title: S-adenosylmethionine inhibits the growth of cancer cells by reversing the hypomethylation status of c-myc and H-ras in human gastric cancer and colon cancer.
abstract: A global DNA hypomethylation might activate oncogene transcription, thus promoting carcinogenesis and tumor development. S-Adenosylmethionine (SAM) serves as a major methyl donor in biological transmethylation events. The object of this study is to explore the influence of SAM on the status of methylation at the promoter of the oncogenes c-myc, H-ras and tumor-suppressor gene p16 (INK4a), as well as its inhibitory effect on cancer cells. The results indicated that SAM treatment inhibited cell growth in gastric cancer cells and colon cancer cells, and the inhibition efficiency was significantly higher than that in the normal cells. Under standard growth conditions, C-myc and H-ras promoters were hypomethylated in gastric cancer cells and colon cancer cells. SAM treatment resulted in a heavy methylation of these promoters, which consequently downregulated mRNA and protein levels. In contrast, there was no significant difference in mRNA and protein levels of p16 (INK4a) with and without SAM treatment. SAM can effectively inhibit the tumor cells growth by reversing the DNA hypomethylation on promoters of oncogenes, thus down-regulating their expression. With no influence on the expression of the tumor suppressor genes, such as P16, SAM could be used as a potential drug for cancer therapy.
authors.affiliation: Department of biochemistry, Tianjin Medical University, Tianjin, 300070 China.
authors.forename: Jin
authors.initials: J
authors.lastname: Luo
authors.forename: Yan-Ni
authors.initials: YN
authors.lastname: Li
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.forename: Wei-Ming
authors.initials: WM
authors.lastname: Zhang
authors.forename: Xin
authors.initials: X
authors.lastname: Geng
mesh_terms: D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects*; D005455:Fluorescent Antibody Technique; D011905:Genes, ras / Q000235:genetics*; D019073:HT29 Cells; D006801:Humans; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics*; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012436:S-Adenosylmethionine / Q000627:therapeutic use*; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000235:genetics
chemical_list: D019941:Cyclin-Dependent Kinase Inhibitor p16; C489427:MYC protein, human; D016271:Proto-Oncogene Proteins c-myc; D012436:S-Adenosylmethionine