The data from the Oncomine database suggested that SPP1 expression was significantly high in glioblastoma compared with normal brain tissues but was not significantly high in lower-grade glioma compared with normal brain tissue.
We have previously shown that HSC niche proteins stromal cell-derived factor-1α (SDF-1α), C-X-C chemokine receptor type 4 (CXCR4), osteopontin (OPN), and cathepsin K (CatK) are expressed in hypoxic GSC niches around arterioles in five human glioblastoma samples.
We conclude that OPN is an important player in dedifferentiation of cells during tumor formation, hence its inhibition can be a therapeutic target for glioblastoma.
Based on these observations, we explored the possibility that knocking down OPN expression in glioblastoma cells could exert an anti-tumoral activity using an avian in vivo glioblastoma model that mimics closely human gliobastoma.