Dendrimer Gel Nanoparticles with Dual-Targeting of uPAR and Ribonucleotide Reductase R2 Influence Necrosis, Apoptosis, and Cell Cycle Arrest in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype with limited treatment options due to the absence of estrogen (ER), progesterone (PR), and human epidermal growth factor receptor 2 (HER2) receptors. We previously developed highly adaptable polyamidoamine (PAMAM) dendrimer-based gel nanoparticles (GDP-uPA/GTI) with dual-targeting capabilities against urokinase-type plasminogen activator receptor (uPAR) and ribonucleotide reductase R2 (R2) to achieve selective antitumor effects. In this study, we investigated the underlying mechanisms of GDP-uPA/GTI-induced tumor inhibition. In vivo, GDP-uPA/GTI significantly downregulated R2 expression and activated caspase 8 and caspase 3, indicating caspase-dependent apoptosis. Histological evaluation of major organs revealed no observable toxicity. In MDA-MB-231 cells, GDP-uPA/GTI induced time-dependent S and G2/M phase cell cycle arrest and significantly increased necrosis, with a moderate rise in apoptotic populations. Compared to naked GTI and nontargeted GDP/GTI, GDP-uPA/GTI consistently showed superior efficacy in R2 knockdown, cell cycle disruption, and apoptosis/necrosis. These findings confirm that GDP-uPA/GTI exerts multilevel antitumor effects through targeted gene suppression, apoptosis induction, and replication blockade and support its continued development as a potent therapeutic strategy for TNBC.