Abstract
Dissection and understanding of the molecular pathways driving triple-negative breast cancer (TNBC) are urgently needed to develop efficient tailored therapies. Aside from cell invasion and metastasis, the urokinase-type plasminogen activator receptor (uPAR) has been linked to apoptosis resistance in breast tumors. We explored the mechanism of uPAR-disrupted apoptosis in breast cancer. We found that depletion of uPAR by RNAi increases death receptor 4 (DR4) and death receptor 5 (DR5) expression and triggers TRAIL-induced apoptosis in TNBC cells. The microRNAs miR-17-5p and miR-20a inhibit cell apoptosis via suppression of DR4/DR5. We provide evidence that uPAR enhances miR-17-5p/20a expression through upregulation of c-myc. Blocking miR-17-5p/20a with antagomiRNA suppressed the growth of uPAR-overexpressing breast tumor xenografts in mice. These results indicate that uPAR suppresses cell apoptosis by inhibiting the c-myc-miR-17/5p/20a-DR4/DR5 pathway. Therapy directed at uPAR-induced miR-17/20a is a potential option for breast cancer and TNBC.