Efficacy evaluation and mechanism study on inhibition of breast cancer cell growth by multimodal targeted fluorescent nanobubbles carrying AMD070 and ICG

Objective: To construct targeted nanobubbles carrying both small-molecule CXCR4 antagonist AMD070 and light-absorbing material indocyanine green (ICG), and to study their in vitro multimodal imaging, as well as their mechanism and efficacy of inhibition of breast cancer cell growth. Methods: Nanobubbles carrying AMD070 and ICG (ICG-TNBs) were constructed by carbodiimide reaction and mechanical oscillation. The physical characteristics and in vitro multimodal imaging were determined. The binding potential of ICG-TNBs to human breast cancer cells were observed by laser confocal microscopy. CCK-8 and flow cytometry were used to analyze the role of ICG-TNBs+US in inhibiting proliferation and inducing apoptosis of tumor cells. Flow cytometry and Western blotting are used to analyse the ROS generation and molecular mechanisms. Results: ICG-TNBs had a particle size of 497.0±29.2 nm and a Zeta potential of -8.05±0.73 mV. In vitro multimodal imaging showed that the image signal intensity of ICG-TNBs increased with concentration. Targeted binding assay confirmed that ICG-TNBs could specifically bind to MCF-7 cells (CXCR4 positive), but not to MDA-MB-468 cells (CXCR4 negative). CCK-8 assay and flow cytometry analysis showed that ICG-TNBs+US could significantly inhibit the growth of MCF-7 breast cancer cells and promote their apoptosis. Flow cytometry and Western blotting showed that ICG-TNBs+US could significantly raise generation of ROS, reduce the expression of CXCR4，inhibit phosphorylation of Akt, and increase the expression of Caspase3 and Cleaved-caspase3. This indicated that ICG-TNBs could effectively inhibit and block the SDF-1/CXCR4 pathway, thus leading to the apoptosis of MCF-7 cells. Conclusion: ICG-TNBs can specifically bind to CXCR4 positive breast cancer cells, furthermore inhibit growth and promote apoptosis of breast cancer cells combined with ultrasonic irradiation by blocking the SDF-1/CXCR4 pathway. This study introduces a novel concept, method and mechanism for integration of targeted diagnosis and treatment of breast cancer.