Mitotic kinase expression and colorectal cancer progression.

Loss of chromosomal integrity as well as genomic stability is considered to act as a driving force during the processes of tumorigenesis and tumor progression (1–3). Recently, two kinase genes involved in mitosis, the genes for aurora and IPL1l ike midbodyassociated protein kinase-1 (4,5) [AIM1, registered in UniGene and also known as aurora1 (6) and ARK2 (7)] and for serine/threonine kinase-6 [STK6, also known as BTAK/STK15 (8,9), Aik (10), aurora2 (6), and ARK1 (7)], which are related to Ipl1 in Saccharomyces cerevisiae and aurora in Drosophila, have been found to be expressed at high levels in cancer cells (5,6,9). These genes encode serine/threonine protein kinases whose functional roles during chromosomal segregation processes in mitosis have been examined (4–10). In transfected human cells in vitro, the overexpression of either AIM-1 or STK6 causes chromosomal abnormalities, which are presumably attributed to a defect in the mitotic processes (5,9). Thus, these genes may be involved in the loss of chromosomal integrity during human cancer development via mitotic subversion.