title: MicroRNA-145 is regulated by DNA methylation and p53 gene mutation in prostate cancer.
abstract: MiR-145 is downregulated in various cancers including prostate cancer. However, the underlying mechanisms of miR-145 downregulation are not fully understood. Here, we reported that miR-145 was silenced through DNA hypermethylation and p53 mutation status in laser capture microdissected (LCM) prostate cancer and matched adjacent normal tissues. In 22 of 27 (81%) prostate tissues, miR-145 was significantly downregulated in the cancer compared with the normal tissues. Further studies on miR-145 downregulation mechanism showed that miR-145 is methylated at the promoter region in both prostate cancer tissues and 50 different types of cancer cell lines. In seven cancer cell lines with miR-145 hypermethylation, 5-aza-2'-deoxycytidine treatment dramatically induced miR-145 expression. Interestingly, we also found a significant correlation between miR-145 expression and the status of p53 gene in both LCM prostate tissues and 47 cancer cell lines. In 29 cell lines with mutant p53, miR-145 levels were downregulated in 28 lines (97%), whereas in 18 cell lines with wild-type p53 (WT p53), miR-145 levels were downregulated in only 6 lines (33%, P < 0.001). Electrophoretic mobility shift assay showed that p53 binds to the p53 response element upstream of miR-145, but the binding was inhibited by hypermethylation. To further confirm that p53 binding to miR-145 could regulate miR-145 expression, we transfected WT p53 and MUT p53 into PC-3 cells and found that miR-145 is upregulated by WT p53 but not with MUTp53. The apoptotic cells are increased after WT p53 transfection. In summary, this is the first report documenting that downregulation of miR-145 is through DNA methylation and p53 mutation pathways in prostate cancer.
authors.affiliation: Department of Urology, Veterans Affairs Medical Center and University of California at San Francisco, 4150 Clement Street, San Francisco, CA 94121, USA.
authors.forename: Seong O
authors.initials: SO
authors.lastname: Suh
authors.forename: Yi
authors.initials: Y
authors.lastname: Chen
authors.forename: Mohd Saif
authors.initials: MS
authors.lastname: Zaman
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hirata
authors.forename: Soichiro
authors.initials: S
authors.lastname: Yamamura
authors.forename: Varahram
authors.initials: V
authors.lastname: Shahryari
authors.forename: Jan
authors.initials: J
authors.lastname: Liu
authors.forename: Z Laura
authors.initials: ZL
authors.lastname: Tabatabai
authors.forename: Sanjay
authors.initials: S
authors.lastname: Kakar
authors.forename: Guoren
authors.initials: G
authors.lastname: Deng
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Rajvir
authors.initials: R
authors.lastname: Dahiya
mesh_terms: D017209:Apoptosis; D047369:Chromatin Immunoprecipitation; D019175:DNA Methylation; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D017403:In Situ Hybridization; D007834:Lasers; D008297:Male; D035683:MicroRNAs / Q000235:genetics*; D042282:Microdissection; D009154:Mutation / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011467:Prostate / Q000378:metabolism / Q000473:pathology; D011470:Prostatic Hyperplasia / Q000235:genetics* / Q000473:pathology; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*
chemical_list: C541010:MIRN145 microRNA, human; D035683:MicroRNAs; D012333:RNA, Messenger; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53