A manganese-oxide nano-rambutan as the intrinsic modifier for hypericin delivery and triple-negative breast cancer treatment

Abstract

The anti-tumor efficacy of naturally derived photosensitizer-hypericin (Hy) is dampened by hypoxia and over-expressed glutathione in the tumor microenvironment (TME). For rewiring the TME, we encapsulated Hy to an intrinsic modifier-manganese oxide-formed nanorambutan (MnO_x-Hy NR). In triple-negative breast cancer cells, MnO_x-Hy NR not only consumed glutathione through Mn²⁺ and hypericin release but also facilitated O₂ production to relieve hypoxia, through which the reactive oxygen species (ROS) generation was strengthened by endoplasmic reticulum targeting hypericin. In the meantime, glutathione consumption-induced glutathione peroxidase 4 (GPX4) inactivation and the elevation of lipid hydroperoxide (LPO) level further triggered ferroptosis. Then, the combination of PDT and ferroptosis contributed to a synergic immunogenic cell death (ICD) effect in 4 T1 cells, facilitating the adaptive anti-tumor immune response activation. Thereby, MnO_x-Hy NR exhibited excellent anti-tumor effects both in primary and distant tumors through the abscopal effect, as well as significant lung metastasis inhibition in the 4 T1 mouse metastatic tumor model.