The epigenetic silencing of tumour suppressor genes is a key step during tumorigenesis. This process involves several mechanisms including DNA methylation and histone modifications. UHRF1 is a key master epigenetic regulator that couples preservation of histone-modification through the cell cycle with maintenance of DNA methylation. Recently it has been demonstrated that UHRF1 over-expression correlates with tumour progression. Non-coding RNAs play a pivotal role in the epigenetic regulation through different mechanisms, including transcriptional gene silencing. Here we show that, in prostate cancer cell lines, over-expression UHRF1 mediates epigenetic silencing of many tumour suppressor genes including CDH1, through the binding with its promoter and the recruitment of the histone-methyltransferase Suv39H1. In the aggressive androgen-independent cells (PC3), which over-express UHRF1, CDH1 expression is low and knock-down of UHRF1 reactivates E-cadherin, whereas in the low tumorigenic androgen-dependent cells (LNCaP) both UHRF1 and CDH1 are normally expressed (Babbio et al. 2012). In the attempt to further investigate the epigenetic regulation of CDH1, we identified two natural non-coding RNAs, sense and antisense directed (paRNA-S and paRNA-AS) transcribed from the CDH1 promoter. We observed that they are differently expressed in the two cell lines: paRNA-AS is transcribed only in CDH1 expressing LNCaP cells, whereas the paRNA-S is present in both cell lines. Silencing of UHRF1 in PC3 impairs Suv39H1 binding to the CDH1 promoter and induces CDH1 and paRNA-AS re-expression. By RNA-ChIP, we further observe that UHRF1, Suv39H1 and DNMT3A bind to paRNA-S in PC3 cells, but these proteins surprisingly bind exclusively to paRNA-AS in LNCaP cells, in which both paRNAs are present. These findings, supported by further investigations, could open new perspectives about the role that natural antisense ncRNAs could play during the epithelial mesenchymal transition in cancer
The role of UHRF1 in E-cadherin epigenetic regulation: a modulation via promoter associated non-coding RNAs?
MAGNANI, ELENA;PISTORE, CHRISTIAN;BABBIO, FEDERICA;BONAPACE, IAN MARC
2013-01-01
Abstract
The epigenetic silencing of tumour suppressor genes is a key step during tumorigenesis. This process involves several mechanisms including DNA methylation and histone modifications. UHRF1 is a key master epigenetic regulator that couples preservation of histone-modification through the cell cycle with maintenance of DNA methylation. Recently it has been demonstrated that UHRF1 over-expression correlates with tumour progression. Non-coding RNAs play a pivotal role in the epigenetic regulation through different mechanisms, including transcriptional gene silencing. Here we show that, in prostate cancer cell lines, over-expression UHRF1 mediates epigenetic silencing of many tumour suppressor genes including CDH1, through the binding with its promoter and the recruitment of the histone-methyltransferase Suv39H1. In the aggressive androgen-independent cells (PC3), which over-express UHRF1, CDH1 expression is low and knock-down of UHRF1 reactivates E-cadherin, whereas in the low tumorigenic androgen-dependent cells (LNCaP) both UHRF1 and CDH1 are normally expressed (Babbio et al. 2012). In the attempt to further investigate the epigenetic regulation of CDH1, we identified two natural non-coding RNAs, sense and antisense directed (paRNA-S and paRNA-AS) transcribed from the CDH1 promoter. We observed that they are differently expressed in the two cell lines: paRNA-AS is transcribed only in CDH1 expressing LNCaP cells, whereas the paRNA-S is present in both cell lines. Silencing of UHRF1 in PC3 impairs Suv39H1 binding to the CDH1 promoter and induces CDH1 and paRNA-AS re-expression. By RNA-ChIP, we further observe that UHRF1, Suv39H1 and DNMT3A bind to paRNA-S in PC3 cells, but these proteins surprisingly bind exclusively to paRNA-AS in LNCaP cells, in which both paRNAs are present. These findings, supported by further investigations, could open new perspectives about the role that natural antisense ncRNAs could play during the epithelial mesenchymal transition in cancer
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