Experimental and clinical research on endocrine therapy and chemotherapy for a subset of CD44＋CD24－/low cells of estrogen receptor-positive breast cancer

Objective: To investigate the influence of endocrine therapy and chemotherapy on a subset of CD44＋CD24－/low cells of estrogen receptor (ER)-positive breast cancer. Methods: Breast cancer MCF-7 cells were treated with estradiol (E2) of three concentrations, E2 plus tamoxifen (TAM), and docetaxel, paclitaxel (PTX), epirubicin (EPI) and 5-fluorouracil (5-Fu) of working concentration, respectively. The proportion of CD44＋CD24－/low cells in each drug-treated group and the proportion of CD45－CD44＋CD24－/low cells in peripheral blood of patients with ER＋ metastatic breast cancer (MBC) before and after chemotherapy were detected by flow cytometry (FCM). Results: The proportions of CD44＋CD24－/low cells after treatment with different concentrations of E2 for 10 d and 20 d were higher than those of the untreated MCF-7 cells, while the proportion of CD44＋CD24－/low cells after treatment with E2 plus TAM was lower than that of the CD44＋CD24－/low cells treated with E2 at the corresponding concentration. The proportions of CD44＋CD24－/low cells after treatment with different chemotherapeutic drugs for 24 h were increased, while decreased after treatment for 20 d. The proportion of CD45－CD44＋CD24－/low cells in peripheral blood was decreased in MBC patients achieving partial remission and stable disease after chemotherapy, while increased in MBC patients achieving progressive disease. Conclusion: E2 can promote the proliferation of a subset of CD44＋CD24－/low cells derived from MCF-7 cells, but TAM can inhibit this effect. The CD44＋CD24－/low cells have resistance to docetaxel, PTX, EPI and 5-Fu. The proportion of CD45－CD44＋CD24－/low cells in peripheral blood of patients response to chemotherapy is decreased. DOI:10.3781/j.issn.1000-7431.2012.05.008