Hence, GSK 3B and FKHR FACE phosphorylation assays were performed to determine the effect of CCL25 on these regulators of cell survival. CCL25 treatment sig nificantly increased phosphorylated total GSK 3B protein levels after 5 and 10 minutes treatments or combined with cisplatin, compared to untreated cells. Wortmannin treatment completely abolished CCL25 mediated GSK 3B phosphorylation. Interestingly, PF 573, 228 plus CCL25 treatment had no effect on phosphoryla tion total GSK 3B protein levels. Moreover, cisplatin treatment had no effect on CCL25 mediated GSK 3B phosphorylation, since CCL25 treatment of OvCa cells co incubated with cisplatin significantly increased phos phorylated total GSK 3B protein levels after 5 and 10 minutes treatments. This activation was inhibited by wortmannin treatment, but not by the FAK inhibitor.

CCL25 also significantly increased phosphorylated total FKHR levels after 5 and 10 minutes treatments, com pared to untreated cells. Wortmannin, but not PF 573, 228, treatment inhibited this increase. Neither cisplatin treatment alone or in combination with the FAK inhibitor affected FKHR phosphorylation following CCL25 treat ment. However, wortmannin treatment completely abro gated the CCL25 mediated increases in FKHR phosphorylation in cisplatin treated OvCa cells. Discussion A major cause of the high mortality rates due to OvCa is chemotherapy resistance. Cisplatin is often the first drug of choice for OvCa treatment. Unfortunately, cisplatin resistance is a major obstacle that impedes successful chemotherapy and a major cause of treatment failure in human OvCa.

The balance between survival and apop totic signals determine a cells sensitivity to chemother apy. Indeed, cancer cells develop resistance to chemotherapy by means of inactivating apoptotic factors and enhancing survival pathways that antagonize apopto sis signals. However, the precise mechanisms of OvCa cell cisplatin sensitivity or survival are not known. Chemokines function to direct leukocyte and cancer cell migration, and play pivotal roles in cell survival. Studies have demonstrated that CXCR4 CXCL12 inter actions promote the survival of tumor cells, allowing growth under less favourable conditions. In particular, CXCR4 mediates survival in glioma cells. Recent studies have also suggested that CCR9 CCL25 interac tions potentiate anti apoptotic signalling to immature T cells.

We have demonstrated that OvCa Brefeldin_A cells and tis sues express CCR9 and play important role in cell migra tion, invasion under the chemotactic gradient of CCL25. Here we show that CCR9 also supports OvCa cell survival and cisplatin resistance. For the first time, we show that CCL25 significantly increases the proliferation of the OvCa cells in a CCR9 dependent fashion. In the presence of cisplatin, CCL25 also supported OvCa cell survival.