Background: Multi-drug resistance is an important challenge in the chemotherapy of cancer. The role of annexin A5 (ANXA5) in the biology of cancer has been the focus of many studies. Breast Cancer (BC) is frequent cancer in women with high morbidity and mortality rate. The present study aimed to investigate the effects of ANXA5 overexpression on the anti-tumor activity of Epirubicin (EPI) in MCF-7 and MCF-7/ADR cells.

Methods: MCF-7 and MCF-7/ADR cells were transfected with the pAdenoVator-CMV-ANXA5-IRES-GFP plasmid or mock plasmid. The overexpression of ANXA5 was evaluated using qPCR. The effects of ANXA5 overexpression and EPI on the cell viability of MCF-7 and MCF-7/ADR cells were measured using an MTT assay. Cell apoptosis was measured by annexin V/7-AAD flow cytometry assay.

Results: Following the overexpression of ANXA5, the viability of MCF-7 and MCF-7/ADR was significantly decreased. Furthermore, the overexpression of ANXA5 in MCF-7 cells increased the cytotoxic effects of EPI in all doses and reduced the IC50 of EPI from 17.69 µM to 4.07 µM. Similarly, the overexpression of ANXA5 in MCF7-ADR cells reduced the IC50 of EPI from 27.3 µM to 6.69 µM. ANXA5 overexpression alone or combined with EPI treatment increased the apoptosis of MCF7 and MCF7-ADR cells. 

Conclusion: The results of the present study demonstrate that ANXA5 overexpression increases the sensitivity of MCF-7 and MCF-7/ADR to EPI, suggesting a possible beneficial role of ANXA5 in the therapy of BC.