Cytidine and deoxycytidine residues (C/dC)

Cytidine and deoxycytidine residues are fundamental building blocks of RNA and DNA, respectively, and are essential components of the cellular nucleotide pools. In a therapeutic context, these residues serve as the primary targets for nucleoside analog antimetabolites and epigenetic modifiers used extensively in oncology (PubChem CID 60750). Drugs such as decitabine and azacitidine are chemical analogs that incorporate into DNA or RNA at these specific sites; once incorporated, they covalently trap and inhibit DNA methyltransferases (DNMTs), leading to global DNA hypomethylation and the reactivation of silenced tumor suppressor genes (NIH/NCI, 2023). Other analogs, like gemcitabine and cytarabine, compete with natural deoxycytidine for incorporation into nascent DNA strands during the S-phase of the cell cycle, causing premature chain termination and triggering apoptosis in rapidly proliferating cancer cells. Furthermore, cytidine residues in DNA are the physiological substrates for the APOBEC family of deaminases, which play critical roles in innate antiviral immunity and are also implicated in generating somatic mutation signatures in various human cancers (Harris & Dudley, Virology, 2015).

Other names

DNA cytidineDeoxycytidineNucleotide pool cytidinedC residuesCytosine nucleosides

Incorporation of synthetic analogs into DNA or RNA in place of natural cytidine/deoxycytidine, leading to DNA methyltransferase (DNMT) inhibition, DNA chain termination, or induction of the DNA damage response (NCI Drug Dictionary; StatPearls, 2023).