Extracellular ATP induces the inactivation of FoxO transcription factors through the PI3K/Akt

SCODELARO BILBAO, PAOLA GABRIELA; BOLAND, RICARDO

Potrero de los Funes

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Forkhead O transcription factors (FoxOs) play a pivotal role in the regulation of cell proliferation and cell death. Thus, perturbation of their function can result in diseases such as cancer. In this work, we studied the effect of extracellular ATP on the phosphorylation and expression of FoxO transcription factors in human breast cancer MCF-7 cells. Western blot analysis showed that 5 μM ATP rapidly (15 min) phosphorylated FoxO1/3a at threonine 24/32. However, ATP did not induce changes in the phosphorylation of FoxO3a at serine 318 or FoxO1 at serine 256, and in the expression of FoxO1 and FoxO3a. In addition, the use of several purinergic agonists ATPgS, ADP, ADPbS, UTP, UDP and adenosine (5 μM) showed that the phosphorylation of FoxO1/3a was due ATP action and not to its degradation products, and suggested the involvement of ATP/UTP-sensitive P2Y receptors in that effect. Moreover, the PI3K inhibitor Ly294002 suppressed the phosphorylation of FoxO1/3a at Thr 24/32 in response to ATP. Immunocytochemistry and subcellular fractionation studies showed that ATP induces the translocation of FoxO3a from the nucleus to the cytoplasm. The results obtained demonstrate that ATP induces the inactivation of FoxO1/3a in a PI3K dependent manner in MCF-7 cells, suggesting a role for these transcription factors in the regulation of breast cancer cell proliferation induced by ATP.