Guanine-Cytosine-rich duplex DNA (GC-rich DNA)

Guanine-Cytosine-rich (GC-rich) duplex DNA refers to double-stranded DNA sequences characterized by a high proportion of G-C base pairs, which are held together by three hydrogen bonds, providing greater thermal stability than A-T pairs (Marmur & Doty, 1962; PubMed: 14470118). These sequences are frequently clustered in "CpG islands" located within the promoter regions of approximately 60-70% of mammalian genes, where they serve as primary sites for transcription initiation and epigenetic regulation via DNA methylation (Gardiner-Garden & Frommer, 1987; PubMed: 3656447). In many cancers, the aberrant binding of transcription factors, such as Sp1, to these GC-rich promoters drives the overexpression of oncogenes and anti-apoptotic factors (Safe & Abdelrahim, 2005; PubMed: 16039168). Consequently, GC-rich DNA is targeted by small-molecule drugs like Mithramycin A and Dactinomycin, which bind to the minor groove or intercalate between bases to physically displace transcription factors and inhibit gene expression (Lombardi et al., 1994; PubMed: 8163974). While these interactions can effectively suppress tumor growth, the ubiquity of GC-rich sequences throughout the genome often leads to significant off-target effects and systemic toxicity, posing a major challenge for clinical development (Previdi et al., 2010; PubMed: 20410177).

Other names

GC-rich sequencesGuanine-Cytosine rich regionsGC-rich DNA motifsCpG-rich DNA

Small molecules target GC-rich duplex DNA by binding to the minor groove or intercalating between base pairs, which sterically hinders the binding of transcription factors like Sp1 and inhibits RNA polymerase activity, leading to suppressed gene expression and cell death (Lombardi et al., 1994; PubMed: 8163974).