Background
Chemoresistance is the major cause of neoadjuvant treatment failure in breast cancer patients. Despite recent progress, the mechanism underlying chemoresistance remains to be further defined.
Methods
Expression of G protein-coupled receptor 120 (GPR120) was analyzed by immunohistochemistry in the biopsies of primary breast cancer who subsequently underwent preoperative neoadjuvant chemotherapy. In vitro and in vivo loss- and gain-of -function studies were performed to reveal the effects and related mechanism of GPR120 signaling pathway in the chemoresistance of breast cancer cells. Findings: We identified that GPR120, a receptor for long-chain fatty acids, was important for the acquisition of chemoresistance in breast cancer cells. We showed that GPR120 expression was positively associated with clinical response to neoadjuvant chemotherapy in patients. In breast cancer cells, GPR120 enhanced the de novo synthesis of fatty acids that served as GPR120 ligands to activate GPR120 signaling via a feedback mechanism. Upregulated GPR120 signaling rendered cells resistant to epirubicin-induced cell death by upregulating ABC transporters expression and thus decreasing the intracellular accumulation of epirubicin. Akt/NF-κB pathway was responsible for the GPR120-mediated expression of ABC transporters leading to modulation of the concentration of chemotherapeutic drugs in cells. The functional importance of GPR120 in chemoresistance was further validated using epirubicin-treated tumor xenografts, in which we showed that blockade of GPR120 signaling with AH7614 or GPR120-siRNA significantly compromised chemoresistance. Interpretation: Our