Dual targeted lipid nanoparticles for enhanced DNA delivery and transfection of breast cancer cells

Lipid nanoparticles (LNPs) have gained much attention as non-viral gene delivery systems due to their large payload capacity, reduced immunogenicity, and cost-effective manufacturing. Surface modification of LNPs by covalent attachment of receptor ligands can improve their tissue specificity and reduce off-target effects. In the present work, DNA-LNPs were therefore designed to target breast cancer, particularly the invasive HER2-positive subtype. Targeting was mediated by trastuzumab (Herceptin®) a monoclonal antibody binding to the extracellular domain of the human epidermal growth factor receptor protein (HER2). To overcome intrinsic trastuzumab resistance for some patients with HER2 positive breast cancer, a dual-targeting strategy was employed by combining Herceptin with folate to enhance LNP uptake by cancer cells. Dual-targeted LNPs encapsulating plasmid DNA, coding for a fluorescent reporter protein (tdTomato or EGFP), were prepared using folate-conjugated PEGylated lipids. Subsequently, thiolated Herceptin was conjugated to the surface of the LNPs. At an N/P ratio of 6, small and uniform targeted LNPs were obtained, with a slightly negative ζ-potential. Cellular uptake and transgene expression were characterized invitro using three breast cancer cell lines (MCF7, MDA-mb453, SKBR3), which express varying level of the HER2 receptor. Cellular uptake correlated with HER2 expression levels and was significantly increased when Herceptin was combined with folate. In all tested breast cancer cell lines, dual-targeted LNPs led to an enhanced transgene expression compared to single-targeted LNPs. Furthermore, invivo zebrafish xenograft studies confirmed superior targeting and transfection efficiency of Dual-LNPs under physiological conditions. Our findings highlight the superior performance of dual-targeted LNPs to deliver a DNA expression plasmid to HER2 positive breast cancer cells, emphasizing their potential as an improved targeting and transfection strategy.