Construction and in vitro evaluation of pH-sensitive nanoparticles to reverse drug resistance of breast cancer stem cells

Breast cancer is a major threat to safety and health of women. The breast cancer stem cells (BCSCs) have multi-drug resistance to chemotherapy drugs, which leads to chemotherapy failure. We proposed a strategy of delivery of tumor-killing drugs and a resistance reversal agent, to enhance inhibition of BCSCs. Here, schisandrin B (SchB)/AP NPs are constructed using acid-grafted-poly (β-amino ester) (ATRA-g-PBAE, AP) grafted polymer nanoparticle encapsulated SchB, with pH-sensitive release function. This drug delivery system has good pharmacological properties and can increase the SchB release with the decrease of pH. The NPs showed cytotoxic effects in reversing ATRA resistance to BCSCs. Lysosomal escape was achieved when the nanoparticles were taken up by BCSCs. In addition, we found that NPs may reverse MDR by inhibiting the expression of P-glycoprotein (P-gp) and affecting the energy supply of drug efflux. This study provides a nanodelivery therapy strategy that reverses BCSCs multidrug resistance (MDR) and demonstrates that it did so by interfering with cancer cell energy metabolism. Therefore, the co-delivery strategy of ATRA and SchB provides a new option for the treatment of breast cancer.