Effective delivery of CRISPR/dCas9-SAM for multiplex gene activation based on mesoporous silica nanoparticles for bladder cancer therapy

The molecular complexity of bladder cancer restricts reliance on single-feature or single-gene targeted therapies, necessitating integrated individualized treatments and multi-gene interventions. In this study, we introduced the CRISPR/dCas9-SAM system to BCa treatment, known for its high specificity, low off-target effects, and reduced genetic toxicity, making it ideal for multiplexed gene activation at minimal cost-just 20 nucleotides per target. However, despite its potential in complex gene therapy and cellular engineering, challenges persist due to safety concerns associated with viral vectors and the risk of off-target effects during in vivo delivery, necessitating the development of new vectors. Herein, we reported pH-sensitive hollow mesoporous silica nanoparticles modified with PLZ4 ligands (PLZ4-Lip@AMSN/CRISPR/dCas9-SAM, PLACS NPs) for precise targeting of bladder tumors and co-delivery of CRISPR/dCas9-SAM system. With good stability and high plasmid loading capacity, they efficiently co-delivered dCas9-VP64, MS2-P65-HSF1, and sgRNA. Compared to Lipofectamine 3000, these nanoparticles exhibited superior lysosomal escape capability, significantly enhancing transfection efficiency in bladder cancer cells. Moreover, PLACS NPs simultaneously activated the expression of four target genes, inhibiting proliferation and migration, and promoting apoptosis in bladder cancer cells. In vivo, they achieved efficient gene editing at tumor sites, significantly inhibiting bladder tumor growth. Real-time imaging revealed their substantial accumulation and prolonged retention at bladder tumor sites without significant liver targeting and major organ damage, showcasing good specificity and biosafety. This study overcomes in vivo delivery challenges of multi-component CRISPR/dCas9 systems, enabling precise gene editing and anti-tumor effects, presenting an innovative strategy for targeted therapy in bladder cancer treatment. STATEMENT OF SIGNIFICANCE: This study introduces a newly-developed approach to address key challenges in bladder cancer gene therapy, namely low gene upregulation efficiency, limited targeting specificity, and inefficient nucleic acid delivery. By integrating the CRISPR/dCas9-SAM system, we achieve highly specific gene activation with minimal off-target effects, enabling the addition of treatment targets with just 20 nucleotides per target. To improve bladder cancer targeting, we developed PLACS NPs, a mesoporous silica nanoparticle system that enhances plasmid delivery, transfection efficiency, and endosomal escape. This system shows good tumor targeting and significant anti-tumor effects in bladder cancer, without significant liver targeting and major organ toxicity, offering promising therapeutic potential and broad clinical applications.