[Dihydroartemisinin enhances doxorubicin-induced apoptosis of triple negative breast cancer cells by negatively regulating the STAT3/HIF-1α pathway].

OBJECTIVES: To investigate the effects of dihydroartemisinin (DHA) combined with doxorubicin (DOX) on proliferation and apoptosis of triple-negative breast cancer cells and explore the underlying molecular mechanism. METHODS: MDA-MB-231 cells were treated with 50, 100 or 150 μmol/L DHA, 0.5 μmol/L DOX, or with 50 μmol/L DHA combined with 0.5 μmol/L DOX. The changes in proliferation and survival of the treated cells were examined with MTT assay and colony-forming assay, and cell apoptosis was analyzed with flow cytometry. Western blotting was performed to detect the changes in protein expression levels of PCNA, cleaved PARP, Bcl-2, Bax, STAT3, p-STAT3, HIF-1α and survivin. RESULTS: The IC(50) of DHA was 131.37±29.87 μmol/L in MDA-MB-231 cells. The cells with the combined treatment with DHA and DOX showed significant suppression of cell proliferation. Treatment with DHA alone induced apoptosis of MDA-MB-231 cells in a dose-dependent manner, but the combined treatment produced a much stronger apoptosis-inducing effect than both DHA and DOX alone. DHA at 150 μmol/L significantly inhibited clone formation of MDA-MB-231 cells, markedly reduced cellular expression levels of PCNA, p-STAT3, HIF-1α and survivin proteins, and obviously increased the expression level of cleaved PARP protein and the Bax/Bcl-2 ratio, and the combined treatment further reduced the expression level of p-STAT3 protein and increased the Bax/Bcl-2 ratio. CONCLUSIONS: DHA combined with DOX produces significantly enhanced effects for inhibiting cell proliferation and inducing apoptosis in MDA-MB-231 cells possibly as result of DHA-mediated negative regulation of the STAT3/HIF-1α pathway.