title: Specific methylation events contribute to the transcriptional repression of the mouse tissue inhibitor of metalloproteinases-3 gene in neoplastic cells.
abstract: The tissue inhibitor of metalloproteinases-3 (TIMP-3) gene is specifically down-regulated in neoplastic cells of the mouse JB6 progression model, suggesting a role for TIMP-3 inactivation in neoplastic progression. On the basis of 5-azacytidine reversal, the mechanism for this down-regulation appears to involve changes in the methylation state of the TIMP-3 promoter. Although total genomic methylation levels are comparable, specific differences in the methylation of the TIMP-3 promoter were observed between preneoplastic and neoplastic JB6 cells at three Hpall sites, with preneoplastic cells being less methylated. Expression of antisense methyltransferase in a neoplastic JB6 variant known to be hypermethylated in TIMP-3 resulted in reactivation of the endogenous TIMP-3 gene and restoration of hypomethylated status to the three implicated Hpall sites. Thus, hypermethylation at specific sequences in the TIMP-3 promoter appears to contribute to the silencing of the gene in neoplastic cells.
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D002874:Chromosome Mapping; D003596:Cytosine / Q000378:metabolism; D019003:Deoxyribonuclease HpaII / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D005809:Genes, Regulator; D008156:Luciferases / Q000378:metabolism; D008745:Methylation; D051379:Mice; D008957:Models, Genetic; D016376:Oligonucleotides, Antisense; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000235:genetics*; D014162:Transfection; D014407:Tumor Cells, Cultured