Yanghe Decoction promotes ferroptosis through PPARγ-dependent autophagy to inhibit the malignant progression of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a heterogeneous subtype of breast cancer that displays highly aggressive with poor prognosis. Yanghe Decoction (YHD) has been used in the treatment of breast cancer for many years. We aimed to explore the effects of YHD on the malignant phenotypes of MDA-MB-231 cells and the potential mechanism related to PPARγ, autophagy and ferroptosis. The serum of rat containing different concentrations of YHD were collected to culture MDA-MB-231 cells. Cell viability and proliferation were assessed by the CCK-8 assay and EDU staining. Wound healing- and transwell assays were used to detect the capacities of MDA-MB-231 cell migration and invasion. Additionally, the levels of lipid peroxidation, Fe²⁺ and the expression of ferroptosis-related proteins were evaluated. The expression of PPARγ and autophagy-related proteins was assessed using immunofluorescence staining or western blot assay. Then, the PPARγ inhibitor (GW9662), autophagy inhibitor (3-MA) and autophagy inducer (rapamycin; Rap) were used to further study the potential mechanism of YHD on TNBC. Results indicated that contained-YHD serum significantly decreased the viability, proliferation, migration and invasion of TNBC cells. Moreover, YHD promoted lipid peroxidation level, elevated Fe²⁺ content and downregulated GPX4, SLC7A11 and SLC3A2 expression. Besides, autophagy was induced and PPARγ was upregulated by YHD in MDA-MB-231 cells. Furthermore, GW9662 alleviated the impacts of YHD on autophagy of MDA-MB-231 cells. Rap reversed the effects of GW9662 on lipid peroxidation, ferroptosis, proliferation, migration and invasion of MDA-MB-231 cells. 3-MA had the similar effects to GW9662. Collectively, YHD suppressed the malignant progression of MDA-MB-231 cells by inducing ferroptosis through PPARγ-dependent autophagy.