Overexpression of Aurora A by loss of CHFR gene expression increases the growth and survival of HTLV-1-infected T cells through enhanced NF-κB activity

Human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent for adult T-cell leukemia (ATL). Aurora A, a mitotic checkpoint protein, is overexpressed in human cancer cells. The cell cycle-dependent turnover of Aurora A is regulated by E3 ubiquitin ligases such as checkpoint with fork head-associated and ring finger (CHFR). Here, we found overexpression of Aurora A protein in HTLV-1-infected T-cell lines and primary ATL cells. The expression of CHFR mRNA was reduced in these cells by abnormal methylation of CHFR promoter region. Knockdown of Aurora A using small interfering RNA suppressed the growth of HTLV-1-infected T-cell line. Transfection of Aurora A expression plasmid enhanced Tax-induced nuclear factor-κB (NF-κB) reporter activity. Transfection of CHFR expression plasmid into an HTLV-1-infected T-cell line reduced cell growth, Aurora A protein level and constitutive NF-κB reporter activity. Aurora kinase inhibitor suppressed the growth and survival of HTLV-1-infected T-cell lines and primary ATL cells. It also reduced constitutive NF-κB activity in an HTLV-1-infected T-cell line by reducing IκB kinase κ phosphorylation and the expression of antiapoptotic protein survivin. Our results suggested that loss of CHFR expression resulted to accumulation of Aurora A, which increased NF-κB activity. These findings highlight the critical role of Aurora A in HTLV-1-infected T cells, making this molecule a potentially suitable target for future therapies for ATL.