Targeted Delivery of Gliotoxin-Loaded Nanocarriers Heightens Therapeutic Potential in Hypoxic Environment of Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) presents significant therapeutic challenges owing to its aggressive nature and the lack of targeted treatments. The hypoxic tumor microenvironment further ameliorates resistance and promotes cancer stem cell maintenance. Gliotoxin, a potent anticancer fungal secondary metabolite, was selected as a therapeutic agent. However, toxicity studies indicate that gliotoxin induces respiratory toxicity, limiting its application in cancer therapy. To address these problems, this study introduces a targeted drug delivery system employing folic acid-functionalized gold nanoclusters conjugated with PLGA nanoparticles (PLGA-AuNC-FA) to deliver gliotoxin to TNBC cells. The nanocarrier was synthesized by encapsulating gliotoxin in PLGA nanoparticles and conjugating them with folic acid-linked gold nanoclusters (AuNC-FA) to achieve a water-dispersible formulation. Comprehensive characterization using various analytical techniques confirmed the structural and functional properties of the drug delivery system. In vitro studies demonstrated dose-dependent cytotoxicity of gliotoxin-loaded nanocarriers in the TNBC cell lines MDA-MB-231 and MDA-MB-468, with IC₅₀ values of 407 and 218.7 nM, respectively. Furthermore, Western blot analysis of the treated cells showed downregulation of HIF-1α and alteration of HES1 and P21, the key components of the Notch signaling pathway. These findings suggest that the GTX-loaded PLGA-AuNC-FA nanocarrier may serve as a promising therapeutic strategy against TNBC by offering targeted cytotoxicity while reducing the off-target effects.