Effect of exosomes from nasopharyngeal carcinoma on endothelium pyroptosis and metastasis.
Authors: Xingrui Chen , Cai Linbo 
Published: August 2023

93 Background: Nasopharyngeal carcinoma (NPC) is a malignant tumor occurring in the epithelium of nasopharyngeal mucosa. Radiotherapy can achieve a good therapeutic effect for NPC in situ. However, there is no effective treatment once distant metastasis occurring. Epstein-Barr virus (EBV) is an important pathogenic factor of NPC and also promotes tumor metastasis. The passage of circulating tumor cells through the vascular barrier is one of the rate-limiting steps of tumor distant metastasis, and vascular endothelial cells are an important component. Exosomes are an important way of information transmission between cells. And some small molecules in exosomes involve in tumor metastasis. How the exosomes of NPC cells affect vascular endothelial cells and promote metastasis has not been studied. Therefore, it is of great significance to explore the effect of the NPC exosomes with EBV component on the vascular endothelial cells of metastatic foci and the mechanism of promoting tumor metastasis, in order to find effective therapeutic targets and molecular markers indicating distant metastasis. Methods: 1. Immunohistochemical analysis was used to analyze the vascular endothelium of liver and lung tissues with NPC metastasis compared with that of non-tumor liver and lung in pathological sections; 2. Using transmission electron microscope, cells and dye molecules through vascular endothelial cell monolayer experiment, immunofluorescence and animal tumorigenesis experiment to detect the effect of NPC exosomes on vascular endothelial cells and NPC metastasis; 3. Using CRISPR-Cas9 knockout EBNA1, cell function test and miRNA sequencing technology to analyze to analyze molecular types that induce vascular endothelial cell pyroptosis in NPC exosomes; 4. Using bioinformatics prediction, luciferase reporter gene, immunofluorescence and animal tumorigenesis experiment to further clarify the molecular pathway of molecules in the NPC exosomes that induce endothelial cell pyroptosis. Results: 1. Immunohistochemistry showed that P20 and NT-GSDMD were significantly higher in vascular endothelial cells of liver and lung tissues with NPC metastasis than in non-tumor liver and lung; 2. NPC exosomes can promote the increase of molecules related to vascular endothelial cell pyroptosis (P20, NT-GSDMD and IL-1 β), the formation of vesicular protrusion of cell membrane and the destruction of vascular endothelial monolayer barrier. And vascular endothelial cell pyroptosis can promote the migration of circulating tumor cells out of blood vessels to form metastatic foci; 3. BART2-5p in NPC exosomes is the main effector molecule that induces vascular endothelial cell pyroptosis; 4. MRE11A is the target molecule of BART2-5p to induce vascular endothelial cell pyroptosis. Conclusions: 1. It was found for the first time that the vascular endothelial cell pyroptosis in liver and lung metastasis of NPC; 2. It is proved that BART2-5p in NPC exosomes is involved in regulating the vascular endothelial cell pyroptosis, and promoting NPC cells to go through blood vessels and form metastatic foci; 3. MRE11A mediates BART2-5p to induce the vascular endothelial cell pyroptosis.