Targeting FN1 to overcome gemcitabine resistance in gallbladder cancer: Mechanistic insights and an iRGD-modified PEG-PLGA nanoparticle delivery strategy

Gallbladder cancer (GBC) is among the most lethal biliary malignancies because it is often diagnosed at an advanced stage, displays a highly desmoplastic tumor microenvironment, and shows intrinsic resistance to gemcitabine (GEM)-based chemotherapy. Fibronectin 1 (FN1), a major extracellular matrix component, is markedly upregulated in GBC and contributes to chemoresistance through activation of the PI3K/AKT signaling pathway. Tumor-penetrating iRGD-modified PEG-PLGA nanoparticles (iRGD-NPs) were engineered to encapsulate FN1 small interfering RNA (siRNA) for targeted stromal modulation. iRGD-NPs improved tumor penetration and enabled efficient intracellular delivery of siRNA in vitro and in orthotopic mouse models. FN1 silencing attenuated PI3K/AKT signaling, reduced tumor cell proliferation, and reshaped the immunosuppressive microenvironment by decreasing stromal density and increasing cytotoxic immune infiltration. Notably, the combination of iRGD-NPs with GEM markedly reduced tumor burden and reversed drug resistance, overcoming both intrinsic and acquired GEM resistance. These findings suggest that the nanoparticle platform may offer a strategy to remodel extracellular matrix-driven stromal barriers and enhance chemotherapy efficacy in GBC. Targeting the FN1–PI3K/AKT axis using iRGD nanoparticles may hold translational potential for other solid tumors with similar stromal-mediated resistance profiles. Schematic of the molecular mechanism by which iRGD-Modified PEG-PLGA NPs delivering FN1 siRNA regulates the formation of the immunosuppressive environment impacting GBC chemotherapy resistance. • Bioinformatics analysis identifies FN1 as a key gene associated with GEM resistance in GBC. • Researchers construct iRGD-modified PEG-PLGA NPs and successfully load them with si-FN1. • Knockdown of FN1 reduces GEM resistance and the formation of an immunosuppressive microenvironment in GBC by inhibiting the activation of the PI3K signaling pathway. • NPs delivering si-FN1 inhibit tumor formation and the development of an immunosuppressive microenvironment in GEM-resistant GBC cells. • iRGD-NPs (si-FN1) are promising as a novel nanomedicine for the immunotherapy of GBC.