Guanine-cytosine-rich DNA sequences (GC-rich DNA)

Guanine-cytosine (GC)-rich DNA sequences are genomic regions characterized by a high frequency of G and C nucleobases, frequently located within gene promoters and regulatory elements known as CpG islands. These sequences play a fundamental role in biological processes by serving as binding sites for specific transcription factors, such as Sp1, and acting as the primary substrate for DNA methyltransferases involved in epigenetic regulation (Gardiner-Garden & Frommer, 1987, Journal of Molecular Biology). In various diseases, particularly cancer, the dysregulation of genes with GC-rich promoters drives tumor growth, metastasis, and resistance to therapy. Consequently, these sequences are targeted by small molecules like Mithramycin A and Dactinomycin, which bind to the DNA minor groove or intercalate between bases to disrupt the transcriptional assembly (Remington's Pharmaceutical Sciences). Modern therapeutic strategies also focus on G-rich sequences capable of forming G-quadruplexes, which are secondary structures that regulate telomere stability and oncogene expression (Brooks et al., 2010, Genes & Development). However, because GC-rich motifs are ubiquitous in the human genome, drugs targeting them often face challenges related to systemic toxicity and a narrow therapeutic index.

Other names

GC-rich regionsCpG islandsG-quadruplex-forming sequencesGC-rich motifsGuanine-cytosine-rich elements

Drugs targeting GC-rich DNA sequences typically act through minor groove binding, intercalation, or covalent adduct formation. These interactions physically obstruct the binding of transcription factors (such as Sp1) and RNA polymerase to the DNA template, thereby inhibiting gene transcription and DNA replication (Choi et al., 2014, Scientific Reports). Additionally, some agents stabilize G-quadruplex structures formed by G-rich sequences, leading to DNA damage responses and telomerase inhibition (Huppert, 2008, Chemical Society Reviews).