Research article

Brca1 breast tumors contain distinct CD44⁺/CD24^- and CD133⁺ cells with cancer stem cell characteristics

Mollie H Wright¹ , Anna Maria Calcagno² , Crystal D Salcido¹ , Marisa D Carlson¹ , Suresh V Ambudkar² and Lyuba Varticovski¹

¹  Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, Maryland 20892, USA

²  Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, 9000 Rockville Pike, Bethesda, Maryland 20892, USA

author email corresponding author email

Breast Cancer Research 2008, 10:R10doi:10.1186/bcr1855

Published:	1 February 2008

See related editorial by Wicha, http://breast-cancer-research.com/content/10/2/105

Abstract

Introduction

Whether cancer stem cells occur in BRCA1-associated breast cancer and contribute to therapeutic response is not known.

Methods

We generated and characterized 16 cell lines from five distinct Brca1deficient mouse mammary tumors with respect to their cancer stem cell characteristics.

Results

All cell lines derived from one tumor included increased numbers of CD44⁺/CD24^- cells, which were previously identified as human breast cancer stem cells. All cell lines derived from another mammary tumor exhibited low levels of CD44⁺/CD24^- cells, but they harbored 2% to 5.9% CD133⁺ cells, which were previously associated with cancer stem cells in other human and murine tumors. When plated in the absence of attachment without presorting, only those cell lines that were enriched in either stem cell marker formed spheroids, which were further enriched in cells expressing the respective cancer stem cell marker. In contrast, cells sorted for CD44⁺/CD24^- or CD133⁺ markers lost their stem cell phenotype when cultured in monolayers. As few as 50 to 100 CD44⁺/CD24^- or CD133⁺ sorted cells rapidly formed tumors in nonobese diabetic/severe combined immunodeficient mice, whereas 50-fold to 100-fold higher numbers of parental or stem cell depleted cells were required to form few, slow-growing tumors. Expression of stem cell associated genes, including Oct4, Notch1, Aldh1, Fgfr1, and Sox1, was increased in CD44⁺/CD24^- and CD133⁺ cells. In addition, cells sorted for cancer stem cell markers and spheroid-forming cells were significantly more resistant to DNA-damaging drugs than were parental or stem cell depleted populations, and they were sensitized to the drugs by the heat shock protein-90 inhibitor 17-DMAG (17-dimethylaminoethylamino-17-demethoxygeldanamycin hydrochloride).

Conclusion

Brca1-deficient mouse mammary tumors harbor heterogeneous cancer stem cell populations, and CD44⁺/CD24^- cells represent a population that correlates with human breast cancer stem cells.