Connexin 43 drives glioblastoma cancer stem cell phenotypes through a WNK lysine-deficient protein kinase 1-c-MYC signaling axis

The coordination of cellular processes such as growth and survival relies on communication between cells through gap junctions. Connexin proteins comprise gap junctions and also function to mediate protein-protein interactions and communication with the extracellular space via hemichannels. Despite their essential roles, connexin function in cancer is context dependent, with connexin 43 (Cx43) reported to both promote and suppress tumor growth in glioblastoma, the most common primary malignant brain tumor. Here, we detect primarily intracellular expression of Cx43 in glioblastoma patient-derived cancer stem cells and demonstrate that Cx43 is essential for their survival, self-renewal, and tumor initiation. Mechanistically, Cx43 depletion reduces c-MYC expression through reduced levels of the upstream mediator WNK lysine-deficient protein kinase 1 (WNK1). WNK1 depletion phenocopies Cx43 knockdown and reduces c-MYC expression and tumor initiation. Together, these results define a signaling axis downstream of Cx43 that promotes tumor growth and cancer stem cell phenotypes in glioblastoma.