Breast Cancer Stem Cell Involves Distant Metastasis Through Epithelial-Mesenchymal Transition Induced by Up-Regulating Twist Expression

[Purpose] Breast cancer cells with a CD44+/CD24-phenotype have been suggested to have tumor-initiating properties with stem cell-like. It is not yet known whether CD44/CD24 phenotype up-regulate Twist gene and increase micrometasis risk. [Methods] The MCF7 breast cancer cell line was cultured by mammosphere and implanted into node mice. Double-staining immunohistochemistry was used to quantify CD44 and CD24 expression in cytospin and tissue samples from animal model and 92 cases with breast tumor. Twist gene expression were examined by RT-PCR. [Results] The cells marked with CD44+/CD24-existed in cell line MCF-7. In animal model,the samples from metastasis tissues had more CD44+/CD24-cells and stronger expression for Twist. In human tumor samples,20.7% contained cells with CD44 +/CD24-phenotype. The CD44+/CD24-phenotype was no relationship with estrogen and progesterone receptors as well as HER2(r =0.452) . In the samples from human metastasis tissues,Twist was over-expression. [Conclusions] MCF-7 breast cancer cell line and human cancer tissue exist CD44+/CD24-cells. Breast cancer stem cells involve distant metastasis through up-regulating the Twist expression in animal model.