Cilengitide targets pediatric glioma and neuroblastoma cells through cell detachment and anoikis induction.

The prognosis of children with high-grade glioma or high-risk neuroblastoma remains poor. Cilengitide is a selective antagonist of αvß3 and αvß5 integrins, which are involved in tumor growth and development of metastasis. We have evaluated the effects of cilengitide on pediatric glioma and neuroblastoma cell lines for the first time. Expression levels of αvß3 and αvß5 were determined by flow cytometry in three neuroblastoma and five pediatric glioma cell lines compared with adult U87-MG before and after irradiation. Cell detachment, cytotoxicity, and cell growth under nonadhesive conditions were measured using the MTS assay. Cell death and apoptosis were assessed by annexin-V/propidium iodide staining. The varying αvß3 and αvß5 expression levels were unrelated to tumor grade. Irrespective of the αvß5 expression level, the pediatric cells expressing αvß3 were dose dependently sensitive to cilengitide. UW479 cells expressed only αvß5 integrin and were not sensitive to cilengitide, suggesting that cilengitide's action largely depends on αvß3 inhibition. Cell detachment resulted in a higher cytotoxicity in pediatric glioma compared with U87-MG cells, which seem able to grow despite the significant cilengitide-induced cell detachment. Growth kinetics on polyHEMA showed that only pediatric glioma cells were sensitive to anoikis and so died after cilengitide-induced detachment. Furthermore, irradiation of glioma cells increased αvß3 expression slightly but not cilengitide sensitivity. Cilengitide's action on glioma and neuroblastoma cells appears to be dependent on αvß3 expression and sensitivity to anoikis. Cilengitide is able to target pediatric glioma and neuroblastoma cells in vitro directly and efficiently. Tumor context could validate these promising observations.