Aurora-A Promotes Cell-Cycle Progression From Quiescence Through Primary Cilia Disassembly.

Aurora-A (AurA) is a member of the mitotic kinase family and is highly expressed in various tumors. Inhibition of AurA generally leads to fetal mitotic errors. We previously reported that AurA inhibition induces G/G cell cycle arrest in noncancerous cells by promoting the reassembly of primary cilia. However, the mechanisms by which AurA regulates cell cycle progression beyond mitosis remain largely unknown. In this study, we generated noncancerous RPE1 and cancerous HCT116 cell lines expressing endogenous AurA tagged with a minimal auxin-inducible degron (mAID) using CRISPR/Cas9-based gene editing. This system enabled specific and rapid depletion of endogenous AurA protein. By combining this approach with cell synchronization in RPE1 cells, we investigated AurA function specifically in the transition from quiescence to the proliferative cell cycle. Targeted degradation of AurA not only delayed cell cycle progression but also impaired the disassembly of primary cilia at the G/G transition in RPE1 cells. Since this delay in cell cycle progression was rescued by forced deciliation via the knockout of IFT20, AurA facilitates deciliation, which in turn accelerates the transition from quiescence to the proliferative phase of the cell cycle in RPE1 cells. AurA depletion for 4 days increased apoptotic markers in HCT116 cells but not in RPE1 cells. Notably, forced deciliation in RPE1 cells partially enhanced apoptosis induced by AurA depletion. These results suggest that the ability to assemble primary cilia may serve as a protective mechanism against cell death following AurA inhibition.