Cancer Genetics and Epigenetics, 2025, Vol.13, No.1, 21-31 http://medscipublisher.com/index.php/cge 25 5 Epigenetic Regulation and Non-Coding RNA Functions 5.1 Regulatory mechanisms of DNA methylation and histone modification DNA methylation and histone chemical modification are important epigenetic methods for regulating gene expression. Abnormal DNA methylation often occurs in prostate cancer. For example, hypermethylation in the promoter region of tumor suppressor genes can lead to silencing of core functional genes such as DNA repair and cycle regulation. The overall hypomethylation status of the genome may activate oncogenes (Nowacka-Zawisza and Wiśnik, 2017; Sugiura et al., 2020). Abnormal modifications such as histone acetylation also have carcinogenic effects. For example, the formation of abnormal enhancers can activate the transcription of tumor-related genes. These epigenetic changes not only reveal the mechanism of disease occurrence, but also provide new directions for diagnosis and treatment. Due to the reversible characteristics of the modification process, the development of targeted inhibitors has become a research hotspot. DNA methyltransferase inhibitors restore gene function through demethylation, while histone deacetylase inhibitors can reshape chromatin structure. Both have shown therapeutic potential (Dobosy et al., 2006; Sugiura et al., 2020). 5.2 The application value of miRNA in the diagnosis and treatment of prostate cancer Microrna (miRNA), as a regulatory factor of gene expression, has important clinical significance. It affects protein translation by binding to the mRNA of target genes and participates in biological processes such as cell proliferation and metastasis. Studies have found that there are changes in the expression profiles of specific mirnas in prostate cancer tissues, and some molecules can act as pro-cancer or tumor suppressor factors (Lu et al., 2020; Orafidiya et al., 2022). For example, the specific expression differences of certain mirnas in cancer tissues make them potential diagnostic markers. miRNA detection has multiple values in disease management: in addition to assisting in diagnosis, it can also predict treatment sensitivity and metastasis risk. Its stable existence in body fluids such as peripheral blood provides the possibility for non-invasive detection. Incorporating miRNA profiles into the clinical evaluation system can improve the accuracy of diagnosis and treatment (Figure 2) (Orafidiya et al., 2022). Figure 2 LncRNAs function as competing endogenous RNAs (ceRNAs) to sponge miRNAs (Adopted from Orafidiya et al., 2022) Image caption: (A) miRNAs bind to the 3′UTR of their target mRNAs to block translation; (B) (1) LncRNAs display complete or partial complementary with miRNAs; (2) LncRNA containing multiple MREs can sequester multiple miRNAs; (3) The increased expression of lncRNAs leads to more binding to miRNAs, resulting in fewer miRNA molecules to bind to other target mRNAs; (4) Different miRNAs bind to lncRNA through same MREs, leading to competition for binding sites; (C) As lncRNAs function as ceRNA to sequester miRNAs away from other target RNA, translation of targets is derepressed (Adopted from Orafidiya et al., 2022)
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