[Mechanism of growth differentiation factor 15 in curcumin-induced ferroptosis in triple-negative breast cancer]

Objective: To investigate the role and potential mechanism of Growth Differentiation Factor 15 (GDF15) in curcumin-induced ferroptosis of triple-negative breast cancer (TNBC) cells. Methods: (1) Cell experiments: Human TNBC cell line MDA-MB-231 was used. After successful cell transfection and modeling, the cells were divided into MDA-MB-231 GDF15 knockdown group (siGDF15 group) and negative control group (siNC group). After treatment with curcumin, they were further divided into siNC curcumin group and siGDF15 curcumin group. Cell viability, ferrous iron, reactive oxygen species, glutathione levels, and the expression of SLC7A11, GPX4, FTH1, and FTL were detected. (2) Animal experiments: a nude mouse xenograft model was established, and mice were randomly assigned using a random number table into NC group (nude mice inoculated with MDA-MB-231 cells transfected with negative sequence, followed by control reagent), KO-GDF15 group (nude mice inoculated with GDF15 knockdown MDA-MB-231 cells, followed by control reagent), curcumin group (nude mice inoculated with MDA-MB-231 cells transfected with negative sequence, followed by curcumin), and KO-GDF15 curcumin group (nude mice inoculated with GDF15 knockdown MDA-MB-231 cells, followed by curcumin), with 10 mice in each group. The in vivo tumor suppression effect and expression of Ki-67, SLC7A11, GPX4, and 4-HNE in tissues were assessed. Results: CCK-8 assay results showed that different concentrations of curcumin significantly reduced the viability of MDA-MB-231 cells; after co-treatment with curcumin and iron inhibitors for 24 hours, the decrease in cell viability was partially restored. Levels of Fe²⁺ and reactive oxygen species significantly increased in the curcumin group, while glutathione levels significantly decreased. GDF15 knockdown significantly enhanced the cytotoxicity of curcumin, further promoting Fe²⁺ and reactive oxygen species accumulation and glutathione depletion. mRNA and protein expression levels of GPX4, SLC7A11, FTL, and FTH1 in the GDF15 knockdown group were lower than those in the control group. Tumor volume and weight in the curcumin group were lower than those in the NC group (P<0.001); tumor volume and weight in the GDF15 knockout curcumin group were lower than those in the curcumin group (both P<0.001). Immunohistochemical staining showed that in nude mouse tumor tissues, expression of Ki-67, SLC7A11, and GPX4 decreased, while 4-HNE increased in the curcumin group. Conclusion: GDF15 knockdown enhances the sensitivity of TNBC cells to curcumin-induced ferroptosis by downregulating the SLC7A11/GPX4 axis and iron storage proteins, exerting a synergistic anti-tumor effect.