ATP stimulates the proliferation of MCF-7 cells through the PI3K/Akt signaling pathway

We studied the modulation of the PI3K/Akt signaling pathway by ATP in MCF-7 cells. Western blot analysis showed that ATP stimulated the phosphorylation of Akt in a dose- and time-dependent manner. Akt phosphorylation in response to nucleotides followed the potency order ATP = UTP = ATPγS ≫≫ ADP = UDP > ADPβS = adenosine, suggesting participation of P2Y2/4 receptors. Inhibitors of PI3K, PLC, PKC and Src or Src antisense oligonucleotides prevented ATP-induced phosphorylation of Akt. Incubation of cells with 2-APB or in a nominally Ca2+-free medium plus EGTA showed that Akt phosphorylation by ATP depends on intracellular calcium release but is independent of calcium influx. The PI3K inhibitor was not effective in reducing MAPKs phosphorylation by ATP. ATP and UTP stimulated MCF-7 cell proliferation, effect that was inhibited by PI3K, PLC, PKC, Src and MAPKs inhibitors. These findings suggest that ATP modulation of P2Y2/4 receptors increases MCF-7 cell proliferation by activation of the PI3K/Akt signaling pathway through PLC/IP3/Ca2+, PKC and Src.