Breaking down glioma primary cilia disassembly.

While many postmitotic cells in the body harbor cilia, certain aggressive cancers such as glioblastoma (GBM) display low frequencies of cells harboring a primary cilium. Ciliated GBM cells that plan to multiply have to disassemble their cilium in order for centrioles to duplicate and re-purpose for mitosis. Little is known about the molecular mechanisms underlying cilia disassembly in GBM, or whether this may represent a driving factor in disease onset, progression, or recurrence. In many cell types, ciliary disassembly is thought to be orchestrated by the aurora kinase A (AURKA) and histone deacetylase 6 (HDAC6) signaling axis. These molecules are often overexpressed in GBM, perhaps owing to the less frequent observation of ciliated GBM cells. Here, we review regulators of the core pathway, and discuss recent studies attempting to inhibit AURKA and HDAC6 in patient and mouse models of GBM and resulting effects on cilia. In the face of potent inhibitors, GBM cells appear to engage pathways independent of the core axis to promote cilia disassembly and/or engage other forms of modified axonemal tubulin to ensure persistence of cilia on GBM cells. GBMs upregulate a host of proteins implicated to drive cilia disassembly. Thus, clarifying these alternate mechanisms may be important as the roles of cilia in tumor formation and propagation, angiogenesis, and treatment resistance are increasingly reported. A deeper understanding of the role of cilia in these hallmarks of glioma may hold clues to the high recurrence rate of GBM.