MiRNA-451 Inhibits The Metastasis And EMT Of Triple-negative Breast Cancer By Targeting C-Myc Expression

Objective:MiRNA expression difference was confirmed between many malignant tumors,and the occurrence and development of the tumor is related closely.The purpose of this study is understand the possible regulatory relationship between miRNA-451 and c-Myc expression and transfection via lentivirus,changes of c-Myc and E-cadherin espression in miRNA-451 under different expression levels,The effects of c-Myc on cells proliferation,migration,invasiveness,cell cycle and apoptosis of the TNBC cells were studied.Methods:1.We collected 16 breast cancer specimens from Xinjiang medical university affiliated tumor hospital from 2016-08 to 2018-02,in which three negative breast cancer specimens were collected,The gene and protein expression difference of miRNA-451?c-Myc and E-cadherin was compared between clinical TNBC specimens and Precancerous tissue by Real time PCR and Western blot.2.Bioinformatics analysis and prediction of possible transcription factor binding sites.PCR amplification of c-Myc gene 3-UTR sequence,The activities of luciferase were detected by luciferase assay,and the changes of luciferase before and after cell intervention were detected with sea kidney luciferase as contrast.3.MDA-MB-231 cells were constructed by using the Sea Kidney Fluorozyme Ratio of Firefly,After culture and passage 2-3,The expression of miR-451 ? c-Myc and E-cadherin in each group were detected by rt-PCR and WesternBlot,The cell proliferation ability was detected by CCK8 method,migration and invasion ability by Transwell method,apoptosis and cell cycle were detected by Flow Cytometer.4.The expression of miRNA-451?c-Myc and E-cadherin in MDA-MB-231 cells was detected by Real time PCR and Western blot.Results:1.The expression level of miRNA-451 and E-cadherin in TNBC carcinoma was significantly decreased by Real time PCR and Western blot.The expression of miRNA-451 and E-cadherin in TNBC tissue was lower than that in paracancerous tissue.The expression of c-Myc in TNBC tissue was higher than that in paracancerous tissue.2?The results of the database showed that miR-451 and c-Myc had complementary binding sites,the activity of luciferase was detected in miR-451 mimic and c-Myc gene3-UTR was inhibited.compared with control group,miR-451 mimic could bind and inhibited luciferase activity,The reported fluorescence activity in wild type vectors decreased significantly(P<0.05),the difference was statistically significant(P<0.05),miRNA-451 and c-Myc gene have complementary regions,miRNA-451 combines c-Myc by combining 3-UTR region,c-Myc is the main target factor of EMT and invasion and metastasis of triple-negative breast cancer in miRNA-451.3.The results of RT-PCR and WseternBlot showed that MDA-MB-231 cells with triple negative breast cancer were transfected with miRNA-451 mimic compared with the control group,The expression level of c-Myc was decreased significantly(P<0.05),and E-cadherin was increased significantly(P<0.05),The expression of c-Myc in miR-451 inhibitor significantly increased after transfection(P<0.05),the expression of E-cadherin decreased significantly(P<0.05),overexpression of miR-451 triple negative breast cancer can inhibit tumor activity.the expression of c-Myc in triple negative breast cancer was high,miR-451 and E-cadherin were low in triple negative breast cancer tissues.The overexpression of miR-451 in MDA-MB-231 cells can not only inhibit the proliferation,migration and invasion of cells,Flow Cytometry revealed an increase in the G0/G1 phase to promote cell death.overexpression of miR-451 in triple negative breast cancer inhibits tumor active c-Myc in highly metastatic breast cancer,Overexpression of miR-451 inhibits EMT and invasion and metastasis in tumor cells.Conclusions:1)c-Myc is higly expression in triple-negative breast cancer tissues,the expression of miR-451 and E-cadherin was low in triple-negative breast cancer tissues and negative correlation between miR-451 and c-Myc has found.2)miR-451 and c-Myc has complementary binding sites,the c-Myc is downstreamtarget gene of miR-451.3)The negative target regulationship between miR-451 and c-Myc was confirmed in triple-negative breast cancer,the expression of miR-451 silencing may lead to the overpression of c-Myc,thus down-regulate the expression of E-cadherin,EMT and tumor invasion and metastasis were induced.