Influence of MiR-34c-Mediated Radiation-Induced Bystander Effect on Cardiac Fibroblasts and Intervention of Astragaloside Ⅳ
Objective:To explore the influence of miR-34c/Notchl-mediated radiation-induced bystander effect on cardiac fibroblasts(CFs)and the intervention of Astragaloside Ⅳ(AST).Methods:CFs were transfected with miR-34c inhibitor and miR-34c inhibitor NC to establish(miR-34c-inhibitor)-CFs and(miR-34c-inhibitor NC)-CFs,respectively.CFs pretreated with 5.1 μmol/L AST for 2 hours were used to cre-ate AST-CFs.These CFs were then irradiated with 2 Gy X-rays and co-cultured with normal CFs for 48 hours to establish a model of radiation-induced bystander effect.The experiment included five groups:normal control,model control,miR-34c-inhibitor NC,miR-34c-inhibitor,and AST 5.1 μmol/L.Techniques such as qRT-PCR,Western Blot,flow cytometry,CCK-8 assay,and scratch assay were used to analyze the ex-pressions of miR-34c and Notch1,the transdifferentiation of CFs,and changes in fibrogenic capability.Results:After irradiation,miR-34c in CFs increased,peaking at 24 hours(P＜0.01),and it was also elevated in CFs with bystander effect,reaching a maximum at 48 hours(P＜0.01).Compared with the normal control group,the model control group had higher miR-34c(P＜0.01)and lower Notchl(P＜0.01),and there was a significant rise in α-SMA and α-SMA-positive cells(P＜0.01).In addition,the proliferation activity and migration rate were ele-vated(P＜0.01),and fibrosis markers TGF-β1 and Col Ⅰ were up-regulated(P＜0.01).No significant differences were observed in the miR-34c-inhibitor NC group compared with the model control group.In contrast,the miR-34c-inhibitor and AST 5.1 μmol/L groups showed reversed expression of miR-34c and Notch1 in CFs with bystander effect,and there were remarkable reductions in α-SMA,α-SMA-positive cells,as well as proliferation and migration(P＜0.01).TGF-β1 and Col Ⅰ were also down-regulated(P＜0.01).Conclusion:X-ray expo-sure increased miR-34c in CFs and subsequently up-regulated miR-34c in CFs with bystander effect.This upregulation negatively regulated the Notch1 signaling pathway,promoting the transdifferentiation of CFs and enhancing their fibrogenic ability.AST exerted a protective role a-gainst radiation-induced cardiac fibrosis by inhibiting the miR-34c/Notch1-mediated radiation-induced bystander effects and thus inhibiting the transdifferentiation and fibrogenic processes of CFs.
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