1,721,420 research outputs found
New pathways for reactive oxygen species generation ininflammation and potential novel pharmacological targets
No full textOxidative agents are generated in large amounts during inflammation. These highly reactive intermediates interact with several extracellular and intracellular molecules and with each other, thus generating a complex network of responses culminating in an outcome that may be detrimental or beneficial for the host. Alongside with the well known systems involved in production of reactive oxygen species or reactive nitrogen species, such as the NADPH oxidase or the nitric oxide synthase, novel enzymatic pathways have been discovered. This has unveiled new targets and functions for oxidant species, and has prompted the development of innovative anti-inflammatory drugs. In the new integrate scenario stemming from these studies oxidant species are increasingly recognized as true messengers, and even their toxic effects are viewed as the result of the perversion of an otherwise physiological extra/intra cellular signaling
COST Action BM1406 "Ion Channels and Immune Response toward a global understanding of immune cell physiology and for new therapeutic approaches (IONCHAN-IMMUNRESPON)"
No full textThe function of ion channels in immune cells is an emerging field of great basic science and clinical interest because they provide powerful molecular targets to modulate immune cell function. The Ionchan-Immunrespon network is a novel and exciting enterprise that involves internationally recognised scientists across 15 European countries. The specific aims are i) to develop a strong European workforce to understand the role of ion channels in immune cells, and how deregulation of their function can cause disease, ii) to identify new targets for therapeutic immuno-interventions through modulation of ion channels. Our unique combination of biophysical approaches combined with molecular biology, cell biology and immunology provides a powerful approach for dissecting the functional cell biology of the immune system.
The Action therefore will strengthen academic research in Immunology within Europe and foster closer collaborations with drug and diagnostics development programs in industry
The P2X7 receptor: a key determinant of cellular metabolic energetics in cancer progression - AIRC IG 18581
No full textBackground
An increased ATP concentration is a typical biochemical feature of the tumor microenvironment (TME). Likewise, many
malignant tumors overexpress plasma membrane receptors for extracellular ATP (P2Rs), and P2Rs play a role in cancer cell
intravasation/extravasation and therefore in metastatic spreading. These observations highlight the importance of purinergic
signalling in cancer research. A substantial breakthrough in the biochemistry and cell biology of extracellular ATP has been the
generation of a bioluminescent probe allowing the in vivo real-time measurement of the extracellular ATP concentration. This
probe, named plasma membrane luciferase (pmeLUC) has allowed to unequivocally demonstrate that the TME is a "high-ATP
environment", and that ATP within this environment can be used by cancer cells to support their metabolic requirements.
Among the P2Rs, P2X7R is mostly involved in cancer as: a) is upregulated in cancer cells; b) promotes growth; c) stimulates the
Warburg effect; d) is necessary for metastatic spreading. In addition, P2X7R is intimately linked to the NLRP3 inflammasome
AIRC IG 13025: The P2X7 receptor is a key switch of cancer cell glycolytic metabolism
No full textIn 1924 Otto Warburg hypothesized that the main cause of malignant transformation was the deviation
of cancer cell metabolism towards direct conversion of pyruvate to lactate rather than its oxidation
within the mitochondria. Persistence of glycolysis in the presence of normal oxygen concentrations
(aerobic glycolysis) is now referred to as the “Warburg effect”. Although it is now clear that this
peculiar glycolytic metabolism is not specific of cancer cells but of any fast growing cells, Warburg
effect has met with rekindled interest in recent years after the discovery that some key oncogenes (e.g.
AKT, c-myc), or suppressor genes (TP53, PTEN) affect expression and function of enzymes that
control the glycolytic pathway, and that key glycolytic enzymes are overexpressed or dysregulated in
cancer (e.g. pyruvate kinase isoform M2, hexokinase). Furthermore, these same oncogenes and
oncosuppressor genes also profoundly modulate mitochondrial oxidative phosphorylation.
Interrelationship between cancer genes, glycolysis and oxidative phosphorylation is intriguing because,
contrary to previous opinion, it is now clear that mitochondrial respiration is by no means shut off in
cancer cells. It appears that tumours set in motion all available machineries to secure the most efficient
energy output (oxidative phosphorylation) and the highest production of building blocks for structural
synthesis (glycolysis). In addition, several reports suggest that modulation of glycolysis or of selected
enzymes involved in this pathway may arrest cancer cell growth and tumour progression. In recent
years we have focused our attention on a plasma membrane receptor for extracellular ATP named
P2X7. This receptor, which is a member of the P2 family, attracted our attention for the following
reasons: a) is overxpressed by all human cancers so far investigated; b) has a strong trophic effect on
mitochondria; c) stimulates oxidative phosphorylation; d) increases total cellular ATP content; e)
causes activation of the transcription factor NFATc1. Furthermore, in vivo preliminary results show
that: a) overexpression of P2X7 accelerates tumor growth and metastasis formation; b) silencing or
pharmacological inhibition of P2X7 slows down tumor progression; c) P2X7 expression and activation
drives VEGF secretion and angiogenesis; d) in primary human tumour cells and human tumour cell
lines P2X7 is up-regulated and the NLRP3 inflammasome is down-modulated. Given the recent
implication of mitochondria in the modulation of NLRP3 inflammasome activation under physiological
conditions, our preliminary findings suggest that in cancer cells a dysregulation of the
P2X7/mitochondria/inflammasome axis might be present. Collectively, these observations suggest that
P2X7 might have an important and as yet neglected role in tumour growth. Therefore, we plan to carry
out the following research program: a) investigate the effect of P2X7 expression/activation or
silencing/inhibition on aerobic glycolysis in vitro (measured as lactate output); b) investigate the effect
of P2X7 expression/activation or silencing/inhibition on expression and function selected glycolytic
enzymes; c) investigate the effect of P2X expression/activation or silencing/inhibition on mitochondrial
metabolism in established models of mouse tumours; d) investigate the effect of mitochondrial
metabolism on NLRP3 inflammasome activity and cell growth; e) investigate the effect of NLRP3
inflammasome silencing on mitochondrial metabolism and on the Warburg effect
I recettori purinergici P2 e le ectonucleotidasi: nuovi bersagli per lo sviluppo di farmaci anti-tumorali/P2 purinergic receptors and ectonucleotidases: novel targets for anti-cancer drugs (FIRB Accordi di programma n. RBAP11FXBC)
No full textNucleotides are basic constituents of tumour microenvironment where they 1) modulate tumour growth, progression and metastatsis formation, 2) stimulate mitochondrial metabolism and aerobic glycolysis acting at the P2X7 receptor, 3) are substrate for ecto-enzymes producing adenosine, a powerful immunosuppressant, and cyclic ADP ribose, an intracellular messenger that participates in the homeostasis of intracellular calcium. We hypothesize that the signaling network based on P2 receptors and on the associated enzymes is a fundamental pathway in cancer. Within tumour microenvironment concentration of immunostimulatory mediators is very low, while on the contrary concentration of immunosoppressive factors is increased, therefore tumour-associated immune cells often have an immunosoppressive phenotype. Thus, biochemical characterization of tumour microenvironment is vital for the design of innovative anti-cancer treatments. Our Group has directly shown that tumour interstitium contains high ATP concentrations (1), and that extracellular ATP accumulates in all sites of inflammation (2). ATP accumulation on one hand can lead to the activation of a distorted Th2 response and to the accumulation of adenosine (3, 4) , and on the other to the activation of the P2X7 receptor, with the associated recruitment and activation of dendritic cells, IL-1 release and efficient presentation of tumour antigens (5). Furthermore, metabolites generated from hydrolysis of extracellular ATP and NAD have a powerful modulatory activity on Treg lymphocytes (CD4+/CD25+/FOXP3+). Treg lymphocytes over-express the ecto-enzymes CD39 and CD73, which are responsible of the hydrolysis of extracellular nucleotides and of generation of the potent immunosuppressant adenosine. Tumour progression and invasiveness depend on the expression level of CD39/CD73 by infiltrating immune cells. Recent data show that anti-CD73 Abs inhibit tumour growth and metastasis (6). Accumulation of ATP within tumour microenvironment can also directly activate tumour cell P2X7 receptor, thus causing NFAT and NFkB activation, stimulation of Warburg effect and growth. Extracellular nucleotides modulate functions of normal and neoplastic precursors. ATP and UTP are growth factors for CD34+ hemopoietic stem cells and stimulates engrafting and bone-marrow repopulation (7). Furthermore, extracellular nucleotides stimulate stem cell migration via Rac2/Rho proteins (8).
This evidence suggest that the purinergic network is a useful target for the development of novel anti-cancer strategies. Several P2X7 inhibitors are currently under experimentation by Pharma Industry: CE-224535 by Pfizer is now in Phase II/III; AZD-9056 by Astra-Zeneca is now in Phase II; EVT-401 by Renovis is now in Phase I. Furthermore, Ablynx has produced humanized anti-P2X7 mAb for therapeutical applications, and preclinical studies are under way by several other Companies, among which Affectis Pharma AG (Germany) and Cordex Inc (USA), with which our Group has an established collaboration. All this clinical studies are focused on the treatment of chronic inflammatory diseases. To our knowledge, there are no Phase II/III studies aimed to test the efficacy of P2X7 blockers in cancer. Should our studies demonstrate that purinergic signalling ha san important role in cancer growth, availability of drugs already allowed for use in humans will strongly accelerate bench-to-bed transition
P2X receptors and inflammation
No full textUntil recently, P2X receptors have not received much attention in the context of immunology and inflammation. While this is justified to a certain extent for P2X1, P2X2, P2X3, P2X5 and P2X6, which still await identification of a convincing role in the pathophysiology of immune cells, it is clearly not any more the case for P2X4 and even more so for P2X7, a molecule that has achieved the status of an essential, nonredundant, immunomodulatory receptor. In this review I will highlight the most important inflammatory responses participated by P2X receptors
Ricerca Finalizzata Ministero della Salute/Finalized Research Ministry of Health (RF-2011-02348435, 480 000 euro) Titolo/Title Investigation of the role of extracellular ATP and the P2X7 receptor in the modulation of immunosuppression within tumour microenvironment.
No full textTumor microenvironment resembles an inflammation site (1). Chronic/smouldering inflammation confers advantages for the
progression of tumor, contributing to both tumor antigen-specific tolerance and generalized T lymphocyte dysfunction (2).
We plan to define the contribution that a dysfunctional purinergic signalling may give to support the immunosuppressive
milieu of the tumour microenvironment. In particular we aim at the:
1. Pharmacological, biochemical, molecular and functional characterization of purinergic receptors expressed by myeloidderived
suppressor cells (MDSCs).
4. Investigate the interplay between extracellular ATP and MDSCs within tumor microenvironment.
5. Verify the role of extracellular ATP in cell-to-cell communication within tumour microenvironment.
6. Test the effect of P2X7 and CD73 blockers on tumor progression and metastasis formation.
7. Develop novel techniques for the in vivo imaging of extracellular ATP
Activation of site I redox-driven H+ pump by exogenous quinones in intact mitochondria.
No full textThe site I redox-driven H+ pump has been activated by the addition of exogenous quinones to antimycin A-KCN-inhibited mitochondria. The rate of quinone reduction and the degree of rotenone sensitivity increase in the order, duroquinone less than ubiquinone0 less than ubiquinone1. Apparent Km, Vmax, and degree of sigmoidicity during e- transfer in the absence and presence of rotenone have been determined for each quinone. The data support the view that the NADH dehydrogenase possesses two redox sites, one accounting for the rotenone-sensitive reduction and another accounting for the rotenone-insensitive reduction. The degree of activation of the redox H+ pump, which reflects the rotenone-sensitive e- transfer, depends, for each quinone, on the relative Km, Vmax, and sigmoidicity of the rotenone-sensitive and insensitive processes. The redox H+ pump activation is highest with ubiquinone1, where the rotenone-sensitive reaction has a lower Km than that of the rotenone-insensitive reaction, and lowest with duroquinone where the rotenone-insensitive reaction has a high Vmax and no sigmoidicity with respect to that of the rotenone-sensitive reaction. Using ubiquinone1 the stoichiometry of the site I redox-driven H+ pump has been determined on either the flow or the force ratios. The flow ratios approached values of 4 H+/2 e- under conditions close to stationary state for H+ pumping and to zero for H+ electrochemical gradient. The force ratio also approached values close to 4 H+/2 e- under static head conditions
Editorial overview: Cancer
No full textThe latest few years have witnessed an unprecedented acceleration in the accumulation of crucial information on basic aspects of cancer cell biology suitable of a rapid transfer to the patients’ bed. Understanding of cancer cell energetics has kindled novel interest in role of intracellular messengers such as Ca2+, and intracellular metabolic pathways such as glycolysis and mitochondrial oxidative phosphorylation. An in-depth knowledge of cancer-stem cell properties and identification of specific factors expressed in these cells has taken off the lid of a Pandora vase of exceptionally important observations on the role of factors, such as transcriptional regulators, that are likely to become new targets for cancer therapy in the near future. An in depth knowledge of the specific biochemical conditions within and around solid tumors (the tumor microenvironment, TME) has allowed to identify specific pathways that are overactivated and conducive to tumor growth and metastatic spreading. Based on the identification of these pathways, novel effective anticancer drugs (or treatments) have been developed, and more importantly a novel “ecology” of cancer saw the light
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