Hypermethylation of the promoter region is an important mean for the transcriptional repression of a number of cancer-associated genes, and over-expression and/or increased activity of DNA methyltransferase are consid...Hypermethylation of the promoter region is an important mean for the transcriptional repression of a number of cancer-associated genes, and over-expression and/or increased activity of DNA methyltransferase are considered to be the main cause of promoter hypermethylation. In order to further explore the epigenetic mechanism of tumor suppressor gene RASSF1A inactivation, 5-aza-2’-deoxycytidine (5-Aza-CdR), a DNA methyltransferase inhibitor, was used to treat the human biliary tract carcinoma cell line QBC-939 at the concentration of 5 μmol/L for 24 h in this study. Af- ter the chemical intervention with 5-Aza-CdR, the methylation status in the promoter region of RASSF1A gene was detected by methylation specific PCR (MS-PCR), and the expression alteration of RASSF1A mRNA and protein were observed by RT-PCR and Western Blot respectively. Following the treatment with 5-Aza-CdR, methylaiton status in the promoter region of RASSF1A gene was re- versed from methylation to unmethylation. A 280 bp DNA band which represented RASS1FA expres- sion at transcriptional level and a 40 kDa (1kDa=0.9921 ku) protein band which represented RASSF1A expression at protein level were detected by RT-PCR and Western Blot respectively in the experimental group cells and there were no corresponding bands in the control group cells. The ex- perimental results suggest that 5-Aza-CdR can induce demethylation in the promoter region of RASSF1A. It can also reverse epigenetic transcriptional silencing caused by DNA methylation and induce the re-expression of RASSF1A in QBC-939. This study also suggest that the mechanism of RASSF1A inactivation is very closely related to the methylation of the promoter region, which may provide a new epigenetic understanding for tumor related gene inactivation and the pathogenesis of biliary tract carcinoma.展开更多
Complementary DNA of partial HCV NS2 NS3 protein gene which encodes viral Zn 2+ dependent metalloprotease and serine protease was amplified by RT nested PCR from serum of a Chinese patient with chronic hepatitis C.The...Complementary DNA of partial HCV NS2 NS3 protein gene which encodes viral Zn 2+ dependent metalloprotease and serine protease was amplified by RT nested PCR from serum of a Chinese patient with chronic hepatitis C.The product was digested with Eco R Ⅰ/ Xba Ⅰ and cloned into pcDNA3.The nucleotide sequence was determined.Comparison of NS2 NS3 with the reported typical isolates HCV 1,HCV J,HC C2,HCV J6,HCV J8 showed as 73.72%,90.20%,91.02%,64.56%,63.37% identity in nucleotide sequence and 83.24%,92.09%,93.13%, 70.88% ,67.86% identity in amino acid sequence respectively, so the isolate could be classified as HCV genotype Ⅱ. This gene fragment was cloned into pBV220 to construct recombinant expression vector pBV220 NS2 3.It was expressed efficiently in E.coli . The cloning and expression of HCV NS2 NS3 may contribute to the investigation of the relation between structure and function of viral encoded protease.展开更多
基金a grant from Hi-Tech Research and Development Program of China (863 Program) (No.2002AA214061)
文摘Hypermethylation of the promoter region is an important mean for the transcriptional repression of a number of cancer-associated genes, and over-expression and/or increased activity of DNA methyltransferase are considered to be the main cause of promoter hypermethylation. In order to further explore the epigenetic mechanism of tumor suppressor gene RASSF1A inactivation, 5-aza-2’-deoxycytidine (5-Aza-CdR), a DNA methyltransferase inhibitor, was used to treat the human biliary tract carcinoma cell line QBC-939 at the concentration of 5 μmol/L for 24 h in this study. Af- ter the chemical intervention with 5-Aza-CdR, the methylation status in the promoter region of RASSF1A gene was detected by methylation specific PCR (MS-PCR), and the expression alteration of RASSF1A mRNA and protein were observed by RT-PCR and Western Blot respectively. Following the treatment with 5-Aza-CdR, methylaiton status in the promoter region of RASSF1A gene was re- versed from methylation to unmethylation. A 280 bp DNA band which represented RASS1FA expres- sion at transcriptional level and a 40 kDa (1kDa=0.9921 ku) protein band which represented RASSF1A expression at protein level were detected by RT-PCR and Western Blot respectively in the experimental group cells and there were no corresponding bands in the control group cells. The ex- perimental results suggest that 5-Aza-CdR can induce demethylation in the promoter region of RASSF1A. It can also reverse epigenetic transcriptional silencing caused by DNA methylation and induce the re-expression of RASSF1A in QBC-939. This study also suggest that the mechanism of RASSF1A inactivation is very closely related to the methylation of the promoter region, which may provide a new epigenetic understanding for tumor related gene inactivation and the pathogenesis of biliary tract carcinoma.
文摘Complementary DNA of partial HCV NS2 NS3 protein gene which encodes viral Zn 2+ dependent metalloprotease and serine protease was amplified by RT nested PCR from serum of a Chinese patient with chronic hepatitis C.The product was digested with Eco R Ⅰ/ Xba Ⅰ and cloned into pcDNA3.The nucleotide sequence was determined.Comparison of NS2 NS3 with the reported typical isolates HCV 1,HCV J,HC C2,HCV J6,HCV J8 showed as 73.72%,90.20%,91.02%,64.56%,63.37% identity in nucleotide sequence and 83.24%,92.09%,93.13%, 70.88% ,67.86% identity in amino acid sequence respectively, so the isolate could be classified as HCV genotype Ⅱ. This gene fragment was cloned into pBV220 to construct recombinant expression vector pBV220 NS2 3.It was expressed efficiently in E.coli . The cloning and expression of HCV NS2 NS3 may contribute to the investigation of the relation between structure and function of viral encoded protease.
