Project description:Cultures of A-498 cells were treated for 120hours with 1000µM zebularine (SIGMA) in three independent biological experiments. Zebularine acts as a DNA methyltransferase (DNMT) inhibitor thereby upregulating genes that are inactivated by e.g. promotor hypermethylation. The experiment aimed to search for upregulated transcripts to provide new targets for biomarker development and therapeutic use. 308 candidates were upregulated more than 1.5-fold. Members of the metallothionein group (MT1G, MT1H, and MT2A) were validated in 49 clinical samples of renal cell carcinomas. Total RNA of treated (1000µM zebularine) and untreated A-498 cells (experiment A05-A07) was subjected to Affymetrix array analysis to detail the overall expression changes after treatment with a DNMT inhibitor. Treated cells showed no obvious signs of zebularine-induced cytotoxicity as revealed by XTT assays. Cell were split twice during the 120hour treatment period.
Project description:Cultures of A-498 cells were treated for 120hours with 1000µM zebularine (SIGMA) in three independent biological experiments. Zebularine acts as a DNA methyltransferase (DNMT) inhibitor thereby upregulating genes that are inactivated by e.g. promotor hypermethylation. The experiment aimed to search for upregulated transcripts to provide new targets for biomarker development and therapeutic use. 308 candidates were upregulated more than 1.5-fold. Members of the metallothionein group (MT1G, MT1H, and MT2A) were validated in 49 clinical samples of renal cell carcinomas.
Project description:Hepatocellular carcinoma is one of the most common cancers in world wide. During tumorigenesis, tumor suppressor and cancer-related genes are commonly silenced by aberrant DNA methylation in their promoter regions. Zebularine [1-(β-ᴅ-ribofuranosyl)-1,2-dihydropyrimidin-2-one] acts as an inhibitor of DNA methylation and exhibits chemical stability and minimal cytotoxicity both in vitro and in vivo. In this study, we explore the effect and possible mechanism of action of zebularine on hepatocellular carcinoma cell line HepG2. Here, we demonstrated that zebularine exhibited antitumor activity on HepG2 cells by inhibiting cell proliferation and inducing apoptosis. Zebularine treatment down-regulated CDK2 and phosphorylation of retinoblastoma protein (RB), and up-regulated p21WAF/CIP1 and p53. We also found that zebularine treatment up-regulated phosphorylation of p44/42 MAPK. These results suggest that p44/42 MAPK pathway play a role in zebularine induced cell cycle arrest by regulating activity of p21WAF/CIP1 and Rb. Furthermore, we found that zebularine induced apoptosis. Although proapoptotic protein Bax levels were not affected, antiapoptotic protein Bcl-2 level was down-regulated with zebularine treatment. The data in the present study suggest that the action of the double-stranded RNA-dependent protein kinase (PKR) is involved in inducing apoptosis with zebularine. These results provide a novel mechanism of zebularine-induced cell growth arrest and apoptosis in hepatocellular carcinoma.