Abstract
Doxorubicin is one of the most widely used chemotherapy agents for the treatment of breast cancer. However, the development of doxorubicin resistance limits the long‑term treatment benefits in patients with breast cancer. Curcumin, a well‑known dietary polyphenol derived from the rhizomes of turmeric (Curcuma longa), enhances the sensitivity of breast cancer cells to chemotherapeutic agents; however, the mechanisms underlying this phenomenon remain unclear. The aim of the present study was to evaluate the effect of curcumin on chemoresistance in doxorubicin‑resistant breast cancerMCF‑7/DOX and MDA‑MB‑231/DOX cell lines. Cell Counting Kit‑8, monolayer transport, western blot and ATPase activity assays were performed during the study. The results revealed that curcumin significantly enhanced the effect of doxorubicin in doxorubicin‑resistant breast cancer cells. The intracellular accumulation of doxorubicin was substantially increased following curcumin treatment in doxorubicin‑resistant breast cancer cells, in a manner that was inversely dependent on the activity of ATP binding cassette subfamily B member 4 (ABCB4). Treatment with a combination of curcumin and doxorubicin decreases the efflux of doxorubicin in ABCB4‑overexpressing cells. Furthermore, curcumin inhibited the ATPase activity of ABCB4 without altering its protein expression. In conclusion, curcumin reversed doxorubicin resistance in human breast cancer MCF‑7/DOX and MDA‑MB‑231/DOX cells by inhibiting the ATPase activity of ABCB4. The study highlights the promising use of curcumin as a chemosensitizer in the treatment of breast cancer.