Intrinsic resistance of tumorigenic breast cancer cells to chemotherapy.

BACKGROUND Tumorigenic breast cancer cells that express high levels of CD44 and low or undetectable levels of CD24 (CD44(>)/CD24(>/low)) may be resistant to chemotherapy and therefore responsible for cancer relapse. These tumorigenic cancer cells can be isolated from breast cancer biopsies and propagated as mammospheres in vitro. In this study, we aimed to test directly in human breast cancers the effect of conventional chemotherapy or lapatinib (an epidermal growth factor receptor [EGFR]/HER2 pathway inhibitor) on this tumorigenic CD44(>) and CD24(>/low) cell population. METHODS Paired breast cancer core biopsies were obtained from patients with primary breast cancer before and after 12 weeks of treatment with neoadjuvant chemotherapy (n = 31) or, for patients with HER2-positive tumors, before and after 6 weeks of treatment with the EGFR/HER2 inhibitor lapatinib (n = 21). Single-cell suspensions established from these biopsies were stained with antibodies against CD24, CD44, and lineage markers and analyzed by flow cytometry. The potential of cells from biopsy samples taken before and after treatment to form mammospheres in culture was compared. All statistical tests were two-sided. RESULTS Chemotherapy treatment increased the percentage of CD44(>)/CD24(>/low) cells (mean at baseline vs 12 weeks, 4.7%, 95% confidence interval [CI] = 3.5% to 5.9%, vs 13.6%, 95% CI = 10.9% to 16.3%; P < .001) and increased mammosphere formation efficiency (MSFE) (mean at baseline vs 12 weeks, 13.3%, 95% CI = 6.0% to 20.6%, vs 53.2%, 95% CI = 42.4% to 64.0%; P < .001). Conversely, lapatinib treatment of patients with HER2-positive tumors led to a non-statistically significant decrease in the percentage of CD44(>)/CD24(>/low) cells (mean at baseline vs 6 weeks, 10.0%, 95% CI = 7.2% to 12.8%, vs 7.5%, 95% CI = 4.1% to 10.9%) and a statistically non-significant decrease in MSFE (mean at baseline vs 6 weeks, 16.1%, 95% CI = 8.7% to 23.5%, vs 10.8%, 95% CI = 4.0% to 17.6%). CONCLUSION These studies provide clinical evidence for a subpopulation of chemotherapy-resistant breast cancer-initiating cells. Lapatinib did not lead to an increase in these tumorigenic cells, and, in combination with conventional therapy, specific pathway inhibitors may provide a therapeutic strategy for eliminating these cells to decrease recurrence and improve long-term survival.

[1]  Gilbert H. Smith,et al.  Stem cells and mammary cancer in mice , 2007, Stem Cell Reviews.

[2]  D. Wickerham,et al.  Effect of preoperative chemotherapy on local-regional disease in women with operable breast cancer: findings from National Surgical Adjuvant Breast and Bowel Project B-18. , 1997, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[3]  Richard J. Jones,et al.  Cancer stem cells: are we missing the target? , 2004, Journal of the National Cancer Institute.

[4]  D. Medina,et al.  A new approach to mammary tumorigenesis in rodents , 1969, Cancer.

[5]  E. Winer,et al.  Predictors of Resistance to Preoperative Trastuzumab and Vinorelbine for HER2-Positive Early Breast Cancer , 2007, Clinical Cancer Research.

[6]  Mike Clarke,et al.  Polychemotherapy for early breast cancer: an overview of the randomised trials , 1998, The Lancet.

[7]  Michael F. Clarke,et al.  Erratum: Prospective identification of tumorigenic breast cancer cells (Proceedings of the National Academy of Sciences of the United States of America (April 1, 2003) 7:100 (3983-3988)) , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[8]  Danila Coradini,et al.  Isolation and in vitro propagation of tumorigenic breast cancer cells with stem/progenitor cell properties. , 2005, Cancer research.

[9]  G. Dontu,et al.  Stem cells in normal breast development and breast cancer , 2003, Breast Cancer Research.

[10]  M. Dowsett,et al.  Trastuzumab after adjuvant chemotherapy in HER2-positive breast cancer. , 2005, The New England journal of medicine.

[11]  Jacob Cohen.  Statistical Power Analysis for the Behavioral Sciences , 1969, The SAGE Encyclopedia of Research Design.

[12]  Fariba Behbod,et al.  Correction for Woodward et al., WNT/β-catenin mediates radiation resistance of mouse mammary progenitor cells , 2007, Proceedings of the National Academy of Sciences.

[13]  S. Hilsenbeck,et al.  Neoadjuvant trastuzumab induces apoptosis in primary breast cancers , 2005, Nature Clinical Practice Oncology.

[14]  S. Hilsenbeck,et al.  Neoadjuvant trastuzumab and docetaxel in breast cancer: preliminary results. , 2003, Clinical breast cancer.

[15]  M. Frotscher,et al.  Defining the actual sensitivity and specificity of the neurosphere assay in stem cell biology , 2006, Nature Methods.

[16]  Syed Mohsin,et al.  Patterns of resistance and incomplete response to docetaxel by gene expression profiling in breast cancer patients. , 2005, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[17]  G. Dontu,et al.  Role of Notch signaling in cell-fate determination of human mammary stem/progenitor cells , 2004, Breast Cancer Research.

[18]  Neoadjuvant Trastuzumab Induces Apoptosis in Primary Breast Cancers , 2005 .

[19]  N. Anderson,et al.  Novel cell culture technique for primary ductal carcinoma in situ: role of Notch and epidermal growth factor receptor signaling pathways. , 2007, Journal of the National Cancer Institute.

[20]  D. Allred,et al.  Prognostic and predictive factors in breast cancer by immunohistochemical analysis. , 1998, Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc.

[21]  H. Li,et al.  Highly purified CD44+ prostate cancer cells from xenograft human tumors are enriched in tumorigenic and metastatic progenitor cells , 2006, Oncogene.

[22]  G. Hortobagyi,et al.  Residual metastatic axillary lymph nodes following neoadjuvant chemotherapy predict disease-free survival in patients with locally advanced breast cancer. , 1998, American journal of surgery.

[23]  Brent A Reynolds,et al.  Neural stem cells and neurospheres—re-evaluating the relationship , 2005, Nature Methods.

[24]  G. Dontu,et al.  Stem cells in normal breast development and breast cancer , 2003, Breast Cancer Research.

[25]  Frank Pajonk,et al.  The response of CD24(-/low)/CD44+ breast cancer-initiating cells to radiation. , 2006, Journal of the National Cancer Institute.

[26]  Gilbert H. Smith,et al.  Label-retaining epithelial cells in mouse mammary gland divide asymmetrically and retain their template DNA strands , 2005, Development.

[27]  G. Dontu,et al.  In vitro propagation and transcriptional profiling of human mammary stem/progenitor cells. , 2003, Genes & development.

[28]  G. Dontu,et al.  Hedgehog signaling and Bmi-1 regulate self-renewal of normal and malignant human mammary stem cells. , 2006, Cancer research.

[29]  M. Berger,et al.  Lapatinib plus capecitabine for HER2-positive advanced breast cancer. , 2006, The New England journal of medicine.

[30]  S. Morrison,et al.  Prospective identification of tumorigenic breast cancer cells , 2003, Proceedings of the National Academy of Sciences of the United States of America.