Platelet-activating factor induces the stemness of ovarian cancer cells via the PAF/PAFR signaling pathway

Background: Cancer stem cells (CSCs) play an important role in tumor recurrence, metastasis, and chemoresistance. CSCs can shift between non-CSC and CSC states in certain tumor microenvironments. The mechanisms of this shift are not well understood. We previously demonstrated that platelet-activating factor (PAF), a lipid mediator of inflammation in the tumor microenvironment, can promote ovarian cancer progression and induce chemoresistance via PAF/PAFR-mediated inflammatory signaling pathways. Here, we investigated the role of PAF/PAFR signaling in the stemness of ovarian cancer cell. Methods: The effects of PAF and PAFR antagonists on the stemness of SKOV3 and A2780 cells were evaluated using sphere-formation assays, FACS analysis and real-time PCR in vitro and a SKOV3 tumor-formation experiment in nude mice in vivo. The potential mechanism of the PAF effect on the stemness of ovarian cancer cells was evaluated by human cytokine antibody microarray analysis. Results: PAF can promote spheroid formation and inhibit the transition of quiescent ovarian cancer cells into the cell cycle. The percentage of cancer stem cells increased significantly, and the expression of stemness genes increased in PAF-treated group. These effects could be blocked by PAFR inhibitors. Ginkgolide B (GB) inhibited tumor growth and decreased the CSC percentage in vivo. Human cytokine antibody microarray analysis showed that some stemness-maintaining proteins increased in PAF-treated group. Conclusion: Our results suggest that PAF can regulate the stemness of ovarian cancer cells through the PAF/PAFR pathway, suggesting a new target for the treatment of ovarian cancer.