ENAH regulates survival, self-renewal, and migration of patient-derived primary glioblastoma neurospheres

Abstract

Abstract Purpose: Glioblastoma (GBM) is the most common primary malignant brain tumor in adults. Despite standard treatment, the median survival of GBM patients is only 15 months. Enabled homolog (ENAH) is a member of the Ena/VASP protein family and regulates actin dynamics. ENAH has been implicated in a wide variety of cancers. But its role in GBM is less explored. We sought to understand the role of ENAH in GBM tumor biology. Methods: Expression of ENAH in GBM tumor specimens was assessed by immunohistochemistry (IHC). Patient-derived primary GBM neurosphere (GBMNS) models transfected with scrambled or target-specific ENAH siRNA were subjected to viability, apoptosis, neurosphere formation, western blot, transwell migration, and F-actin immunofluorescence assays. In vivo, we implanted mice with ENAH-intact and -depleted GBMNS intracranially and analyzed survival duration. Results: IHC analysis suggests that the expression of ENAH is higher in GBM tumor samples compared to low-grade gliomas and normal brain tissues. In vitro, ENAH knockdown reduced the viability of GBMNS by more than 50% by inducing apoptosis and significantly decreased the self-renewal ability. Also, we show that depletion of ENAH reduced the migration of GBMNS and demonstrated that ENAH is required for actin polymerization. Further, the expression of AXL-GAS6 was downregulated with the knockdown of ENAH. In vivo, transient depletion of ENAH significantly increased the survival of tumor-bearing mice. Conclusions: Our results suggest that ENAH is required for survival, self-renewal, and migration of GBMNS. Hence, ENAH can serve as a potential target for GBM therapy.