Objective To investigate the potential mechanism of tumor-derived exosome miR-3173-5p promoting the activation of cancer-associated fibroblasts(CAFs)and regulating the proliferation,invasion and apoptosis of non-small cell lung cancer(NSCLC)cells.Methods Exosome(Exo)of NSCLC cell A549 was extracted,the morphology of Exo was observed by transmission electron microscopy,and the expression of Exo marker protein was detected by Western blot.Real-time quantitative fluorescent PCR(qRT-PCR)was used to detect the expression of miR-3173-5p in A549 cells and Exo.The binding of miR-3173-5p to F-box/WD-40 domain protein11(FBXW11)was predicted by Starbase database,and verified by luciferase reporter gene analysis.Human lung fibroblast cell line(MRC-5)was treated with Exo and Exo inhibitor GW4869 or NC inhibitor/mimic or miR-3173-5p inhibitor/mimic and/or FBXW11 overexpression/empty vector,NC group,Exo group,Exo+GW4869 group,Exo-NC inhibitor group,Exo-miR-3173-5p inhibitor group,Exo-NC mimic group,Exo-miR-3173-5p mimic group,Exo-miR-3173-5p mimic+Vector group and Exo-miR-3173-5p mimic+FBXW11 group were set up respectively.The level of CAFs marker protein[Matrix metalloproteinase-9(MMP-9),α-Smooth muscle aorta(α-SMA),Chemokine(C-X-C motif)ligand 12(CXCL12),Fibronectin,Vimentin,Interleukin-1β(IL-1β),Interleukin-6(IL-6),Interleukin-8(IL-8)]in cells of each group was detected by Western blot analysis,and the influence of exosome miR-3173-5p and FBXW11 expression on CAFs activation was analyzed.Exo and Exo-miR-3173-5P mimic were separated and the supernatant of MRC-5 cells incubated with Exo-FBXW11 was used as conditioned medium(CM)to culture A549 cells.The NC-CM group,Exo-CM group,Exo-miR-3173-5p mimic-CM group and Exo-FBXW11-CM group were set up respectively.MTT assay,Transwell assay and flow cytometry were used to detect the effects of CAFs activation on proliferation,invasion and apoptosis of NSCLC cells.Results Transmission electron microscopy showed that the diameter of exosomal vesicles derived from NSCLC cells was about 30～100 nm.Western blot analysis showed that all exosome labeled proteins were positive.The expression of miR-3173-5p(33.45±3.16)in NSCLC-derived exosomes was significantly higher than that in tumor cells(1.01±0.07),and the difference was statistically significant(t=1.263,P<0.001).MiR-3173-5p targets FBXW11 and inhibits its expression.Compared with NC group,CAFs marker protein levels in Exo group were significantly increased(t=12.214～24.908),the expression of CAFs marker protein in Exo+GW4869 group was significantly inhibited compared with Exo group(t=13.160～25.143),the differences were statistically significant(all P<0.01),respetively.Compared with Exo group,miR-3173-5p inhibitor inhibited EXO-induced CAFs marker protein expression(t=11.059～21.094),and miR-3173-5p mimic promoted the expression of CAFs marker protein(t=12.943～18.671),the differences were statistically significant(all P<0.01),respectively.Overexpression of FBXW11 reversed the induction of CAFs activation by miR-3173-5p mimic.Compared with the NC-CM group,the proliferation activity and invasion rate of A549 cells in the Exo-CM group were significantly enhanced,and the apoptosis rate was significantly inhibited(t=10.207,2.359,3.001),miR-3173-5p mimic enhanced the promoting effect of Exo-CM on proliferation and invasion of A549 cells and the inhibitory effect on apoptosis(t=9.399,3.438,3.208),while overexpression of FBXW11 can antagonize the promotion effect of Exo-CM on proliferation and invasion of A549 cells and the inhibition effect on apoptosis(t=18.868,7.070,9.813),the differences were statistically significant(all P<0.05),respectively.Conclusion Tumor-derived exosome miR-3173-5p promotes CAFs activation through targeted inhibition of FBXW11 expression,further promotes proliferation and invasion of NSCLC cells,inhibits cell apoptosis,and regulates the occurrence and development of NSCLC.

Objective To investigate the potential mechanism of tumor-derived exosome miR-3173-5p promoting the activation of cancer-associated fibroblasts(CAFs)and regulating the proliferation,invasion and apoptosis of non-small cell lung cancer(NSCLC)cells.Methods Exosome(Exo)of NSCLC cell A549 was extracted,the morphology of Exo was observed by transmission electron microscopy,and the expression of Exo marker protein was detected by Western blot.Real-time quantitative fluorescent PCR(qRT-PCR)was used to detect the expression of miR-3173-5p in A549 cells and Exo.The binding of miR-3173-5p to F-box/WD-40 domain protein11(FBXW11)was predicted by Starbase database,and verified by luciferase reporter gene analysis.Human lung fibroblast cell line(MRC-5)was treated with Exo and Exo inhibitor GW4869 or NC inhibitor/mimic or miR-3173-5p inhibitor/mimic and/or FBXW11 overexpression/empty vector,NC group,Exo group,Exo+GW4869 group,Exo-NC inhibitor group,Exo-miR-3173-5p inhibitor group,Exo-NC mimic group,Exo-miR-3173-5p mimic group,Exo-miR-3173-5p mimic+Vector group and Exo-miR-3173-5p mimic+FBXW11 group were set up respectively.The level of CAFs marker protein[Matrix metalloproteinase-9(MMP-9),α-Smooth muscle aorta(α-SMA),Chemokine(C-X-C motif)ligand 12(CXCL12),Fibronectin,Vimentin,Interleukin-1β(IL-1β),Interleukin-6(IL-6),Interleukin-8(IL-8)]in cells of each group was detected by Western blot analysis,and the influence of exosome miR-3173-5p and FBXW11 expression on CAFs activation was analyzed.Exo and Exo-miR-3173-5P mimic were separated and the supernatant of MRC-5 cells incubated with Exo-FBXW11 was used as conditioned medium(CM)to culture A549 cells.The NC-CM group,Exo-CM group,Exo-miR-3173-5p mimic-CM group and Exo-FBXW11-CM group were set up respectively.MTT assay,Transwell assay and flow cytometry were used to detect the effects of CAFs activation on proliferation,invasion and apoptosis of NSCLC cells.Results Transmission electron microscopy showed that the diameter of exosomal vesicles derived from NSCLC cells was about 30～100 nm.Western blot analysis showed that all exosome labeled proteins were positive.The expression of miR-3173-5p(33.45±3.16)in NSCLC-derived exosomes was significantly higher than that in tumor cells(1.01±0.07),and the difference was statistically significant(t=1.263,P<0.001).MiR-3173-5p targets FBXW11 and inhibits its expression.Compared with NC group,CAFs marker protein levels in Exo group were significantly increased(t=12.214～24.908),the expression of CAFs marker protein in Exo+GW4869 group was significantly inhibited compared with Exo group(t=13.160～25.143),the differences were statistically significant(all P<0.01),respetively.Compared with Exo group,miR-3173-5p inhibitor inhibited EXO-induced CAFs marker protein expression(t=11.059～21.094),and miR-3173-5p mimic promoted the expression of CAFs marker protein(t=12.943～18.671),the differences were statistically significant(all P<0.01),respectively.Overexpression of FBXW11 reversed the induction of CAFs activation by miR-3173-5p mimic.Compared with the NC-CM group,the proliferation activity and invasion rate of A549 cells in the Exo-CM group were significantly enhanced,and the apoptosis rate was significantly inhibited(t=10.207,2.359,3.001),miR-3173-5p mimic enhanced the promoting effect of Exo-CM on proliferation and invasion of A549 cells and the inhibitory effect on apoptosis(t=9.399,3.438,3.208),while overexpression of FBXW11 can antagonize the promotion effect of Exo-CM on proliferation and invasion of A549 cells and the inhibition effect on apoptosis(t=18.868,7.070,9.813),the differences were statistically significant(all P<0.05),respectively.Conclusion Tumor-derived exosome miR-3173-5p promotes CAFs activation through targeted inhibition of FBXW11 expression,further promotes proliferation and invasion of NSCLC cells,inhibits cell apoptosis,and regulates the occurrence and development of NSCLC.