CS-20 * TRANSCRIPTIONAL CONTROL OF THE OSMOTIC ENGINE BY TEAD4 POTENTIATES INVASION AND CONFERS POOR PROGNOSIS IN GLIOBLASTOMA

Abstract

Glioblastomas are characterized by their ability to disseminate into the local brain parenchyma; thus, confounding surgical excision and radiotherapy. Hence, it is imperative to identify and decipher the signaling networks that drive invasion. Glioblastoma cells utilize molecular transporters at both their leading (inward facing) and lagging (outward facing) edge to modulate cell volume and invade the confined microenvironment of the brain. These transporters include solute transporters as well as the aquaporins, and collectively behave as an osmotic engine for cellular invasion. However, the transcriptional regulators of these transporters have not been fully identified. Here, we report that TEAD4, a transcription factor implicated in neural development, is a potent regulator of the osmotic engine through transcriptional control of solute and water transporters. In particular, our data demonstrates that loss of TEAD4 decreases glioblastoma cells ability to migrate and invade through small pores (Boyden chamber and Matrigel transwell, respectively) mimicking the confined microenvironment of the brain (p < 0.05). Additionally, we uncover the role of TEAD4 in regulating members of the Na + /H+ exchanger, chloride co-transporter and aquaporin families, as well as the volume regulated anion channel to enable water permeation (p < 0.05). Apart from regulating cell dispersal, our data also shows that TEAD4 regulates glioblastoma proliferation (p < 0.05). Using the TCGA and REMBRANDT datasets, we observed TEAD4 is selectively overexpressed and hyperactive in glioblastomas compared to non-cancer cortex and lower grade gliomas (p < 0.05). Furthermore, we found that patients with elevated TEAD4 expression have a significantly shorter progression free survival and overall survival (p < 0.05). Taken together, our results show that TEAD4 is a potent regulator of cell dispersal through transcriptional control of the osmotic engine and has relevance to clinical outcomes of glioblastoma patients. Hence, TEAD4 may be a selective and potent therapeutic target that warrants further exploration.