Is the metabolism of extracellular ATP involved in thalium-mediated cytotoxicity?

VERSTRAETEN, SANDRA V.; VERSTRAETEN, SANDRA V.; SCHWARZBAUM, PABLO J.; SCHWARZBAUM, PABLO J.; SALVATIERRA FRÉCHOU, DAMIANA M.; SALVATIERRA FRÉCHOU, DAMIANA M.

CABA

Congreso; III International Congress In Translational Medicine; 2016

We demonstratedpreviously that Tl(III) -but no Tl(I)- promotes rapid release of ATP (eATP)from adherent PC12 cells via pannexin channels and exocytosis. Tl(III) alsoinhibits irreversibly the activity of ectoATPases that act in the micromolarrange of eATP concentration. In this work we investigated the effects of Tl oncell viability and if those effects could be related to altered eATP metabolism. Cellincubation in the presence of 100 μM Tl(I) or Tl(III) for 1-72 h caused time-dependentdecrease of cell viability evaluated from MTT reduction. This effect wasaccompanied by decreased amounts of adhered cells, with no viable cells detectedin the culture media. To discriminate the causes of Tl-mediated cell death,samples were analyzed by flow cytometry to evaluate the content of hypodiploidcells, and the supernatants were tested for lactate dehydrogenase activity toassess necrosis. While necrosis was negligible, the amount of hypodiploid cells wassignificantly increased after 72 h of Tl(III) exposure. To investigate ifalterations in eATP metabolism may be involved in the early steps of cellresponse to Tl(III), eATP was removed by adding apyrase to the culture media.The removal of eATP enhanced the noxious effect of Tl on cell viability,suggesting that eATP may play a protective role in Tl-mediated cell death.