Objective The aim of this study was to construct a functionalized nanogold radiosensitizer (tAuNMs-siRNA) with endothelial-targeting properties. Targeting the angiogenically active regions of liver cancer increases the local radiation dose delivered to the hepatocellular carcinoma cells in these areas. Concurrently, VEGF expression is downregulated to inhibit tumor neovascularization through the targeted release of VEGF-siRNA, organically integrating radiosensitization and antiangiogenic gene therapy.

Methods tAuNMs was synthesized in situ via an ion-induced method using glutathione (GSH), an angiogenesis-targeting peptide (cNGR), and a polylysine short peptide (CK9) as a template. Au serves as a radiosensitizer, cNGR is used to recognize angiogenically active regions in liver cancer, and CK9 provides siRNA loading sites. The composite nanodrug, tAuNMs-siRNA, was produced via loading VEGF-siRNA onto tAuNMs. A subcutaneous xenograft tumor model was established in BALB/c mice using H22 hepatocellular carcinoma cells. The survival status, body weight, and tumor volume of the mice were observed and measured during treatment to evaluate the therapeutic efficacy. Statistics were analyzed using one-way ANOVA and an independent sample t-test.

Results Transmission electron microscopy revealed that the tAuNMs were uniformly spherical and had a particle size of approximately 20 nm. Infrared spectroscopy confirmed the successful conjugation of cNGR and CK9 to tAuNMs via primary amide bonds. Agarose gel electrophoresis showed that tAuNMs completely loaded VEGF-siRNA at a mass ratio of 10:1 (tAuNMs:siRNA). At this ratio, the characteristic infrared double peak of the primary amine group became a single peak, indicating successful construction of tAuNMs-siRNA. Western blot results demonstrated that tAuNMs-siRNA had a stronger VEGF gene-silencing effect than free siRNA and the commercial gene carrier lipo2000. A clonogenic assay results showed substantially reduced cell clone formation rate after treatment with tAuNMs-siRNA. The animal experiment results indicated that the combined radiosensitization-antiangiogenic gene therapy group more significantly inhibited tumor growth than the blank control group and the single-treatment groups (P<0.05).

Conclusions The tAuNMs-siRNA combination therapy reduces the resistance of hepatocellular carcinoma cells to X-rays by inhibiting DNA damage repair and suppressing tumor neovascularization through downregulation of VEGF expression. The combination of these mechanisms strongly inhibits tumor growth.