title: Characterization of ectonucleotidases in human medulloblastoma cell lines: ecto-5'NT/CD73 in metastasis as potential prognostic factor.
abstract: Medulloblastoma (MB) is the most common malignant brain tumor in children and occurs mainly in the cerebellum. Important intracellular signaling molecules, such those present in the Sonic Hedgehog and Wnt pathways, are involved in its development and can also be employed to determine tumor grade and prognosis. Ectonucleotidases, particularly ecto-5'NT/CD73, are important enzymes in the malignant process of different tumor types regulating extracellular ATP and adenosine levels. Here, we investigated the activity of ectonucleotidases in three malignant human cell lines: Daoy and ONS76, being representative of primary MB, and the D283 cell line, derived from a metastatic MB. All cell lines secreted ATP into the extracellular medium while hydrolyze poorly this nucleotide, which is in agreement with the low expression and activity of pyrophosphate/phosphodiesterase, NTPDases and alkaline phosphatase. The analysis of AMP hydrolysis showed that Daoy and ONS76 completely hydrolyzed AMP, with parallel adenosine production (Daoy) and inosine accumulation (ONS76). On the other hand, D283 cell line did not hydrolyze AMP. Moreover, primary MB tumor cells, Daoy and ONS76 express the ecto-5'NT/CD73 while D283 representative of a metastatic tumor, revealed poor expression of this enzyme, while the ecto-adenosine deaminase showed higher expression in D283 compared to Daoy and ONS76 cells. Nuclear beta-catenin has been suggested as a marker for MB prognosis. Further it can promotes expression of ecto-5'NT/CD73 and suppression of adenosine deaminase. It was observed that Daoy and ONS76 showed greater nuclear beta-catenin immunoreactivity than D283, which presented mainly cytoplasmic immunoreactivity. In summary, the absence of ecto-5'NT/CD73 in the D283 cell line, a metastatic MB phenotype, suggests that high expression levels of this ectonucleotidase could be correlated with a poor prognosis in patients with MB.
authors.affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas e da Saúde, UFRGS, Porto Alegre, Rio Grande do Sol, Brasil.
authors.forename: Angélica Regina
authors.initials: AR
authors.lastname: Cappellari
authors.forename: Liliana
authors.initials: L
authors.lastname: Rockenbach
authors.forename: Fabrícia
authors.initials: F
authors.lastname: Dietrich
authors.forename: Vanessa
authors.initials: V
authors.lastname: Clarimundo
authors.forename: Talita
authors.initials: T
authors.lastname: Glaser
authors.forename: Elizandra
authors.initials: E
authors.lastname: Braganhol
authors.forename: Ana Lúcia
authors.initials: AL
authors.lastname: Abujamra
authors.forename: Rafael
authors.initials: R
authors.lastname: Roesler
authors.forename: Henning
authors.initials: H
authors.lastname: Ulrich
authors.forename: Ana Maria Oliveira
authors.initials: AM
authors.lastname: Battastini
authors.forename: Ana Maria liveira
authors.initials: AM
authors.lastname: Battastini
mesh_terms: D015720:5'-Nucleotidase / Q000235:genetics* / Q000378:metabolism; D000241:Adenosine / Q000378:metabolism; D000243:Adenosine Deaminase / Q000235:genetics / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D001932:Brain Neoplasms / Q000175:diagnosis / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D002531:Cerebellum / Q000201:enzymology / Q000473:pathology; D002648:Child; D011756:Diphosphates / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008527:Medulloblastoma / Q000175:diagnosis / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D009362:Neoplasm Metastasis; D009928:Organ Specificity; D010727:Phosphoric Diester Hydrolases / Q000235:genetics / Q000378:metabolism; D011379:Prognosis; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; C495270:CTNNB1 protein, human; D011756:Diphosphates; D051176:beta Catenin; D000249:Adenosine Monophosphate; C107241:diphosphoric acid; D000255:Adenosine Triphosphate; D000469:Alkaline Phosphatase; D015720:5'-Nucleotidase; D010727:Phosphoric Diester Hydrolases; D000243:Adenosine Deaminase; D011755:Pyrophosphatases; D000241:Adenosine