Lead exposure promotes NF2-wildtype meningioma cell proliferation through the Merlin-Hippo signaling pathway

Lead is a persistent inorganic environmental pollutant with global implication for human health. Among the diseases associated with lead exposure, the damage to the central nervous system has received considerable attention. It has been reported that long-term lead exposure increases the risk of meningioma; however, the underlying mechanism remains poorly understood. Clinical studies have indicated that loss-of-function and mutations in the neurofibromin-2 (NF2) gene play a crucial role in promoting meningioma formation.

The effect of Pb on meningioma were tested in-vitro and in-vivo. Two human meningioma cell lines were used in this study, including NF2-wildtype IOMM-Lee cell and NF2-null CH157-MN cell. Cell viability, cell cycle and cell size were examined after Pb exposure. The expression of Merlin, mammalian sterile 20-like kinases 1 and 2 (MST1/2) and Yes-associated protein (YAP) from these two meningioma cells were analyzed by Western blot. A xenograft mouse model was constructed by subcutaneous injection of IOMM-Lee meningioma cells.

This study demonstrated that treatment with lead induce dose-dependent proliferation in IOMM-Lee cell (with an EC₅₀ value of 19.6 µM). Moreover, IOMM-Lee cell exhibited augmented cell size in conjunction with elevated levels of phosphorylated histone H3, indicative of altered cell cycle progression resulting from lead exposure. However, no significant change was observed in the CH157-MN cell. Additionally, the Merlin-Hippo signaling pathway was inactivated with decreased Merlin and phosphorylation levels of MST1/2 and YAP, leading to increased YAP nuclear translocation in IOMM-Lee cells. However, there was no change in the Merlin-Hippo signaling pathway in CH157-MN cells after lead treatment. The administration of Pb resulted in an acceleration of the subcutaneous IOMM-Lee meningioma xenograft growth in mice.

Overall, the current study elucidates the potential mechanism by which lead exposure promotes the proliferation of meningioma with NF2 expression for the first time.