Breast cancer cells acquire stem cell-like properties upon contact with functionally impaired T cells

Breast cancer is the most common malignancy in women and prone to relapse. This has been ascribed to a small subpopulation of so-called tumor initiating or cancer stem cells (CSC) characterized by increased clonogenicity, sphere formation and tumor initiation capacity. We investigated interactions between T cells and breast cancer stem cells which can be recognized by the marker combination CD44highCD24low. Upon cell-cell-contact with polyclonally expanded and activated CD4+ and CD8+ T cells from healthy donors, the CSC population in MCF7 breast cancer cells is not only spared from killing and thus enriched by s…