Centrosome amplification in adult T‐cell leukemia and human T‐cell leukemia virus type 1 Tax‐induced human T cells

Centrosomes play pivotal roles in cell polarity, regulation of the cell cycle and chromosomal segregation. Centrosome amplification was recently described as a possible cause of aneuploidy in certain solid tumors and leukemias. ATL is a T‐cell malignancy caused by HTLV‐1. Although the precise mechanism of cell transformation is unclear, the HTLV‐1‐encoded protein, Tax, is thought to play a crucial role in leukemogenesis. Here we demonstrate that lymphocytes isolated from patients with ATL show centrosome amplification and that a human T cell line shows centrosome amplification after induction of Tax, which was suppressed by CDK inhibitors. Micronuclei formation was also observed after centrosome amplification in Tax‐induced human T cells. These findings suggest that Tax deregulates CDK activity and induces centrosome amplification, which might be associated with cellular transformation by HTLV‐1 and chromosomal instability in HTLV‐1‐infected human T cells. ( Cancer Sci 2006; 97: 836–841)