beta-catenin, a novel prognostic marker for breast cancer: Its roles in cyclin D1 expression and cancer progression

beta-Catenin can function as an oncogene when it is translocated to the nuc leus, binds to T cell factor or lymphoid enhancer factor family members, an d transactivates its target genes. In this study, we demonstrate that cycli n D1 is one of the targets of beta-catenin in breast cancer cells. Transact ivation of beta-catenin correlated significantly with cyclin D1 expression both in eight breast cell lines in vitro and in 123 patient samples. More i mportantly, we found that high beta-catenin activity significantly correlat ed with poor prognosis of the patients and was a strong and independent pro gnostic factor in breast cancer. Our studies, therefore, indicated that bet a-catenin can be involved in breast cancer formation and/or progression and may serve as a target for breast cancer therapy.