Cancer Genetics and Epigenetics 2024, Vol.12, No.2, 106-114 http://medscipublisher.com/index.php/cge 111 Figure 3 Histone methylation and gene expression Histone acetylation is usually associated with gene activation. In cancer, abnormal acetylation of certain genes may lead to their overactivation, promoting cancer cell proliferation and survival. Conversely, dysregulation of histone acetylation can also lead to the inactivation of tumor suppressor genes. Histone phosphorylation is involved in multiple key biological processes such as cell signaling, cell cycle regulation, and gene expression. In cancer, abnormal histone phosphorylation can disrupt cellular signals, increasing the proliferation and metastatic potential of cancer cells. Histone ubiquitination is a modification process that regulates histones by attaching small ubiquitin proteins. In cancer, abnormal ubiquitination can lead to the degradation of certain tumor suppressor proteins, thereby promoting uncontrolled cancer cell growth. Some histone proteolytic modifications, such as those by protein kinases and proteases, are involved in regulating multiple cell signaling pathways. In cancer, abnormal changes in these enzymatic modifications can cause cell cycle dysregulation and evasion of apoptosis. 4.3 Regulatory mechanisms of Non-coding RNA in tumorigenesis Non-coding RNAs (ncRNAs) play key regulatory roles in the development and progression of tumors, including miRNA, lncRNA, siRNA, and circRNA. These ncRNAs participate in multiple biological processes of tumors through various mechanisms. miRNAs, as short non-coding RNAs, regulate gene expression by binding to the mRNA of target genes. In tumors, abnormal expression of certain miRNAs leads to aberrant expression of target genes, thereby promoting or inhibiting tumor growth and metastasis. miRNAs also regulate multiple cell signaling pathways, affecting cell proliferation, apoptosis, and invasion. lncRNAs regulate chromatin structure and stability by interacting with chromatin, thus influencing gene accessibility. In tumors, abnormal expression of certain lncRNAs may lead to the silencing of tumor suppressor genes or the overexpression of oncogenes. Additionally, some lncRNAs act as "sponges" for miRNAs, binding to miRNAs and mitigating their negative regulation on target genes. siRNA, as part of the RNA interference (RNAi) pathway, achieves gene silencing by specifically degrading the mRNA of target genes. In cancer therapy, siRNA technology is widely used to inhibit the expression of oncogenes. circRNAs act as "sponges" for miRNAs, absorbing miRNAs and preventing them from negatively regulating target genes, thereby affecting cellular biological processes. Moreover, some circRNAs interact with proteins, regulating protein function. 5 Interrelationship Between Cancer Genomics and Epigenetics Cancer genomics and epigenetics are two critical aspects of understanding cancer complexity, with a close interrelationship between them. Cancer genomics focuses on genomic variations and mutations, while epigenetics
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