EZH2 overexpression is associated with aggressive behavior and promotes cell proliferation in CNS WHO grade 3 meningiomas.

Background: Central nervous system (CNS) World Health Organization (WHO) grade 3 meningiomas are aggressive tumors of the CNS whose clinical management is particularly challenging due to the lack of effective systemic treatment options. Recent multiomic studies revealed increasing expression and activity of the histone methyltransferase enhancer of zeste homolog 2 (EZH2) in parallel with the increase in meningioma grade. This study primarily aims to characterize in detail the clinical and molecular correlates of EZH2 expression in grade 3 meningiomas and to investigate its functional role both in vitro and in vivo. Methods: EZH2 expression was correlated with clinical outcome data as well as with the loss of p16 and H3 K27me3, 9p21.3 deletion, and Results: Higher levels of EZH2 overexpression were associated with shorter overall and local progression-free survival and higher proliferative activity in our grade 3 meningioma cohort. Deletion of the 9p21.3 region and loss of H3 K27me3 were related to higher EZH2 expression, while loss of p16 and Conclusions: Our findings demonstrate that EZH2 is functionally relevant in grade 3 meningiomas, primarily through promoting cell proliferation.