Notch1 Inhibition Alters the CD44hi/CD24lo Population and Reduces the Formation of Brain Metastases from Breast Cancer
Molecular Cancer Research, 2011•AACR
Brain metastasis from breast cancer is an increasingly important clinical problem. Here we
assessed the role of CD44hi/CD24lo cells and pathways that regulate them, in an
experimental model of brain metastasis. Notch signaling (mediated by γ-secretase) has
been shown to contribute to maintenance of the cancer stem cell (CSC) phenotype. Cells
sorted for a reduced stem-like phenotype had a reduced ability to form brain metastases
compared with unsorted or CD44hi/CD24lo cells (P< 0.05; Kruskal–Wallis). To assess the …
assessed the role of CD44hi/CD24lo cells and pathways that regulate them, in an
experimental model of brain metastasis. Notch signaling (mediated by γ-secretase) has
been shown to contribute to maintenance of the cancer stem cell (CSC) phenotype. Cells
sorted for a reduced stem-like phenotype had a reduced ability to form brain metastases
compared with unsorted or CD44hi/CD24lo cells (P< 0.05; Kruskal–Wallis). To assess the …
Abstract
Brain metastasis from breast cancer is an increasingly important clinical problem. Here we assessed the role of CD44hi/CD24lo cells and pathways that regulate them, in an experimental model of brain metastasis. Notch signaling (mediated by γ-secretase) has been shown to contribute to maintenance of the cancer stem cell (CSC) phenotype. Cells sorted for a reduced stem-like phenotype had a reduced ability to form brain metastases compared with unsorted or CD44hi/CD24lo cells (P < 0.05; Kruskal–Wallis). To assess the effect of γ-secretase inhibition, cells were cultured with DAPT and the CD44/CD24 phenotypes quantified. 231-BR cells with a CD44hi/CD24lo phenotype was reduced by about 15% in cells treated with DAPT compared with DMSO-treated or untreated cells (P = 0.001, ANOVA). In vivo, mice treated with DAPT developed significantly fewer micro- and macrometastases compared with vehicle treated or untreated mice (P = 0.011, Kruskal–Wallis). Notch1 knockdown reduced the expression of CD44hi/CD24lo phenotype by about 20%. In vitro, Notch1 shRNA resulted in a reduction in cellular growth at 24, 48, and 72 hours time points (P = 0.033, P = 0.002, and P = 0.009, ANOVA) and about 60% reduction in Matrigel invasion was observed (P < 0.001, ANOVA). Cells transfected with shNotch1 formed significantly fewer macrometastases and micrometastases compared with scrambled shRNA or untransfected cells (P < 0.001; Kruskal–Wallis). These data suggest that the CSC phenotype contributes to the development of brain metastases from breast cancer, and this may arise in part from increased Notch activity. Mol Cancer Res; 9(7); 834–44. ©2011 AACR.
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