Cancer progression and its treatment-response are regulated by the tumor microenvironment (TME). Tumor-initiating cancer stem cells (CSCs) remain in constant communication with the TME, and modulate it through several mechanisms. Here, from in-silico findings and analyzing breast cancer patient tissue-derived data, CSCs and Tregs were found to be positively correlated. Furthermore, our in-silico analyses highlighted a positive relationship between CSC genes and Treg signature marker, FOXP3, even in cancer cell lines that do not contain any T cell or Treg cells, thus raising the possibility of CSCs expressing FOXP3. Validating our hypothesis, higher expression of FOXP3, both at mRNA and protein levels, was observed in breast CSCs than non-stem cancer cells. Since a small population of CSCs initiate tumor in immune cell-dominated TME, we aimed at exploring whether breast CSCs directly transfer FOXP3 to CD4