Association Of CD44~-/CD24~- Breast Cancer Cells With Delayed Tumor Metastasis

Background:At present,the incidence of breast cancer is increasing annually,showing a trend of younger age.Many breast cancer patients suffer relapse or metastasis years after removal of the primary tumor,that even happens 10 to 20 years after surgery,which is the principal cause of breast cancer-related death.Cancer stem cells(CSC)is considered prime drivers of tumor recurrence and metastasis,making them important therapeutic targets.Breast cancer is a highly heterogeneous disease and the function of different subsets of breast cancer cells and related mechanisms have been explored.In the aspects of postoperative treatment of breast cancer and postoperative recurrence and metastasis,we also urgently need to find new biomarkers to predict the therapeutic effect and effectively improve the prognosis of breast cancer patients.Objective:The aim of this research was to demonstrate the dedifferentiation of CD44~-/CD24~-tumor cells into CD44~+/CD24~-tumor stem cells.The biological behavior of stem cells was compared with that of stem cells directly selected from parent cells.The relationship between CD44~-/CD24~-tumor cells and clinicopathological features of breast cancer and its clinical prognostic value were further analyzed.To seek new therapeutic strategies for postoperative treatment of breast cancer.Methods:First,we retrospectively analyzed 355 clinical samples by immunofluorescence staining and HE staining to explore the relationship between CD44~-/CD24~-cancer cells and clinicopathological features,and analyzed its prognostic value by univariate and multivariate Cox regression.Then Kaplan Meier survival curve was used to analyze the relationship between CD44~-/CD24~-cancer cell percentage and DFS.In vitro and in vivo experiments were conducted to verify that CD44~-/CD24~-tumor cells could spontaneously dedifferentiate into CD44~+/CD24~-after 7 days in vitro by flow cytometry sorting and analysis.In vitro and in vivo experiments were conducted to further analyze the biological behaviors of CD44~+/CD24~-cancer stem cells in tumor formation,proliferation,tumorigenesis and differentiation in vivo.Results:The percentage of CD44~-/CD24~-cancer cell is associated with delayed metastasis after breast cancer surgery.CD44~-/CD24~-cell,CD44~+/CD24~-tumor stem cell,N stage,and molecular subtype were independent predictors of DFS in breast cancer patients.In addition,CD44~-/CD24~-cells in TNBC spontaneously transformed into CD44~+/CD24~-cancer stem cells(CSC)in vitro.Similar tumorigenesis of CSCs derived from conversion of CD44~-/CD24~-TNBC cells and directly from parental TNBC MDA-MB-231 cells in vivo in terms of tumor formation,proliferation,differentiation and tumorigenicity in vivo.Conclusion:These data suggested that the percentage of CD44~-/CD24~-tumor cells could predict breast cancer prognosis,metastasis,and response to adjuvant therapy.