TY - JOUR
T1 - Prolonged drug selection of breast cancer cells and enrichment of cancer stem cell characteristics
AU - Calcagno, Anna Maria
AU - Salcido, Crystal D.
AU - Gillet, Jean Pierre
AU - Wu, Chung Pu
AU - Fostel, Jennifer M.
AU - Mumau, Melanie D.
AU - Gottesman, Michael M.
AU - Varticovski, Lyuba
AU - Ambudkar, Suresh V.
N1 - Funding Information:
This research was supported by the Intramural Research Program of the National Institutes of Health (NIH), National Cancer Institute, Center for Cancer Research. A.M.C. was supported by the NIGMS Pharmacology Research Associate (PRAT) Program. J.F. was supported by the Intramural Research Program of the NIH and National Institutes of Environmental Health Sciences, contract HHSN273200700046U.
PY - 2010/11/3
Y1 - 2010/11/3
N2 - BackgroundCancer stem cells are presumed to have virtually unlimited proliferative and self-renewal abilities and to be highly resistant to chemotherapy, a feature that is associated with overexpression of ATP-binding cassette transporters. We investigated whether prolonged continuous selection of cells for drug resistance enriches cultures for cancer stem-like cells.MethodsCancer stem cells were defined as CD44+/CD24- cells that could self-renew (ie, generate cells with the tumorigenic CD44+/CD24- phenotype), differentiate, invade, and form tumors in vivo. We used doxorubicin-selected MCF-7/ADR cells, weakly tumorigenic parental MCF-7 cells, and MCF-7/MDR, an MCF-7 subline with forced expression of ABCB1 protein. Cells were examined for cell surface markers and side-population fractions by microarray and flow cytometry, with in vitro invasion assays, and for ability to form mammospheres. Xenograft tumors were generated in mice to examine tumorigenicity (n = 52). The mRNA expression of multidrug resistance genes was examined in putative cancer stem cells and pathway analysis of statistically significantly differentially expressed genes was performed. All statistical tests were two-sided. ResultsPathway analysis showed that MCF-7/ADR cells express mRNAs from ABCB1 and other genes also found in breast cancer stem cells (eg, CD44, TGFB1, and SNAI1). MCF-7/ADR cells were highly invasive, formed mammospheres, and were tumorigenic in mice. In contrast to parental MCF-7 cells, more than 30% of MCF-7/ADR cells had a CD44+/CD24- phenotype, could self-renew, and differentiate (ie, produce CD44+/CD24- and CD44+/CD24+ cells) and overexpressed various multidrug resistance-linked genes (including ABCB1, CCNE1, and MMP9). MCF-7/ADR cells were statistically significantly more invasive in Matrigel than parental MCF-7 cells (MCF-7 cells = 0.82 cell per field and MCF-7/ADR = 7.51 cells per field, difference = 6.69 cells per field, 95% confidence interval = 4.82 to 8.55 cells per field, P <. 001). No enrichment in the CD44+/CD24- or CD133+ population was detected in MCF-7/MDR.ConclusionThe cell population with cancer stem cell characteristics increased after prolonged continuous selection for doxorubicin resistance.
AB - BackgroundCancer stem cells are presumed to have virtually unlimited proliferative and self-renewal abilities and to be highly resistant to chemotherapy, a feature that is associated with overexpression of ATP-binding cassette transporters. We investigated whether prolonged continuous selection of cells for drug resistance enriches cultures for cancer stem-like cells.MethodsCancer stem cells were defined as CD44+/CD24- cells that could self-renew (ie, generate cells with the tumorigenic CD44+/CD24- phenotype), differentiate, invade, and form tumors in vivo. We used doxorubicin-selected MCF-7/ADR cells, weakly tumorigenic parental MCF-7 cells, and MCF-7/MDR, an MCF-7 subline with forced expression of ABCB1 protein. Cells were examined for cell surface markers and side-population fractions by microarray and flow cytometry, with in vitro invasion assays, and for ability to form mammospheres. Xenograft tumors were generated in mice to examine tumorigenicity (n = 52). The mRNA expression of multidrug resistance genes was examined in putative cancer stem cells and pathway analysis of statistically significantly differentially expressed genes was performed. All statistical tests were two-sided. ResultsPathway analysis showed that MCF-7/ADR cells express mRNAs from ABCB1 and other genes also found in breast cancer stem cells (eg, CD44, TGFB1, and SNAI1). MCF-7/ADR cells were highly invasive, formed mammospheres, and were tumorigenic in mice. In contrast to parental MCF-7 cells, more than 30% of MCF-7/ADR cells had a CD44+/CD24- phenotype, could self-renew, and differentiate (ie, produce CD44+/CD24- and CD44+/CD24+ cells) and overexpressed various multidrug resistance-linked genes (including ABCB1, CCNE1, and MMP9). MCF-7/ADR cells were statistically significantly more invasive in Matrigel than parental MCF-7 cells (MCF-7 cells = 0.82 cell per field and MCF-7/ADR = 7.51 cells per field, difference = 6.69 cells per field, 95% confidence interval = 4.82 to 8.55 cells per field, P <. 001). No enrichment in the CD44+/CD24- or CD133+ population was detected in MCF-7/MDR.ConclusionThe cell population with cancer stem cell characteristics increased after prolonged continuous selection for doxorubicin resistance.
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U2 - 10.1093/jnci/djq361
DO - 10.1093/jnci/djq361
M3 - Article
C2 - 20935265
AN - SCOPUS:78149306403
SN - 0027-8874
VL - 102
SP - 1637
EP - 1652
JO - Journal of the National Cancer Institute
JF - Journal of the National Cancer Institute
IS - 21
ER -