Isolinderalactone enhances the inhibition of SOCS3 on STAT3 activity by decreasing miR-30c in breast cancer.

Development of an efficient treatment for triple-negative breast cancer is an urgent issues. Compounds from plant extracts are a potential source of novel cancer treatment. Isolinderalactone, a kind of sesquiterpenoids compound, was purified from the root of Lindera strychnifolia and Neolitsea daibuensis and shows anti-inflammatory and anticancer capacity. In the present study, isolinderalactone induced apoptosis in MDA-MB-231 cells which is a kind of triple-negative breast cancer cell line through induction of an intrinsic mitochondria-mediated and caspase-independent cell death. Treatment of isolinderalactone increased the protein level of the suppressor of cytokine signaling 3 (SCOS3), decreased phosphorylation of the signal transducer and activator of transcription 3 (STAT3), and suppressed expression of the down-stream genes of the X-linked inhibitor of apoptosis protein in MDA-MB-231 cells. Our results further showed that the level of SOCS3 expression was induced by isolinderalactone due to inhibiting the microRNA hsa-miR-30c-5p (miR-30c) expression. In addition, intraperitoneal injection of isolinderalactone induced apoptosis in a xenograft breast tumor while it did not significantly affect the histology of liver, kidney and lung of the treated mice. In conclusion, isolinderalactone induces apoptosis in MDA-MB‑231 cells and suppresses STAT3 signaling pathway through regulation of SOCS3 and miR-30c. It may become a novel treatment for triple-negative breast cancer in the future.