Abstract: Objective: To identify differentially expressed proteins in the lymph fluid of rabbits with breast cancer lymphatic metastasis and normal rabbits, and to analyze and verify using proteomics technology. Materials and Methods: Rabbits with breast cancer lymph node metastasis and healthy rabbits were selected. Lymph fluids were precisely extracted under the guidance of percutaneous contrast-enhanced ultrasound (CEUS). Label-free quantitative proteomics (LFQ) was used to detect and compare differences, and differential protein expression was obtained. Bioinformatics analysis was performed using KEGG and GO analysis software, selecting the most significantly differentially expressed proteins. Finally, parallel reaction monitoring technology (PRM) was applied for validation. Results: A total of 547 significantly differentially expressed proteins were found in this study, including 371 upregulated proteins and 176 downregulated proteins. They were mainly involved in various cellular and metabolic pathways, including upregulated proteins such as BLVRA, IDH2, and downregulated proteins such as PDXK. The upregulated proteins PDIA3, PRKAR1A, and ABCC4 participated in immune regulation, endocrine regulation, and anti-tumor drug resistance regulation, respectively. Conclusion: These proteins are involved in the pathophysiological processes of tumor development and metastasis, and can be used as predictive indicators for breast cancer metastasis and as new targets for treatment.

The metastasis of breast cancer is believed to have a negative effect on its prognosis. Benefiting from the remarkable deep-penetrating and non-invasive characteristics, sonodynamic therapy (SDT) demonstrates a whole series of potential leading to cancer treatment. To relieve the limitation of monotherapy, a multifunctional nanoplatform has been explored to realize the synergistic treatment efficiency. Herein, we establish a novel multifunctional nano-system which encapsulates chlorin e6 (Ce6, for SDT), perfluoropentane (PFP, for ultrasound imaging), and docetaxel (DTX, for chemotherapy) in a well-designed PLGA core-shell structure. The synergistic nanoparticles (CPDP NPs) featured with excellent biocompatibility and stability which primarily enables its further application. Upon low intensity focused ultrasound (LIFU) irradiation, the enhanced ultrasound imaging could be revealed both in vitro and in vivo. More importantly, combined with LIFU, the nanoparticle exhibits intriguing antitumor capability through Ce6 induced cytotoxic reactive oxygen species (ROS) as well as DTX releasing to generate a concerted therapeutic efficiency. Furthermore, this treating strategy actives a strong anti-metastasis capability by which lung metastatic nodules have been significantly reduced. The results indicate that the SDT-oriented nanoplatform combined with chemotherapy could be provided as a promising approach in elevating effective synergistic therapy and suppressing lung metastasis of breast cancer.