OSW-1 Induces Apoptosis and Cyto-Protective Autophagy, and Synergizes with Doxorubicin on Spontaneous Metastasis of Triple Negative Breast Cancer

Abstract Background Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer and chemotherapy using drugs such as doxorubicin is the main treatment strategy. However, drug resistance and dose-dependent toxicities restricted its clinical use. Natural products are major sources of anti-tumor drugs. OSW-1 is a natural compound that has shown strong anti-cancer effects in several cancer types, but its effects on the efficacies of chemotherapy in TNBC and the underlying mechanism remain unclear. Methods We investigated the effects of OSW-1 on the viabilities, apoptosis and autophagy in 4T1 and MDA-MB-231 cells. The synergistic effects of combination with OSW-1 and doxorubicin on TNBC growth and spontaneous metastasis were examined in vitro and in vivo. Results OSW-1 induces mitochondria-dependent apoptosis and cyto-protective autophagy in TNBC cells in vitro. In addition, OSW-1 and doxorubicin exhibits strong synergistic anti-TNBC capabilities both in vivo and in vitro. The combination treatment can strongly inhibit spontaneous metastasis in 4T1 model. Consistent with this inhibition, the proportion of CD8+ T lymphocytes in the lung microenvironment were significantly increased after combination treatment. Conclusions This study indicates that the combination therapy with natural compound and chemotherapeutic drug could be a promising anti-TNBC strategy which deserves further investigation.