Cholesterol-Conjugated Polyion Complex Nanoparticles for Combination Delivery of Hydrophobic Paclitaxel and Hydrophilic miR-34a for Colon Cancer Therapy

In recent years, combination chemotherapy with therapeutic nucleic acids has emerged as a promising strategy to enhance the effectiveness of cancer therapy. However, developing an effective co-delivery system to simultaneously transport both chemotherapeutic drugs and nucleic acids remains challenging. Herein, we fabricated cholesterol-conjugated polyion complex nanoparticles (PCNs) for combination delivery of hydrophobic paclitaxel (PTX) and hydrophilic miR-34a. Cholesterol was conjugated to polyethylenimine (PEI) and hyaluronic acid (HA), producing C–PEI and C–HA, respectively. PTX was initially encapsulated within the hydrophobic core formed by the self-assembly of C–HA and C–PEI, yielding polyion complex nanoparticles (PTX@C–HA/C–PEI PCNs). Subsequently, the negatively charged miR-34a was electrostatically complexed with the cationic C–PEI moieties to generate miR-34a/PTX@C–HA/C–PEI PCNs. These PCNs exhibited a nanoscale structure with a uniform size distribution and demonstrated low cytotoxicity in colon cancer cells. Fluorescence microscopy confirmed efficient cytosolic delivery of C–HA/C–PEI PCNs in colon carcinoma cells. Furthermore, combination delivery of PTX and miR-34a using C–HA/C–PEI PCNs exhibited significantly enhanced transfection efficiency and cellular uptake for human colon cancer cells. Notably, PTX/miR-34a@C–HA/C–PEI PCNs effectively downregulated critical oncogenic targets, including Notch1, Snail1, and BCL-2, resulting in reduced cancer cell migration and proliferation. These findings indicate that PTX/miR-34a@C–HA/C–PEI PCNs hold significant potential as an innovative combination delivery platform, offering improved therapeutic efficacy for colon cancer therapy.