Hypermethylation of CpG island in cystathionine-beta-synthase promoter down-regulates gene expression and function

Abstract

Objective To explore the association between the hypermethylation of cystathioninebeta-synthase (CBS) promoter and gene expression and function.Methods Bisulfate sequencing polymerase chain reaction (PCR),real-time PCR,fluorescence polarization immunoassay and immunostaining were used to investigate the relationship between the hypermethylation of CpG island in CBS promoter and gene expression and function in NCM460 cultured with varying folate concentrations and patients' tissues.Results In the NCM460 cultured with low concentrations of folate,the expression of CBS was down-regulated,and there was significant difference in the gene expression of CBS between H-M group and L-M group (P ＜0.01 ).In NCM460 cells,the results represented that along with the down-regultaion of CBS,there was a significant accumulation of homocysteine,and the HCY level was higher in L-mRNA group than in H-mRNA group.Conclusion Hypermethylation of CBS promoter is likely to induce decrease of CBS gene expression,thereby it may influence intracellular methyl metabolism and involved in the occurrence and progression of colorectal cancer. Key words: Cystathionine-beta-synthase; Hypermethylation; Gene expression