Centrosomal kinase AIK1 is overexpressed in invasive ductal carcinoma of the breast

A centrosomal serine/threonine kinase, AIK1(3)/ breast tumor amplified kina se/aurora2, which was recently identified as an oncogene, shows high amino acid identity with chromosome segregation kinases, fly Aurora, and yeast Ip l1. Immunohistochemical analyses of invasive ductal adenocarcinomas of the breast revealed that overexpression of AIK1 was observed in 94% of the case s, irrespective of the histopathological type, whereas the protein was not detected in normal ductal and lobular cells. Benign breast lesions includin g fibrocystic disease and fibroadenoma (epithelial components) displayed we akly detectable AIK1 expression in part of the lesions. This is the first i mmunohistochemical report of AIK1 expression in primary human breast carcin omas. Although the physiological function(s) of AIK1 kinase during cell div ision remains to be determined, the markedly high positivity of AIK1 staini ng in the cancer lesions suggested a possible involvement of its overexpres sion in the tumorigenesis of some of breast cancer cells.