Role of IKKalpha in skin tumorigenesis. The inflammatory microenvironment promotes skin tumorigenesis. However, the mechanisms of how cells protect themselves from inflammatory signals have yet to be revealed. Downregulation of IKKalpha promotes skin tumor progression from papillomas to squamous cell carcinomas, which is frequently accompanied by genomic instability, including aneuploid chromosomes and extra centrosomes. In this study, we found that IKKalpha promoted oligomerization of nucleophosmin (NPM), a negative centrosome duplication regulator, which further enhanced NPM and centrosome association, inhibited centrosome amplification, and maintained genome integrity. Levels of NPM hexamers and IKKalpha were conversely associated with skin tumor progression. Importantly, pro-inflammatory cytokine-induced IKKalpha activation promoted the formation of NPM oligomers and reduced centrosome numbers in mouse and human cells, whereas kinase-dead IKKalpha blocked this connection. Therefore, our findings suggest a previously unknown mechanism in which an IKKalpha-NPM axis may use the inflammatory signal to suppress centrosome amplification, promote genomic integrity, and prevent tumor progression.
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