title: Differential antineoplastic effects of butyrate in cells with and without a functioning DNA mismatch repair.
abstract: The aim of this study was to investigate the differential antineoplastic effects of butyrate in cells with and without a functional mismatch repair and to determine the molecular mechanisms underlying these effects. SW48 colon cancer cells in which the MLH1 gene is silenced by promoter hypermethylation and demethylated SW48 cells in which the MLH1 gene is reexpressed were treated with butyrate (0-5mM) for 8 days and the effects on cell number, MLH1 gene promoter methylation, and expression of two cell cycle regulatory genes, CDK4 and GADD45A, were assessed. Butyrate suppressed viable cell number (P < 0.001) and reduced MLH1 promoter methylation (P < 0.05) in SW48 cells. However, in demethylated SW48 cells, butyrate caused an increase in viable cells (P < 0.05) and promoter methylation (P < 0.05). CDK4 expression was downregulated by butyrate exposure, but the effect was significantly greater for demethylated SW48 cells (P = 0.025). Butyrate treatment caused upregulation of GADD45A expression in SW48 cells but downregulation of GADD45A expression in demethylated SW48 cells (P = 0.045). This study supports the hypothesis that butyrate has more potent antineoplastic effects on colon cancer cells with MLH1 dysfunction. Differential expression of key cell cycle regulatory genes may explain some of the molecular mechanisms underlying these effects.
authors.affiliation: Newcastle University, Framlington Place, Newcastle upon Tyne, United Kingdom.
authors.forename: Shridhar S
authors.initials: SS
authors.lastname: Dronamraju
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Coxhead
authors.forename: Seamus B
authors.initials: SB
authors.lastname: Kelly
authors.forename: John C
authors.initials: JC
authors.lastname: Mathers
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002087:Butyrates / Q000494:pharmacology*; D018797:Cell Cycle Proteins / Q000235:genetics; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms; D051358:Cyclin-Dependent Kinase 4 / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics; D053843:DNA Mismatch Repair / Q000235:genetics* / Q000502:physiology*; D015870:Gene Expression / Q000187:drug effects; D020868:Gene Silencing; D018095:Germ-Line Mutation; D006801:Humans; D000070957:MutL Protein Homolog 1; D009687:Nuclear Proteins / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D000097642:GADD45 Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000970:Antineoplastic Agents; D002087:Butyrates; D018797:Cell Cycle Proteins; D051358:Cyclin-Dependent Kinase 4; D000070957:MutL Protein Homolog 1; D009687:Nuclear Proteins; C439070:GADD45A protein, human; D000097642:GADD45 Proteins; C501486:MLH1 protein, human