Two de novo DNA methyltransferases, Dnmt3a and Dnmt3b, have been identified in humans and mice to contribute to the methylation of unmodified DNA. We recently showed a transition of de novo DNA methyltransferase expre...Two de novo DNA methyltransferases, Dnmt3a and Dnmt3b, have been identified in humans and mice to contribute to the methylation of unmodified DNA. We recently showed a transition of de novo DNA methyltransferase expression from Dnmt3b to Dnmt3a during mouse embryogenesis and in tissue-specific stem cells, suggesting distinct functions of Dnmt3a and Dnmt3b during these processes. In this study, to characterize the functions of Dnmt3a and Dnmt3b in pluripotent stem cells, we exogenously transfected ES cells with Dnmt3a and Dnmt3b cDNAs linked to an internal ribosome entry site-green fluorescent protein gene, and then analyzed the effects of expression of these de novo DNA methyltransferases on ES cell growth and differentiation. ES cells expressing Dnmt3b showed specific downregulation of pluripotency marker genes such as Nanog and Oct 3/4. In addition, Dnmt3a-transfected ES cells showed a specific increase in mitotic index, while Dnmt3b-transfected ES cells showed a decrease in mitotic index. These results suggest that Dnmt3b has important physiological roles in the initial process of stem cell differentiation and that Dnmt3a has a function in stem cell proliferation.展开更多
AIM: To investigate the association between single nucleotide polymorphism (SNP)in promoter of the DNA methyltransferase 3B (DNNT3B) gene and risk for development and lymphatic metastasis of gastric cardiac adenocarci...AIM: To investigate the association between single nucleotide polymorphism (SNP)in promoter of the DNA methyltransferase 3B (DNNT3B) gene and risk for development and lymphatic metastasis of gastric cardiac adenocarcinoma (GCA).METHODS: The hospital based case-control study included 212 GCA patients and 294 control subjects without overt cancer. The DNMT3B SNP was genotyped by PCR and restriction fragment length polymorphism (RFLP) analysis. RESULTS: The C/C genotype was not detected in both GCA patients and controls. In control subjects, the frequency of T/T and C/T genotypes was 94.9% and 5.1% respectively,and that of T and C alleles was 97.4% and 2.6%, respectively.The genotype and allelotype distribution in the GCA patients was not significantly different from that in controls (P = 0.34 and 0.33, respectively). When stratified by smoking status and family history of upper gastrointestinal cancer, significant difference in the genotype distribution was not observed between GCA patients and controls. The distribution of DNMT3Bgenotypes in GCA patients with or without lymphatic metastasis did not show significant difference (P = 0.42). CONCLUSION: The distribution of DNMT3BSNP in North China is distinct from that in Caucasians. Although this SNP has been associated with susceptibility to lung, head, neck and breast cancer, it may not be used as a stratification marker to predict susceptibility and lymphatic metastasis of GCA, at least in the population of North China.展开更多
BACKGROUND: Alterations in DNA methylation occur during the pathogenesis of human tumors. In this study, we investigated the influence of DNA methyltransferase 3b (DNMT3b) on fragile histidine trial (FHIT) expression ...BACKGROUND: Alterations in DNA methylation occur during the pathogenesis of human tumors. In this study, we investigated the influence of DNA methyltransferase 3b (DNMT3b) on fragile histidine trial (FHIT) expression and on DNA methylation of the FHIT promoter region in the hepatoma cell line SMMC-7721. METHODS: DNMT3b siRNA was used to down-regulate DNMT3b expression. DNMT3b and FHIT proteins were determined by Western blotting. Methylation-specific PCR was used to analyze the methylation status of the FHIT gene. RESULTS: After DNMT3b siRNA transfection, the expression of DNMT3b was inhibited in SMMC-7721 cells, and the expression of FHIT was significantly higher than that in the control group. There was no significant difference in methylation status between the DNMT3b siRNA transfected cells and control cells. CONCLUSION: DNMT3b may play an important role in regulation of FHIT expression in hepatoma SMMC-7721 cells, but not through methylation of the FHIT promoter. (Hepatobiliary Pancreat Dis Int 2009; 8: 273-277)展开更多
Background:Apolipoprotein B mRNA editing catalytic polypeptide(APOBEC),an endogenous mutator,induces DNA damage and activates the ataxia telangiectasia and Rad3-related(ATR)-checkpoint kinase 1(Chk1)pathway.Although c...Background:Apolipoprotein B mRNA editing catalytic polypeptide(APOBEC),an endogenous mutator,induces DNA damage and activates the ataxia telangiectasia and Rad3-related(ATR)-checkpoint kinase 1(Chk1)pathway.Although cisplatin-based therapy is the mainstay for muscle-invasive bladder cancer(MIBC),it has a poor survival rate.Therefore,this study aimed to evaluate the efficacy of an ATR inhibitor combined with cisplatin in the treatment of APOBEC catalytic subunit 3B(APOBEC3B)expressing MIBC.Methods:Immunohistochemical staining was performed to analyze an association between APOBEC3B and ATR in patients with MIBC.The APOBEC3B expression in MIBC cell lines was assessed using real-time polymerase chain reaction and western blot analysis.Western blot analysis was performed to confirm differences in phosphorylated Chk1(pChk1)expression according to the APOBEC3B expression.Cell viability and apoptosis analyses were performed to examine the anti-tumor activity of ATR inhibitors combined with cisplatin.Results:There was a significant association between APOBEC3B and ATR expression in the tumor tissues obtained from patients with MIBC.Cells with higher APOBEC3B expression showed higher pChk1 expression than cells expressing low APOBEC3B levels.Combination treatment of ATR inhibitor and cisplatin inhibited cell growth in MIBC cells with a higher APOBEC3B expression.Compared to cisplatin single treatment,combination treatment induced more apoptotic cell death in the cells with higher APOBEC3B expression.Conclusion:Our study shows that APOBEC3B’s higher expression status can enhance the sensitivity of MIBC to cisplatin upon ATR inhibition.This result provides new insight into appropriate patient selection for the effective application of ATR inhibitors in MIBC.展开更多
目的探讨稳定低表达DNA甲基转移酶3b(DNMT3b)基因对人膀胱癌细胞生长和凋亡的影响。方法包装表达DNMT3b si RNA和阴性对照si RNA的慢病毒,通过慢病毒感染的方法获得稳定低表达DNMT3b的膀胱癌细胞BIU-87及对照细胞。MTT和流式细胞仪检测D...目的探讨稳定低表达DNA甲基转移酶3b(DNMT3b)基因对人膀胱癌细胞生长和凋亡的影响。方法包装表达DNMT3b si RNA和阴性对照si RNA的慢病毒,通过慢病毒感染的方法获得稳定低表达DNMT3b的膀胱癌细胞BIU-87及对照细胞。MTT和流式细胞仪检测DNMT3b稳定低表达对细胞增殖和凋亡的影响;体内裸鼠成瘤实验观察DNMT3b稳定低表达对肿瘤的抑制效果;荧光定量PCR和Western blot检测DNMT3b稳定低表达对细胞生长和凋亡相关基因表达的影响;甲基化特异性PCR检测对细胞生长和凋亡相关基因甲基化的影响。结果荧光定量PCR和Western blot检测结果显示,DNMT3b m RNA和蛋白水平在BIU-87稳定细胞株中稳定低表达;DNMT3b稳定低表达可以抑制BIU-87细胞的生长,并且抑制裸鼠皮下瘤体的生长;DNMT3b稳定低表达可以促进BIU-87细胞的凋亡;DNMT3b稳定低表达可以增加凋亡及细胞生长相关基因DAPK,Bax和RASSF1A m RNA和蛋白水平的表达;DNMT3b稳定低表达可以减少凋亡及细胞生长相关基因DAPK,Bax和RASSF1A启动子区域的甲基化水平。结论 DNMT3b稳定低表达可能通过调控凋亡相关基因以及细胞生长相关基因启动子区域的甲基化水平来影响基因的表达,从而抑制BIU-87细胞的生长,诱导细胞凋亡。展开更多
文摘Two de novo DNA methyltransferases, Dnmt3a and Dnmt3b, have been identified in humans and mice to contribute to the methylation of unmodified DNA. We recently showed a transition of de novo DNA methyltransferase expression from Dnmt3b to Dnmt3a during mouse embryogenesis and in tissue-specific stem cells, suggesting distinct functions of Dnmt3a and Dnmt3b during these processes. In this study, to characterize the functions of Dnmt3a and Dnmt3b in pluripotent stem cells, we exogenously transfected ES cells with Dnmt3a and Dnmt3b cDNAs linked to an internal ribosome entry site-green fluorescent protein gene, and then analyzed the effects of expression of these de novo DNA methyltransferases on ES cell growth and differentiation. ES cells expressing Dnmt3b showed specific downregulation of pluripotency marker genes such as Nanog and Oct 3/4. In addition, Dnmt3a-transfected ES cells showed a specific increase in mitotic index, while Dnmt3b-transfected ES cells showed a decrease in mitotic index. These results suggest that Dnmt3b has important physiological roles in the initial process of stem cell differentiation and that Dnmt3a has a function in stem cell proliferation.
基金Supported by the National Natural Science Foundation of China,No.30371591the Natural Science Foundation of Hebei Province,No.C20040062
文摘AIM: To investigate the association between single nucleotide polymorphism (SNP)in promoter of the DNA methyltransferase 3B (DNNT3B) gene and risk for development and lymphatic metastasis of gastric cardiac adenocarcinoma (GCA).METHODS: The hospital based case-control study included 212 GCA patients and 294 control subjects without overt cancer. The DNMT3B SNP was genotyped by PCR and restriction fragment length polymorphism (RFLP) analysis. RESULTS: The C/C genotype was not detected in both GCA patients and controls. In control subjects, the frequency of T/T and C/T genotypes was 94.9% and 5.1% respectively,and that of T and C alleles was 97.4% and 2.6%, respectively.The genotype and allelotype distribution in the GCA patients was not significantly different from that in controls (P = 0.34 and 0.33, respectively). When stratified by smoking status and family history of upper gastrointestinal cancer, significant difference in the genotype distribution was not observed between GCA patients and controls. The distribution of DNMT3Bgenotypes in GCA patients with or without lymphatic metastasis did not show significant difference (P = 0.42). CONCLUSION: The distribution of DNMT3BSNP in North China is distinct from that in Caucasians. Although this SNP has been associated with susceptibility to lung, head, neck and breast cancer, it may not be used as a stratification marker to predict susceptibility and lymphatic metastasis of GCA, at least in the population of North China.
基金supported by a grant from the National Natural Science Foundation of China(No.30571814)
文摘BACKGROUND: Alterations in DNA methylation occur during the pathogenesis of human tumors. In this study, we investigated the influence of DNA methyltransferase 3b (DNMT3b) on fragile histidine trial (FHIT) expression and on DNA methylation of the FHIT promoter region in the hepatoma cell line SMMC-7721. METHODS: DNMT3b siRNA was used to down-regulate DNMT3b expression. DNMT3b and FHIT proteins were determined by Western blotting. Methylation-specific PCR was used to analyze the methylation status of the FHIT gene. RESULTS: After DNMT3b siRNA transfection, the expression of DNMT3b was inhibited in SMMC-7721 cells, and the expression of FHIT was significantly higher than that in the control group. There was no significant difference in methylation status between the DNMT3b siRNA transfected cells and control cells. CONCLUSION: DNMT3b may play an important role in regulation of FHIT expression in hepatoma SMMC-7721 cells, but not through methylation of the FHIT promoter. (Hepatobiliary Pancreat Dis Int 2009; 8: 273-277)
基金supported by St.Vincent’s Hospital,the Research Institute of Medical Science(Grant Number:SVHR-2021-03).
文摘Background:Apolipoprotein B mRNA editing catalytic polypeptide(APOBEC),an endogenous mutator,induces DNA damage and activates the ataxia telangiectasia and Rad3-related(ATR)-checkpoint kinase 1(Chk1)pathway.Although cisplatin-based therapy is the mainstay for muscle-invasive bladder cancer(MIBC),it has a poor survival rate.Therefore,this study aimed to evaluate the efficacy of an ATR inhibitor combined with cisplatin in the treatment of APOBEC catalytic subunit 3B(APOBEC3B)expressing MIBC.Methods:Immunohistochemical staining was performed to analyze an association between APOBEC3B and ATR in patients with MIBC.The APOBEC3B expression in MIBC cell lines was assessed using real-time polymerase chain reaction and western blot analysis.Western blot analysis was performed to confirm differences in phosphorylated Chk1(pChk1)expression according to the APOBEC3B expression.Cell viability and apoptosis analyses were performed to examine the anti-tumor activity of ATR inhibitors combined with cisplatin.Results:There was a significant association between APOBEC3B and ATR expression in the tumor tissues obtained from patients with MIBC.Cells with higher APOBEC3B expression showed higher pChk1 expression than cells expressing low APOBEC3B levels.Combination treatment of ATR inhibitor and cisplatin inhibited cell growth in MIBC cells with a higher APOBEC3B expression.Compared to cisplatin single treatment,combination treatment induced more apoptotic cell death in the cells with higher APOBEC3B expression.Conclusion:Our study shows that APOBEC3B’s higher expression status can enhance the sensitivity of MIBC to cisplatin upon ATR inhibition.This result provides new insight into appropriate patient selection for the effective application of ATR inhibitors in MIBC.
文摘目的探讨稳定低表达DNA甲基转移酶3b(DNMT3b)基因对人膀胱癌细胞生长和凋亡的影响。方法包装表达DNMT3b si RNA和阴性对照si RNA的慢病毒,通过慢病毒感染的方法获得稳定低表达DNMT3b的膀胱癌细胞BIU-87及对照细胞。MTT和流式细胞仪检测DNMT3b稳定低表达对细胞增殖和凋亡的影响;体内裸鼠成瘤实验观察DNMT3b稳定低表达对肿瘤的抑制效果;荧光定量PCR和Western blot检测DNMT3b稳定低表达对细胞生长和凋亡相关基因表达的影响;甲基化特异性PCR检测对细胞生长和凋亡相关基因甲基化的影响。结果荧光定量PCR和Western blot检测结果显示,DNMT3b m RNA和蛋白水平在BIU-87稳定细胞株中稳定低表达;DNMT3b稳定低表达可以抑制BIU-87细胞的生长,并且抑制裸鼠皮下瘤体的生长;DNMT3b稳定低表达可以促进BIU-87细胞的凋亡;DNMT3b稳定低表达可以增加凋亡及细胞生长相关基因DAPK,Bax和RASSF1A m RNA和蛋白水平的表达;DNMT3b稳定低表达可以减少凋亡及细胞生长相关基因DAPK,Bax和RASSF1A启动子区域的甲基化水平。结论 DNMT3b稳定低表达可能通过调控凋亡相关基因以及细胞生长相关基因启动子区域的甲基化水平来影响基因的表达,从而抑制BIU-87细胞的生长,诱导细胞凋亡。
