P2X7 Receptor: Warburg effect revisited

Ability 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 add metabolic adaptation in serum and glucose deprivation

none4noneAmoroso F.; Falzoni S.; Adinolfi E.; Di Virgilio F.Amoroso, Francesca Saveria; Falzoni, Simonetta; Adinolfi, Elena; DI VIRGILIO, Francesc

Insight on P2X7 receptor role as oncogene

Activation 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

P2X7 expression increases tumoral growth,acting at proliferation and neovascularization

none8P2X7 receptor role in tumoral proliferation and neovascularizationnoneAdinolfi E.; Raffaghello L.; Giuliani A.L.; Amoroso F.; Cavazzini L.; Biondi G.; Pistoia V.; Di Virgilio F.Adinolfi, Elena; Raffaghello, L.; Giuliani, Anna Lisa; Amoroso, Francesca Saveria; Cavazzini, L.; Biondi, G.; Pistoia, V.; DI VIRGILIO, Francesc

Involvement of the P2X7-NLRP3 axis in leukemic cell proliferation and death

Lymphocyte growth and differentiation are modulated by extracellular nucleotides and P2 receptors. We previously showed that the P2X7 receptor (P2X7R or P2RX7) is overexpressed in circulating lymphocytes from chronic lymphocytic leukemia (CLL) patients. In the present study we investigated the P2X7R/NLRP3 inflammasome axis in lymphocytes from a cohort of 23 CLL patients. P2X7R, ASC and NLRP3 were investigated by Western blot, PCR and transfection techniques. P2X7R was overexpressed and correlated with chromosome 12 trisomy in CLL patients. ASC mRNA and protein were also overexpressed. On the contrary, NLRP3 was dramatically down-modulated in CLL lymphocytes relative to lymphocytes from healthy donors. To further investigate the correlation between P2X7R, NLRP3 and cell growth, NLRP3 was silenced in THP-1 cells, a leukemic cell line that natively expresses both NLRP3 and P2X7R. NLRP3 silencing enhanced P2X7R expression and promoted growth. On the contrary, NLRP3 overexpression caused accelerated apoptosis. The P2X7R was also up-modulated in hematopoietic cells from NLRP3-KO mice. In conclusion, we show that NLRP3 down-modulation stimulates P2X7R expression and promotes growth, while NLRP3 overexpression inhibits cell proliferation and stimulates apoptosis. These findings suggest that NLRP3 is a negative regulator of growth and point to a role of the P2X7R/NLRP3 axis in CLL

People living with undiagnosed HIV infection and a low CD4 count: Estimates from surveillance data, Italy, 2012 to 2014

Background and aims: Late HIV diagnosis is associated with onward HIV transmission, higher morbidity, mortality and healthcare costs. In Italy, more than half of people living with HIV were diagnosed late during the last decade, with a CD4 count < 350 cells/mm3 at diagnosis. We aimed to determine the number and characteristics of people living with undiagnosed HIV infection and low CD4 counts in Italy. Methods: Data on newly reported HIV diagnoses from 2012 \u20132014 were obtained from the national HIV surveillance system. We used the European Centre for Disease Prevention and Control HIV modelling tool to calculate the undiagnosed prevalence and yearly diagnosed fraction (YDF) in people with low CD4 count. Results: The estimated annual number undiagnosed HIV infections with low CD4 count was on average 6,028 (95% confidence interval (CI): 4,954\u20138,043) from 2012\u20132014. In 2014, most of the undiagnosed people with low CD4 count were men (82.8%), a third acquired HIV through sex between men (MSM) (35.0%), and heterosexual transmission (33.4%), respectively. The prevalence of undiagnosed HIV infection was 11.3 (95% CI: 9.3\u201314.9) per 100,000 residents ranging from 0.7 to 20.8 between Italian regions. Nationally the prevalence rate was 280.4 (95% CI: 173.3\u2013450.2) per 100,000 MSM, 8.3 (95% CI: 4.9\u201313.6) per 100,000 heterosexual men, and 3.0 (95% CI: 1.4\u20135.6) per 100,000 women. The YDF was highest among heterosexual women (27.1%; 95% CI: 16.9\u201345.2%). Conclusions: These findings highlight the importance of improving efforts to identify undiagnosed HIV infections primarily among men, both MSM and heterosexual men