CNSC-78. NESPRIN-2 IS UPREGULATED IN GLIOBLASTOMA AND CONTRIBUTES TO TUMOR PROGRESSION

Abstract Glioblastoma is an incurable brain cancer with a median survival time of eight months. One of the most prominent features associated with glioblastoma cells are changes in their nuclei: they are unusually large and have irregular contours, unlike the smooth contours of nuclei in non-neoplastic cells. These nuclear features are used in the clinical diagnosis of glioblastoma, yet the molecular basis for these features or whether they contribute to glioblastoma cell behavior has not been explored. Based on single nucleus transcriptomics, we identified three nuclear envelope genes that were upregulated in proliferative type glioblastoma: SYNE2 (encoding nesprin-2), SUN1 and FHOD3. These proteins are components of the linker of nucleoskeleton and cytoskeleton (LINC) complex that spans the nuclear envelope with outer and inner nuclear membrane proteins, nesprin and Sun family proteins. This mediates force transmission between the nucleus and the cytoskeleton. We confirmed these findings using immunohistochemistry of brain tumor tissue samples. To examine the importance of these proteins in brain tumor progression, we inhibited LINC complex by disrupting Nesprin and Sun connection with KASH dominant negative construct. Also, we knocked down either Nesprin-2 or Sun1/2 in glioblastoma cells. All of these slowed down the growth of brain tumor cells. Furthermore, we knocked down nesprin-2 in two mouse glioblastoma cells lines by shRNA and injected the cells into mouse brains. Compared to mice injected with control cells, both mice injected with either nesprin-2 knockdown cell lines exhibited reduced tumor growth and prolonged survival. These results show that nesprin-2 is a key factor in the progression of glioblastoma and suggest that the LINC complex may be a therapeutic target for the treatment of glioblastoma.