title: Chromatin composition alterations and the critical role of MeCP2 for epigenetic silencing of progesterone receptor-B gene in endometrial cancers.
abstract: OBJECTIVE
  To understand the epigenetic mechanism underlying the PR-B gene silencing in endometrial cancer (EC) cells, we compared the chromatin composition between transcriptionally active and silenced PR-B genes in EC cell lines and cancer tissues.
  
  
  METHODS
  Chromatin Immunoprecipitation (ChIP) assay was performed to measure MBD occupancy and histone acetylation/methylation in transcriptionally active and silenced PR-B genes. PR-B-positive/-negative, as well as epigenetic inhibitor-treated/-untreated EC cells were used as study models. Real-time polymerase chain reaction (PCR) and Western blot analysis were applied to measure the mRNA and protein levels of PR-B, MBD, and histones.
  
  
  RESULTS
  A close association among PR-B methylation, MBD binding and PR-B gene silencing was observed. Treatment with epigenetic inhibitors led to dynamic changes in the PR-B chromatin composition and gene expression. Increased H3/H4 acetylation and H3-K4 methylation, and decreased H3-K9 methylation were found to be associated with re-activation of silenced PR-B genes. MeCP2 knockdown resulted in a decreased MeCP2 binding to PR-B genes and an increased PR-B expression. ChIP analysis of MeCP2 binding to PR-B genes in the PR-B-positive/-negative EC samples confirmed the significant role of MeCP2 in PR-B silencing.
  
  
  CONCLUSIONS
  PR-B gene expression is regulated by a concerted action of epigenetic factors including DNA methylation, MBD binding, and histone modifications. MeCP2 occupancy of PR-B genes plays a critical role in PR-B gene silencing. These findings enriched our knowledge of the epigenetic regulation of PR-B expression in EC, and suggested that the epigenetic re-activation of PR-B could be explored as a potential strategy to sensitize the PR-B-negative endometrial cancers to progestational therapy.
authors: Yantai Yuhuangding Hospital Affiliated to Qingdao University, Yantai, 264000, China.
authors: Yongli
authors: Y
authors: Chu
authors: Yanlin
authors: Y
authors: Wang
authors: Guanghua
authors: G
authors: Zhang
authors: Haibin
authors: H
authors: Chen
authors: Sean C
authors: SC
authors: Dowdy
authors: Yuning
authors: Y
authors: Xiong
authors: Fengming
authors: F
authors: Liu
authors: Run
authors: R
authors: Zhang
authors: Jinping
authors: J
authors: Li
authors: Shi-Wen
authors: SW
authors: Jiang
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology; D001374:Azacitidine / Q000494:pharmacology; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D018899:CpG Islands; D019175:DNA Methylation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism; D016889:Endometrial Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006657:Histones / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D051783:Methyl-CpG-Binding Protein 2 / Q000502:physiology*; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D012333:RNA, Messenger / Q000096:biosynthesis; D012334:RNA, Neoplasm / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000494:pharmacology; D060888:Real-Time Polymerase Chain Reaction; D011980:Receptors, Progesterone / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; C066141:MBD1 protein, human; C497392:MECP2 protein, human; D051783:Methyl-CpG-Binding Protein 2; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D034741:RNA, Small Interfering; D011980:Receptors, Progesterone; D014157:Transcription Factors; C097314:progesterone receptor B; C012589:trichostatin A; D001374:Azacitidine