Effect and Mechanism of miR-206/MECOM/TGF-β/smad3 Axis in Inhibiting the Malignant Progression of Triple-negative Breast Cancer

GU Zehui; WANG Yadi; TAN Qi; CHEN Suxian; HE Dongning

Abstract：Objective Taking triple-negative breast cancer cell line 231 as the study object,to investigate the effect and mechanism of miR-206/MECOM/TGF-β/smad3 axis in inhibiting the malignant progression of triple-negative breast cancer.Methods Ualcan online analysis and Kaplan Meier Plotter online analysis were used to analyze the differential expression of MECOM,TGF-βR1,TGF-βR2,smad3,smad4,HDAC1,HDAC2 and CTBP between breast cancer group and normal breast cancer group and their prognostic relationship.Using cell co-culture and co-transfection techniques,transcription factor MECOM,overexpression and silencing miR-206 in MDA-MB-231 cells were respectively silenced,and both were co-transfected.The mrna expression levels of TGF-βR1,TGF-βR2,smad3,smad4,HDAC1,HDAC2 and CTBP were detected by RT-qPCR.Results Ualcan online analysis showed that MECOM and TGF-βR2 breast cancer groups were lower than normal breast cancer groups in TCGA-BRCA,and the difference was statistically significant(P＜0.05);Kaplan Meier Plotter online analyzed the differential expression of MECOM,TGF-βR1,TGF-βR2,smad3,smad4,HDAC1,HDAC2 and CTBP and their prognostic relationship.The results in the TCGA database indicated that patients with low and high MECOM expression had longer median survival(OS)(P＜0.05).Patients with high expression of smad3 and smad4 had longer median survival(OS)than those with low expression(P＜0.05).There was no significant difference in median survival(OS)between patients with high expression of TGF-βR1,TGF-βR2,HDAC1,HDAC2 and CTBP(P＞0.05).After simple silence of MECOM,mRNA expression levels of TGF-βR2,HDAC1,HDAC2,smad3,smad4 and CTBP in Si-MECOM group were decreased compared with blank control group(P＜0.05);after simple intervention with miR-206,mRNA expression levels of MECOM,TGF-βR1,TGF-βR2,HDAC1,HDAC2,smad4 and CTBP were decreased(P＜0.05);after co-transfection with MECOM and miR-206,mma expression levels of TGF-βR1,HDAC1,smad3 and SMad4 of siMECOM+inhibitor miR-206 group were decreased compared with those of Si-MECOM group(P＜0.05).The mRNA expression levels of TGF-βR2,HDAC2 and CTBP were increased(P＜0.05).Conclusion The regulation of miR-206 on MECOM may inhibit the activation of TGF-β/SMAD pathway and prevent TNBC progression by affecting the expression of TGF-BR2,HOAC2,and CTBPm RNA.