Apoptosis and Paraptosis Induced by Disulfiram-Loaded Ca²⁺/Cu²⁺ Dual-Ions Nano Trap for Breast Cancer Treatment

Regarded as one of the hallmarks of tumorigenesis and tumor progression, the evasion of apoptotic cell death would also account for treatment resistance or failure during cancer therapy. In this study, a Ca²⁺/Cu²⁺ dual-ion "nano trap" to effectively avoid cell apoptosis evasion by synchronously inducing paraptosis together with apoptosis was successfully designed and fabricated for breast cancer treatment. In brief, disulfiram (DSF)-loaded amorphous calcium carbonate nanoparticles (NPs) were fabricated via a gas diffusion method. Further on, the Cu²⁺-tannic acid metal phenolic network was embedded onto the NPs surface by self-assembling, followed by mDSPE-PEG/lipid capping to form the DSF-loaded Ca²⁺/Cu²⁺ dual-ions "nano trap". The as-prepared nanotrap would undergo acid-triggered biodegradation upon being endocytosed by tumor cells within the lysosome for Ca²⁺, Cu²⁺, and DSF releasing simultaneously. The released Ca²⁺ could cause mitochondrial calcium overload and lead to hydrogen peroxide (H₂O₂) overexpression. Meanwhile, Ca²⁺/reactive oxygen species-associated mitochondrial dysfunction would lead to paraptosis cell death. Most importantly, cell paraptosis could be further induced and strengthened by the toxic dithiocarbamate (DTC)-copper complexes formed by the Cu²⁺ combined with the DTC, the metabolic products of DSF. Additionally, the released Cu²⁺ will be reduced by intracellular glutathione to generate Cu⁺, which can catalyze the H₂O₂ to produce a toxic hydroxyl radical by a Cu⁺-mediated Fenton-like reaction for inducing cell apoptosis. Both in vitro cellular assays and in vivo antitumor evaluations confirmed the cancer therapeutic efficiency by the dual ion nano trap. This study can broaden the cognition scope of dual-ion-mediated paraptosis together with apoptosis via a multifunctional nanoplatform.