title: Tumor suppressor RASSF1A promoter: p53 binding and methylation.
abstract: Oncogenes and tumor suppressors work in concert to regulate cell growth or death, which is a pair of antagonist factors for regulation of tumorigenesis. Here we show promoter characteristic of tumor suppressor RASSF1A, which revealed a p53 binding site in the distal and a GC-rich region in the proximal promoter region of RASSF1A, in despite of TATA box-less. The GC-rich region, which is ∼300 bp upstream from the RASSF1A ATG, showed the strongest promoter activity in an assay of RASSF1A-driving GFP expression. Methylation analysis of the CpG island showed that 78.57% of the GC sties were methylated in testis tumor samples compared with methylation-less in normal testis. Hypermethylation of the GC-rich region is associated with RASSF1A silencing in human testis tumors. In addition, electrophoretic mobility shift assay indicated that p53 protein bound to the RASSF1A promoter. Further chromatin immunoprecipitation confirmed p53 binding to the RASSF1A. Moreover, p53 binding to the promoter down-regulated RASSF1A expression. These results suggest that p53 protein specifically binds to the RASSF1A promoter and inhibits its expression. Our results provide new insight into the mechanism of action of tumor suppressors and may be a starting point for development of new approaches to cancer treatment.
authors.affiliation: Department of Genetics and Center for Developmental Biology, College of Life Science, Wuhan University, Wuhan, China.
authors.forename: Yihao
authors.initials: Y
authors.lastname: Tian
authors.forename: Yu
authors.initials: Y
authors.lastname: Hou
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhou
authors.forename: Hanhua
authors.initials: H
authors.lastname: Cheng
authors.forename: Rongjia
authors.initials: R
authors.lastname: Zhou
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D019556:COS Cells; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D019175:DNA Methylation / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D008297:Male; D008954:Models, Biological; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding / Q000502:physiology; D013737:Testis / Q000378:metabolism / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: C411762:RASSF1 protein, human; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins