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EZH2 is a marker of aggressive breast cancer and promotes neoplastic transformation of breast epithelial cells.

ABSTRACT: The Polycomb Group Protein EZH2 is a transcriptional repressor involved in controlling cellular memory and has been linked to aggressive prostate cancer. Here we investigate the functional role of EZH2 in cancer cell invasion and breast cancer progression. EZH2 transcript and protein were consistently elevated in invasive breast carcinoma compared with normal breast epithelia. Tissue microarray analysis, which included 917 samples from 280 patients, demonstrated that EZH2 protein levels were strongly associated with breast cancer aggressiveness. Overexpression of EZH2 in immortalized human mammary epithelial cell lines promotes anchorage-independent growth and cell invasion. EZH2-mediated cell invasion required an intact SET domain and histone deacetylase activity. This study provides compelling evidence for a functional link between dysregulated cellular memory, transcriptional repression, and neoplastic transformation.

SUBMITTER: Kleer CG

PROVIDER: S-EPMC208805 | biostudies-literature | 2003 Sep

REPOSITORIES: biostudies-literature

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EZH2 is a marker of aggressive breast cancer and promotes neoplastic transformation of breast epithelial cells.

Kleer Celina G CG Cao Qi Q Varambally Sooryanarayana S Shen Ronglai R Ota Ichiro I Tomlins Scott A SA Ghosh Debashis D Sewalt Richard G A B RG Otte Arie P AP Hayes Daniel F DF Sabel Michael S MS Livant Donna D Weiss Stephen J SJ Rubin Mark A MA Chinnaiyan Arul M AM

Proceedings of the National Academy of Sciences of the United States of America 20030919 20

The Polycomb Group Protein EZH2 is a transcriptional repressor involved in controlling cellular memory and has been linked to aggressive prostate cancer. Here we investigate the functional role of EZH2 in cancer cell invasion and breast cancer progression. EZH2 transcript and protein were consistently elevated in invasive breast carcinoma compared with normal breast epithelia. Tissue microarray analysis, which included 917 samples from 280 patients, demonstrated that EZH2 protein levels were str ...[more]

PMID: 14500907

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Project description:Exposure to genotoxic stresses such as radiation and tobacco smoke can cause increased cancer incidence rate as reflected in an in depth meta-analysis of data for women and breast cancer incidence. Published reports have indicated that exposures to low dose radiation and tobacco smoke are factors that contribute to the development of breast cancer. However, there is a scarcity of information on the combinatorial effects of low dose radiation and tobacco smoke on formation and progression of breast cancer. The combination of these two genotoxic insults can induce significant damage to the genetic material of the cells resulting in neoplastic transformation.To study the effects of low dose ionizing radiation and tobacco smoke on breast cells, MCF 10A cells were treated either with radiation (Rad - 0.1 Gray) or cigarette smoke condensate (Csc - 10 microgram/ml of medium) or a combination of Rad + Csc. Following treatments, cells were analyzed for cell cycle distribution patterns and the ability to extrude the Hoechst 33342 dye. In addition, in vitro invasion and migration as well as mammosphere formation assays were performed. Finally, differential gene expression profiles were generated from the individual and combination treatment.Exposure of MCF 10A cells to the combination of radiation plus cigarette smoke condensate generated a neoplastic phenotype. The transformed phenotype promoted increased mammosphere numbers, altered cell cycle phases with a doubling of the population in S phase, and increased invasion and motility. Also, exclusion of Hoechst 33342 dye, a surrogate marker for increased ABC transporters, was observed, which indicates a possible increase in drug resistance. In addition, changes in gene expression include the up regulation of genes encoding proteins involved in metabolic pathways and inflammation.The results indicate that when normal breast cells are exposed to low dose radiation in combination with cigarette smoke condensate a phenotype is generated that exhibits traits indicative of neoplastic transformation. More importantly, this is the first study to provide a new insight into a possible etiology for breast cancer formation in individuals exposed to low dose radiation and tobacco smoke.

Project description:Estrogen is a risk factor for breast cancer, yet its mechanism in the initiation of this disease is not clear. Here we use a model of estrogen-mediated malignant transformation of MCF-10F cells to identify the temporal acquisition of changes in genome structure and gene expression that correspond to the progressive transformed phenotype culminating in tumorigenesis. Genomic DNA and total RNA were isolated from MCF10F, trMCF (MCF10F transformed by 70 nM 17-beta estradiol), bsMCF (trMCF selected by Boyden chamber, tumorigenic), bcMCF(clones of bsMCF), and caMCF (cells from tumors of bsMCF grown in SCID mice). The Affymetrix 100k SNP and HG-U133_Plus_2 chips were used for genotyping and gene expression analyses. Changes in chromosomal copy number and loss of heterozygosity were progressive. Gross changes were rarely observed in the trMCF10F cells; the earliest was a gain in chromosome 1p, 1p36.12-1p36.21. In the bsMCF and their sub-clones bcMCF, additional gains were seen in chromosomes 1p, 1p36.12-1pter, 5q, 5q21.1-5q35.3, and 13q, 13q21.32-13q34; losses were detected in chromosomes 4 and 8p, 8p11.1-8p23.1. In the caMCF, additional losses were seen in chromosomes 3p, 3p12.1-3p14.1, 9p, 9p22.1-9p24.3, and 18q, 18q11.2-18q23. Using microarray analysis we were able, in some cases, to narrow the regions of interest and their associated candidate cancer genes. The observation of progressive genomic changes, along with the tumor phenotype of a poorly differentiated adenocarcinoma, indicate an underlying mechanism common to breast cancer development in humans, and adds to the evidence indicating that estrogens are mutagenic and contribute early to the process of breast cancer. Experiment Overall Design: Human MCF-10F cells were transformed by 70nM 17-beta-estradiol. The transformed cells were selected by Boyden chamber. The selected cells were injected into SCID mice and also cloned and expanded. The thus grown tumors were harvested for cell culture. Genomic DNA and total RNA were isolated from cell lines in each step for 100K SNP and gene expression microarray assay.

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EZH2 is a marker of aggressive breast cancer and promotes neoplastic transformation of breast epithelial cells.

Publications

EZH2 is a marker of aggressive breast cancer and promotes neoplastic transformation of breast epithelial cells.

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