Introduction: Primary, non-motile, cilia are microtubule-based organelles that protrude from the cell membrane into the extracellular environment of virtually all nucleated mammalian cells. They function as signalling platforms involved in the transduction of extracellular stimuli and have an important role in cell cycle regulation. Disruption of primary cilia structure and therefore function has been identified in a range of cancers including kidney, breast, pancreatic and prostate, implying a role in tumorigenesis.
Primary cilia disruption is a cardinal feature of clear cell renal cancer; the subtype associated with von Hippel-Lindau (VHL) disease. One of the functions of protein VHL is to maintain the primary cilium by stabilising microtubules. There are no data regarding primary cilia and the other (non-renal) pathologies seen in VHL. We sought to investigate whether primary cilia are disrupted in phaeochromocytomas; both in the context of sporadic and familial (including VHL) cases.
Methods: Tissue/cells: tissue sections and primary cell culture from phaeochromocytomas and adjacent adrenal gland. Cilia detection: dual labelled immunofluorescence was performed against two components of the ciliary axoneme (acetylated α tubulin and Arl13b). Primary cilia incidence and length was quantified from maximum intensity projections generated from confocal Z stacks (n>1000 for incidence, n>100 for length measurements).
Results: Primary cilia structure is disrupted in phaeochromocytomas; both sporadic cases and those occurring in patients with germline mutations. Cilia are shorter and less frequent (P<0.05) in phaeochromocytomas compared to adjacent adrenal gland.
Discussion: Primary cilia structure is disrupted in phaeochromocytomas which may impact on cilia-mediated signalling, dysregulation of which is relevant to phaeochromocytoma pathogenesis.