Nicotine reduces effectiveness of doxorubicin chemotherapy and promotes CD44<sup>+</sup>CD24<sup>-</sup> cancer stem cells in MCF-7 cell populations.

Abstract

Breast cancer is the most common type of cancer in females and the second most common cause of cancer mortality after lung cancer. Cancer stem cells represent a novel approach to target cancer and reduce cancer recurrence and metastasis. Many patients with breast cancer continue to smoke after receiving their diagnosis. Nicotine is a key factor in tobacco addiction and also changes some cellular functions, such as activation of mitogenic pathways, angiogenesis and cell proliferation. In the present study, the impact of nicotine was assessed in a population of MCF-7 human breast cancer cells. Cluster of differentiation (CD)44(+)CD24(-) cancer stem cell population of MCF-7 cells were evaluated using flow cytometry and scanning electron microscopy. Chemoresistance effects of nicotine were demonstrated in these cells. These findings demonstrated harmful effects of nicotine following metastasis of cancer, owing to the chemoresistance produced through uninterrupted smoking, which may impact the effectiveness of treatment.