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. Gap junction intercellular communication is driven by connexin proteins, which also 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 expression of Cx43 in glioblastoma patient-derived cancer stem cells and demonstrate that Cx43 is essential for their survival and self-renewal. Mechanistically, depletion of Cx43 reduces c-MYC expression through reduced levels of the upstream mediator WNK lysine-deficient protein kinase 1 (WNK1). Depletion of WNK1 phenocopies Cx43 knockdown and reduces MYC expression and tumor growth. Together, these results define a novel signaling axis downstream of Cx43 that promotes tumor growth and cancer stem cell phenotypes in glioblastoma. To establish the functional effects of Cx43 and WNK1 in glioblastoma cells, we reduced expression of Cx43 or WNK1 in DI318 glioblastoma patient xenograft model cells using shRNA.