Deoxyribonucleic acid (DNA) N7-guanine and N7-adenine adducts (N7-G/A DNA adducts)

DNA adducts at the N7 position of guanine and adenine are the primary molecular targets for many alkylating antineoplastic agents used in cancer therapy (PubChem, CID 767). The N7 position of guanine is the most nucleophilic site in DNA, making it highly susceptible to attack by electrophilic drugs like nitrogen mustards and nitrosoureas (National Cancer Institute). While N7-alkylguanine adducts themselves may not always block DNA polymerases, they can lead to the formation of apurinic sites through depurination or undergo imidazole ring-opening to form formamidopyrimidines, both of which are highly cytotoxic and mutagenic (PubMed, PMID: 25133745). Bifunctional alkylators can further react to form interstrand or intrastrand cross-links, which are particularly effective at stalling replication forks and inducing apoptosis in rapidly dividing cells (StatPearls, Alkylating Agents). However, the persistence of these adducts and the resulting DNA damage also contribute to the significant side effects of these drugs, including myelosuppression and the risk of secondary leukemias (American Cancer Society). Monitoring these adducts serves as a biomarker for both drug exposure and the efficacy of the alkylation process in clinical settings (PubMed, PMID: 11459311).

Other names

N7-alkylguanineN7-alkyladenineN7-guanine DNA lesionsN7-adenine DNA lesionsDNA alkylation productsN7-methylguanine

Alkylating agents transfer alkyl groups to the N7 position of guanine and adenine, leading to DNA damage, cross-linking, and induction of apoptosis.