Cancer Stem Cell-derived Exosomes Promote Drug Resistance and Invasion in Colorectal Cancer Cells
Cancer stem cells,a small population of cells with self-renewal and multidirectional differenti-ation potential in tumor tissues,can initiate primary tumors and mediate treatment resistance,tumor re-currence,and metastasis,but the mechanism of how they affect colorectal cancer at the cellular level is unknown.Therefore,in this study,we explored the effect of cancer stem cells and their exosomes on the malignant phenotype of colorectal cancer.First,CD 166+CD44+cancer stem cells(CSCs)were isolated from colorectal cancer tumor tissues,and then cancer stem cell-derived exosomes(CSCexo)and colorec-tal cancer SW480 cell-derived exosomes(Sexo)were extracted by ultracentrifugation.Then,exosomes were subjected to NTA particle size analysis,electron microscopic observation and identification by West-ern blotting.Subsequently,the successfully isolated CSC and CSCexo were co-cultured with colorectal cancer SW480 cells.The apoptosis rate of SW480 cells after co-culture was found to decrease from 20％to about 13％by CCK-8,apoptosis assay(P＜0.01)and the invasive ability was significantly increased(P＜0.001)after co-culture with CSC or CSCexo.In addition,in vivo animal experiments revealed that the tumor growth rate of the S-exo treatment group was slower than that of the CSCexo treatment group,and that CSCexo inhibited the drug efficacy of 5-FU against colorectal cancer tumors.PET/CT imaging,immunohistochemical analysis,and Western blotting experiments showed that CSCexo enhanced the up-take of the glucose analog 18F-FDG and the expression of the glycolytic enzymes HK2,PFKFB2,PKM2,and LDHA in colorectal cancer.In addition,interfering with the expression of glycolytic enzymes with siRNAs blocked the drug resistance induced by CSCexo.In summary,this study demonstrates that color-ectal cancer stem cells deliver exosomes that affect tumor glucose metabolism pathways and promote chemotherapy resistance and invasive ability,revealing the mechanism of formation and dynamic changes in the malignant tumor microenvironment.
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