Experimental Study Of Triple-negative Breast Cancer By Optical-targeting Nanoprobe Diagnosis And Microwave Ablation Treatment Based On Molecular Imaging Technology

Background:Molecular imaging (MI) combines medical imaging technology and molecular biotechnology. MI is a new discipline arising from the fast development of modern science, technology, and medicine in recent years. Using multiple imaging methods and molecular probes, MI allows quantitative and qualitative research of biological process at the cellular, molecular, or even genetic level in vivo. MI aims to explore biochemical processes and physiological changes in vivo. MI allows non-invasive imaging of specific, or individual, cells and/or molecules by using leading-edge molecular probes and multiple imaging methods such as MRI, CT, nuclide, PET, ultrasound, and optical imaging to select specific medium.Objective:We conducted optical imaging using a self-constructed molecular-targeted probe. To examine the biocompatibility and target specificity of our probe, we conducted a series of studies including in vivo/ex vivo experiments, construction of a nude mouse model of triple negative breast cancer (TNBC), imaging diagnosis, and treatment of tumors in vivo.Method:We synthesized an arginine-glycine-aspartic acid (RGD)-conjugated mesoporous silica nanoparticle (MSN) highly loaded with indocyanine green (ICG) to produce strong fluorescence. For this purpose, we prepared mesoporous silica nanoparticles (MSNs) using the reverse microemulsion method. Then we selected the near-infrared fluorescence (NIF) ICG dye as the fluorescence source and manufactured an ICG-MSNs fluorescent biochemical nanoparticle. We bound ICG-MSNs with RGD, the targeting ligand of neovascularization with tumor-targeted specialty. Thus, we synthesized an ICG/MSNs-RGD fluorescent probe. Using fluorescence microscopy, we observed the probe’s targeting efficiency in the RGD+ MDA-MB-231 triple negative breast cancer (TNBC) cell line. In contrast, in RGD-MCF-7 breast cancer cell lines, we examined the efficiency of the probe in detecting and targeting phagocytizing tumor cells.TNBC cell line-xenografts were used to construct an orthotopic nude mouse model of breast cancer metastasis in the peritoneum. To generate a xenograft model of human TNBC in nude mice, we established a bioluminescent MDA-MB-231 cell line stably expressing luciferase and green fluorescent protein (GFP). After subculture, cells were implanted subcutaneously under the scapular region, or breast pad, or intravenously into the tail vein of nude BALB/C mice.Thermal tomography and ultrasound imaging were used to detect tumor formation, growth, and metastasis in vivo and to measure the active targeting efficiency of the probe. Thermal tomography imaging detected abnormal tissue in nude mice in the transfected area five days after transfection with tumor cells. After nine days, ultrasound imaging detected some nodular structures in the same area. Therefore, thermal tomography imaging detected small tumors earlier than ultrasound imaging. Luminoscope monitoring, in vivo, showed that the fluorescent probe can accurately target breast cancer cells in the subcutaneous or shallow orthotopic area of a living mouse, and target multiple lymph nodes metastases in the abdomen of nude mice.Additionally, we wished to establish a new method for the treatment of tumors and of assessing the visible damage of orthotopic tumor cells. We treated the nude mouse model of TNBC with ultrasound-guided microwave ablation to see if we could destroy the tumor cells. We used contrast-enhanced ultrasound pre-and post-operatively to evaluate the perfusion and damage to the tumor vasculature.Result:Our studies indicate that:1. In nude mice xenografts, the RGD+ MDA-MB-231 TNBC cell lines exhibited greater phagocytosis of fluorescent nanoparticles than the RGD-MCF-7 breast cancer cell lines.2. RGD-ICG-MSNs have the advantages of excellent biocompatibility, low cytotoxicity, and good chemical stability.3. We successfully constructed an orthotopic nude mouse model of TNBC metastasis in the peritoneum, which can be analyzed using thermal tomography and fluorescence imaging in vivo. We examined the target specificity of the probe in vivo and the time taken to detect tumor cells post-transfection.4. We were able to detect tumor cells in the early stages of tumor growth by thermal tomography and ultrasound imaging. Thermal tomography imaging detected small tumors five days after transfection with tumor cells, while ultrasound imaging detected some nodular structures in the same area on the ninth day.5. The fluorescent targeting probe can accurately target breast cancers in the subcutaneous area or the shallow orthotopic area of a living mouse, as well as target the multiple metastases of lymph nodes in the abdomen of a nude mouse.6. Ultrasound-guided microwave ablation can treat the breast cancers in the subcutaneous, or the shallow orthotopic, area of a nude mouse. In addition, we used contrast-enhanced ultrasound to evaluate the perfusion and damage to the tumor vasculature pre-and post-operatively, with the aim to provide a new method of assessing orthotopic tumor cells for the treatment of tumors.Conclusion:RGD-ICG-MSNs have excellent biocompatibility, low cytotoxicity, and good chemical stability; thus, it can be used in the targeting diagnosis of the subcutaneous and orthotopic of nude mice modified with human TNBC. Our experiments have shown that thermal tomography and fluorescent imaging can be used for the accurate diagnosis of tumors in the early stages. Additionally, ultrasound-guided microwave ablation can destroy tumor cells.