Resistin potentiates chemoresistance and stemness of breast cancer cells: Implications for racially disparate therapeutic outcomes.

Breast cancer (BC) continues to be the most frequently diagnosed cancer in American women, which disproportionately affects women of African-American (AA) descent. Previously, we reported greater serum levels of resistin in AA BC patients relative to Caucasian-American (CA) patients, and established its role in growth and aggressiveness of breast tumor cells. Here we have investigated the role of resistin in BC-chemoresistance. MDA-MB-231 and MDA-MB-468 BC cells of CA and AA origin, respectively, were incubated with resistin prior to doxorubicin treatment. Our data suggest that resistin conferred chemoresistance to both BC cell lines; however, the effect on AA cells was more profound. Furthermore, the resistin-induced doxorubicin-resistance was shown to occur due to suppression of apoptosis. Resistin treatment also affected the stemness of BC cells, as suggested by reduced cell surface expression of CD24, induced expression of CD44 and ALDH1, and increased capability of cells to form mammospheres. Mechanistic studies revealed that resistin-induced chemoresistance, apoptosis and stemness of BC cells were mediated through STAT3 activation. Taken together, our findings provide novel insight into the role of resistin in BC biology, and strengthen its role in racially disparate clinical outcomes.