Targeting breast cancer resistance protein (BCRP/ABCG2) in cancer.

Breast cancer is one of the most common cancers among women. Nowadays postoperative adjuvant chemotherapy is the mainstay for clinical treatment of breast cancer. However, the emergence of multidrug resistance (MDR) in breast cancer has become a main reason for the failure of clinical chemotherapy. Multiple studies have demonstrated that the formation of MDR in breast cancer is combined with ATP-binding transporters, which are the proteins that can lead to the drug resistance by pumping out chemotherapeutic drugs to reduce their intracellular accumulation. This kind of protein mainly includes P-glycoprotein (Pgp, ABCB1, MDR1), multidrug resistance-associated protein (MRP-1, ABCC1) and breast cancer resistance protein (BCRP, ABCG2). The former two transporters have been investigated deeply and widely, while the molecular mechanism of BCRP regulation of breast cancer drug resistance has relatively not much been explored in the area of breast cancer. How to design a novel, effective and non-toxic BCRP inhibitor to reverse the MDR of breast cancer, and boost the success rate of chemotherapy is a serious challenge at present. A detailed overview of the molecular role of BCRP-mediated breast cancer MDR and its inhibitors reported in recent years is provided in this article. The expectation is to provide ideas for clinically addressing MDR in breast cancer, and further guide the direction for the development of new anti-breast cancer drugs and reversal of breast cancer MDR drugs.