Targeting CSC in a Most Aggressive Subtype of Breast Cancer TNBC.

Triple negative breast cancer (TNBC) is a more aggressive subtype of breast cancer and is characteristic of the absence of the expressions of estrogen receptor, progesterone receptor, and human epithelial growth factor receptor 2 in breast tumor tissues. This subtype of breast cancer has the poorest prognosis, compared to other subtypes of breast cancer. TNBC is heterogeneous by showing several different histo-pathological and molecular subtypes with different prognosis and is more commonly found in younger age of women, especially African-American and Hispanic women. Recent epidemiological data indicate that TNBC is highly associated with overweight/obesity. Due to the absence of the common tumor biomarkers of breast cancer, the current molecular target therapy is not effective. TNBC patients have a shorter survival rate and an increased tumor recurrence. The concept of cancer stem cells (CSC), also called tumor initiating cells (TIC) has been more and more accepted and considered to contribute to aggressive phenotypes of many tumors including breast cancer. Moreover, CSC/TIC has been identified in the tumor tissues of breast cancer including TNBC. These rare subpopulations of CSC/TIC cells might be one of the key contributors to the aggressive phenotypes of TNBC such as drug treatment resistance, metastasis, and tumor recurrence. Therefore, targeting these CSC/TIC cells will provide a new therapeutic strategy for the treatment of TNBC.