DNA guanine N7 nucleobase (N7-G)

The N7 position of guanine is the most nucleophilic site in the DNA molecule, making it a primary target for many classical chemotherapeutic agents (StatPearls, 2023). Platinum-based drugs, such as cisplatin, and alkylating agents, such as cyclophosphamide, interact with this site to form stable covalent adducts (NIH, 2022). These modifications often lead to the formation of intrastrand or interstrand cross-links, which physically obstruct the machinery required for DNA replication and RNA transcription (PubMed, 2021). The resulting structural damage to the genome triggers cellular stress responses and eventually leads to apoptosis, particularly in rapidly dividing malignant cells (Wikipedia, 2024). Beyond its role in oncology, the N7 position is also a site for endogenous methylation, which can be mutagenic if not properly repaired by cellular enzymes (PubChem, 2024). Therapeutic targeting of this site is a cornerstone of treatment for various cancers, including lung, ovarian, and testicular cancers (Journal of Clinical Oncology, 2020). However, because these drugs do not discriminate between cancerous and healthy DNA, they cause significant systemic toxicities such as bone marrow suppression and kidney damage (StatPearls, 2023). Resistance to these therapies often arises through the upregulation of DNA repair pathways, such as nucleotide excision repair, which remove the adducts from the N7 position (PubMed, 2021).

Other names

N7-guanineGuanine N7 positionN7-deoxyguanosineN7-GuaDNA guanine N7

Covalent modification (alkylation or platination) of the N7 nitrogen atom of guanine bases, leading to the formation of DNA adducts and cross-links that interfere with DNA replication and transcription (StatPearls, 2023; NIH, 2022).