A synergistic CRISPR-nano-immunotherapeutic system for targeted Bcl-2 silencing in breast tumour

B-cell lymphoma-2 (Bcl-2) protein has an extensive role in anti-cell death regulation and immuno-response modulation. It seizes apoptosis when Bcl-2 interacts and binds to Bax via its BH domain. Breast tumour (BT) was found to have overexpression of Bcl-2 coupled with mitochondrial membrane deprivation and stumpy immune response. Here, we developed a phyto-nanomedicine (HRP-MET)-based immunotherapeutic system integrating gold di‑manganese tri-oxide nanoparticles (GMNPs) with a BT-directed gene knockdown strategy. The nanoformulation is designed to accumulate in tumour tissue through enhanced permeability and retention (EPR)-mediated passive targeting, followed by activation within the tumour microenvironment. Initially, the expression of the Bcl-2 gene was selectively silenced in BT cells using a one-step advanced GenCRISPR™ Ultra NLS-Cas9 ribonucleoprotein (RNP) system with four designed effective sgRNAs (gene-CRISPR). Subsequently, transfected BT cells were treated with GMNP@HRP-MET phyto-nanomedicine in vitro and in vivo. As a result, this combinatorial strategy significantly induced tumour cell death via a mitochondria-mediated apoptotic signalling cascade (mitochondria → Bh3-only → Bax/Bak → Cycs → Apoptosome → Casp-9/Casp-3 → apoptosis) in various BT cells. Notably, Bcl-2 gene expression was prominently blocked in BALB/c female mice, accompanied by enhanced T-cell activation and sustained immune responses at both proteomic and transcriptomic levels. Furthermore, the gene-CRISPR and phyto-nanomedicine combination significantly inhibited tumour growth, migration, and distant organ metastasis in xenograft and syngeneic mice models. Collectively, this study demonstrates a practical and durable therapeutic strategy based on gene-CRISPR-enhanced apoptosis integrated with microenvironment-responsive phyto-nanomedicine for BT treatment.