Controlled delivery of iNOS antagonist, 1400W, for synergistic breast cancer therapy

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that lacks effective targeted therapies and is frequently associated with chemotherapy resistance and immunosuppression. Inducible nitric oxide synthase (iNOS) is overexpressed in breast cancer and has been strongly correlated with poor clinical outcomes, owing to its role in promoting tumor progression, invasiveness, and resistance to therapy. Although highly selective iNOS inhibitors such as N-(3-(Aminomethyl)benzyl)acetamidine (1400W) exhibit considerable therapeutic promise, their clinical translation has been hindered by unfavorable pharmacokinetic properties. To overcome these limitations, we developed a pH-responsive nanoscale formulation based on Schiff base conjugation between 1400W and oxidized PEGylated alginate (OPA), in combination with ionic interactions. The resulting nanoparticles (NPs) exhibited efficient release of 1400W under acidic conditions and effectively suppressed nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. While the NPs alone did not induce significant cytotoxicity, they synergistically enhanced the anticancer efficacy of paclitaxel (PTX) in MDA-MB-231 TNBC cells, significantly inhibiting cell viability and migration. In addition, the NP–PTX combination markedly reduced endothelial tube formation in HUVECs, compared to PTX alone indicating potentiation of the anti-angiogenic activity of PTX. In conclusion, the pH-responsive NPs enables effective modulation of NO signaling and enhances the therapeutic activity of PTX in TNBC cells. These findings support the potential of iNOS-targeted nanomedicine as an adjuvant strategy for TNBC treatment and warrant further investigation using in vivo models to evaluate pharmacokinetics, tumor accumulation, and antitumor efficacy of the NPs.