Aurora-a contributes to radioresistance by increasing NF-kappaB DNA binding

Aurora-A, a serine/threonine kinase that is overexpressed in certain human cancer cell lines, plays an important role in mitotic progression. Aurora-A has also been reported to be involved in the activation of nuclear factor kappa B (NF-kappaB). The purpose of the present study was to identify the role of Aurora-A in the radiation-induced activation pathway of NF-kappaB. Wild-type and Aurora-A knockdown (Aurora-A(KD)) HeLa cells were irradiated with 4 Gy of gamma rays and the EMSA, luciferase reporter gene assay and immunoblot analysis were performed. The siRNA-based gene knockdown and overexpression system was adopted to elucidate the role of Aurora-A in radiation-induced NF-kappaB pathway activation. The clonogenic survival study indicated that Aurora-A(KD) cells and the wild-type cells transfected with Aurora-A siRNA or RelA/p65 siRNA were more radiosensitive than the wild-type cells. In both the wild-type and Aurora-A(KD) cells, radiation caused IkappaB kinase-mediated phosphorylation, degradation of IkappaBalpha and phosphorylation of RelA/p65. The nuclear translocation of RelA/p65 was also similar in the wild-type and Aurora-A(KD) cells. However, RelA/p65-DNA binding was markedly suppressed in Aurora-A(KD) cells compared to that in wild-type cells. It was concluded that Aurora-A enhances the binding of NF-kappaB to DNA, thereby increasing the gene transcription by NF-kappaB and decreasing the radiosensitivity of the cells.