Deoxyribonucleic acid at GpC dinucleotide sites (GpC DNA)

DNA at GpC sites refers to the specific dinucleotide sequence 5'-guanine-cytosine-3' within the deoxyribonucleic acid polymer. These sites serve as critical recognition and binding motifs for several potent antitumor antibiotics, most notably Dactinomycin (Actinomycin D) (Sobell, 1985, PNAS). Dactinomycin intercalates specifically at GpC sequences, with its phenoxazone ring system stacking between the base pairs and its cyclic peptides resting in the minor groove (Gao & Patel, 1989, Biochemistry). This binding stabilizes the DNA-drug complex, effectively blocking the movement of RNA polymerase and inhibiting the synthesis of messenger RNA (PubChem). Consequently, GpC-targeting agents are primarily used in the treatment of various cancers, including Wilms tumor, rhabdomyosarcoma, and certain germ cell tumors, by disrupting the proliferative capacity of rapidly dividing cells (FDA, Dactinomycin Label). Other agents like Plicamycin (Mithramycin) also target G-C rich regions, including GpC motifs, to inhibit transcription of genes like c-myc (Cons & Fox, 1989, NAR). However, the lack of absolute sequence specificity leads to significant side effects such as myelosuppression and hepatotoxicity (StatPearls, Dactinomycin). Therapeutic challenges include the high toxicity profile and the potential for extravasation injury during administration (StatPearls).

Other names

GpC sites5'-GpC-3' DNAGuanine-Cytosine dinucleotide sites

Intercalation and minor groove binding at GpC sequences, which sterically hinders RNA polymerase progression and inhibits DNA-dependent RNA synthesis (transcription) (Sobell, 1985, PNAS; PubChem CID 2019).