Cancer Genetics and Epigenetics 2024, Vol.12, No.2, 106-114 http://medscipublisher.com/index.php/cge 108 Epigenetic technologies have also made significant progress. Techniques such as methylation arrays and whole-genome bisulfite sequencing (WGBS) efficiently detect DNA methylation levels, uncovering epigenetic variations in cancer. ChIP-Seq (chromatin immunoprecipitation sequencing) technology analyzes the interaction between proteins and DNA, providing researchers with an important tool to study the regulatory mechanisms of histone modifications in cancer. The rise of single-cell sequencing technology allows for a more detailed understanding of tumor heterogeneity and genomic variations at the single-cell level. Single-cell RNA sequencing (scRNA-seq) reveals potential differences among tumor cell populations, while single-cell DNA sequencing (scDNA-seq) uncovers genomic variations at the individual cell level. The application of big data analysis and artificial intelligence enables genomics research to handle large datasets more effectively. The integration of these technologies not only enhances researchers' deep understanding of cancer genomics but also provides strong support for personalized medicine and precision therapy. 3 Basic Concepts of Epigenetic Modifications 3.1 DNA methylation DNA methylation is a key epigenetic modification that regulates gene expression by adding methyl groups to the DNA molecule (Pan et al., 2021). This modification occurs on the cytosine rings of DNA molecules, specifically at the C5 position of cytosine nucleotides. The methylation process primarily involves the DNA methyltransferases (DNMTs) family and demethylases (Figure 1). DNMTs are responsible for transferring methyl groups onto DNA, while demethylases are capable of removing methyl groups from DNA. Figure 1 Mechanism of DNA methylation This modification pattern exhibits significant dynamism, varying not only among different cell types and stages of life but also demonstrating the ability to adjust dynamically in disease states. Particularly in CpG islands (regions rich in CpG dinucleotides), DNA methylation patterns are especially prominent. These islands are usually located in gene promoter regions, directly influencing the transcriptional activity of adjacent genes. DNA methylation affects gene expression through various mechanisms, including blocking the binding of transcription factors and recruiting methylation recognition proteins to influence chromatin structure. This impact mechanism can be both stable and reversible, providing multiple levels of regulation for gene expression. In cancer, abnormal changes in DNA methylation are a common phenomenon. Cancer cells typically exhibit a genome-wide hypomethylation state, especially in CpG island regions. This hypomethylation state may lead to the inactivation of certain tumor suppressor genes and the overactivation of oncogenes, thereby driving tumor development. 3.2 Histone modifications Histone modification is another important form of epigenetic modification that regulates gene accessibility and transcriptional activity by altering the structure and compactness of chromatin. This modification involves various
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