Downregulation of annexin A3 inhibits tumor metastasis and decreases drug resistance in breast cancer.

Annexin A3 (ANXA3) is dysregulated and plays an important role in various cancers. However, the role of ANXA3 in breast cancer is still unclear. Here, we observed that the expression level of ANXA3 was significantly upregulated in breast cancer tissues. ANXA3 knockdown inhibited cell invasion but promoted cell proliferation in both in vitro and in vivo assays. Furthermore, we found that ANXA3 knockdown inhibited the NFκB pathway via upregulating IκBα, resulting in mesenchymal-epithelial transition (MET) and a heterogeneity change of breast cancer stem cells (BCSCs). In addition, we demonstrated that ANXA3 knockdown increased the sensitivity of breast cancer cells to doxorubicin by increasing the drug uptake. The combination of ANXA3 knockdown and doxorubicin treatment simultaneously inhibited tumor growth and metastasis in vivo. This study described the role and mechanisms of ANXA3 in regulating BCSCs and breast cancer growth and metastasis, indicating that downregulating ANXA3 together with chemotherapy might be a novel therapeutic strategy for treating breast cancer.