title: Differential expression of thrombospondin (THBS1) in tumorigenic and nontumorigenic prostate epithelial cells in response to a chromatin-binding soy peptide.
abstract: The chemopreventive properties of the chromatin-binding soy peptide, lunasin, are well documented, but its mechanism of action is unclear. To elucidate the mechanism by which lunasin reduces tumor foci formation in cultured mammalian cells, nontumorigenic (RWPE-1) and tumorigenic (RWPE-2) human prostate epithelial cells were treated with lunasin followed by gene expression profiling and characterization of the chromatin acetylation status for certain chemopreventive genes. The genes HIF1A, PRKAR1A, TOB1, and THBS1 were upregulated by lunasin in RWPE-1 but not in RWPE-2 cells. Using histone acetyltransferase (HAT) assays with acid-extracted histones as templates, we showed that lunasin specifically inhibited H4K8 acetylation while enhanced H4K16 acetylation catalyzed by HAT enzymes p300, PCAF, and HAT1A. These results suggest a novel mechanism for lunasin-dependent upregulation of gene expression. Chromatin immunoprecipitation (ChIP) revealed hypoacetylation of H4K16 in RWPE-2 cells, specifically at the 5' end of THBS1 containing a CpG island. Moreover, bisulfite PCR (BSP) and subsequent DNA sequencing indicated that this CpG island was hypomethylated in RWPE-1 but hypermethylated in RWPE-2 cells. Histone hypoacetylation and DNA hypermethylation in the 5' region of THBS1 may explain the inability of lunasin to upregulate this gene in RWPE-2 cells.
authors.affiliation: Center of Excellence in Nutritional Genomics, Department of Molecular and Cellular Biology, University of California Davis, Davis, California 95616, USA.
authors.forename: Alfredo F
authors.initials: AF
authors.lastname: Galvez
authors.forename: Liping
authors.initials: L
authors.lastname: Huang
authors.forename: Mark M J
authors.initials: MM
authors.lastname: Magbanua
authors.forename: Kevin
authors.initials: K
authors.lastname: Dawson
authors.forename: Raymond L
authors.initials: RL
authors.lastname: Rodriguez
mesh_terms: D000818:Animals; D018890:Chemoprevention; D002843:Chromatin / Q000378:metabolism; D047369:Chromatin Immunoprecipitation / Q000379:methods; D018899:CpG Islands / Q000187:drug effects; D019175:DNA Methylation; D057890:Epigenomics; D004847:Epithelial Cells / Q000187:drug effects*; D006657:Histones / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology*; D011467:Prostate / Q000166:cytology / Q000473:pathology; D017422:Sequence Analysis, DNA; D030262:Soybean Proteins / Q000494:pharmacology*; D019699:Thrombospondins / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
chemical_list: D002843:Chromatin; D006657:Histones; D010936:Plant Extracts; D030262:Soybean Proteins; D019699:Thrombospondins