Objective To investigate the effect of folic acid–modified liposome quercetin (FLQ) on the proliferation and apoptosis of triple negative breast cancer (TNBC) cells and explore its underlying mechanism.

Methods CCK-8 was used to detect the effect of FLQ on TNBC cell viability. Colony formation assay was conducted to detect the effect of FLQ on TNBC cell proliferation. Flow cytometry was performed to detect the effect of FLQ on TNBC cell apoptosis, the levels of intracellular ROS, and mitochondrial membrane potential. Western blot analysis was conducted to detect the expression levels of JAK2/STAT3 signaling pathway-related and apoptosis-related proteins.

Results FLQ inhibited the proliferation and promoted the apoptosis of MDA-MB-231 cells (P=0.023, P<0.001). It promoted mitochondrial membrane potential collapse and increased the intracellular ROS levels of MDA-MB-231 cells (P=0.003, P=0.034); inhibited the phosphorylation levels of JAK2 and STAT3; upregulated the expression levels of the proapoptotic proteins Bax, Bak, cytochrome C, and Cleaved-Caspase-3 (P<0.001, P<0.001); and downregulated the expression levels of the antiapoptotic proteins Bcl2 and Bcl-x_L (P=0.037, 0.028).

Conclusion FLQ inhibits the proliferation and induces the apoptosis of MDA-MB-231 cells. These effects may be related to the activation of the mitochondrial apoptosis pathway through the inhibition of the JAK2/STAT3 signaling pathway.