Adenosine 5'-triphosphate (
ATP) is found in high concentrations in the extracellular microenvironment of tumours and is postulated to play critical roles in
cancer progression. In the present study, we found that stimulation of human MCF-7
breast cancer cells with 30 µM
ATP increased their migration by 140 ± 31%, whereas it had minor or no effect on their proliferation. This effect was prevented by the ectonucleotidase
apyrase and was antagonized by
suramin and pyridoxalphosphate-6-azophenyl-2',4'-disulfonic
acid, consistently with the participation of P2 receptors. MCF-7 cells expressed
messenger RNA for all known P2Y receptors and for P2X2, P2X4, P2X5, P2X6 and P2X7 receptors. Brief applications (20 s) of external
ATP resulted in a 50 pA P2X-like inward current.
ATP, but not
adenosine diphosphate or
uridine diphosphate, increased the intracellular
calcium concentration in absence of extracellular
calcium, and this effect was prevented by the inhibition of
phospholipase C.
Uridine triphosphate (
UTP) (10 µM) and 2-thio-UTP (10 µM) increased intracellular
calcium concentration and cell migration to the same extent as
ATP. The
UTP-dependent increase in cell migration was absent in cells knocked-down for P2Y2. It was inhibited by
MEK inhibitor
PD98059.
UTP induced a time-dependent phosphorylation of
extracellular signal-regulated kinases 1 and 2 (ERK1/2), which was prevented by the incubation with
PD98059. Taken together, these results highlight the importance of the purinergic signalling in
cancer cells and indicate that the activation of
P2Y2 receptors enhances
breast cancer cells migration through the activation of a
MEK-ERK1/2-dependent signalling pathway.