To elucidate the molecular mechanisms of mammary
carcinogenesis and discover novel therapeutic targets for
breast cancer, we previously carried out genome-wide expression profile analysis of 81
breast cancer cases by means of
cDNA microarray coupled with
laser microbeam microdissection of
cancer cells. Among the dozens of transactivated genes, in the present study we focused on the functional significance of
kinesin family member 2C (KIF2C)/mitotic centromere-associated
kinesin (MCAK) in the growth of
breast cancer cells. Northern blot and immunohistochemical analyses confirmed KIF2C/MCAK overexpression in
breast cancer cells, and showed that it is expressed at undetectable levels in normal human tissues except the testis, suggesting KIF2C/MCAK to be a
cancer-testis antigen. Western blot analysis using
breast cancer cell lines revealed a significant increase in the endogenous KIF2C/MCAK
protein level and its phosphorylation in G(2)/M phase. Treatment of
breast cancer cells with
small interfering RNA against KIF2C/MCAK effectively suppressed KIF2C/MCAK expression and inhibited the growth of the
breast cancer cell lines T47D and HBC5. In addition, we found that KIF2C/MCAK expression was significantly suppressed by ectopic introduction of p53. These findings suggest that overexpression of KIF2C/MCAK might be involved in breast
carcinogenesis and is a promising therapeutic target for breast
cancers.