“ATP Modulation of Mitogen Activated Protein Kinases (MAPKs) and c-fos Expression in Osteoblastic and Breast Cancer Cells”

SCODELARO BILBAO, PAOLA GABRIELA; KATZ, SEBASTIÁN; BOLAND, RICARDO; RUSSO DE BOLAND, ANA; SANTILLÁN, GRACIELA

Honolulu, Hawaii, USA

Congreso; 29TH American Society for Bone and Mineral Research Annual Meeting; 2007

American Society for Bone and Mineral Research

We previously showed that ATP and UTP increase intracellular calcium concentration ([Ca2+]i) in MCF-7 breast cancer and osteoblastic ROS 17/2.8 osteosarcoma cells. The elevation of [Ca2+]i was due to Ca2+ release from inner stores through activation of the PI-PLC/IP3 pathway. In addition, mechanical stimulation after ATP or UTP but not ADP induced a transient Ca2+ influx in both cell lines, suggesting that P2Y2/4 receptor activation is required for this mechanical stress-activated Ca2+ (SAC) influx. Moreover, ATP-dependent SAC influx mediated the phosphorylation of mitogen-activated protein kinases (MAPKs) ERK1/2, p38 and JNK1 only in ROS 17/2.8 cells. In this work, we investigated the expression of P2Y (1,2,4) subtype purinoceptors and the  participation of PKC and Src family kinases in the activation of MAPKs by ATP in both cell lines. The involvement of ATP dependent SAC influx in the regulation of c-fos expression was examined. RT-PCR studies supported the expression of P2Y2 subtype receptor in osteoblastic and breast cells, while P2Y1 was not detected neither in MCF-7 nor ROS17/2.8 cells, and P2Y4 was weakly expressed only in MCF-7 cells. The use of Ro 318220, a PKC inhibitor, showed that PKC participates in the phosphorylation of MAPKs by ATP in both cell lines. Otherwise, the use of PP1 or PP2, Src family kinases inhibitors, involved the participation of such kinases in the phosphorylation of MAPKs by ATP only in ROS 17/2.8 cells, although phosphorylation of Src (Tyr 416) was also observed in MCF-7 cells. Maximum levels of c-fos induction were observed after 30 min treatment with ATP in both cell lines, and the use of Gd3+, a SAC influx inhibitor, reduced its expression in ROS17/2.8 but not in MCF-7cells. These results show that P2Y2 is the main receptor subtype involved in ATP-dependent SAC influx in osteoblasts and breast cells. Unlike MCF-7 cells, Src family kinases and SAC influx, respectively, participate in MAPKs activation and c-fos expression induced by ATP only in ROS17/2.8 cells.