Selective NTPDase2 expression modulates in vivo rat glioma growth
Elizandra Braganhol1, Fernanda B Morrone, Andressa Bernardi
1Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
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.
Insights
Re-establishing ectonucleoside triphosphate diphosphohydrolase 2 (NTPDase2) in glioma cells enhanced tumor growth and malignancy. This suggests purinergic signaling, particularly involving NTPDase2, plays a key role in glioma progression and angiogenesis.
Area of Science:
- Neuroscience
- Biochemistry
- Oncology
Background:
- Ectonucleoside triphosphate diphosphohydrolases (E-NTPDases) regulate purinergic signaling by hydrolyzing extracellular nucleotides.
- Gliomas exhibit reduced E-NTPDase expression compared to normal astrocytes.
- Extracellular nucleotides can promote glioma cell proliferation.
Purpose of the Study:
- To investigate the effect of re-establishing NTPDase2 expression on glioma growth and malignant characteristics.
- To explore the role of NTPDase2 in regulating tumor angiogenesis and inflammation.
Main Methods:
- Overexpression of NTPDase2 in C6 glioma cells.
- In vitro proliferation assays.
- In vivo tumor growth assessment in a glioma model.
- Immunohistochemical analysis of tumor markers (CD31, VEGF, OX-42).
- Treatment with clopidogrel, a P2Y(12) antagonist.
Main Results:
- NTPDase2 overexpression did not affect in vitro glioma proliferation but significantly increased tumor growth and malignancy in vivo.
- Increased platelet sequestration, CD31, vascular endothelial growth factor, and OX-42 expression were observed in NTPDase2-overexpressing gliomas.
- Clopidogrel treatment reversed these pro-tumorigenic effects.
Conclusions:
- NTPDase2 activity promotes glioma progression by stimulating platelet migration and regulating angiogenesis and inflammation.
- ADP, generated by NTPDase2, appears to be a key mediator in this process.
- Purinergic signaling is critically involved in glioma pathogenesis.
