ANG peptide-modified exosomes loaded with oleanolic acid target GPX4 for enhanced breast cancer brain metastasis therapy.

PURPOSE: Breast cancer brain metastasis (BCBM) is a major clinical challenge due to the blood-brain barrier (BBB) restricting effective drug delivery, resulting in limited therapeutic options and poor prognosis. This study aims to develop ANG peptide-modified exosomes loaded with oleanolic acid (ANG-Exo-OA) to enhance brain-targeted delivery and investigate its anti-tumor mechanisms through GPX4-mediated ferroptosis in BCBM treatment.

METHODS

Oleanolic acid was encapsulated into mesenchymal stem cell-derived exosomes via electroporation, with ANG peptide conjugated using thiol-maleimide chemistry. ANG-Exo-OA was characterized using nanoparticle tracking analysis, transmission electron microscopy, and Western blot. Biocompatibility was evaluated via cytotoxicity assays, hematoxylin and eosin staining, and serum biochemistry. Brain-targeting efficiency was assessed using an in vitro BBB model and in vivo imaging. Anti-tumor effects and GPX4 pathway involvement were examined in a Luc-labeled MDA-MB-231 BCBM mouse model using Western blot, malondialdehyde, glutathione assays, and GPX4 overexpression rescue experiments. Statistical analyses included t-tests and ANOVA.

RESULTS

ANG-Exo-OA exhibited excellent biocompatibility, stability, and enhanced BBB penetration, with significant brain accumulation. It suppressed MDA-MB-231 cell proliferation, migration, and induced apoptosis, accompanied by decreased GPX4 expression and increased lipid peroxidation. In vivo, ANG-Exo-OA reduced tumor growth and promoted ferroptosis, effects reversed by GPX4 overexpression.

CONCLUSION

ANG-Exo-OA represents a promising therapeutic strategy for BCBM, achieving enhanced brain-targeted delivery and effective GPX4-mediated ferroptosis induction in a TNBC model. While the findings highlight its potential value for BCBM treatment, further studies involving additional breast cancer subtypes and more clinically relevant models are required to determine its broader applicability.