title: Association of DNA methyltransferases expression with global and gene-specific DNA methylation in colorectal cancer cells.
abstract: There are conflicting reports regarding the association between DNA methyltransferases (DNMTs) expression and global or gene-specific DNA methylation in colorectal cancer (CRC) cells. To correlate DNMTs expression with DNA methylation, we quantified DNMT1, DNMT3A and DNMT3B mRNA levels in five CRC cell lines (HCT116, LS180, HT29/219, Caco2 and SW742) by real-time reverse-transcriptase polymerase chain reaction (PCR) assay. In addition, we examined the global 5-methyl cytosine levels and the methylation patterns of 12 CpG islands in these CRC cells by enzyme-linked immunosorbent assay and methylation-specific PCR methods, respectively. The average expression levels of three DNMTs in HCT116, Caco2, HT29/219 and SW742, relative to the expression level in LS180 (taken to be 1), were 90.1, 31.6, 2.66 and 1.86. Our data indicated that overall about 1.45%, 1.03%, 0.98%, 0.86% and 0.85% of the cytosines were methylated in the genome of HCT116, Caco2, HT29/219, SW742 and LS180 cells, respectively. The 5-mC percentages were positively correlated with the relative cellular DNMTs expression in five CRC cell lines as verified by Pearson correlation test. However, we found no positive correlation between mRNA expression of DNMTs and gene promoter hypermethylation in these cells. Our results suggest that cellular DNMT expression is positively correlated with global DNA methylation level but not with regional DNA hypermethylation at each locus.
authors.affiliation: Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Mostafa Moradi
authors.initials: MM
authors.lastname: Sarabi
authors.affiliation: Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.|Autoimmune Diseases Research Center, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Fakhraddin
authors.initials: F
authors.lastname: Naghibalhossaini
mesh_terms: D044503:5-Methylcytosine / Q000032:analysis; D002460:Cell Line; D015179:Colorectal Neoplasms / Q000235:genetics*; D018899:CpG Islands; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics*; D019175:DNA Methylation; D000090205:DNA Methyltransferase 3A; D006801:Humans; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000097584:DNA Methyltransferase 3B
chemical_list: D044503:5-Methylcytosine; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A; D012333:RNA, Messenger; D000097584:DNA Methyltransferase 3B; C000717967:DNMT3A protein, human; C000619380:DNMT1 protein, human
keywords: CpG island; DNA methyltransferase; cancer cell lines; global methylation; promoter methylation