NEK2-AURKA axis drives ubiquitin-dependent IFT88 degradation to suppress ciliogenesis and promote basal-type bladder cancer

Abstract

Loss of primary cilia is common in cancer, but its relevance to molecular subtypes of muscle-invasive bladder cancer (MIBC) is unclear. Here, we combined transcriptomic and co-expression analyses with experiments in bladder cancer cell lines, human tumor specimens, and xenografts to investigate the basis of cilia loss in basal MIBC. Primary cilia were less frequent in basal than in luminal MIBC. Depletion of IFT88 reduced ciliogenesis and increased cell proliferation and migration. Conversely, IFT88 overexpression restored cilia, delayed the appearance of palpable xenografts, and limited xenograft growth. NEK2 was enriched in basal MIBC, and higher expression in TCGA was associated with shorter disease-free survival. In basal bladder cancer cells, NEK2 knockdown increased IFT88 abundance and cilia formation and reduced proliferation and migration; NEK2 overexpression had the opposite effects. Rescue experiments showed that these effects of NEK2 depended on IFT88. NEK2 interacted with IFT88, increased its ubiquitination, and accelerated its proteasomal turnover. AURKA knockdown reduced IFT88 ubiquitination after NEK2 overexpression and attenuated the associated cilia loss, proliferation, and migration, whereas AURKA overexpression reversed the effects of NEK2 knockdown. In a xenograft experiment, pretreating IFT88-overexpressing cells with the NEK2 inhibitor JH295 produced the greatest reduction in tumor establishment and growth among the four conditions tested. These data identify a NEK2-AURKA-IFT88 pathway that promotes ubiquitin-dependent IFT88 degradation and cilia loss in basal MIBC models, providing a preclinical basis for further testing of NEK2 targeting in cilia-deficient basal MIBC.