Potential activity of adiponectin‐expressing regulatory T cells against triple‐negative breast cancer cells through the cell‐in‐cell phenomenon

BACKGROUND: A population of regulatory T cells (Treg), which reside within thymic nurse cell complexes, express adiponectin and abrogate breast cancer development in transgenic mice. In this study, we examined whether adiponectin‐expressing Treg could impair triple‐negative breast cancer, which is defined by a lack of estrogen receptors, progesterone receptors, and human epidermal growth factor receptor‐2. METHODS: CD4‐ and CD25‐positive cells were sorted from cultured T lymphocytes of a previously characterized experimental thymic tumor model composed of thymic nurse cells and abundant lymphoid stroma. These sorted cells were examined for FOXP3 and adiponectin immunoreactivity and subsequently exposed to triple‐negative breast cancer MDA‐MB‐157 and ‐231 cells. RESULTS: Adiponectin‐expressing Treg were obtained by CD4‐ and CD25‐positive sorting and cell death was induced in triple‐negative breast cancer cells through the cell‐in‐cell phenomenon. CONCLUSIONS: Adiponectin‐expressing Treg may be candidates for adoptive cell therapy against triple‐negative breast cancer.