G250 Antigen-Targeting Drug-Loaded Nanobubbles Combined with Ultrasound Targeted Nanobubble Destruction: A Potential Novel Treatment for Renal Cell Carcinoma.

Purpose: We intended to design G250 antigen-targeting temsirolimus-loaded nanobubbles (G250-TNBs) based on the targeted drug delivery system and to combine G250-TNBs with ultrasound targeted nanobubble destruction (UTND) to achieve a synergistic treatment for renal cell carcinoma (RCC). Methods: The filming-rehydration method was combined with mechanical shock and electrostatic interactions to prepare temsirolimus-loaded nanobubbles (TNBs). G250-TNBs were prepared by attaching anti-G250 nanobodies to the surface of TNBs using the biotinstreptavidin-bridge method. The ability of G250-TNBs to target the G250 antigen of RCC cells and the synergistic efficacy of G250-TNBs and UTND in the treatment of RCC were assessed. Results: The average diameter of the prepared G250-TNBs was 368.7 +/- 43.4 nm, the encapsulation efficiency was 68.59% +/- 5.43%, and the loading efficiency was 5.23% +/- 0.91%. In vitro experiments showed that the affinity of G250-TNBs to the human RCC 786-O cells was significantly higher than that of TNBs (P <0.05), and the inhibitory effect on 786-O cell proliferation and the induction of 786-O cell apoptosis was significantly enhanced in the group treated with G250-TNBs and UTND (G250-TNBs+ UTND group) compared with the other groups (P <0.05). In a nude mouse xenograft model, compared with TNBs, G250-TNBs could target the transplanted tumors and thus significantly enhance the ultrasound imaging of the tumors. Compared with all other groups, the G250-TNBs+UTND group exhibited a significantly lower tumor volume, a higher tumor growth inhibition rate, and a higher apoptosis index (P <0.05). Conclusion: The combined G250-TNBs and UTND treatment can deliver anti-tumor drugs to local areas of RCC, increase the local effective drug concentration, and enhance antitumor efficacy, thus providing a potential novel method for targeted therapy of RCC.