1,720,970 research outputs found
P2X7 Receptor: Warburg effect revisited
No full textAbility to adapt to conditions of limited nutrient supply is a key feature of all cells. This may require a complex re-organization of metabolic pathways to balance energy generation and production of biosynthetic intermediates. Several fast-growing cells overexpress the P2X7 receptor (P2X7R) for extracellular ATP. A peculiar feature of this receptor is that it allows growth in the absence of serum. We show here that transfection of P2X7R allows proliferation of HEK293 (HEK293-P2X7) cells not only in the absence of serum but also in low (4 mM) glucose and strongly increases lactate output compared to mock-transfected cells (HEK293-mock). In HEK293-P2X7 lactate output is further stimulated upon addition of exogenous ATP or of the mitochondrial uncoupler FCCP. In another tumour cell line constitutively expressing the P2X7R, the human neuroblastoma cell line ACN, lactate output is also dependent on P2X7R function. P2X7R-expressing cells up-regulate a) the glucose transporter Glut-1, b) the glycolytic enzymes glyceraldehyde 3-phosphate dehydrogenase (G3PDH), c) pyruvate kinase M2 (PK-M2) and d) pyruvate dehydrogenase kinase 1 (PDHK1), e) increase phosphorylated Akt/PKB (ph- Akt/PKB) and f) the level of intracellular glycogen stores. In HEK293-P2X7 cells glucose deprivation strongly increases lactate production, expression of glycolytic enzymes and ph-Akt/PKB level. These data show that the P2X7R has an intrinsic ability to reprogram cell metabolism to meet the needs imposed by adverse environmental conditions
Expression of the P2X7 receptor and metabolic adaptation in serum and glucose deprivation
No full textOne of the main features in cancers is the adaptation to stressing conditions. This adaptation confers them the ability to
grow under reduced nutrient availability shape. Several findings point to the PI3K/Akt pathway as the main pathway
involved. Lately, adaptation to glucose deprivation, as well as to serum starvation, is considered a crucial event in tumour
progression. Recently, in our laboratory, we have demonstrated a close relationship between expression of the P2X7
receptor and increased proliferation in the absence of serum (Adinolfi et al. 2009). Here, we analyze the adaptation of
HEK293 cells stably expressing the P2X7 receptor (HEK293-P2X7) to two key metabolic stress factors: glucose
deprivation and serum starvation. In the absence of glucose (4 mM), HEK293-P2X7 have a higher growth rate compared
with HEK293 cells transfected with the empty vector (HEK293-mock). In addition, HEK293-P2X7 are shown to produce
twofold more ATP and release twice as much lactate (p<0.05) than HEK293-mock. Moreover, in the absence of serum,
PKM2 and PDHK1 are overexpressed in HEK293-P2X7 and are hypermodulated by the glucose deprivation. GLUT1 is
overexpressed in HEK293-P2X7. Akt is activated in HEK293-P2X7. These observations suggest a higher efficiency in
glucose uptake and employment by HEK293-P2X7, explaining a possible role for the P2X7 receptor in cancer cell survival
Expression of the P2X7 receptor add metabolic adaptation in serum and glucose deprivation
No full textP2X7 Receptor Function in Bone-Related Cancer
Full text linkModulation of tumor microenvironment by different mediators is central in determining neoplastic formation and progression. Among these molecules extracellular ATP is emerging as a good candidate in promoting cell growth, neovascularization, tumor-host interactions, and metastatization. This paper summarizes recent findings on expression and function of P2X7 receptor for extracellular ATP in primary and metastatic bone cancers. Search of mRNA expression microchip databases and literature analysis demonstrate a high expression of P2X7 in primary bone tumors as well as in other malignancies such as multiple myeloma, neuroblastoma, breast, and prostate cancer. Evidence that P2X7 triggers NFATc1, PI3K/Akt, ROCK, and VEGF pathways in osteoblasts promoting either primary tumor development or osteoblastic lesions is also reported. Moreover, P2X7 receptor is involved in osteoclast differentiation, RANKL expression, matrix metalloproteases and cathepsin secretion thus promoting bone resorption and osteolytic lesions. Taken together these data point to a pivotal role for the P2X7 receptor in bone cancer biology
P2X7/PI3K/AKT/HIF1a pathway: a novel network influencing neuroblastoma growth
No full textIntroduction. P2X7 receptor for extracellular ATP has been
focus of interest over the last years as a receptor promoting cell
proliferation, tumor growth, engraftment, tumor vascularization
and aerobic glycolysis.1,2 In support of these findings, P2X7 expression
was reported to be increased in several tumors, including
breast and skin cancers, leukemia and neuroblastoma.3,4,5
Neuroblastoma is a common and aggressive extra cranial solid
tumor in childhood and still causes death in 40% of the cases.
Here we elucidate the role of P2X7 receptor in neuroblastoma.
Materials and Methods. For in vitro and in vivo experiments
we took advantage of two P2X7 expressing neuroblastoma cell
lines: human ACN, that release VEGF in a P2X7 dependent
fashion1, and murine Neuro-2a. We injected them in nude/nude
and Albino J mice to obtain an allogeneic and a syngeneic model,
respectively.
Results. We show here that basal P2X7 receptor expression
supported ACN and Neuro-2a tumor growth in vivo. P2X7 silencing
and antagonism with AZ10606120 and A740003 caused
cell growth arrest through the PI3K/Akt/HIF1α/GSK3β pathway
modulation, both in vitro and in vivo. Pharmacological
treatment of P2X7 also reduced mitochondrial potential in Neuro-
2a cells. Moreover, we found a correlation between P2X7
mRNA expression and a decreased overall survival of stage IV
neuroblastoma patients.
Conclusions. Altogether, these data show that P2X7 receptor
plays an important role in neuroblastoma growth by modulating
PI3K/Akt/HIF1α/GSK3β pathway. Thus, we suggest P2X7 receptor
as a possible pharmacological target for neuroblastoma
treatment.
1Adinolfi, E; Raffaghello, L; Giuliani, AL; et al (2012), Cancer
Res. 72(12):2957-69.
2Amoroso, F; Falzoni, S; Adinolfi, E; Ferrari, D; Di Virgilio, F
(2012), Cell Death Dis. 3:e370.
3Adinolfi, E; Amoroso, F and Giuliani, AL (2012), J Osteoporosis
2012:637863
Inhibitory effect of P2X7 receptor antagonists on in vivo tumor growth
No full textP2X7 receptor (P2RX7) is an ATP gated ion channel localized in immunitary cells. P2RX7 plays a role in both cell death and survival, participating in
necrosis and apoptosis but also in cell proliferation and tumor transformation. Recent studies reported increased P2RX7 expression in several tumors and
analysis of different Affimetrix Databases retrieved high P2RX7 expression in neuroblastoma andmelanoma.We have recently demonstrated P2RX7 central
role in growth and neovascularization of tumors derived from B16 murine melanoma and in ACN human neuroblastoma cell lines (Adinolfi et al., 2012).
In the last years, several P2RX7 inhibitors have been developed and are actually in advanced stage trials for the therapy of inflammatory diseases. Here
we suggest P2RX7 as target for antitumoral therapy. The aim of this study was to verify if systemic P2RX7 inhibition reduces tumoral growth in vivo
both in human and in murine tumoral cell lines using xenograft and syngeneic mouse models, respectively.
Tumors were obtained by subcutaneous injection of either B16melanoma or ACN neuroblastoma cell lines in syngeneicmice (C57Bl/6) or in nude/nude
mice, respectively. B16 and ACN tumoral growth was monitored for up to 14 and 33 day, respectively. C57Bl/6 and nude/nude mice were treated with
PBS (placebo) or two different P2RX7 antagonists, A74003 or AZ10606120, every 2 days from 5th day post-inoculum. B16 derived tumors excised at
day 14th showed a significantly reduced volume after treatment with both A74003 (10uM) or AZ10606120 (300 nM) (~1⁄2 and~1⁄4 compared to placebo,
respectively). The decreased tumoral growth caused by P2RX7 inhibition was significantly different from day 9th post inoculum both for A74003 and
AZ10606120 treatment groups. ACN derived tumors excised at day 33rd showed a significantly reduced volume after treatment with both A74003 (5
uM) and AZ10606120 (300 nM) (~3⁄4 compared to placebo). Although not significantly different, a trend of reduction of tumoral growth, following
P2RX7 inhibition, was also appreciable during in vivo measurement.
In conclusion, present data show for the first time that systemic inhibition of P2RX7 affects tumoral growth both in murine and in human tumoral cell
lines indicating the involvement of P2RX7 in cancer development. In this view it is convincible to identify P2RX7 as therapeutical target in cancer
P2X7 receptor supports proliferation and progression of neuroblastoma cells, in vitro
No full textIt is largely demonstrated that expression of P2X7 receptor (P2X7R) drives proliferation of tumor cells by modulating NFATc1 pathway via Ca2+ influx
(Adinolfi E et al.; J Biol Chem.; 284(15):10120–8. 2009). Moreover P2X7 receptor expression is shown to be tightly related to the re-organization of
metabolic pathways for balancing energy generation in restricted metabolites viability, as fast growing tumors need (Amoroso F et al.; Cell Death Dis.;
3:e370. 2012). Neuroblastoma is the most common extra cranial solid tumor in childhood and one of the most aggressive. ACN human neuroblastoma
cell line is known to express P2X7 receptor (Raffaghello L et al.; Cancer Res. 66(2):907–14. 2006) and release VEGF in a P2X7 dependent fashion
(Adinolfi E et al.; Cancer Res. 72(12):2957–69. 2012).We showhere that basal P2X7 receptor expression leadsACNproliferation, while silencing P2X7
receptor causes a down-modulation of PI3K/HIF1α/GSK3β pathway. Furthermore proliferation and metabolism modulation as well, can be affected by
pharmacological treatment of ACN cells with P2X7 antagonists. These data show that P2X7R plays an important role in neuroblastoma tumor
progression and adaptation to environmental condition. Thus, we suggest P2X7R as a possible pharmacological target for neuroblastoma treatment
The P2X7 receptor is a key modulator of aerobic glycolysis.
No full textAbility to adapt to conditions of limited nutrient supply requires a reorganization of the metabolic pathways to balance energy generation and production of biosynthetic intermediates. Several fast-growing cells overexpress the P2X7 receptor (P2X7R) for extracellular ATP. A feature of this receptor is to allow growth in the absence of serum. We show here that transfection of P2X7R allows proliferation of P2X7R-transfected HEK293 (HEK293-P2X7) cells not only in the absence of serum but also in low (4 mM) glucose, and increases lactate output compared with mock-transfected HEK293 (HEK293-mock) cells. In HEK293-P2X7, lactate output is further stimulated upon addition of exogenous ATP or the mitochondrial uncoupler carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP). In the human neuroblastoma cell line ACN, lactate output is also dependent on P2X7R function. P2X7R-expressing cells upregulate (a) the glucose transporter Glut1, (b) the glycolytic enzymes glyceraldehyde 3-phosphate dehydrogenase (G3PDH), (c) phosphofructokinase (PFK), (d) pyruvate kinase M2 (PKM2) and (e) pyruvate dehydrogenase kinase 1 (PDHK1); furthermore, P2X7R expression (a) inhibits pyruvate dehydrogenase (PDH) activity, (b) increases phosphorylated Akt/PKB and hypoxia-inducible factor 1α (HIF-1α) expression and (c) enhances intracellular glycogen stores. In HEK293-P2X7 cells, glucose deprivation increases lactate production, expression of glycolytic enzymes and ph-Akt/PKB level. These data show that the P2X7R has an intrinsic ability to reprogram cell metabolism to meet the needs imposed by adverse environmental conditions
Emerging roles of P2X receptors in cancer
No full textTumor microenvironment composition strongly conditions cancer growth and progression, acting not only at cancer itself but also modifying its interactions with immune, endothelial and nervous cells. Extracellular ATP and its receptors recently gained increasing attention in the oncological field. ATP accumulates in cancer milieu through spontaneous release, tumor necrosis or chemotherapy exerting a trophic activity on cancer cells, modulating the cross talk among tumor, and surrounding tissues. Accordingly, ATP gated P2X receptors emerged as central players in tumor development, invasion, progression and related symptoms. Indeed, P2X receptors are expressed and are functional not only on tumor cells but also in immune-infiltrate and nearby neurons. In this review, we summarize recent findings on P2X receptors role in tumor cell differentiation, bioenergetics, angiogenesis, metastasis and associated pain, giving an outline of the potential anti-neoplastic activity of receptor agonists and antagonists
Insight on P2X7 receptor role as oncogene
No full textActivation of P2X7 receptor is impacting almost all recognized cancer hallmarks [Hanahan D, Weinberg RA. Cell. 2011;144(5):646–674] including
sustained proliferation [Baricordi OR, Melchiorri L, Adinolfi E, Falzoni S, Chiozzi P, Buell G, Di Virgilio F. J Biol Chem. 1999; 274(47):33206–8;
Adinolfi E, CallegariMG, Ferrari D, Bolognesi C, Minelli M,Wieckowski MR, Pinton P, Rizzuto R, Di Virgilio F. Mol Biol Cell. 2005; 16(7):3260–72],
deregulation of cellular energetics [Adinolfi et al. 2005; Amoroso F, Falzoni S, Adinolfi E, Ferrari D, Di Virgilio F. Cell Death Dis. 2012; 3:e370],
activation of tissue invasion [Jelassi B, Chantôme A, Alcaraz-Pérez F, Baroja-Mazo A, Cayuela ML, Pelegrin P, Surprenant A, Roger S. Oncogene. 2011;
30(18):2108–22] and neovascularization [Adinolfi E, Raffaghello L, Giuliani AL, Cavazzini L, Capece M, Chiozzi P, Bianchi G, Kroemer G, Pistoia V, Di
Virgilio F. Cancer Res. 2012;72(12):2957–69]. Nevertheless, a clear cut demonstration that P2X7 receptor can affect carcinogenesis in vivo was missing.
Aim of our studies was to verify the effect of P2X7 expression and blockade in animal models of cancer. Tumor tested included colon cancer, melanoma
and neuroblastoma modeled either in syngeneic or in xenograft systems. In all this settings P2X7 was increasing tumoral engraftment and growth rate also
affecting blood vessels formation [Adinolfi et al., 2012]. Signaling cascades involved in P2X7 mediated transformation included the HIF-1 alpha-VEGF
and PI3Kinase-GSK3 axes. Of interest for the therapy of cancers that are still lacking a cure, such as advanced stages neuroblastoma and melanoma, was
the power of different P2X7 inhibitors to in vivo reduce cancer growth. In summary, our data demonstrate an oncogenic role for P2X7 receptor and suggest
it as easily approachable therapeutic target as its antagonists are in clinical trials for other diseases and will be soon available at patient’s bed
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