Solitary Fibrous Tumor/Hemangiopericytoma Metastasizes Extracranially, Associated with Altered Expression of WNT5A and MMP9.

Solitary fibrous tumor/hemangiopericytoma (SFT/HPC) is a mesenchymal tumor originating from various soft tissues and meninges, which carries the - fusion gene. Meningeal/intracranial SFT/HPCs (SFT/HPC) have a poor clinical outcome with metastatic behavior compared to soft tissue/extracranial SFT/HPCs (SFT/HPC), but the underlying genetic factors are unclear. Differentially expressed genes (DEGs) were analyzed by NanoString nCounter assay using RNA extracted from formalin-fixed paraffin-embedded (FFPE) tissue samples. Additionally, immunohistochemistry (IHC) was performed on 32 cases of SFT/HPC, 18 cases of SFT/HPC, and additional recurrent or metastatic cases to verify the findings. Pathway analysis revealed that the WNT signaling pathway was enriched in SFT/HPC. Analysis of DEGs showed that expression of was lower and that of was higher in SFT/HPC than in SFT/HPC ( = 0.008 and = 0.035, respectively). IHC showed that WNT5A and CD34 expression was high in SFT/HPC ( < 0.001, both), while that of MMP9 was high in SFT/HPC ( = 0.001). Expression of CLDN5 in tumoral vessels was locally decreased in SFT/HPC ( < 0.001). The results suggested that decreased WNT5A expression, together with increased MMP9 expression, in SFT/HPC, may affect vascular tightness and prompt tumor cells to metastasize extracranially.