Project description:Common epithelial cancers are believed to become more aggressive through the accumulation of multiple independent molecular events that lead to the deregulation of cell signaling. However, the discovery that the majority of prostate cancers harbor gene fusions of the 5'-untranslated region of androgen regulated TMPRSS2 promoter with ETS transcription factor family members has brought this paradigm into question1,2. TMPRSS2-ERG gene fusion is the most common molecular sub-type of prostate cancer. Recent work suggests that the TMPRSS2-ERG fusion is associated with a more aggressive clinical phenotype3. In the most advanced castration resistant prostate cancers where the androgen receptor has been inactivated, the TMPRSS2-ERG fusion remains functionally active. Here we show compelling clinical and gene expression data supporting the existence of a TMPRSS2-ERG fusion prostate cancer subclass. Using expression array profiling on 455 primary prostate tumors, we identified an 87 gene expression signature, distinguishing TMPRSS2-ERG fusion prostate cancer as a discrete molecular entity. Computational analysis suggested that this fusion signature was associated with estrogen receptor signaling. Functional studies demonstrated regulation of the TMPRSS2-ERG fusion transcript by estrogenic compounds. These data identify a previously unrecognized mechanism for regulation of the TMPRSS2-ERG, even in the absence of a functional androgen receptor, and thus may have broader implications in the treatment of prostate cancer. Keywords: Prostate cancer, Expression array, Illumina, gene fusion, TMPRSS2, ERG, Signatures, Estrogen Test Cohort: 388 cases from the population based Swedish-Watchful Waiting cohort. The cohort consists of men with localized prostate cancer (clinical stage T1-T2, Mx, N0); Validation cohort: The PhysiciansM-bM-^@M-^Y Health Study (PHS) cohort included 116 US men diagnosed with incidental prostate cancer between 1983 and 2003; 455 cases were annotated for TMPRSS2-ERG fusion. Test Set: GSM208029 ... GSM208392 Validation Set: GSM208404 ... GSM208512

Project description:TMPRSS2-ERG gene fusions that are frequently identified in prostate cancer can be generated either through chromosomal translocation or via interstitial deletion. The latter mechanism deletes an interstitial region of ~3Mb and it remains largely unanswered whether genes deleted within this region contribute to prostate cancer. By characterizing two knockin mouse models recapitulating TMPRSS2-ERG fusions with or without the interstitial deletion, we found that only those with deletion developed poorly differentiated adenocarcinomas with epithelial-to-mesenchymal transition, when under a Pten-null background. We identified several interstitial genes, including ETS2 and BACE2, whose reduced expression correlates with worse disease-free survival and lethal disease. By using an Ets2 conditional knockout allele, we demonstrated that loss of one copy of Ets2 was sufficient for prostate cancer progression when under a Pten-null background. Collectively, our data suggest that ETS2 is a prostate tumor suppressor and haploinsufficiency of one or more interstitial genes contributes to prostate cancer progression. Genotyped male mice were euthanized at 12 months of age and prostates isolated. Prostates were fixed overnight in 10% formalin and stored in 70% ethanol until tissue processing and paraffin embedding. Serial sections were cut from paraffin blocks which were stained for H&E and analyzed by a trained rodent histopathologist. Using these sections as a visual guide for specific types of lesions, the sequential sections were stained with hematoxylin and used for laser capture microdissection on ArcturusXT system. Epithelial cells within notable high grade prostate intraepithelial neoplasia (HG-PIN) lesions were microdissected from 3 mice from each corresponding genotype. In addition, poorly differentiated adenocarcinomas from PbCre;T-3Mb-Erg/+;PtenL/L mice were also dissected. RNA was isolated from the microdissected tissue using the Qiagen RNeasy FFPE kit and subjected to Nugen Amplification before microarray analysis on an Affymetrix Mouse Gene 2.0 ST chip.

Project description:Antineoplastic effects of siRNA against TMPRSS2-ERG junction oncogene in prostate cancer: from molecular and cellular studies to preclinical investigations. Background of the study.:TMPRSS2-ERG junction oncogene is present in more than 50% of patients with prostate cancer, and its expression is frequently associated with poor prognosis. We knockdown by siRNA the two TMPRSS2-ERG fusion variants (III and IV) most frequently identified in patients’ biopsies and found an inhibition of TMPRSS2-ERG of above 70% in human prostate cancer VCaP cell line expressing TMPRSS2-ERG junction oncogene. To point out genes regulated after TMPRSS2-ERG oncogene silencing, microarray analysis was performed.. Materiel and Methods. Human prostate cancer VCaP cell line expressing TMPRSS2-ERG oncogene (ATCC® CRL-2876™ Manassas, USA) was grown in Dulbecco's Modified Eagle Medium (DMEM) (Invitrogen, Cergy-Pontoise, France) supplemented with 10% fetal bovine serum (FBS), 100 units/ml penicillin and 100 μg/ml streptomycin (Invitrogen). Cells were incubated at 37°C in a humidified atmosphere containing 5% CO2. Transfection was carried out using Lipofectamine RNAiMAX transfecting agent (Invitrogen) according to manufacturer's instructions. Briefly, 8×105 VCaP cells were seeded in six-well plates in DMEM supplemented with 10% FCS, penicillin (100U/ml) and streptomycin (10µg/ml) and transfected with 50 nM siRNA TMPRSS2-ERG III, siRNA TMPRSS2-ERG IV and siRNA Control and 6 μL Lipofectamine® RNAiMAX. Cells were incubated with siRNA for 48h. At the end of the treatments, total RNAs of untreated cells (NT) and transfected cells were extracted using RNeasy mini-kit (Quiagen, Courtaboeuf, France). Three independent experiments were performed. Results. Microarray analysis confirmed ERG inhibition by both siRNA TMPRSS2-ERG III and IV and revealed a common down-regulated gene, ADRA2A, involved in cell proliferation and migration. Experiments are performed with Agilent Whole Genome 8x60K (028004) microarray. In triplicate with a non treated control cells, a control with ascramble siRNA, a siRNA TMPRSS2-ERG III, a siRNA TMPRSS2 IV.

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