Development of silver-based hybrid nanoparticles loaded with eEF2 K-siRNA and quercetin against triple-negative breast cancer

Breast cancer is the most common cancer among women, with approximately 2.3 million new cases globally. Triple-negative breast cancer (TNBC) is an aggressive subtype characterized by the lack of estrogen receptor (ER), progesterone receptor (PR), and HER2 expression, making it unresponsive to traditional therapies. Eukaryotic Elongation Factor 2 Kinase (eEF2K) is overexpressed in TNBC, promoting cell survival by inhibiting apoptosis through phosphorylation of eEF2. Recently, eEF2K has been targeted for cancer therapy, and siRNA-based gene therapy has emerged as an effective approach to silence overexpressed genes. However, siRNA delivery is challenging due to its instability and susceptibility to degradation. In this study, we developed a novel hybrid nanoparticle (HNP) using a Layer-by-Layer (LbL) method for siRNA delivery targeting eEF2K in TNBC. The HNPs consist of a silver nanoparticle (AgNP) core, coated with poly (allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS), and loaded with eEF2K-siRNA and quercetin (QU), a chemotherapeutic agent, in separate layers. The nanoparticles also incorporated 4-ATP molecules for Raman traceability. In vitro experiments on TNBC cell lines (MDA-MB-231, BT-549, 4T1) showed that the combination therapy of eEF2K-siRNA and QU reduced cell viability, inhibited colony formation, and suppressed cell migration. At high 120 nM of siRNA concentration, 3D spheroid disintegration, activation of apoptotic pathways, and eventual necrotic cell death were observed. The results demonstrate that the developed HNPs are non-toxic, effective, and offer potential as a theranostic platform for TNBC treatment.