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초록

Triple-negative breast cancer (TNBC) treatment is frequently limited by both intrinsic resistance and normal tissue toxicity in radiation therapy (RT) and chemotherapy. Herein, we report reactive oxygen species (ROS)activatable DOX prodrug loaded liposome nanoparticles (ROS-LNPs) for precision therapy against TNBC. First, the ROS-activatable DOX prodrug was prepared by chemically conjugating caspase-3-cleavable peptide (AcetylLys-Gly-Asp-Glu-Val-Asp, KGDEVD) to DOX using self-immolative PABC linker, resulting in DEVD-DOX. The prodrug of DEVD-DOX is inactive and nontoxic in cancer cells, but it exhibits ROS-activatable cytotoxicity following low-dose radiation. Second, DEVD-DOX is encapsulated into 1,2-dioleoyl-sn-glycero-3-phospho-Lserine (PS)-containing liposome nanoparticles (ROS-LNPs) to improve blood stability and uniformly penetrate into tumor tissue. The resulting ROS-LNPs form very stable nanoparticles with an average diameter of 108.1 +/- 7.3 nm. In particular, ROS-LNPs exhibit low-dose radiation (5 Gy) generated ROS-activatable cytotoxicity in 4 T1 cells, wherein ROS-induced activated caspase-3 can cleave DEVD-DOX released from ROS-LNPs into free DOX that further shows the ROS-induced amplified cytotoxicity without lose-dose radiation. To overcome physiological barriers of the tumor targeting of ROS-LNPs in tumor microenvironment (TME), micro-syringe chip (MSC)-mediated intratumoral delivery strategy is employed to ensure uniform intratumoral delivery. MSCmediated intratumoral administration of ROS-LNPs exhibit 3.26-fold higher tumor-targeting efficiency than conventional intratumoral administration in 4 T1 tumor-bearing mice. The combination of ROS-LNPs and lowdose radiation greatly suppresses tumor growth with potential anticancer immunity, such elevated ICD, dendritic cell (DC) activation, and cytotoxic T cell infiltration, in 4 T1 tumor-bearing mice. Furthermore, the combination of ROS-LNPs and low-dose radiation exhibits the minimal off-target toxicity in normal tissues. This study highlights the clinical potential of ROS-activable doxorubicin loaded liposome nanoparticles as a promising stimulus-responsive platform to bridge the gap between low-dose RT and precision chemotherapy in TNBC treatment.

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