Fig. 2

The role of epigenetic modifications in CRC liver metastasis. Epigenetic modification plays a vital role in gene regulation, mainly for various covalent modifications of histones and nucleic acids. The change of nucleic acid is in DNA and RNA. In addition, epigenetic modification also includes chromatin remodeling, non-coding RNA regulation, and other mechanisms. DNA methylation mainly occurs at the C of 5′-CpG-3′ to generate 5-methylcytosine (5mC). Under the action of DNA methyltransferase (DNMT), methyl groups are covalently bonded to the 5' carbon of cytosines of CpG dinucleotide residues. Hypermethylated gene expression is suppressed. Chromatin remodeling can regulate gene expression by regulating chromatin changes in chromatin structure and location, such as PU.1 opening chromatin regions of downstream effector genes and recruiting additional epigenetic modifiers to regulate gene expression. N6-Adenylate methylation (m⁶A), which inserts a methyl substituent on the N atom at the 6-position of adenosine. During transcription, m⁶A deposited on RNA transcripts affects gene expression post-transcriptionally by altering the structure of RNA or the specific recognition of m6-binding proteins. Non-coding RNAs are endogenous RNA molecules that cannot be translated into proteins but have particular gene expression regulatory functions, regulating post-transcriptional gene expression by complementary binding to RNA transcripts of the target gene