SPDR-5 ESTABLISHMENT OF A CONTINUOUS CULTURE METHOD FOR MENINGIOMAS AND THE EFFECTS OF THE GREM2-BMP SIGNALLING PATHWAY ON PROLIFERATION AND ANGIOGENESIS

PURPOSE: Meningiomas are closely related to osteogenesis, including calcification and hyperostosis at the site of attachment. Signaling pathways involved in tumor formation and extension of meningioma have not yet been elucidated. Treatment options include surgical removal and radiotherapy, but there are no reports of effective drug treatment. This is due to the difficulty of culturing non-malignant meningiomas, which has made basic experiments difficult. In this study, we established a continuous culture method for meningiomas and investigated the signaling pathways involved in meningioma growth. METHODS: 67 consecutive cases of meningiomas treated in our department for three years from Apr, 2019 to March, 2022. Primary continuous culture was performed by modifying the conditional reprogramming (CR) method. Sixty-four cases were studied, excluding three cases in which culture was abandoned due to contamination. The mean age was 62.6 years, Grade 3 (6%), Grade 2 (14%) and Grade 1 (80%). These were used to observe morphology, proliferation and genetic analysis involved in angiogenesis. RESULTS: 1) Sustained culture lasted an average of 150 days with no differences between Grades; 2) Inhibition of BMP signaling involved in osteogenesis suppressed cell proliferation regardless of Grade, and the IC50 of the inhibitor suggested the involvement of the receptor ALK3; 3) We identified GREM2 as upstream regulator of BMP signals 4) GREM2 is highly expressed in menigotherial meningiomas and immunostaining showed strong expression around whole and calcified areas. 5) GREM2 expression is negatively correlated with MIB-1 L.I., so overexpression of GREM2 in malignant meningioma cells decreased ID, which is involved in proliferation downstream of BMP signaling, and increased angiogenic factor VEGFA, which is involved in proliferation. CONCLUSION: A method for the continuous culture of meningiomas was established. Using this experimental system, we identified the involvement of the GREM2-BMP signaling pathway in proliferation and angiogenesis in meningiomas as well as calcification.