MATERIAL and METHODS: In an immunohistochemistry experiment, three expert pathologists examined 100 meningioma slides stained for HIF1?, CD133, and CD44 antibodies. Statistical analyses were performed using the SPSS 23 Statistics packet program. P values <0.05 were statistically significant.

RESULTS: HIF1? staining was correlated with high grade (Grade 2) meningioma. Cytoplasmic staining was negatively correlated with meningioma grade. High grade meningioma was positive for nuclear HIF1? and showed increased cytoplasmic expression of CD44 and CD133.

CONCLUSION: In accordance with previous studies, the level of hypoxia and HIF1? were correlated with meningioma grade. Furthermore, expression of HIF1? was correlated with expression of CD133 and CD44, which are cancer stem cell surface markers, as well as with meningioma grade. In light of these data, new treatment modalities related to CD44 and CD133 stem cell markers and to HIF1? may be developed. Keywords : Hypoxia, HIF1?, CD133, CD44, Cancer stem cell, Meningioma