Polyethylenimine-Mediated Delivery of miR-379-5p Suppresses MTDH and FOXP2 in Colorectal Cancer Cells

PEI-Mediated miR-379-5p Delivery

Abstract

Objective: To develop an optimized polyethylenimine (PEI)-based nanocarrier for the intracellular delivery of miR-379-5p and to evaluate its efficacy in suppressing the oncogenic targets metadherin (MTDH) and Forkhead box P2 (FOXP2) in KRAS-wild-type colorectal cancer cells.
Methods: PEI-miRNA nanocomplexes were synthesized at various nitrogen-to-phosphate (N:P) ratios and characterized via dynamic light scattering, zeta potential measurements, and scanning electron microscopy (SEM). Cytotoxicity was assessed in Caco-2 cells using MTT assays to determine the optimal therapeutic concentration. Gene silencing efficiency and intracellular uptake were quantified using reverse transcription quantitative polymerase chain reaction.
Results: The formulation prepared at an N:P ratio of 20:1 exhibited optimal physicochemical properties, featuring a mean hydrodynamic diameter of ~254 nm, a compact spherical morphology, and a highly positive zeta potential (+56.9 mV). At the optimized concentration of 50 nM, the nanocomplexes maintained favorable cell viability while facilitating significant intracellular accumulation of miR-379-5p. Consequently, this delivery strategy achieved robust downregulation of MTDH and FOXP2 expression compared to naked miRNA treatment.
Conclusion: The optimized PEI-miRNA nanocomplexes effectively overcome delivery barriers, enabling successful gene silencing in Caco-2 cells. By restoring the miR-379-5p regulatory axis and suppressing FOXP2, this system constitutes a promising molecular platform for targeted RNAi-based interventions in colorectal malignancy.