Celular/genéticaRESUMO
Meningioma and schwannoma are common tumours of the nervous system. They occur sporadically or as part of the hereditary NF2-related schwannomatosis syndrome. There is an unmet need for new effective drug treatments for both tumour types. In this paper, we demonstrate overexpression/activation of TAM (TYRO3/AXL/MERTK) receptors (TAMs) and overexpression/release of ligand GAS6 in patient-derived meningioma tumour cells and tissue. For the first time, we reveal the formation of MERTK/TYRO3 heterocomplexes in meningioma and schwannoma tissue. We demonstrate the dependence of AXL and TYRO3 expression on MERTK in both tumour types, as well as interdependency of MERTK and AXL expression in meningioma. We show that MERTK and AXL contribute to increased proliferation and survival of meningioma and schwannoma cells, which we inhibited in vitro using the MERTK/FLT3 inhibitor UNC2025 and the AXL inhibitor BGB324. UNC2025 was effective in both tumour types with superior efficacy over BGB324. Finally, we found that TAMs are expressed by tumour-associated macrophages in meningioma and schwannoma tumours and that UNC2025 strongly depleted macrophages in both tumour types.
RESUMO
Meningiomas are the most common intracranial brain tumours. These tumours are heterogeneous and encompass a wide spectrum of clinical aggressivity. Treatment options are limited to surgery and radiotherapy and have a risk of post-operative morbidities and radiation neurotoxicity, reflecting the need for new therapies. Three-dimensional (3D) patient-derived cell culture models have been shown to closely recapitulate in vivo tumour biology, including microenvironmental interactions and have emerged as a robust tool for drug development. Here, we established a novel easy-to-use 3D patient-derived meningioma spheroid model using a scaffold-free approach. Patient-derived meningioma spheroids were characterised and compared to patient tissues and traditional monolayer cultures by histology, genomics, and transcriptomics studies. Patient-derived meningioma spheroids closely recapitulated morphological and molecular features of matched patient tissues, including patient histology, genomic alterations, and components of the immune microenvironment, such as a CD68 + and CD163 + positive macrophage cell population. Comprehensive transcriptomic profiling revealed an increase in epithelial-to-mesenchymal transition (EMT) in meningioma spheroids compared to traditional monolayer cultures, confirming this model as a tool to elucidate EMT in meningioma. Therefore, as proof of concept study, we developed a treatment strategy to target EMT in meningioma. We found that combination therapy using the MER tyrosine kinase (MERTK) inhibitor UNC2025 and the histone deacetylase (HDAC) inhibitor Trichostatin A (TSA) effectively decreased meningioma spheroid viability and proliferation. Furthermore, we demonstrated this combination therapy significantly increased the expression of the epithelial marker E-cadherin and had a repressive effect on WHO grade 2-derived spheroid invasion, which is suggestive of a partial reversal of EMT in meningioma spheroids.
Assuntos
Neoplasias Meníngeas , Meningioma , Humanos , Meningioma/patologia , Técnicas de Cultura de Células/métodos , Neoplasias Meníngeas/patologia , Microambiente TumoralRESUMO
Loss of the tumor suppressor merlin causes development of the tumors of the nervous system, such as schwannomas, meningiomas, and ependymomas occurring spontaneously or as part of a hereditary disease Neurofibromatosis Type 2 (NF2). Current therapies, (radio) surgery, are not always effective. Therefore, there is a need for drug treatments for these tumors. Schwannomas are the most frequent of merlin-deficient tumors and are hallmark for NF2. Using our in vitro human schwannoma model, we demonstrated that merlin-deficiency leads to increased proliferation, cell-matrix adhesion, and survival. Increased proliferation due to strong activation of extracellular-signal-regulated kinase 1/2 (ERK1/2) is caused by overexpression/activation of platelet-derived growth factor receptor-ß (PDGFR-ß) and ErbB2/3 which we successfully blocked with AZD6244, sorafenib, or lapatinib. Schwannoma basal proliferation is, however, only partly dependent on PDGFR-ß and is completely independent of ErbB2/3. Moreover, the mechanisms underlying pathological cell-matrix adhesion and survival of schwannoma cells are still not fully understood. Here, we demonstrate that insulin-like growth factor-I receptor (IGF-IR) is strongly overexpressed and activated in human primary schwannoma cells. IGF-I and -II are overexpressed and released from schwannoma cells. We show that ERK1/2 is relevant for IGF-I-mediated increase in proliferation and cell-matrix adhesion, c-Jun N-terminal kinases for increased proliferation and AKT for survival. We demonstrate new mechanisms involved in increased basal proliferation, cell-matrix adhesion, and survival of schwannoma cells. We identified therapeutic targets IGF-IR and downstream PI3K for treatment of schwannoma and other merlin-deficient tumors and show usefulness of small molecule inhibitors in our model. PI3K is relevant for both IGF-IR and previously described PDGFR-ß signaling in schwannoma.
Assuntos
Neoplasias Encefálicas/metabolismo , Neurilemoma/metabolismo , Neurofibromatose 2/metabolismo , Transdução de Sinais/fisiologia , Somatomedinas/metabolismo , Neoplasias Encefálicas/patologia , Proliferação de Células , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Neurilemoma/patologia , Neurofibromatose 2/patologia , Neurofibromina 2/genética , Neurofibromina 2/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismoRESUMO
Deficiency of the tumor suppressor Merlin causes development of schwannoma, meningioma, and ependymoma tumors, which can occur spontaneously or in the hereditary disease neurofibromatosis type 2 (NF2). Merlin mutations are also relevant in a variety of other tumors. Surgery and radiotherapy are current first-line treatments; however, tumors frequently recur with limited treatment options. Here, we use human Merlin-negative schwannoma and meningioma primary cells to investigate the involvement of the endogenous retrovirus HERV-K in tumor development. HERV-K proteins previously implicated in tumorigenesis were overexpressed in schwannoma and all meningioma grades, and disease-associated CRL4DCAF1 and YAP/TEAD pathways were implicated in this overexpression. In normal Schwann cells, ectopic overexpression of HERV-K Env increased proliferation and upregulated expression of c-Jun and pERK1/2, which are key components of known tumorigenic pathways in schwannoma, JNK/c-Jun, and RAS/RAF/MEK/ERK. Furthermore, FDA-approved retroviral protease inhibitors ritonavir, atazanavir, and lopinavir reduced proliferation of schwannoma and grade I meningioma cells. These results identify HERV-K as a critical regulator of progression in Merlin-deficient tumors and offer potential strategies for therapeutic intervention. SIGNIFICANCE: The endogenous retrovirus HERV-K activates oncogenic signaling pathways and promotes proliferation of Merlin-deficient schwannomas and meningiomas, which can be targeted with antiretroviral drugs and TEAD inhibitors.
Assuntos
Antirretrovirais/farmacologia , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Retrovirus Endógenos/metabolismo , Neoplasias Meníngeas/metabolismo , Meningioma/metabolismo , Neurilemoma/metabolismo , Neurofibromina 2/metabolismo , Proteínas Virais/metabolismo , Carcinogênese/genética , Carcinogênese/metabolismo , Células HEK293 , Humanos , Neoplasias Meníngeas/complicações , Neoplasias Meníngeas/patologia , Neoplasias Meníngeas/virologia , Meningioma/complicações , Meningioma/patologia , Meningioma/virologia , Neurilemoma/complicações , Neurilemoma/patologia , Neurilemoma/virologia , Neurofibromatose 2/complicações , Neurofibromina 2/genética , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Transfecção , Proteínas Virais/antagonistas & inibidores , Proteínas Virais/genéticaRESUMO
BACKGROUND: Meningiomas are the most common primary intracranial tumours. They are classified as grade I, II, and III based on their histopathological features. While most meningiomas can be managed by surgery alone, adjuvant treatment may be required in case of recurrent, or high-grade tumours. To date, chemotherapy has proven ineffective in meningioma patients, reinforcing the need for novel therapeutic targets and molecular biomarkers. METHODS: Using meningioma tissues and in vitro models, we investigated microRNA levels in meningioma samples of different grades, as well as their regulation. Based on this, we also investigated candidate miRNAs expression in serum, and their potential as biomarkers. FINDINGS: We found that miR-497~195 cluster expression in meningioma decreases with increasing malignancy grade, and that Cyclin D1 overexpression correlated with downregulation of the miR-497~195 cluster. GATA binding protein 4, a transcription factor upregulated in malignant meningioma, caused increased cell viability by controlling the expression of the miR-497~195 cluster, resulting in increased Cyclin D1 expression. Accordingly, GATA-4 inhibition via the small-molecule inhibitor NSC140905 restored miR-497~195 cluster expression, resulting in decreased viability, and Cyclin D1 downregulation. Analysis of the miR-497~195 cluster expression in serum exosomes derived from high-grade meningioma patients, revealed lower levels of miR-497 compared to those of benign origin. INTERPRETATION: Our data suggest that GATA-4 could be a novel potential therapeutic target, and miR-497 could serve as a potential non-invasive biomarker for high-grade meningioma.
Assuntos
Biomarcadores Tumorais , MicroRNA Circulante , Fator de Transcrição GATA4/metabolismo , Regulação Neoplásica da Expressão Gênica , Meningioma/genética , Meningioma/metabolismo , MicroRNAs/genética , Apoptose/genética , Linhagem Celular Tumoral , Feminino , Humanos , Biópsia Líquida , Masculino , Meningioma/diagnóstico , Meningioma/terapia , MicroRNAs/sangue , Família Multigênica , Gradação de Tumores , Prognóstico , Curva ROCRESUMO
Meningioma is the most common primary intracranial tumour, and surgical resection is the main therapeutic option. Merlin is a tumour suppressor protein that is frequently mutated in meningioma. The activity of the E3 ubiquitin ligase complex, CRL4-DCAF1, and the Raf/MEK/ERK scaffold protein Kinase suppressor of Ras 1 (KSR1) are upregulated in Merlin-deficient tumours, which drives tumour growth. Identifying small molecules that inhibit these key pathways may provide an effective treatment option for patients with meningioma. We used meningioma tissue and primary cells derived from meningioma tumours to investigate the expression of DDB1 and Cullin 4-associated factor 1 (DCAF1) and KSR1, and confirmed these proteins were overexpressed. We then used primary cells to assess the therapeutic potential of MLN3651, a neddylation inhibitor which impacts the activity of the CRL family of E3 ubiquitin ligases and the MAPK/ERK kinase (MEK1/2) inhibitor selumetinib. MLN3651 treatment reduced proliferation and activated apoptosis, whilst increasing Raf/MEK/ERK pathway activation. The combination of MLN3651 and the MEK1/2 inhibitor selumetinib prevented the increase in Raf/MEK/ERK activity, and had an additive effect compared with either treatment alone. Therefore, the combined targeting of CRL4-DCAF1 and Raf/MEK/ERK activity represents an attractive novel strategy in the treatment of Merlin-deficient meningioma.
RESUMO
BACKGROUND: Meningiomas are the most frequent primary brain tumors of the central nervous system. The standard of treatment is surgery and radiotherapy, but effective pharmacological options are not available yet. The well-characterized genetic background stratifies these tumors in several subgroups, thus increasing diversification. We identified epidermal growth factor receptor-signal transducer and activator of transcription 1 (EGFR-STAT1) overexpression and activation as a common identifier of these tumors. METHODS: We analyzed STAT1 overexpression and phosphorylation in 131 meningiomas of different grades and locations by utilizing several techniques, including Western blots, qPCR, and immunocytochemistry. We also silenced and overexpressed wild-type and mutant forms of the gene to assess its biological function and its network. Results were further validated by drug testing. RESULTS: STAT1 was found widely overexpressed in meningioma but not in the corresponding healthy controls. The protein showed constitutive phosphorylation not dependent on the JAK-STAT pathway. STAT1 knockdown resulted in a significant reduction of cellular proliferation and deactivation of AKT and ERK1/2. STAT1 is known to be activated by EGFR, so we investigated the tyrosine kinase and found that EGFR was also constitutively phosphorylated in meningioma and was responsible for the aberrant phosphorylation of STAT1. The pharmaceutical inhibition of EGFR caused a significant reduction in cellular proliferation and of overall levels of cyclin D1, pAKT, and pERK1/2. CONCLUSIONS: STAT1-EGFR-dependent constitutive phosphorylation is responsible for a positive feedback loop that causes its own overexpression and consequently an increased proliferation of the tumor cells. These findings provide the rationale for further studies aiming to identify effective therapeutic options in meningioma.
RESUMO
Cancer cells can develop a strong addiction to discrete molecular regulators, which control the aberrant gene expression programs that drive and maintain the cancer phenotype. Here, we report the identification of the RNA-binding protein HuR/ELAVL1 as a central oncogenic driver for malignant peripheral nerve sheath tumors (MPNSTs), which are highly aggressive sarcomas that originate from cells of the Schwann cell lineage. HuR was found to be highly elevated and bound to a multitude of cancer-associated transcripts in human MPNST samples. Accordingly, genetic and pharmacological inhibition of HuR had potent cytostatic and cytotoxic effects on tumor growth, and strongly suppressed metastatic capacity in vivo. Importantly, we linked the profound tumorigenic function of HuR to its ability to simultaneously regulate multiple essential oncogenic pathways in MPNST cells, including the Wnt/ß-catenin, YAP/TAZ, RB/E2F, and BET pathways, which converge on key transcriptional networks. Given the exceptional dependency of MPNST cells on HuR for survival, proliferation, and dissemination, we propose that HuR represents a promising therapeutic target for MPNST treatment.
Assuntos
Carcinogênese/metabolismo , Proliferação de Células , Proteína Semelhante a ELAV 1/metabolismo , Proteínas de Neoplasias/metabolismo , Neoplasias de Bainha Neural/metabolismo , Transdução de Sinais , Animais , Carcinogênese/genética , Carcinogênese/patologia , Linhagem Celular Tumoral , Proteína Semelhante a ELAV 1/genética , Humanos , Camundongos , Metástase Neoplásica , Proteínas de Neoplasias/genética , Neoplasias de Bainha Neural/genética , Neoplasias de Bainha Neural/patologiaRESUMO
Nicotinic acid adenine dinucleotide phosphate (NAADP) is involved in the Ca2+ response observed at fertilization in several species, including starfish. In this study, we have employed Ca2+ imaging and the single-electrode voltage-clamp technique to investigate whether the NAADP-mediated Ca2+ entry discovered in our laboratory in starfish oocytes was underlain by a membrane current and whether the response to NAADP required an intact cytoskeleton. Uncaging of preinjected NAADP evoked a cortical Ca2+ flash that was followed by the spreading of the wave to the remainder of the cell. No Ca2+ increase was detected in Ca2+-free sea water. Under voltage-clamp conditions, the photoliberation of NAADP activated an inward rectifying membrane current, which reversed at potentials more positive than +50 mV and was abolished by removal of Ca2+ but not of Na+. The current was affected by preincubation with verapamil, SKF 96356, and thapsigargin but not by preinjection of heparin, 8-NH2- cyclic ADP-ribose, or both antagonists. The membrane current and the Ca2+ wave were inhibited by latrunculin-A and jasplakinolide, which depolymerize and stabilize actin cytoskeleton, respectively. These data offer the first demonstration that NAADP initiates a Ca2+ sweep by activating a Ca2+-permeable membrane current that requires an intact F-actin cytoskeleton as other Ca2+-permeable currents, such as ICRAC and IARC.
Assuntos
Citoesqueleto de Actina/fisiologia , Canais de Cálcio/metabolismo , Sinalização do Cálcio , Depsipeptídeos , NADP/análogos & derivados , NADP/farmacologia , Citoesqueleto de Actina/efeitos dos fármacos , Animais , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Cálcio/fisiologia , Membrana Celular/fisiologia , Condutividade Elétrica , Modelos Biológicos , Oócitos/efeitos dos fármacos , Oócitos/metabolismo , Técnicas de Patch-Clamp , Peptídeos Cíclicos/farmacologia , Estrelas-do-Mar , Tiazóis/farmacologia , TiazolidinasRESUMO
Neurofibromatosis type 2 (NF2) is an inherited predisposition cancer syndrome characterized by the development of multiple benign tumors in the nervous system including schwannomas, meningiomas, and ependymomas. Using a disease model comprising primary human schwannoma cells, we previously demonstrated that adherens junctions (AJs) are impaired in schwannoma cells because of a ubiquitous, upregulated Rac activity. However, the mechanism by which loss of contact inhibition leads to proliferation remains obscure in merlin-deficient tumors. In this study, we show that proliferative Wnt/ß-catenin signaling is elevated as active ß-catenin (dephosphorylated at serine 37 and threoine 41) localizes to the nucleus and the Wnt targets genes c-myc and cyclin D1 are upregulated in confluent human schwannoma cells. We demonstrate that Rac effector p21-activated kinase 2 (PAK2) is essential for the activation of Wnt/ß-catenin signaling because depletion of PAK2 suppressed active ß-catenin, c-myc, and cyclin D1. Most importantly, the link between the loss of the AJ complex and the increased proliferation in human schwannoma cells is connected by Src and platelet-derived growth factor receptor-induced tyrosine 654 phosphorylation on ß-catenin and associated with degradation of N-cadherin. We also demonstrate that active merlin maintains ß-catenin and N-cadherin complex at the plasma membrane through direct regulation. Finally, we demonstrate that phosphorylation of tyrosine 654 is critical for the increased proliferation in human schwannoma cells because overexpression of a Y654F mutant ß-catenin reduces hyperproliferation of schwannoma cells. We suggest a model that these pathways are coordinated and relevant for proliferation in merlin-deficient tumors.
Assuntos
Inibição de Contato/genética , Neurilemoma/genética , Neurilemoma/metabolismo , Neurofibromina 2/deficiência , Proteínas Wnt/metabolismo , Via de Sinalização Wnt , beta Catenina/metabolismo , Caderinas/metabolismo , Membrana Celular/metabolismo , Proliferação de Células , Inativação Gênica , Células HEK293 , Humanos , Modelos Biológicos , Neurofibromina 2/genética , Fosforilação , Ligação Proteica , RNA Interferente Pequeno/genética , Receptores do Fator de Crescimento Derivado de Plaquetas/metabolismo , beta Catenina/genética , Quinases Ativadas por p21/metabolismo , Proteínas rac1 de Ligação ao GTP/metabolismo , Domínios de Homologia de src , Quinases da Família src/metabolismoRESUMO
The synthesis of nonsymmetrical polyamines (PAs) has, up to now, been problematic due to lengthy synthetic procedures, lack of regioselectivity, and very poor atom economy. An innovative synthetic protocol for nonsymmetrical PAs using a modified Ugi reaction ( N-split Ugi) which simplifies the synthesis of these tricky compounds is described. We believe that this new synthesis may open the door for the generation of new and pharmacologically active PAs.
Assuntos
Poliaminas/síntese química , Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Produtos Biológicos/síntese química , Produtos Biológicos/farmacologia , Linhagem Celular Tumoral , Humanos , Concentração Inibidora 50 , Poliaminas/farmacologiaRESUMO
Recent evidence has shown that NAD(P) plays a variety of roles in cell-signaling processes. Surprisingly, the presence of NAD(P) utilizing ectoenzymes suggests that NAD(P) is present extracellularly. Indeed, nanomolar concentrations of NAD have been found in plasma and other body fluids. Although very high concentrations of NAD have been shown to enter cells, it is not known whether lower, more physiological concentrations are able to be taken up. Here we show that two mammalian cell types are able to transport low NAD concentrations effectively. Furthermore, extracellular application of NAD was able to counteract FK866-induced cell death and restore intracellular NAD(P) levels. We propose that NAD uptake may play a role in physiological NAD homeostasis.
Assuntos
NADP/metabolismo , NAD/metabolismo , Transdução de Sinais/fisiologia , Acrilamidas/farmacologia , Animais , Transporte Biológico/efeitos dos fármacos , Transporte Biológico/fisiologia , Morte Celular/efeitos dos fármacos , Morte Celular/fisiologia , Relação Dose-Resposta a Droga , Células HeLa , Homeostase/efeitos dos fármacos , Homeostase/fisiologia , Humanos , Células K562 , Camundongos , NAD/farmacologia , Células NIH 3T3 , Piperidinas/farmacologia , Transdução de Sinais/efeitos dos fármacosRESUMO
One of the great challenges of medicinal chemistry is to create novel, effective, chemotherapeutic agents that show specificity for cancer cells combined with low systemic toxicity. A novel idea is to target the enzymes of the NAD biosynthesis and recycling pathways given that cancer cells display a higher NAD turnover rate than healthy cells. To this end, the compound FK866 (APO866; (E)-N-[4-(1-benzoylpiperidin-4-yl) butyl]-3-(pyridin-3-yl) acrylamide), which blocks nicotinamide phosphoribosyltransferase (NMPRTase) has entered clinical trials as a potential chemotherapeutic agent. Here we report the synthesis of analogues of FK866 synthesized by click chemistry.
Assuntos
Acrilamidas/síntese química , Antineoplásicos/síntese química , NAD/metabolismo , Piperidinas/síntese química , Triazóis/síntese química , Antineoplásicos/farmacologia , Catálise , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Cobre/química , Humanos , Triazóis/farmacologiaRESUMO
Cofilin is a small protein that belongs to the family of actin-depolymerizing factors (ADF). The main cellular function of cofilin is to change cytoskeletal dynamics and thus to modulate cell motility and cytokinesis. We have recently demonstrated that the actin cytoskeleton is involved in the modulation of Ca(2+) signalling in starfish oocytes. To extend these observations, we have explored whether cofilin influences Ca(2+) signalling in the oocytes. Here we show that microinjection of the functionally active cofilin alters the Ca(2+) signalling mediated by the three major second messengers, InsP(3), NAADP, and cADPr. Cofilin intensifies the Ca(2+) signals induced by InsP(3) and NAADP, and delays those induced by cADPr. Furthermore, the injection of cofilin increases the Ca(2+) signals during hormone-induced oocyte maturation and fertilization. The results suggest that the dynamic regulation of F-actin by its binding proteins may play an important role in the modulation of intracellular Ca(2+) signalling.
Assuntos
Fatores de Despolimerização de Actina/metabolismo , Sinalização do Cálcio , Fatores de Despolimerização de Actina/farmacologia , Actinas/metabolismo , Animais , Sinalização do Cálcio/efeitos dos fármacos , ADP-Ribose Cíclica/metabolismo , Fosfatos de Inositol/metabolismo , NADP/análogos & derivados , NADP/metabolismo , Oócitos/metabolismo , Estrelas-do-MarRESUMO
The resumption of the meiotic cycle (maturation) induced by 1-methyladenine in prophase-arrested starfish oocytes is indicated by the breakdown of the germinal vesicle and is characterized by the increased sensitivity of the Ca2+ stores to inositol 1,4,5-trisphosphate (InsP3) to InsP3 starting at the animal hemisphere (where the germinal vesicle was originally located) and propagating along the animal/vegetal axis of the oocyte. This initiates Ca2+ signals around the germinal vesicle before nuclear envelope breakdown. Previous studies have suggested that the final activation of the maturation-promoting factor (MPF), a cyclin-dependent kinase, which is the major element controlling the entry of eukaryotic cells into the M phase, occurs in the nucleus. MPF is then exported to the cytoplasm where its activity is autocatalytically amplified following a similar animal/vegetal spatial pattern. We have investigated whether activated MPF was involved in the increased sensitivity of the Ca2+ response to InsP3. We have found that the development of increased sensitivity of the Ca2+ stores to InsP3 receptors together with the Ca2+ signals in the perinuclear region was blocked in oocytes treated with the specific MPF inhibitor roscovitine. That the nuclear MPF activation is indeed required for changes of the InsP3 receptors sensitivity was shown by enucleating or by dissecting oocytes into vegetal and animal hemispheres prior to the addition of 1-MA. MPF activity 50 min after 1-methyladenine addition was much lower in the enucleated oocytes and in the vegetal hemisphere, which did not contain the germinal vesicle, as compared with the animal hemisphere, which did contain it. The Ca2+ increase induced by InsP3 under these experimental conditions correlated with the changes in actin cytoskeleton induced by MPF.