Zebularine

Zebularine, a chemically stable cytidine analog containing a 2-(1H)-pyridimidinone ring, is an effective DNA methylation inhibitor which can act with DNA methyltransferases to form a covalent complex. It has been shown to cause demethylation and reactivation of a silenced and hypermethylated p16 gene. Zebularine is able to induce the myogenic phenotype in 10T1/2 cells, which is a phenomenon unique to DNA methylation inhibitors. zebularine can act as a pro-drug leading to inhibition of DNA methylation and gene activation in fungal and mammalian cells. It was the only slightly cytotoxic to T24 cells in vitro. Zebularine is stable in aqueous solution up to a pH of 12.

Reference

C.B. Yoo, J.C. Cheng and P.A. Jones. Zebularine: a new drug for epigenetic therapy. Biochemical Society Transactions. 2004; 32(6): 910 – 912.

Jonathan C. Cheng, Cindy B. Matsen, Felicidad A. Gonzales, Wei Ye, Sheldon Greer, Victor E. Marquez, Peter A. Jones, Eric U. Selker. Inhibition of DNA Methylation and Reactivation of Silenced Genes by Zebularine. Journal of the National Cancer Institute. 2003; 95(5): 399 – 409.

Zebularine enhances apoptosis of human osteosarcoma cells by suppressing methylation of ARHI.[Pubmed:27685841]

Cancer Sci. 2016 Dec;107(12):1851-1857.

ARHI is an imprinted tumor suppressor gene and its methylation suppresses ARHI transcription levels to cause the development and progression of malignant tumors. Zebularine exerts a demethylation function for tumor suppressor genes. Our study aims to investigate the effect and mechanism of action of Zebularine on the epigenetic modification of the ARHI gene, and whether this effect may modulate the viability and apoptosis of human osteosarcoma cells. We found that Zebularine inhibited the viability and promoted apoptosis in osteosarcoma cells. Zebularine potentiated the expression of ARHI at both the protein and mRNA level. This was related to the downregulation of methylation of ARHI caused by Zebularine. Zebularine suppressed the interaction of DNA methyltransferase 1 (DNMT1) with histone methyltransferase G9a, but had no effect on G9a alone. Knockdown of DNMT1 or G9a can induce a reduction of ARHI methylation. Therefore, we inferred that Zebularine was likely to directly repress DNMT1 alone, but G9a was necessary to regulate the function of DNMT1 on ARHI methylation. Moreover, knockdown of ARHI rescued cell viability and apoptosis under the Zebularine-treated condition. We showed that Zebularine inhibited viability and promoted apoptosis by disturbing the interaction between DNMT1 and G9a, thereby resulting in lower ARHI methylation and elevated ARHI expression in osteosarcoma cells.

The DNA methyltransferase inhibitor zebularine exerts antitumor effects and reveals BATF2 as a poor prognostic marker for childhood medulloblastoma.[Pubmed:27785591]

Invest New Drugs. 2017 Feb;35(1):26-36.

Medulloblastoma (MB) is the most common solid tumor among pediatric patients and corresponds to 20 % of all pediatric intracranial tumors in this age group. Its treatment currently involves significant side effects. Epigenetic changes such as DNA methylation may contribute to its development and progression. DNA methyltransferase (DNMT) inhibitors have shown promising anticancer effects. The agent Zebularine acts as an inhibitor of DNA methylation and shows low toxicity and high efficacy, being a promising adjuvant agent for anti-cancer chemotherapy. Several studies have reported its effects on different types of tumors; however, there are no studies reporting its effects on MB. We analyzed its potential anticancer effects in four pediatric MB cell lines. The treatment inhibited proliferation and clonogenicity, increased the apoptosis rate and the number of cells in the S phase (p < 0.05), as well as the expression of p53, p21, and Bax, and decreased cyclin A, Survivin and Bcl-2 proteins. In addition, the combination of Zebularine with the chemotherapeutic agents vincristine and cisplatin resulted in synergism and antagonism, respectively. Zebularine also modulated the activation of the SHH pathway, reducing SMO and GLI1 levels and one of its targets, PTCH1, without changing SUFU levels. A microarray analysis revealed different pathways modulated by the drug, including the Toll-Like Receptor pathway and high levels of the BATF2 gene. The low expression of this gene was associated with a worse prognosis in MB. Taken together, these data suggest that Zebularine may be a potential drug for further in vivo studies of MB treatment.

Zebularine upregulates expression of CYP genes through inhibition of DNMT1 and PKR in HepG2 cells.[Pubmed:28112215]

Sci Rep. 2017 Jan 23;7:41093.

Drug-induced hepatotoxicity is one of the major reasons cited for drug withdrawal. Therefore, it is of extreme importance to detect human hepatotoxic candidates as early as possible during the drug development process. In this study, we aimed to enhance hepatocyte functions such as CYP gene expression in HepG2 cells, one of the most extensively used cell lines in evaluating hepatotoxicity of chemicals and drugs. We found that Zebularine, a potent inhibitor of DNA methylation, remarkably upregulates the expression of CYP genes in HepG2 cells. In addition, we revealed that the upregulation of CYP gene expression by Zebularine was mediated through the inhibition of both DNA methyltransferase 1 (DNMT1) and double-stranded RNA-dependent protein kinase (PKR). Furthermore, HepG2 cells treated with Zebularine were more sensitive than control cells to drug toxicity. Taken together, our results show that Zebularine may make HepG2 cells high-functioning and thus could be useful for evaluating the hepatotoxicity of chemicals and drugs speedily and accurately in in-vitro systems. The finding that Zebularine upregulates CYP gene expression through DNMT1 and PKR modulation sheds light on the mechanisms controlling hepatocyte function and thus may aid in the development of new in-vitro systems using high-functioning hepatocytes.

Metabolic activation of zebularine, a novel DNA methylation inhibitor, in human bladder carcinoma cells.[Pubmed:15885659]

Biochem Pharmacol. 2005 Jul 1;70(1):121-33.

Zebularine (2(1H)-pyrimidinone riboside, Zeb), a synthetic analogue of cytidine that is a potent inhibitor of cytidine deaminase, has been recently identified as a general inhibitor of DNA methylation. This inhibition of DNA methyltransferase (DNMT) is hypothesized to be mechanism-based and result from formation of a covalent complex between the enzyme and Zebularine-substituted DNA. Metabolic activation of Zeb thus requires that it be phosphorylated and incorporated into DNA. We have quantitatively assessed the phosphorylation and DNA incorporation of Zeb in T24 cells using 2-[(14)C]-Zeb in conjunction with gradient anion-exchange HPLC and selected enzymatic and spectroscopic analyses. The corresponding 5'-mono-, di- and triphosphates of Zeb were readily formed in a dose- and time-dependent manner. Two additional Zeb-containing metabolites were tentatively identified as diphosphocholine (Zeb-DP-Chol) and diphosphoethanolamine adducts. Intracellular concentrations of Zeb-TP and Zeb-DP-Chol were similar and greatly exceeded those of other metabolites. DNA incorporation occurred but was surpassed by that of RNA by at least seven-fold. Equivalent levels and similar intracellular metabolic patterns were also observed in the Molt-4 (human T-lymphoblasts) and MC38 (murine colon carcinoma) cell lines. For male BALB/c nu/nu mice implanted s.c. with the EJ6 variant of T24 bladder carcinoma and treated i.p. with 500mg/kg 2-[(14)C]-Zeb, the in vivo phosphorylation pattern of Zeb in tumor tissue examined 24h after drug administration was similar to that observed in vitro. The complex metabolism of Zeb and its limited DNA incorporation suggest that these are the reasons why it is less potent than either 5-azacytidine or 5-aza-2'-deoxycytidine and requires higher doses for equivalent inhibition of DNMT.

Potent inhibitors for the deamination of cytosine arabinoside and 5-aza-2'-deoxycytidine by human cytidine deaminase.[Pubmed:1375134]

Cancer Chemother Pharmacol. 1992;30(1):7-11.

Deamination of the nucleoside analogues ARA-C and 5-AZA-CdR by CR deaminase results in a loss of antileukemic activity. To prevent the inactivation of these analogues, inhibitors of CR deaminase may prove to be useful agents. In the present study we investigated the effects of the deaminase inhibitors Zebularine, 5-F-Zebularine, and diazepinone riboside on the deamination of CR, ARA-C, and 5-AZA-CdR using highly purified human CR deaminase (EC 3.5.4.5). These inhibitors produced a competitive type of inhibition with each substrate, the potency of which followed the patterns diazepinone riboside greater than 5-F-Zebularine and THU greater than Zebularine. 5-AZA-CdR was more sensitive than ARA-C to the inhibition produced by these deaminase inhibitors. The inhibition constants for diazepinone riboside lay in the range of 5-15 nM, suggesting that this inhibitor could be an excellent candidate for use in combination chemotherapy with either ARA-C or 5-AZA-CdR in patients with leukemia.

Zebularine (NSC309132; 4-Deoxyuridine) is a DNA methyltransferase inhibitor. Zebularine also inhibits cytidine deaminase with a Ki of 0.95 μM.

Zebularine,3690-10-6,NSC 309132,Natural Products,DNA Methyltransferase, buy Zebularine , Zebularine supplier , purchase Zebularine , Zebularine cost , Zebularine manufacturer , order Zebularine , high purity Zebularine