pH-Sensitive Cationic Liposomes for Oridonin and siRNA Co-Delivery to Inhibit Triple-Negative Breast Cancer.

To investigate the therapeutic efficacy of co-delivering a small molecule compound and an interfering RNA in triple-negative breast cancer (TNBC), a disease characterized by poor prognosis, this study developed pH-sensitive nanocomposite cationic liposomes for the simultaneous delivery of oridonin and siCX26. CX26 (Connexin 26), a gap junction protein associated with stem-like properties and chemoresistance, was targeted to enhance therapeutic efficacy against this aggressive subtype. Oridonin liposomes were prepared using thin-film dispersion followed by hydrated ultrasonication. Subsequently, siCX26 was incorporated and modified with carboxymethyl chitosan (CMCS) to produce pH-sensitive nanocomposite cationic liposomes (CMCS-Ori-siCX26-LipoPH+). Liposome stability was assessed via particle size analysis and zeta-potential measurement. TUNEL staining and western blotting were performed to evaluate apoptosis and related intracellular signaling. The effect of CMCS-Ori-siCX26-LipoPH+ on tumor apoptosis was further assessed in animal models. CMCS-Ori-siCX26-LipoPH+ preserved siRNA integrity for up to 8 h and maintained stable particle size for up to 12 days. TUNEL staining and western blotting showed that the liposomes significantly enhanced apoptosis in MDA-MB-231 breast cancer cells at extracellular pH 6.5. Moreover, the liposomes delivered siRNA into the cytoplasm while protecting it from lysosomal degradation. Animal studies confirmed that CMCS-Ori-siCX26-LipoPH+ inhibited tumor growth and induced tumor cell apoptosis in nude mice. The CMCS-Ori-siCX26-LipoPH+ liposome system effectively delivers oridonin to TNBC, inducing tumor cell apoptosis.