Project description:Ten-Eleven Translocation 1 (TET1) is a member of methylcytosine dioxygenase, which catalyse 5-methylcytosine (5-mC) to 5-hydroxymethylcytosine (5-hmC) that promote the demethylation process. The diminished expression of TET1 protein and 5-hmC in many tumors indicate a critical role for the maintenance of cell stability. However, role of TET1 in bladder cancer development remains unclear. Here we found that TET1 expression was downregulated in bladder cancer tissues compared with normal urothelium and was inversely related to patient overall survival. TET1 silencing in bladder cancer cells increase proliferation and inhibited cell migration and invasion while its re-expression inhibits their proliferation and the growth of tumor xenografts. Furthermore, we found that TET1 binds to the promoter of the TSG to maintain its hypomethylated which interacts with β-catenin and suppress its nuclear translocation, thus inhibiting β-catenin transcriptional activity and downstream genes. In conclusion, TET1 acts as a tumor suppressor gene in bladder cancer cells by suppressing β-catenin signaling. This study may facilitate efforts to therapeutic strategy for patients with bladder cancer.
Project description:Ten eleven translocation (TET) enzymes catalyse the oxidative reactions of 5-methylcytosine (5mC) to promote the demethylation process. The reaction intermediate 5-hydroxymethylcytosine (5hmC) has been shown to be abundant in embryonic stem cells and tissues, but strongly depleted in human cancers. Genetic mutations of TET2 gene were associated with lleukemia, whereas TET1 downregulation has been shown to promote malignancy in breast cancer. Here, we report that TET1 is downregulated in colon tumours from the initial stage. TET1 silencing in primary epithelial colon cells increase their cellular proliferation while its re-expression in colon cancer cells inhibits their proliferation and the growth of tumour xenografts even at later stages. We found that TET1 binds and maintains hypomethylated the promoter of the DKK genes inhibitors of the WNT signalling to promote their expression. Downregulation of TET1 during colon cancer initiation leads to repression, by DNA methylation the promoters of the inhibitors of the WNT pathway resulting in a constitutive activation of the WNT pathway. Thus the DNA hydroxymethylation mediated by TET1 controlling the WNT signalling is a key player of tumour growth. These results provide new insights for understanding how tumours escape cellular controls
Project description:The Polycomb Group Proteins (PcG) are epigenetic regulatory complexes, dysregulation of which has been associated with multiple biological processes, including maintenance of cell identity, differentiation, proliferation, and cancer progression.PcGs form two multiprotein complexes, Polycomb repressive complex 1 (PRC1) and PRC2(1).The PRC2 protein complex mainly consists of Early embryonic deficient (EED), Suppressor of Zeste (SUZ12) and Enhancer of Zeste (EZH), which can catalyzes the trimethylation of histone H3 lysine 27 (H3K27me3), thereby leaving a transcriptionally repressive mark on the chromatin . Such alterations are recognized and read by canonical PRC1 which is composed of CBX (polycomb), PCGF (polycomb group factor), HPH (human polyhomeotic homolog), and the E3-ligase protein (RING) that catalyzes the monoubiquitination of histone H2A on lysine 119 (H2AK119ub1). The H3K27me3 mark is identified by and binds to the chromodomain within the CBX protein in PRC1, thereby ubiquitinating H2AK119 via the RING proteins. The interaction of PRC2 and PRC1 in chromatin contributes to chromatin compaction and transcriptional silencing of target genes.There are five chromobox proteins in humans, CBX2, 4, 6, 7 and 8. Increasing evidence supports essential roles of CBX proteins in tumorigenesis. Remarkably, CBX proteins have shown an opposite function in distinct cancer types in tumor development. For example, CBX7 is overexpressed in ovarian and prostate cancer , implying its oncogenic role in these tumor types. In contrast, CBX7 functions as a tumor suppressor and loss of CBX7 has been associated with increasing the malignancy grade in bladder, breast, pancreatic, glioma, and colon carcinomas (3 4 5 6 7), but its tumor suppression mechanism is unclear.
Project description:Bladder tumours used to construct a tumour stage classifier Keywords = bladder cancer, disease stages, classification Keywords: other
Project description:Epigenetic pathways that regulate DNA methylation and chromatin modifications are frequently found to be dysregulated in human cancers. The TET methylcytosine dioxygenase 1 (TET1) enzyme is an important regulator of hydroxymethylcytosine (5hmC) in embryonic stem cells, neural progenitors,adult cells and reprogrammed cells. Decreased expression of TET proteins and loss of 5hmC has been reported in many tumors, suggesting a critical role for the maintenance of this epigenetic modification in normal cellular function. However, loss of TET1 function in the etiology of cancer has not been directly investigated. Here, we show that deletion of the Tet1 gene promotes the development of B cell lymphoma. Tet1 is required for maintaining normal levels of 5hmC, preventing aberrant DNA hypermethylation and for the regulation of transcriptional programs involved in B-cell lineage specification, chromosome maintenance, and DNA repair. Progenitor B cells in the absence of Tet1 accumulate DNA damage and whole-exome sequencing of Tet1-deficient tumors revealed a high correlation of mutations with those most frequently found in Non-Hodgkin B cell lymphoma (B-NHL) patients. In addition, we show that the TET1 gene is deleted, hypermethylated and transcriptionally silenced in B-NHL patients. These findings provide the first in vivo evidence of TET1 function as a tumor suppressor of hematopoietic malignancy. We did hydroxymethylation tests for two wild type mice and two Tet1 knockout mice.
Project description:Epigenetic pathways that regulate DNA methylation and chromatin modifications are frequently found to be dysregulated in human cancers. The TET methylcytosine dioxygenase 1 (TET1) enzyme is an important regulator of hydroxymethylcytosine (5hmC) in embryonic stem cells, neural progenitors,adult cells and reprogrammed cells. Decreased expression of TET proteins and loss of 5hmC has been reported in many tumors, suggesting a critical role for the maintenance of this epigenetic modification in normal cellular function. However, loss of TET1 function in the etiology of cancer has not been directly investigated. Here, we show that deletion of the Tet1 gene promotes the development of B cell lymphoma. Tet1 is required for maintaining normal levels of 5hmC, preventing aberrant DNA hypermethylation and for the regulation of transcriptional programs involved in B-cell lineage specification, chromosome maintenance, and DNA repair. Progenitor B cells in the absence of Tet1 accumulate DNA damage and whole-exome sequencing of Tet1-deficient tumors revealed a high correlation of mutations with those most frequently found in Non-Hodgkin B cell lymphoma (B-NHL) patients. In addition, we show that the TET1 gene is deleted, hypermethylated and transcriptionally silenced in B-NHL patients. These findings provide the first in vivo evidence of TET1 function as a tumor suppressor of hematopoietic malignancy.
Project description:The contribution of the majority of frequently mutated genes to tumourigenesis is not fully defined. Many aggressive human cancers, such as triple negative breast cancers (TNBCs), have a poor prognosis and lack tractable biomarkers and targeted therapeutic options. Here, we systematically characterize loss-of-function mutations to generate a functional map of novel driver genes in a 3-dimensional model of breast cancer heterogeneity that more readily recapitulates the unfavourable tumour microenvironment in vivo. This identified the histone acetyltransferase CREBBP as a potent tumour suppressor gene whose silencing provided a 3D-specific growth advantage only under oxygen and nutrient deplete conditions. CREBBP protein expression was altered in a substantial proportion of TNBCs as well as several other solid tumours, including endometrial, bladder, ovarian and squamous lung cancers. In multiple primary tumours and cell models, loss of CREBBP activity resulted in upregulation of the FOXM1 transcriptional network. Strikingly, treatment with a range of CDK4/6 inhibitors (CDK4/6i), that indirectly target FOXM1 activity, selectively impaired growth in both CREBBP-altered spheroids and cell line xenografts and patient derived models from multiple tumour types. This study is the first to provide rationale for CREBBP as a biomarker for CDK4/6i response in cancer representing a new treatment paradigm for tumours that harbour CREBBP alterations that have limited therapeutic options.