Freeing the brake: Proliferation needs primary cilium to disassemble

Primary cilia are non-motile, microtubule-based, antennae-like organelle that protrude out from the cell surface and perform sensory function or transduce physiological signals in majority of the vertebrate cells. Cilia are assembled on basal bodies that are transformed centrioles. The assembly-disassembly of primary cilia may pose an additional measure on regulating cell cycle in vertebrate cells. While primary cilia are commonly found in differentiated or quiescent cells that are not cycling, disassembly of primary cilia may promote re-entry of these cells into the mitotic cycle, and support proliferation. Many cancer tissues or cancer-derived cells exhibit loss of primary cilia. However, primary cilia may also promote tumorigenesis in some contexts through growth-promoting signalling. This review will shed light on recent advancements of temporal coordination of ciliary disassembly and cell cycle progression, with a focus on how cilia loss may support tumorigenesis in various epithelial cancers.