Thyroid hormone upregulates ecto-5′-nucleotidase/CD73 in C6 rat glioma cells

Thyroid hormones have profound effects on the central nervous system, such as proliferation, secretion of growth factors and gene expression regulation. Ecto-NTPDases and ecto-5'-nucleotidase can control the extracellular ATP/adenosine levels, which have been described as proliferation factors. Here, we investigated the influence of T-3 on the enzyme cascade which catalyzes interconversion of purine nucleotides in rat C6 glioma cells. Exposure of C6 cells to T-3 caused a dose dependent increase of 30% in the AMP hydrolysis up to 0.25 nM, which was suppressed by actinomycin. No significant alteration was observed on ATP/ADP hydrolysis and T-4 at higher concentrations (10-1000 nM) promoted an increase in AMP hydrolysis that was not dose dependent. T-3 treatment also increased the expression of CD73 mRNA. Besides the importance of the ecto-5'-NT in the cell proliferation and differentiation, its overexpression can enhance extracellular adenosine levels, which could also be an important proliferation signal. (C) 2003 Elsevier Ireland Ltd. All rights reserved.