The Mechanism Of VMIP-?N-terminal Peptide Reverses Paclitaxel Resistance In Breast Cancer By Regulating MiR-155-3p

Objective: To investigate the molecular mechanism of NT21 MP reversing paclitaxel resistance in human breast cancer cells via miR-155-3p.Methods: 1.The regulation of miR-155-3p by NT21 MP and differential expression levels of miR-155-3p in human breast cancer cell line MCF-7 and paclitaxel resistant MCF-7/PR;2.Biology software predicts and dual-luciferase reporter vectors to validate the respective target gene MYD88 of miR-155-3p p;3.Construction and screening of stable target gene interference fragments and overexpression vector;4.The regulation of apoptosis-related genes Bcl-2,Bax,Bak-1,Caspase-3 by miR-155-3p,target gene MYD88 by qRT-PCR and Western Blot;5.Wound healing assay,cells migration and invasion assays and flow cytometry were used to detect the effects of miR-155-3p,target gene MYD88 on cells migration,invasion,cycle and apoptosis in breast cancer cells;6.Construction of human breast cancer in vivo to study the effect miR-155-3p on the tumor and the tumor growth;7.The effect of NT21 MP combined with miR-155-3p mimics,si-MYD88 on the apoptosis-related genes Bcl-2,Bax,Bak and Caspase-3 in MCF-7/PR;8.The synergy effects of NT21 MP combined with miR-155-3p mimics,si-MYD88 on the cells migration,invasion,cells cycle and apoptosisc in MCF-7/PR were evaluated using Wound healing assay,cells migration and invasion assays and flow cytometry.Results: 1.NT21 MP up-regulated the expression of miR-155-3p(P <0.05).2.Compared with MCF-7 cells,miR-155-3p showed a low level of expression in MCF-7 /PR.Bioinformatics software predicted MYD88 as a potential target gene ofmiR-155-3p and verified by qRT-PCR,Western Blot and dual luciferase reporter gene.4.MiR-155-3p could inhibit the growth of breast cancer cells,Upregulation of proapoptotic genes Bax,Bak-1 and Caspase-3 down-regulated the expression of anti-apoptotic gene Bcl-2 and inhibited the migration and invasion of cells,while its target gene MYD88 had the opposite effects,mainly promoting breast cancer cells(P<0.05).5 Compared with single factor treatment,NT21 MP combined with miR-155-3p mimics showed significant effects in the regulation of apoptosis and invasion of MCF-7/ PR cells(P <0.05),whereas the overall effect on cell migration was shown to be partially additive(P <0.05).7.Compared with the single NT21 MP or si-MYD88 treatment,NT21MP combined with si-MYD88 showed a synergistic effect(P <0.05)in the inhibition of apoptosis and invasiveness of MCF-7 / PR cells,while the total Inhibits cell migration effect is partially superimposed(P <0.05).Conclusion: NT21 MP can down-regulate the expression of MYD88 by up-regulating miR-155-3p,reversing paclitaxel resistance in breast cancer cells,increasing the sensitivity of breast cancer cells to paclitaxel,and exerting anti-breast cancer effect.