Enhanced therapy for triple-negative breast cancer (TNBC) using combinatorial drug delivery

Breast cancer (BrCa) is the most common cancer among women. Although there has been progress in early detection and specific therapies, long-term success is still limited, especially for triple-negative breast cancer (TNBC). This challenge arises from issues such as recurrence, drug resistance, and side effects associated with treatments. Chemoprevention, which involves using natural compounds to delay, suppress, or prevent cancer development in individuals at high risk, shows promise, but clinical success is limited by poor bioavailability. Hedgehog (Hh) signaling pathways are being studied for the growth and metastasis of BrCa; thus, targeting Hh represents a promising therapeutic strategy. To address these challenges, we studied the effects of combining two drugs: honokiol (HNK), a natural compound derived from Magnolia officinalis , alongside the chemotherapy drug docetaxel (DTX) for treating TNBC. For this purpose, we employed gold nanoparticles (AuNPs). Our results show that dual drug delivery (HNK+DTX), combined with sonic hedgehog (Shh) DNA aptamer (AP32)- conjugated AuNPs, effectively targets the Hh pathway in TNBC cells that express it at high levels. We characterized the formulated AuNPs, including a Zetasizer for charge and size analysis, Transmission Electron Microscope (TEM), Fourier-Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), and Nanoparticle Tracking Analysis (NTA), before applying them to TNBC cells (MDA-MB-468 and MDA-MB-231). A cell viability/ cytotoxicity assay was performed to determine the IC 50 values and assess drug combination synergy. Additionally, 3D cell models confirmed the internalization of AuNPs and the efficacy of combination AuNPs compared to single-drug or scramble aptamer AuNPs (control). Mechanistic studies using immunofluorescence, flow cytometry, qRT-PCR, and Western blot analysis show that Shh-targeted delivery suppresses the expression of downstream signaling molecules, Gli1 and Ptch1, induces cell cycle arrest at the G 0 /G 1 phase, and triggers apoptosis. Furthermore, results from molecular dynamics simulations suggest that HNK influences both NF-κB-driven transcription and Shh-mediated signaling, subsequently affecting tumor cell-environment interactions. These findings highlight the potential of combination AuNPs for pathway-specific intervention in addressing TNBC, providing a foundation for further research in this area.