Designing Nanomedicines for Breast Cancer Therapy.

In 2020, breast cancer became the most diagnosed cancer worldwide. Conventional chemotherapies have major side effects due to their non-specific activities. Alternatively, short interfering RNA(siRNA)-carrying nanoparticles (NPs) have a high potential to overcome this non-specificity. Lipid-substituted polyethyleneimine (PEI) polymers (lipopolymers) have been reported as efficient non-viral carriers of siRNA. This study aims to engineer novel siRNA/lipopolymer nanocomplexes by incorporating anionic additives to obtain gene silencing through siRNA activity with minimal nonspecific toxicity. We first optimized our polyplexes in GFP+ MDA-MB-231 cells to effectively silence the GFP gene. Inclusion of phosphate buffer with pH 8.0 as complex preparation media and N-Lauroylsarcosine Sodium Salt as additive, achieved ~80% silencing with the least amount of undesired cytotoxicity, which was persistent for at least 6 days. The survivin gene was then selected as a target in MDA-MB-231 cells since there is no strong drug (i.e., small organic molecule) for inhibition of its oncogenic activity. The qRT-PCR, flow cytometry analysis and MTT assay revealed >80% silencing, ~95% cell uptake and >70% cell killing by the same formulation. We conclude that our lipopolymer can be further investigated as a lead non-viral carrier for breast cancer gene therapy.