Zebularine (NSC 309132) Zebularine (NSC 309132, 4-Deoxyuridine) is a DNA methylation inhibitor that forms a covalent complex with DNA methyltransferases , also inhibits cytidinedeaminase with K i of 2 μM in a cell-free assay. In vitro
Zebularine is a cytidine analogue containing a 2-(1H)-pyrimidinone ring, originally synthesized as a cytidine deaminase inhibitor. Zebularine is shown to form a tight, covalent complex with bacterial methyltransferases. In N. crassa, zebularine inhibits DNA methylation and reactivates a gene previously silenced by methylation. Zebularine is a global inhibitor of DNA methylation, similar to 5-Aza-CR, rather than a selective inhibitor. Zebularine induces the myogenic phenotype in 10T1/2 cells, which is a phenomenon unique to DNA methylation inhibitors. Zebularine reactivates a silenced p16 gene and demethylates its promoter region in T24 bladder carcinoma cells. Zebularine is only slightly cytotoxic to T24 cells. Zebularine is preferentially incorporated into DNA and exhibits greater cell growth inhibition and gene expression in cancer cell lines compared to normal fibroblasts. In addition, zebularine preferentially depletes DNA methyltransferase 1 (DNMT1) and induces expression of cancer-related antigen genes in cancer cells relative to normal fibroblasts.
In vivo
Zebularine is only slightly cytotoxic to tumor-bearing mice (average maximal weight change in mice treated with 1000 mg/kg zebularine = 11% [95% CI = 4% to 19%]). Compared with those in control mice, tumor volumes are statistically significantly reduced in mice treated with high-dose zebularine administered by intraperitoneal injection or by oral gavage. Cell Data