CpG-rich guanine residues in DNA (CpG-DNA)

CpG-rich guanine residues in the DNA of actively transcribed genes represent a critical structural and functional target for several classes of antineoplastic agents. These regions, often referred to as CpG islands, are typically located in or near the promoter regions of genes and serve as essential regulatory elements for gene expression. In actively transcribed genes, the DNA is in an open chromatin configuration, making the guanine residues more accessible to chemical modification by therapeutic agents. (Source: PubMed, PMC2613627; National Cancer Institute). Drugs such as trabectedin and various alkylating agents interact with these residues by forming covalent adducts, primarily at the N2 or N7 positions of guanine. This interaction disrupts the binding of transcription factors and interferes with the transcription-coupled repair machinery, leading to cell cycle arrest and programmed cell death. Because cancer cells often exhibit aberrant methylation patterns and high transcriptional activity in oncogenic pathways, these CpG-rich sites are leveraged as selective targets to inhibit tumor growth and overcome resistance to conventional therapies. (Source: Nature Reviews Cancer, doi:10.1038/nrc2607; PubChem).

Other names

CpG islandsGuanine-cytosine rich DNA sequencesCpG sitesDNA guanine residuesN7-guanine sitesN2-guanine sites

Drugs targeting these residues typically act via covalent alkylation or adduct formation at the N2 or N7 positions of guanine. This leads to DNA strand breaks, inhibition of transcription factors, and interference with the DNA repair machinery (such as Transcription-Coupled Nucleotide Excision Repair), ultimately triggering apoptosis in rapidly dividing or transcriptionally active cells.