Deoxyribonucleic acid (DNA) guanine N7 position (DNA N7-G)

The N7 position of guanine is the most nucleophilic site within the DNA major groove, serving as a primary target for electrophilic anti-cancer agents (Guainazzi & Schärer, 2010). This site is particularly susceptible to alkylation by nitrogen mustards and coordination by platinum-based drugs like cisplatin (PubChem, 2024). When these drugs bind to the N7 position, they form stable covalent adducts that can lead to the formation of intrastrand or interstrand cross-links (Alberts et al., 2014). These cross-links create physical lesions in the DNA template, which effectively stall the progression of DNA polymerase during replication and RNA polymerase during transcription (National Cancer Institute, 2023). The resulting DNA damage and replication stress activate cellular checkpoints and DNA repair pathways, such as nucleotide excision repair. If the damage is too extensive to be repaired, the cell undergoes programmed cell death or apoptosis. This mechanism is the basis for the cytotoxic effect of many classic chemotherapies used to treat a wide range of solid tumors and hematologic malignancies. However, the non-specific nature of this targeting leads to significant side effects in healthy, rapidly dividing tissues, such as the bone marrow and gastrointestinal tract (StatPearls, 2023). Furthermore, the mutagenic potential of these DNA modifications carries a long-term risk of inducing secondary cancers in survivors (American Cancer Society, 2024).

Other names

N7-guanineGuanine N7N7-alkylguanineDNA N7 positiond(G) sequencesDeoxyguanosine N7N7-platinated guanine

Covalent modification of the N7 position of guanine residues in DNA sequences, leading to the formation of DNA-drug adducts and cross-links that interfere with DNA replication and transcription (PubChem, 2024; National Cancer Institute, 2023).