Serine/Threonine kinase MLK4 determines Mesenchymal identify in glioma stem cells in an NFkB-dependent manner

Activation of NF-kB induces MES trans-differentiation and radio-resistance in glioma stem cells (GSCs), but molecular mechanisms for NF-kB activation in GSCs are currently unknown. Here we report that Mixed Lineage Kinase 4 (MLK4) is overexpressed in MES but not PN GSCs. Silencing MLK4 suppresses self-renewal, motility, tumorigenesis, and radio-resistance of MES GSCs via a loss of the MES signature. MLK4 binds and phosphorylates the NF-κB regulator IKKα, leading to activation of NF-κB signaling in GSCs. MLK4 expression is inversely correlated with patient prognosis in MES, but not PN high-grade gliomas. Collectively, our results uncover MLK4 as an upstream regulator of NF-kB signaling and a potential molecular target for the MES subtype of GBMs. We used microarrays to validate MLK4 target gene expression. GSCs were treated with shNT (control), shMLK4_1. Total RNA was isolated using the Qiagen RNeasy kit(Qiagen).