Abstract 2519: A novel role for brachyury as a key regulator of sonic hedgehog signaling (Shh) and maintenance of stemness in gliomas

Glioblastomas are the most common and aggressive form of adult primary brain tumors and are associated with a dismal prognosis. Accumulating evidences suggest that a subset of therapy-resistant cancer stem cells are responsible for recurrence in tumors targeting which may help in gliomas. We identified a significant overexpression of Brachyury (T-box transcription factor) in correlation with glioma histological grade when compared to non-tumor brain controls, with the highest expression being in grade IV gliomas. We also observed increased expression of Brachyury in several glioma cell lines and stem cells (GSCs) when compared to normal human astrocytes. Serum-induced differentiation of GSCs resulted in loss of Brachyury expression along with decreased stem-cell marker levels in these cells, which prompted us to study the potential role of Brachyury in glioma stemness and to delineate the underlying signaling mechanisms. Specific shRNA-mediated knockdown of Brachyury significantly decreased proliferation, migration and invasion in glioma cell lines. Brachyury suppression led to inhibition of sphere formation of GSCs and decreased stem cells marker expression including CD133, nestin and Nanog. Brachyury knockdown also inhibited the activation of sonic hedgehog (Shh) signaling and decreased Gli1 levels in these cells. On the other hand, stable overexpression of Brachyury resulted in the activation of Shh pathway and elevated stem cell marker expression in GSCs. Based on these in vitro findings, our future studies will be focused on determining the role of Brachyury in orthotopic tumor growth in vivo. In summary, our data reveals a novel role for Brachyury in the regulation of tumor invasiveness and stemness, and indicates a potential for therapeutic targeting of Brachyury in patients with gliomas. Citation Format: Divya Kesanakurti, Alessandro Canella, Jihong Xu, Vinay K. Puduvalli. A novel role for brachyury as a key regulator of sonic hedgehog signaling (Shh) and maintenance of stemness in gliomas. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2519.