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Conference Paper: Correlation between the single-site CpG mutationwithin the gene promoter and the expression silencingof XIAP-Associated Factor 1 (XAF1) in human coloncancer cell lines

TitleCorrelation between the single-site CpG mutationwithin the gene promoter and the expression silencingof XIAP-Associated Factor 1 (XAF1) in human coloncancer cell lines
Authors
Issue Date2005
PublisherBlackwell Publishing Asia.
Citation
Asian Pacific Digestive Week, Seoul, Korea, 25-28 September 2005. In Journal of Gastroenterology and Hepatology, 2005, v. 20 n. S2, p. A253 Abstract no. TP057 How to Cite?
AbstractBackground and Aims XIAP-Associated Factor 1 (XAF1) is anovel inhibitor of X-linked inhibitor of apoptosis protein (XIAP).TheXAF1 mRNA is expressed at low or undetectable levels in variouscancer cell lines, suggesting that the silencing expression of XAF1 incancer cells is important for malignant cell survival.The mechanismsin regulating XAF1 expression has not been clearly determined. Inthis study, we examined the potential epigenetic gene silencing mechanisms of XAF1 in colon cancer cell lines.Methods (1) We cloned 3 different fragments around TSS (Transcription Start Site) of XAF1 gene and examined their putativepromoter activities by Luciferase Report Assay. (2) We mutated theCpG sites in fragment F291 by Site-Directed Mutagenesis techniqueand detected the change of promoter activity of this fragment byLuciferase Report Assay. (3) Genomic DNAs were isolated from 6colon cancer cell lines and normal human blood cells and the methy-lation status was determined by bisulfite DNA sequencing analysis of8 CpG sites located around TSS (nucleotides from -59 to +194).Results By bisulfite DNA sequencing method, we showed thatnormal blood cells do not display XAF1 methylation around TSS. Incontrast, all cancer cell lines except Colo 205 showed different levelsof hypermethylation which can be removed by 5¢-AZA treatment.Thefragment F291 that contains 8 sporatic CpG sites around TSS showedthe highest promoter activity, which could be downregulated by muta-tion of some CpG sites in this fragment especially the mutation at -2 CpG site, which suppressed promoter activity by over 50%. In con-trast, single-site mutation at -1 CpG site suppressed activity by only20%.Conclusions Results from our study showed that the hypermethy-lation status of sporatic CpG sites around TSS of XAF1 coincidenceswith the gene expression suggesting that the aberrant methylationcontributes at least in part to the epigenetic silencing of XAF1 gene,which may be important for malignant cell survival. In those CpGsites in XAF1 gene promoter, -2 CpG dinucleotides appears to befunctionally more important than others associated with transcrip-tional inactivation of the XAF1 gene.
Persistent Identifierhttp://hdl.handle.net/10722/101119
ISSN
2014 Impact Factor: 3.504
2014 SCImago Journal Rankings: 1.128

 

DC FieldValueLanguage
dc.contributor.authorZou, Ben_HK
dc.contributor.authorChim, JCSen_HK
dc.contributor.authorLin, MCen_HK
dc.contributor.authorZeng, Hen_HK
dc.contributor.authorHe, Hen_HK
dc.contributor.authorYu, Len_HK
dc.contributor.authorSun, Yen_HK
dc.contributor.authorJiang, SHen_HK
dc.contributor.authorWong, BCYen_HK
dc.date.accessioned2010-09-25T19:36:43Z-
dc.date.available2010-09-25T19:36:43Z-
dc.date.issued2005en_HK
dc.identifier.citationAsian Pacific Digestive Week, Seoul, Korea, 25-28 September 2005. In Journal of Gastroenterology and Hepatology, 2005, v. 20 n. S2, p. A253 Abstract no. TP057en_HK
dc.identifier.issn0815-9319en_HK
dc.identifier.urihttp://hdl.handle.net/10722/101119-
dc.description.abstractBackground and Aims XIAP-Associated Factor 1 (XAF1) is anovel inhibitor of X-linked inhibitor of apoptosis protein (XIAP).TheXAF1 mRNA is expressed at low or undetectable levels in variouscancer cell lines, suggesting that the silencing expression of XAF1 incancer cells is important for malignant cell survival.The mechanismsin regulating XAF1 expression has not been clearly determined. Inthis study, we examined the potential epigenetic gene silencing mechanisms of XAF1 in colon cancer cell lines.Methods (1) We cloned 3 different fragments around TSS (Transcription Start Site) of XAF1 gene and examined their putativepromoter activities by Luciferase Report Assay. (2) We mutated theCpG sites in fragment F291 by Site-Directed Mutagenesis techniqueand detected the change of promoter activity of this fragment byLuciferase Report Assay. (3) Genomic DNAs were isolated from 6colon cancer cell lines and normal human blood cells and the methy-lation status was determined by bisulfite DNA sequencing analysis of8 CpG sites located around TSS (nucleotides from -59 to +194).Results By bisulfite DNA sequencing method, we showed thatnormal blood cells do not display XAF1 methylation around TSS. Incontrast, all cancer cell lines except Colo 205 showed different levelsof hypermethylation which can be removed by 5¢-AZA treatment.Thefragment F291 that contains 8 sporatic CpG sites around TSS showedthe highest promoter activity, which could be downregulated by muta-tion of some CpG sites in this fragment especially the mutation at -2 CpG site, which suppressed promoter activity by over 50%. In con-trast, single-site mutation at -1 CpG site suppressed activity by only20%.Conclusions Results from our study showed that the hypermethy-lation status of sporatic CpG sites around TSS of XAF1 coincidenceswith the gene expression suggesting that the aberrant methylationcontributes at least in part to the epigenetic silencing of XAF1 gene,which may be important for malignant cell survival. In those CpGsites in XAF1 gene promoter, -2 CpG dinucleotides appears to befunctionally more important than others associated with transcrip-tional inactivation of the XAF1 gene.-
dc.languageengen_HK
dc.publisherBlackwell Publishing Asia.en_HK
dc.relation.ispartofJournal of Gastroenterology and Hepatologyen_HK
dc.titleCorrelation between the single-site CpG mutationwithin the gene promoter and the expression silencingof XIAP-Associated Factor 1 (XAF1) in human coloncancer cell linesen_HK
dc.typeConference_Paperen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0815-9319&volume=20&spage=Supp A253&epage=&date=2005&atitle=Correlation+between+the+single-site+CpG+mutation+within+the+gene++promoter+and+the+expression+silencing+of+XIAP+-Associated+Factor+1+(XAF1)+in+human+colon+cancer+cell+lines.+Asian+Pacific+Digestive+Week,+Sept.+25-28,+2005,+Seoul,+Korea.en_HK
dc.identifier.emailZou, B: zoubing@hkucc.hku.hken_HK
dc.identifier.emailChim, JCS: jcschim@hku.hken_HK
dc.identifier.emailLin, MC: mcllin@HKUCC.hku.hken_HK
dc.identifier.emailHe, H: cecily_bb3@hotmail.comen_HK
dc.identifier.emailYu, L: graceyu1028@sohu.comen_HK
dc.identifier.emailSun, Y: stephen_syw@sohu.comen_HK
dc.identifier.emailWong, BCY: bcywong@hku.hken_HK
dc.identifier.authorityChim, JCS=rp00408en_HK
dc.identifier.authorityLin, MC=rp00746en_HK
dc.identifier.authorityWong, BCY=rp00429en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1111/j.1440-1746.2005.04100.x-
dc.identifier.hkuros117564en_HK
dc.identifier.volume20en_HK

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