Knockdown von PDCD10 führt in Glioblastom- und Endothelzellen zu Tumorwachstum über die Aktivierung der EphB4-Kinase in vitro und in vivo
Programmed cell death 10 (PDCD10) plays crucial roles in multiple cellular processes. Our laboratory has previously demonstrated that loss of endothelial PDCD10 stimulated endothelial angiogenesisand activated glioblastoma (GBM) cells and promoted GBM tumor growth. The aims of present study are to further explore that the role of tumoral PDCD10 in tumor cells (TCs) and to check whether EphB4 is involved in these effects; and to test the possible influence of tumoral PDCD10 on endothelial cells (ECs). To this end, the phenotype of TCs lines and the EphB4 expression/activity were investigated in PDCD10 knockdown (shPDCD10) TCs. The endothelia angiogenesis was studied in HUVECs after treatment with the conditioned media (CM) from shPDCD10-TCs. In present study, we demonstrated that knockdown of PDCD10 in TCs resulted in the activation of shPDCD10-TCs via significant upregulation of EphB4 expression and a remarkable increase in the EphB4 kinase activity. Treatment of shPDCD10-TCs with NVP inhibited the activation of EphB4 kinase, suppressed the aggressive behavior of shPDCD10 TCs in vitro, and hindered tumor growth in PDCD10 knockdown tumor. These findings indicated that the upregulation/activation of EphB4 is involved in the tumor-promoting effect resulted from PDCD10 knockdown. In addition, treatment of HUVECs with CM from shPDCD10-TCs promoted the angiogenesis in vitro. The protein array revealed that the level of 8 of 55 angiogenic factors was significantly upregulated in the CM from the shPDCD10-TCs, which may play crucial roles in stimulation of endothelial angiogenesis. In conclusion, knockdown of PDCD10 activated TCs and promoted tumor growth via significant upregulation of EphB4 expression. Knockdown of tumoral PDCD10 can trigger HUVECs through the increase in release of proangiogenic factors. Therefore, targeting PDCD10 together with its downstream effector EphB4 might be an effective strategy for personalized therapy in GBM patients with PDCD10-deficiency.