Epigenetic Mechanism Of EZH2/H3K27me3 Complex Regulating MIR22HG Expression And Influencing Prostate Cancer Progression

Background:The incidence rate of prostate cancer(PCa)is the second male malignancy in the world.With the rapid development of social economy,in recent years,the incidence rate of the prostate cancer has increased year by year in China.Notably,the five-year survival rate of prostate cancer in China is 66.4%,which is far lower than that in the developed countries such as 99.5% of the United States.Therefore,it has the pivotal scientific value and clinical application to actively explore the early diagnostic markers of prostate cancer.Studies show that the epigenetic modifications(such as DNA methylation,histone modification,chromatin remodeling,small RNA interference,etc.)in prostate cancer cells play an important role in the regulation process of cancerization and malignant transformation from normal cells to cancer cells.In the vitro experimental data,the analysis of PCa tissues showed that EZH2 /H3K27me3 complex regulated MIR22 HG in downstream PCa tissues,which conducted the regulatory function through MIR22 HG.Based on the in vitro experimental data,the following two questions have been proposed.What is the mechanism of MIR22 HG in the metastasis and progression of prostate cancer? Can MIR22 HG be involved in the regulation of other downstream tumor metastasis related genes or tumor proteins to affect the distant metastasis of prostate cancer?Objective:1.To illustrate the expression of long non-coding RNA-MIR22 HG in prostate cancer tissues and its biological function in prostate cancer cells.2.To illustrate that EZH2-mediated H3K27me3 epigenetic modification regulates the down-regulation of MIR22 HG expression in prostate cancer tissues mechanism.Methods:1.The high-throughput chip was used to screen the differentially expressed lnc RNAs in clinical prostate malignant tumor tissues of different pathological stages,and bioinformatics methods were used to determine the key tissue-specific expression lnc RNAs,and analyze their association with prostate cancer.2.The RNA interference technology was used to construct stable prostate cancer cell lines,and experiments illustrate the mechanism of MIR22 HG in prostate cancer cells in vitro.3.Bioinformatics analysis,PCR,Western blotting were used to identify the correlation between EZH2/H3K27me3 complex and MIR22 HG.Results:1.High-throughput chip results showed that the expression of MIR22 HG in prostate cancer tissues was significantly lower than that in adjacent normal tissues;the data analysis extracted from database showed that the m RNA level of MIR22 HG in metastatic prostate cancer tissues was significantly lower than that in matched adjacent tissues(P < 0.05);the expression level of MIR22 HG in metastatic prostate cancer tissues was significantly lower than that in non-metastatic prostate cancer tissues,There was statistical significance(P < 0.05);in the pathological TNM stage of prostate cancer,the m RNA level of MIR22 HG decreased with the higher stage(P <0.05).TCGA database analysis showed that the overall survival rate of patients with low expression of MIR22 HG was significantly lower than that of patients with high expression of MIR22HG(P < 0.05),and the disease-free survival time of patients with high expression of MIR22 HG was significantly higher than that of patients with low expression of MIR22HG(P < 0.05).Enrichment analysis of GO and KEGG showed that MIR22 HG was negatively correlated with biological activity,catabolism,EMT and cell receptor activity.CCK-8 cell proliferation experiment showed that compared with the control group(si-NC,NC),si-MIR22HG-2 transfected into prostate cancer cell DU145 and prostate epithelial cell RWPE-1 decreased the expression of MIR22 HG,and the proliferation ability of cell enhanced.2.The results of database analysis showed that EZH2 gene was highly expressed and MIR22 HG gene was lowly expressed in prostate cancer patients(P < 0.05);there was a negative correlation between EZH2 gene and MIR22 HG gene(r =-0.3274,P <0.05),PCR results showed that the m RNA expression of MIR22 HG was negatively correlated with EZH2(P < 0.05);Western blotting results showed that EZH2 was significantly down regulated with the increase of malignancy,and H3K27me3 was consistent with EZH2 protein expression.Conclusion:EZH2 down-regulates the expression of MIR22 HG through H3K27me3,which in turn affects the proliferation and progression of prostate cancer.