title: Inactivation of BLU is associated with methylation of Sp1-binding site of BLU promoter in gastric cancer.
abstract: BLU is a candidate tumor suppressor gene, which is epigenetically inactivated in many human malignancies. However, the expression and biological functions of BLU in gastric cancer has not yet been reported. In the present study, we identified a functional BLU promoter which was regulated by the transcription activator Sp1. Bisulfite sequencing and qRT-PCR assays indicated that the silence of BLU expression in gastric cancer was significantly associated with DNA hypermethylation of BLU promoter including -39 CpG site located in the Sp1 transcription element. The expression of BLU was notably restored in AGS and SGC7901 cells following the demethylation-treatment with 5'-Aza-2'-deoxycytidine. Moreover, the results from ChIP, EMSA and luciferase reporter gene showed that -39 CpG methylation could prevent Sp1 from binding to the promoter of BLU and decreased transcription activity of the BLU gene by ~70%. In addition, knockdown of BLU significantly promoted cellular proliferation and colony formation in gastric cancer cells. In conclusion, we identified a novel functional BLU promoter and proved that BLU promoter activity was regulated by Sp1. Furthermore, we found that hypermethylated -39 CpG in BLU proximal promoter directly reduced its binding with Sp1, which may be one of the mechanisms accounting for the inactivation of BLU in gastric cancer.
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital of Soochow University, Medical College of Soochow University, Suzhou 215006, P.R. China.
authors.forename: Kunting
authors.initials: K
authors.lastname: Xiao
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital of Soochow University, Medical College of Soochow University, Suzhou 215006, P.R. China.
authors.forename: Zhuwen
authors.initials: Z
authors.lastname: Yu
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital of Soochow University, Medical College of Soochow University, Suzhou 215006, P.R. China.
authors.forename: Dong-Tao
authors.initials: DT
authors.lastname: Shi
authors.affiliation: Soochow University Laboratory of Cancer Molecular Genetics, Medical College of Soochow University, Suzhou 215123, P.R. China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Lei
authors.affiliation: Soochow University Laboratory of Cancer Molecular Genetics, Medical College of Soochow University, Suzhou 215123, P.R. China.
authors.forename: Hongbing
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Gastroenterology, The Affiliated Suzhou Municipal Hospital (Main Campus), Suzhou 215004, P.R. China.
authors.forename: Jian
authors.initials: J
authors.lastname: Cao
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital of Soochow University, Medical College of Soochow University, Suzhou 215006, P.R. China.
authors.forename: Wenyan
authors.initials: W
authors.lastname: Tian
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital of Soochow University, Medical College of Soochow University, Suzhou 215006, P.R. China.
authors.forename: Weichang
authors.initials: W
authors.lastname: Chen
authors.affiliation: Soochow University Laboratory of Cancer Molecular Genetics, Medical College of Soochow University, Suzhou 215123, P.R. China.
authors.forename: Hong-Tao
authors.initials: HT
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001665:Binding Sites; D045744:Cell Line, Tumor; D003598:Cytoskeletal Proteins; D019175:DNA Methylation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D008875:Middle Aged; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D055815:Young Adult
chemical_list: D003598:Cytoskeletal Proteins; D016329:Sp1 Transcription Factor; C108209:SP1 protein, human; D025521:Tumor Suppressor Proteins; C472720:ZMYND10 protein, human