Selective NTPDase2 expression modulates in vivo rat glioma growth

Abstract

The ectonucleoside triphosphate diphosphohydrolases (E-NTPDases) are a family of ectoenzymes that hydrolyze extracellular nucleotides, thereby modulating purinergic signaling. Gliomas have low expression of all E-NTPDases, particularly NTPDase2, when compared to astrocytes in culture. Nucleotides induce glioma proliferation and ATP, although potentially neurotoxic, does not evoke cytotoxic action on the majority of glioma cultures. We have previously shown that the co-injection of apyrase with gliomas decreases glioma progression. Here, we tested whether selective re-establishment of NTPDase2 expression would affect glioma growth. NTPDase2 overexpression in C6 glioma cells had no effect on in vitro proliferation but dramatically increased tumor growth and malignant characteristics in vivo. Additionally, a sizable platelet sequestration in the tumor area and an increase in CD31 or platelet/endothelial cell adhesion molecule-1 (PECAM-1), vascular endothelial growth factor and OX-42 immunostaining were observed in C6-Enhanced Yellow Fluorescent Protein (EYFP)/NTPDase2-derived gliomas when compared to controls. Treatment with clopidogrel, a P2Y 12 antagonist with anti-platelet properties, decreased these parameters to control levels. These data suggest that the ADP derived from NTPDase2 activity stimulates platelet migration to the tumor area and that NTPDase2, by regulating angiogenesis and inflammation, seems to play an important role in tumor progression. In conclusion, our results point to the involvement of purinergic signaling in glioma progression. (Cancer Sci 2009; 100: 1434-1442) G lioblastoma multiforme, the most common form of malignant brain tumor, is relatively resistant to therapeutic strategies and has a median survival after first diagnosis of only around 12 months. This median survival has remained unchanged for decades despite multiple clinical trials designed to optimize radiation and/or chemotherapy regimens.(1,2) Although systemic metastases of malignant gliomas are relatively rare, the highly infiltrative nature exhibited by these tumors is the main cause of treatment failure and high recurrence rates. Recent works suggest that malignant gliomas have a stem cell population, which is fundamental for tumor maintenance and growth. Such cellular subpopulations seem to be more resistant to radiotherapy, exhibit enhanced proliferative and migratory potential, and can overcome diverse paths of differentiation.(3) In addition to neoplastic cells, a number of non-malignant cells such as lymphocytes, endothelial cells, microglial cells, and macrophages comprise the tumor microenvironment and appear to be associated with tumor progression by influencing cell proliferation and angiogenesis. (4) Glioma invasion is a multifactorial process consisting of numerous genetic and physiological alterations, which affect glioma cell interactions with neurons, glia, and vascular cells in the central nervous system.(3) Among the pathological alterations that give tumor cells invasive potential, purinergic signaling is...

NTPDase3 and ecto-5′-nucleotidase/CD73 are differentially expressed during mouse bladder cancer progression

“…4a). This result was confirmed by quantitative analysis of the ecto-5′-NT/CD73 immunofluorescence, which increased in a time-response profile of BBN exposition (4,8,12,18, and 24 weeks). Moreover, it was observed that an increase in the areas of increased cell proliferation and decreased presence of umbrella cells are important pathological characteristics of a malignant bladder process.…”

“…White scale bars= 25 μm. b Quantification of ecto-5′-NT/CD73 staining of bladder urothelium from mice which received BBN for 4,8,12,18, and 24 weeks. The immunofluorescent images of ecto-5′-NT/CD73 were quantified in MacBiophotonics ImageJ software as described in Materials and methods.…”

“…In this work, bladder cancer was induced by the addition of 0.05 % of BBN in the drinking water for 4,8,12,18, and 24 weeks with a respective control group for each induction time. The number of mice per group was 8 for control groups of 4, 8, and 12 weeks and 9, 10, and 10 for BBN groups of 4, 8, and 12 weeks, respectively; and for the cancer induction times of 18 and 24 weeks, it was 3 for control groups and 5 and 4 for groups that received BBN, respectively.…”

“…The ecto-nucleoside triphosphate diphosphohydrolases refer to a family of cell-surface enzymes that hydrolyze extracellular ATP and ADP to AMP. Studies have demonstrated the involvement of these enzymes in cancer progression [16][17][18]. The final dephosphorylation of nucleotides, conversion of nucleoside monophosphates (e.g., AMP) to their respective nucleosides (e.g., adenosine), is catalyzed by ecto-5′-nucleotidase/CD73 (ecto-5′-NT/CD73).…”

Overexpression of NTPDase2 in gliomas promotes systemic inflammation and pulmonary injury

“…As NTPDase2 is the major ectonucleotidase present in astrocytes in culture, we analyzed whether the overexpression of a preferential ecto-ATPase would affect the in vivo glioma growth. Surprisingly, NTPDase2 overexpression dramatically increased tumor malignity [24]. In the present study, we evaluated whether NTPDase2 reconstitution to gliomas could modulate the systemic inflammatory response.…”