Plasma extracellular vesicle-derived circ_0001874 mediates immune escape of gastric cancer MGC-803 cells by negatively regulating miR-515-5p
To investigate the effect of circ_0001874 derived from plasma extracellular vesicle(EV)on the immune escape of gas-tric cancer MGC-803 cells,cancer tissue and its adjacent tissue of 89 gastric cancer patients were collected,and Evs in blood were isolated.circ_0001874 siRNA interference plasmid,circ_0001874 overexpression plasmid,and their related negative control plasmids were transfected into Evs,and qRT-PCR was used to detect the expression levels of circ_0001874 and miR-515-5p.miR-515-5p inhibitor and its negative control NC inhibitor were transfected into MGC-803 cells,respectively,and then co-cultured with Evs for 48 h.qRT-PCR was used to detect the expression levels of circ_0001874 and miR-515-5p in each group.MTT was used to detect the cell proliferation activity.Transwell was used to detect the cell invasion.Western blotting was used to detect the expression levels of proteins involved in the immune escape of tumor cells including factor related apoptosis ligand(FasL),indoleamine 2,3-dioxygenase 1(IDO1),PD-L2,and PD-L1.The results showed that compared to those of the adjacent tissue,the expression level of circ_0001874 in gastric cancer tissue was increased(P＜0.05),while the expression level of miR-515-5p was decreased(P＜0.05).After overexpression or knockdown of circ_0001874,the expression level of miR-515-5p in Evs decreased and increased,respectively(P＜0.05).After co-cultured with si-circ_0001874 EV,the expression level of miR-515-5p in MGC-803 cells increased while the cell proliferation,the invasion cell number,and the immune escape related proteins FasL,PD-L1,PD-L2 and IDO1 expression levels were all decreased(P＜0.05).However,inhibition of miR-515-5p could reverse the effects of si-circ_0001874 Evs on MGC-803 cell proliferation,invasion,and immune escape.This study suggests that plasma EV-derived circ_0001874 promotes the proliferation,invasion,and immune escape of gastric cancer MGC-803 cells by targeting and negatively regulating miR-515-5p.
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