ERG Transcripts Research Articles

TMPRSS2:ERG Gene Fusion Might Predict Resistance to PARP Inhibitors in Metastatic Castration-resistant Prostate Cancer.

The emergence of novel DNA damage repair (DDR) pathways in molecular-target therapy drugs (MTTD) has shown promising outcomes in treating patients with metastatic castration-resistant prostate cancer (mCRPC). About 25% of mCRPC patients have actionable deleterious aberrations in DDR genes, primarily in the homologous recombination (HR) pathway. However, the response rate in patients with BRCA1/2 or mutations in HRR-related genes is only 45%-55%, when exposed to poly ADP ribose polymerase (PARP) inhibitor-based therapy (PARPi). A frequent characteristic feature of prostate cancer (PC) is the occurrence of genomic rearrangement that affects the transmembrane protease serine 2 (TMPRSS2) and E26 transformation-specific (ETS)- transcription factor-related gene (ERG). In this study, a total of 114 patients with mCRPC had their RNA and DNA sequenced using next-generation sequencing. Based on their genetic profile of deleterious gene alterations of BRCA1/2 or ATM, six patients were selected for PARPi. Patients with TMPRSS2:ERG gene fusion and homozygous alteration in ATM or BRCA2 (n=2) or heterozygous alterations (BRCA1 or BRCA2) and lack of TMPRSS2:ERG gene fusion (n=2) did not show clinical benefit from PARPi (treatment duration <16 weeks). In contrast, patients (n=2) without TMPRSS2:ERG gene fusion and homozygous deleterious alterations in ATM or BRCA2 all had clinical benefit from PARPi (treatment duration ≥16 weeks). The TMPRSS2:ERG transcript product might be used as a PARPi resistance biomarker.

The performance and limitations of PCA3, TMPRSS2:ERG, HOXC6 and DLX1 urinary markers combined in the improvement of prostate cancer diagnostics

BackgroundProstate cancer (PCa) is the second most commonly diagnosed cancer in men. To date, the role of the combined application of long non-coding RNAs (PCA3, DLX1, HOXC6, TMPRSS2:ERG) for obtaining the most accurate method of detection of PCa has not yet been comprehensively investigated. MethodsIn total 240 persons were included in the retrospective study. Among them were 150 patients with confirmed PCa, 30 patients with benign prostatic hyperplasia, 30 patients with active chronic prostatitis and 30 healthy volunteers. In all patients, the urine samples were collected prior to biopsy or treatment. Polymerase chain reaction with reverse transcription was performed to detect the expression level of PCA3, HOXC6, DLX1 and the presence of the TMPRSS2:ERG transcript. ResultsPCA3 was detected in urine samples in all cases. Using a PCA3 score of 56 allowed the differentiation between PCa and all other cases with a sensitivity of 61% and specificity of 96% (p < 0.001) while a PCA3 score threshold value of 50 resulted in a differentiation between clinically significant PCa (ISUP grades 2–5) and all other cases with a sensitivity of 93% and specificity of 93% (p < 0.001). The TMPRSS2:ERG expression in urine was detected exclusively in the group of patients with PCa and only in 16% of all cases. ConclusionsPCA3 score detected in urine demonstrated moderate sensitivity and good specificity in differentiation between PCa and non-PCa and high sensitivity and specificity in differentiation between clinically significant PCa and non-PCa.

Transcriptional regulation of ergosterol biosynthesis genes in response to iron deficiency.

Iron participates as an essential cofactor in the biosynthesis of critical cellular components, including DNA, proteins and lipids. The ergosterol biosynthetic pathway, which is an important target of antifungal treatments, depends on iron in four enzymatic steps. Our results in the model yeast Saccharomyces cerevisiae show that the expression of ergosterol biosynthesis (ERG) genes is tightly modulated by iron availability probably through the iron-dependent variation of sterol and heme levels. Whereas the transcription factors Upc2 and Ecm22 are responsible for the activation of ERG genes upon iron deficiency, the heme-dependent factor Hap1 triggers their Tup1-mediated transcriptional repression. The combined regulation by both activating and repressing regulatory factors allows for the fine-tuning of ERG transcript levels along the progress of iron deficiency, avoiding the accumulation of toxic sterol intermediates and enabling efficient adaptation to rapidly changing conditions. The lack of these regulatory factors leads to changes in the yeast sterol profile upon iron-deficient conditions. Both environmental iron availability and specific regulatory factors should be considered in ergosterol antifungal treatments.

New Selective Inhibitors of ERG Positive Prostate Cancer: ERGi-USU-6 Salt Derivatives.

Prostate cancer is among the leading causes of cancer related death of men in the United States. The ERG gene fusion leading to overexpression of near full-length ERG transcript and protein represents most prevalent (50–65%) prostate cancer driver gene alterations. The ERG oncoprotein overexpression persists in approximately 35% of metastatic castration resistant prostate cancers. Due to the emergence of eventual refractoriness to second- and third-generation androgen axis-based inhibitors, there remains a pressing need to develop drugs targeting other validated prostate cancer drivers such as ERG. Here we report the new and more potent ERG inhibitor ERGi-USU-6 developed by structure–activity studies from the parental ERGi-USU. We have developed an improved procedure for the synthesis of ERGi-USU-6 and identified a salt formulation that further improves its activity in biological assays for selective targeting of ERG harboring prostate cancer cells.

Impact TMPRSS2-ERG Molecular Subtype on Prostate Cancer Recurrence.

Currently, seven molecular subtypes of prostate cancer (PCa) are known, the most common of which being the subtype characterized by the presence of the TMPRSS2–ERG fusion transcript. While there is a considerable amount of work devoted to the influence of this transcript on the prognosis of the disease, data on its role in the progression and prognosis of PCa remain controversial. The present study is devoted to the analysis of the association between the TMPRSS2–ERG transcript and the biochemical recurrence of PCa. The study included two cohorts: the RNA–Seq sample of Russian patients with PCa (n = 72) and the TCGA–PRAD data (n = 203). The results of the analysis of the association between the TMPRSS2–ERG transcript and biochemical recurrence were contradictory. The differential expression analysis (biochemical recurrence cases versus biochemical recurrence-free) and the gene set enrichment analysis revealed a list of genes involved in major cellular pathways. The GNL3, QSOX2, SSPO, and SYS1 genes were selected as predictors of the potential prognostic model (AUC = 1.000 for a cohort of Russian patients with PCa and AUC = 0.779 for a TCGA–PRAD cohort).

Intragenic ERG Deletions Do Not Explain the Biology of ERG-Related Acute Lymphoblastic Leukemia.

Intragenic ERG deletions occur in 3–5% of B-cell precursor acute lymphoblastic leukemia, specifically in B-other subtype lacking the classifying genetic lesions. They represent the only genetic lesion described so far present in the majority of cases clustering into a subgroup of B-other subtype characterized by a unique gene expression profile, probably sharing a common, however, not yet fully described, biological background. We aimed to elucidate whether ERG deletions could drive the specific biology of this ERG-related leukemia subgroup through expression of aberrant or decreased expression of wild type ERG isoforms. We showed that leukemic cells with endogenous ERG deletion express an aberrant transcript translated into two proteins in transfected cell lines and that one of these proteins colocalizes with wild type ERG. However, we did not confirm expression of the proteins in acute lymphoblastic leukemia cases with endogenous ERG deletion. ERG deletions resulted in significantly lower expression of wild type ERG transcripts compared to B-other cases without ERG deletion. However, cases with subclonal ERG deletion, clustering to the same ERG deletion associated subgroup, presented similar levels of wild type ERG as cases without ERG deletion. In conclusion, our data suggest that neither the expression of aberrant proteins from internally deleted allele nor the reduced expression of wild type ERG seem to provide a plausible explanation of the specific biology of ERG -related leukemia subgroup.

A simple, rapid, low-cost technique for naked-eye detection of urine-isolated TMPRSS2:ERG gene fusion RNA.

The TMPRSS2:ERG gene fusion is one of a series of highly promising prostate cancer (PCa) biomarker alternatives to the controversial serum PSA. Current methods for detecting TMPRSS2:ERG are limited in terms of long processing time, high cost and the need for specialized equipment. Thus, there is an unmet need for less complex, faster, and cheaper methods to enable gene fusion detection in the clinic. We describe herein a simple, rapid and inexpensive assay which combines robust isothermal amplification technique with a novel visualization method for evaluating urinary TMPRSS2:ERG status at less than USD 5 and with minimal equipment. The assay is sensitive, and rapidly detects as low as 105 copies of TMPRSS2:ERG transcripts while maintaining high levels of specificity.

Expression of an Oncogenic ERG isoform Characterizes a Distinct Subtype of B-Progenitor Acute Lymphoblastic Leukemia

Introduction. Prior studies have described a subset of B-progenitor ALL cases with a distinct gene expression profile and/or deletions involving ERG (encoding the ETS family member v-ets avian erythroblastosis virus E26 oncogene), however the relationship of these alterations and their role in leukemogenesis are poorly understood. We performed integrated genomic and epigenetic analyses, biochemical studies and leukemogenesis assays to define the genetic basis of this form of ALL.Methods. We studied 1674 childhood, adolescent and young adult B-progenitor ALL cases with microarray gene expression profiling and/or RNA-sequencing data to enable the identification of ERG ALL by unsupervised clustering and predictive analysis of microarrays. Detailed genomic analysis was performed for 144 ERG ALL cases, including whole genome (N=38), exome (n=46) and/or RNA-sequencing (n=57) cases, and single nucleotide polymorphism array analysis. Epigenetic profiling, including whole genome bisulfite sequencing, chromatin immunoprecipitation and sequencing for ERG and histone modifications and ATAC-sequencing were performed for a subset of 8 xenografted ERG tumors and reference cell lines. ERG transcript expression was measured by analysis of RNA-seq analysis and quantitative RT-PCR assays, and by interrogation of TCGA and PCGP RNA-seq data. The function of ERG isoforms was evaluated by EMSA and transcriptional reporter assays, immunofluoresence, colony forming assays and retroviral bone marrow transplant assays.Results. One hundred and forty four cases (8.6%) of B-ALL cases exhibited a distinct gene expression profile and lacked known chromosomal rearrangements (ERG ALL). Such cases had favorable outcome. Eighty cases (55.6%) had focal deletions of ERG with no evidence of oncogenic or chimeric ERG fusions. The deletions were most commonly heterozygous and involving exons 3-7 (n=27) or 3-9 (n=22) of 10 coding exons, and less commonly involving exon 1, or a larger region of the gene. No ERG deletions were identified in non-ERG ALL. Two cases harbored missense mutations in the ETS domain. Analysis of whole genome and exome sequencing data of 71 cases identified a high frequency of alterations of lymphoid transcription factors (46.5%; IKZF1 36.7%, PAX5 11.3%); mutation of transcription factors otherwise uncommon in ALL (21%; MYC, MYCBP2, MGA, ZEB2, GATA3); activation of signaling pathways, most commonly NRAS or KRAS (35.2%); cell cycle regulation (22.5%); and epigenetic modifiers (56.3%), most commonly KMT2D, SETD2, ARID2 and NCOR1. Notably, the five year event-free survival of ERG ALL cases with IKZF1 alterations exceeded 85% in both St Jude and Children's Oncology Group cohorts.We observed striking transcriptional deregulation at the ERG locus. Most (51/56) ERG- deleted cases expressed an ERG isoform encoded by a novel exon in intron 6 that splices in frame to distal exons, resulting in expression of a truncated C-terminal ERG protein that lacks the pointed and central regulatory domains, but retains the ETS and transactivation domain (ERGalt). ERGalt was also present in most (36/44) cases lacking an ERG deletion, and was strongly associated with presence of ERGalt protein in leukemic cells. We also identified expression of an Antisense Long non-coding RNA associated with the ERG locus (ALE) in ERG ALL. ERGalt and ALE were absent, or uncommonly expressed at very low levels in non-ERG ALL. ERGalt was absent, and ALE rarely expressed in non-ALL PCGP and TCGA samples.ERGalt and point mutant ERG were retained in the nucleus, bound DNA targets and acted as competitive inhibitors of wild type (WT) ERG in transcriptional reporter assays. Lineage-negative Arf -null bone marrow cells transduced with ERG WT induced an aggressive erythro-megakaryoblastic leukemia; in contrast ERGalt induced an immature lymphoid progenitor leukemia.Conclusions. Genomic alterations drive aberrant transcription of ERG, resulting on expression of a truncated, C-terminal oncogenic ERG protein. This represents a novel mechanism of transcription factor deregulation in leukemia. As a subset of ERG ALL cases lack ERG deletion, and as IKZF1 alterations are not associated with inferior outcome in this form of ALL, diagnostic approaches must incorporate gene expression profiling in addition to identification of ERG and IKZF1 alterations to accurately identify this form of leukemia. DisclosuresEvans:Prometheus Labs: Patents & Royalties: Royalties from licensing TPMT genotyping. Stock:Gilead: Membership on an entity's Board of Directors or advisory committees. Voorhees:Oncopeptides: Consultancy; Onyx Pharmaceuticals: Research Funding; GSK: Consultancy; Oncopeptides: Research Funding; Janssen: Research Funding; A Takeda Oncology Company: Consultancy, Research Funding; Celgene: Consultancy; Millennium Pharmaceuticals: Consultancy, Research Funding; Acetylon Pharmaceuticals, Inc.: Research Funding; Novartis: Consultancy; Array BioPharma: Consultancy; GSK: Research Funding; Celgene: Research Funding. Hunger:Spectrum Pharmaceuticals: Consultancy; Jazz Pharmaceuticals: Consultancy; Sigma Tau: Consultancy; Merck: Equity Ownership. Mullighan:Incyte: Consultancy; Amgen: Honoraria.

The role of TMPRSS2:ERG in molecular stratification of PCa and its association with tumor aggressiveness: a study in Brazilian patients.

Recurrent gene fusions between the genes TMPRSS2 and ERG have been described in prostate cancer (PCa) and are found in 27% to 79% of radical prostatectomy. This fusion transcription results in ERG overexpression, which can be detected by immunohistochemistry (IHC) and provide a potential diagnostic marker for PCa. Three tissue microarrays (TMAs) containing samples from 98 patients with PCa and one TMA of 27 samples from individuals without PCa were tested for ERG immunostaining, and the presence of TMPRSS2:ERG transcripts was confirmed by quantitative real time PCR (qRT-PCR). The results showed that 46.9% of tumors tested positive for ERG immunostaining, and this finding was consistent with the results of qRT-PCR testing (k = 0.694, p < 0.001). IHC had a specificity of 83.3% and a sensitivity of 81% in detecting TMPRSS2:ERG fusion. Patients with PSA < 4.0 ng/mL showed positive immunoreactivity for ERG (p = 0.031). Kaplan-Meier analysis suggested that ERG expression did not influence the time of biochemical recurrence. This study demonstrates that both IHC and qRT-PCR are useful tools in detecting TMPRSS2:ERG fusions. A correlation between ERG expression and clinical and pathological parameters was not found, but the frequency, specificity and recurrence of ERG in PCa suggests that it may be a potential adjunct diagnostic tool.

Urine TMPRSS2:ERG fusion transcript integrated with PCA3 score, genotyping, and biological features are correlated to the results of prostatic biopsies in men at risk of prostate cancer

Detection of fusion gene TMPRSS2:ERG transcripts in urine have been recently described in order to refine urine-based detection of prostate cancer (PCa), but data its clinical impact remain scarce. We aimed at investigating the correlation of TMPRSS2:ERG, prostate cancer antigen 3 (PCA3), prostate specific antigen (PSA) density, genetic variants, and androgenic status with outcome and pathological findings at prostatic biopsy. Between 2007 and 2011, 291 patients at risk of PCa because of PSA > 3.0 ng/ml (55%) or candidate to active surveillance protocol justifying restaging biopsy management (45%) were recruited. TMPRSS2:ERG was detected by urine assay (Progensa™). PCA3-score, PSA level, bioavailable testosterone level, prostate volume, rs1447295 and rs6983267 genotypes were prospectively assessed. Univariate and multivariate analysis by logistic regression model (logit) were conducted to study the correlation of TMPRSS2:ERG status, PCA3, and PSA density with biopsy results, and Gleason score. Of 291 patients, 173 had PCa and 118 had negative biopsy. PCA3 score, PSA density and TMPRSS2:ERG-score were correlated with presence of PCa (P < 0.0001, P = 0.046, and P < 0.0001, respectively). This correlation remained strong on multivariable analysis model (area under curve 0.743). PCA3 score and PSA density were significantly associated with presence of Grade 4 through multivariable analysis. PCA3 score was also correlated to the percentage of positive cores at biopsy (P = 0.008). Integration of levels TMPRSS2:ERG transcripts in urine, with PCA3-score, androgenic status, genetic status and traditional clinical variables could significantly increase detection of high risk localized PCa.

Presence of FLT3-ITD and high BAALC expression are independent prognostic markers in childhood acute myeloid leukemia

AbstractMutation status of FLT3, NPM1, CEBPA, and WT1 genes and gene expression levels of ERG, MN1, BAALC, FLT3, and WT1 have been identified as possible prognostic markers in acute myeloid leukemia (AML). We have performed a thorough prognostic evaluation of these genetic markers in patients with pediatric AML enrolled in the Nordic Society of Pediatric Hematology and Oncology (NOPHO) 1993 or NOPHO 2004 protocols. Mutation status and expression levels were analyzed in 185 and 149 patients, respectively. Presence of FLT3-internal tandem duplication (ITD) was associated with significantly inferior event-free survival (EFS), whereas presence of an NPM1 mutation in the absence of FLT3-ITD correlated with significantly improved EFS. Furthermore, high levels of ERG and BAALC transcripts were associated with inferior EFS. No significant correlation with survival was seen for mutations in CEBPA and WT1 or with gene expression levels of MN1, FLT3, and WT1. In multivariate analysis, the presence of FLT3-ITD and high BAALC expression were identified as independent prognostic markers of inferior EFS. We conclude that analysis of the mutational status of FLT3 and NPM1 at diagnosis is important for prognostic stratification of patients with pediatric AML and that determination of the BAALC gene expression level can add valuable information.

ERG, BAALC, and MN1 RNA Levels Are Correlatively Over-Expressed, and Relate to Risk-Defining Prognostic Mutations in Intermediate-Risk Acute Myeloid Leukemia

Abstract 1471 Introduction:A variety of prognostic molecular markers have been proposed for risk stratification of intermediate-risk AML, which includes patients with normal cytogenetics (CN) and patients with cytogenetic abnormalities other than the recurrent prognostically informative cytogenetic aberrations (CA). Acquired mutations of FLT3 ITD, NPM1, and CEBPA have well-established prognostic significance, and have been incorporated into consensus classification schemes. In addition, several gene expression markers (WT1, ERG, BAALC, and MN1) have been proposed as prognostic indicators, but with less extensive validation. Whether these new gene expression markers should be incorporated into proposed “molecular risk scores” for AML has not been well refined. In this study, we have determined the transcript levels of WT1, ERG, BAALC, and MN1 in AML patients, and correlated these quantitative levels with other validated clinical and laboratory prognostic indicators. Methods: Diagnostic blood or bone marrow samples were analyzed from 56 pre-treatment AML patients from our institution (48% male; median age 59). Metaphase cytogenetics showed 4 patients with inv(16), 4 with a monosomal karyotype, 25 with a CN karyotype and 23 with a CA karyotype (intermediate-risk cytogenetics). The expression levels of WT1, ERG, BAALC, and MN1 were quantified with TaqMan real-time PCR and normalized to ABL. The FLT3 ITD, NPM1, DNMT3A R882, CEBPA, and MLL PTD mutations were detected with either HRM, direct sequencing, and/or PCR fragment analysis. The WT1 SNP rs16754 was determined with a TaqMan genotyping assay. Results: In the 56 AML patients, the prevalence of the FLT3 ITD, NPM1, MLL-PTD, and DNMT3A R882 mutations were similar to previously reported values at 37%, 27%, 6%, and 13%, respectively. The frequency of patients carrying the minor allele of the WT1 SNP (combined heterozygous and homozygous) was 30%. Compared with their expression level in 29 normal control individuals, all four genes were significantly over-expressed in the AML patients, with mean RNA level differences of 1.98-log for WT1 (P<0.0001), 1.18-log for ERG (P<0.0001), 1.02-log for BAALC (P<0.0001), and 0.53-log for MN1 (P = 0.005). ERG, BAALC, and MN1 were expressed at low but detectable levels in 100% of the normal control samples, while WT1 was not detectably expressed in 48% of the controls. For all 4 genes, there were no significant differences in the expression levels between the CA & CN cytogenetic subclasses. As high transcript levels of WT1, ERG, BAALC, and MN1 have been proposed to impart a high risk AML phenotype, one might predict that the RNA levels of each of these 4 genes would correlate with one another. To confirm that hypothesis, we found a highly significant correlation of quantitative RNA levels among the ERG, BAALC, and MN1 genes (P <.004; R=0.42–0.72). WT1 RNA levels were highly correlated with ERG (P<0.0001; R=0.59), but less highly correlated with BAALC & MN1 (P=0.04; R=0.3). Categorization of the gene expression level as “high” or “low” (above or below the median) also revealed a similar relationship, in which ERG, BAALC, and MN1 RNA were all significantly correlated (P<0.01), but there was no significant correlation of WT1 RNA with the other 3 genes (P>0.9). Consistent with its role as a prognostic risk marker, ERG transcript levels were significantly lower in CN-AML patients with the low-risk NPM+/FLT3- genotype than in those with other genotypes (0.42 log expression difference; P<0.04). Consistent with WT1’s role as a risk marker, in the CA-AML patients, WT1 RNA levels were significantly higher in patients with the high-risk FLT3+ genotype than in those with other genotypes (1.3 log expression difference; P<0.04). Conclusions: To better define prognostic risk markers in AML, we have performed comprehensive mutation and gene expression analysis on 56 diagnostic AML samples. WT1, ERG, BAALC, and MN1 RNA were significantly over-expressed in AML patients compared to normal controls. ERG, BAALC, and MN1 RNA levels significantly correlated with one another. The prevalence of FLT3, NPM, DNMT3A, and MLL mutations in these AML patients was predictably high, and some of these well-characterized prognostic mutations were significantly associated with gene expression levels. Additional details on the relationship of these new prognostic RNA markers to the clinical outcome of this AML cohort will be reported at the meeting. Disclosures:No relevant conflicts of interest to declare.

Molecular analysis of multifocal prostate cancer cases

Background. Prostate cancer (PCa) is usually a multifocal disease with different foci displaying histological and molecular heterogeneity. Biopsy-based pathology diagnosis of PCa may not be representative of the entire tumour; thus, markers more precisely characterizing every focus of multifocal PCa are highly instrumental for a better testing of PCa. Materials and Methods. Two distant foci of prostate adenocarcinoma were obtained from prostatectomy specimens of ten patients with pT2–pT3 stage PCa. The expression of TMPRSS2 : ERG, TMPRSS2 : ETV1, and TERT was assessed by means of reverse transcription PCR and quantified using the real-time-based approach. Ki-67, ERG, EMA, AMACR, p16, and p53 expression was evaluated by means of immunohistochemistry (IHC) on tissue microarrays (TMA). Results. Two out of ten cases were identified with different Gleason scores in paired foci of PCa. The expression of most of the IHC markers was quite even between TMA cores of each PCa case, with p16 showing the highest level of heterogeneity (44%; 4/9); 80% (8/10) of multifocal PCa expressed different variants of the TMPRSS2 : ERG transcript or showed a varying status of fusion positivity in paired foci, and the expression levels of the transcript were also heterogeneous. Similarly, 90% (9/10) of PCa showed a different positivity for TERT expression in paired foci. Conclusions. Measurement of TMPRSS2 : ERG and TERT expression offers a valuable tool for identifying most aggressive tumour foci and selecting a relevant treatment of PCa. Keywords: prostate cancer, multifocality, TMPRSS2 : ERG, telomerase

TMPRSS2–ERG-Mediated Feed-Forward Regulation of Wild-Type ERG in Human Prostate Cancers

Recurrent gene fusions involving ETS family genes are a distinguishing feature of human prostate cancers, with TMPRSS2-ERG fusions representing the most common subtype. The TMPRSS2-ERG fusion transcript and its splice variants are well characterized in prostate cancers; however, not much is known about the levels and regulation of wild-type ERG. By employing an integrative approach, we show that the TMPRSS2-ERG gene fusion product binds to the ERG locus and drives the overexpression of wild-type ERG in prostate cancers. Knockdown of TMPRSS2-ERG in VCaP cells resulted in the downregulation of wild-type ERG transcription, whereas stable overexpression of TMPRSS2-ERG in the gene fusion-negative PC3 cells was associated with the upregulation of wild-type ERG transcript. Further, androgen signaling-mediated upregulation of TMPRSS2-ERG resulted in the concomitant upregulation of wild-type ERG transcription in VCaP cells. The loss of wild-type ERG expression was associated with a decrease in the invasive potential of VCaP cells. Importantly, 38% of clinically localized prostate cancers and 27% of metastatic prostate cancers harboring the TMPRSS2-ERG gene fusions exhibited overexpression of wild-type ERG. Taken together, these results provide novel insights into the regulation of ERG in human prostate cancers.

Abstract 2155: The origins and functional consequences of ETS gene fusions in prostate cancer

Abstract The purpose of this study is to unravel the cellular mechanisms underlying the oncogenic ETS gene fusions, which are a hallmark of prostate cancer development. Recurrent gene fusions involving the 5’untranslated region of the androgen-regulated gene TMPRSS2 and the ETS family genes are observed in a majority of prostate cancers. Among the ETS family gene fusions, the TMPRSS2-ERG fusions involving the 5’untranslated region of TMPRSS2 with the ERG gene are the most common and found in approximately 50% of prostate cancers. However, the origins and functional consequences of ETS gene fusions are not clear. Using dual color fluorescence in situ hybridization (FISH), we demonstrate that stimulation with dihydrotestosterone (DHT) induces proximity between TMPRSS2 and ERG genomic loci in LNCaP cells, which are androgen sensitive and lack the TMPRSS2-ERG gene fusions. This effect was dependent on androgen receptor (AR). Importantly, androgen did not induce proximity between the TMPRSS2 and ERG loci in DU145 human prostate cancer cells, which are androgen insensitive. Further, a combination of androgen signaling and genotoxic stress that induces DNA double strand breaks results in the formation of TMPRSS2-ERG gene fusions in LNCaP cells. Interestingly, we observe that the ERG protein formed as a result of gene fusion binds to the promoter of wild type ERG and activates its transcription. The VCaP cell line that endogenously harbors the TMPRSS2-ERG gene fusion has high levels of wild type ERG. Treatment with androgens induces the expression of both the TMPRSS2-ERG and wild type ERG transcripts in VCaP cells. Lenti virus mediated stable over expression of TMPRSS2-ERG in PC3 cells results in an increase in the expression levels of wild type ERG. This auto-activation of wild type ERG is observed in about 50% of clinically localized and 25% of metastatic prostate cancers harboring the TMPRSS2-ERG gene fusions, but not in ETS negative prostate cancers. Taken together, our studies provide a mechanistic framework for the up-regulation of ERG transcription in prostate cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2155. doi:10.1158/1538-7445.AM2011-2155

ETS family-associated gene fusions in Japanese prostate cancer: analysis of 194 radical prostatectomy samples

The incidence and clinical significance of the TMPRSS2:ERG gene fusion in prostate cancer has been investigated with contradictory results. It is now common knowledge that significant variability in gene alterations exists according to ethnic background in various kinds of cancer. In this study, we evaluated gene fusions involving the ETS gene family in Japanese prostate cancer. Total RNA from 194 formalin-fixed and paraffin-embedded prostate cancer samples obtained by radical prostatectomy was subjected to reverse-transcriptase polymerase chain reaction to detect the common TMPRSS2:ERG T1-E4 and T1-E5 fusion transcripts and five other non-TMPRSS2:ERG fusion transcripts. We identified 54 TMPRSS2:ERG-positive cases (54/194, 28%) and two HNRPA2B1:ETV1-positive cases (2/194, 1%). The SLC45A3-ELK4 transcript, a fusion transcript without structural gene rearrangement, was detectable in five cases (5/194, 3%). The frequencies of both TMPRSS2:ERG- and non-TMPRSS2:ERG-positive cases were lower than those reported for European, North American or Brazilian patients. Internodular heterogeneity of TMPRSS2:ERG was observed in 5 out of 11 multifocal cases (45%); a frequency similar to that found in European and North American cases. We found a positive correlation between the TMPRSS2:ERG fusion and a Gleason score of ≤7 and patient age, but found no relationship with pT stage or plasma prostate-specific antigen concentration. To exclude the possibility that Japanese prostate cancer displays novel TMPRSS2:ERG transcript variants or has unique 5′ fusion partners for the ETS genes, we performed 5′ RACE using fresh-frozen prostate cancer samples. We identified only the normal 5′ cDNA ends for ERG, ETV1 and ETV5 in fusion-negative cases. Because we identified a relatively low frequency of TMPRSS2:ERG and other fusions, further evaluation is required before this promising molecular marker should be introduced into the management of Japanese prostate cancer patients.

Abstract 4963: ERG expression levels reflect functional status of androgen receptor in prostate cancer

Abstract Background: Expression of the ERG proto-oncogene, is activated in 50-70% of prostate tumors by androgen receptor (AR) mediated signals due to the fusion of AR regulated promoters (primarily TMPRSS2 and to a lesser extent SLC45A3 and NDRG1) to the ERG protein coding sequence. Our previous studies of quantitative expression levels of ERG or TMPRSS2-ERG fusion transcripts have noted that relatively low or no ERG expression in prostate tumors significantly associated with progressive disease. Here, we have tested the hypothesis that ERG expression levels in prostate tumor cells reflect AR transcriptional regulatory function in a given biological context of the tumor progression. Therefore, tumors with lower ERG may represent a subset with attenuated AR signaling. Experimental procedures: Expression of ERG and other AR regulated genes were evaluated in a GeneChip dataset obtained from a panel of laser capture micro-dissected well/moderately differentiated (WD) or poorly differentiated (PD) tumor cells derived from primary tumors of patients, who had no prior androgen ablation treatment. Results: ERG expression pattern was similar to that of other AR regulated genes. Low frequency of ERG expression was noted in PD tumor cells (30%) in comparison to WD tumor cells (80%), suggesting for subdued AR function in a significant fraction of tumors with genomic alterations of ERG. Conclusions: We developed a cumulative AR Function Index (ARFI) by integrating ERG into a panel of defined AR target genes, may have future potential in stratifying patients for targeted therapy on the basis of overall AR functional status in primary tumors. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4963.

1429 IN VIVO READOUT OF ANDROGEN RECEPTOR (AR) FUNCTIONAL STATUS IN PRIMARY TUMORS FOR PATIENT STRATIFICATION

You have accessJournal of UrologyProstate Cancer: Basic Research VIII1 Apr 20101429 IN VIVO READOUT OF ANDROGEN RECEPTOR (AR) FUNCTIONAL STATUS IN PRIMARY TUMORS FOR PATIENT STRATIFICATION Gyorgy Petrovics, Bungo Furusato, Syed Shaheduzzaman, Yongmei Chen, Timothy Nydam, Lakshmi Ravindranath, Amina Ali, Maryanne Vahey, Isabell Sesterhenn, David McLeod, Albert Dobi, and Shiv Srivastava Gyorgy PetrovicsGyorgy Petrovics Rockville, MD More articles by this author , Bungo FurusatoBungo Furusato Washington, DC More articles by this author , Syed ShaheduzzamanSyed Shaheduzzaman Rockville, MD More articles by this author , Yongmei ChenYongmei Chen Rockville, MD More articles by this author , Timothy NydamTimothy Nydam Washington, DC More articles by this author , Lakshmi RavindranathLakshmi Ravindranath Rockville, MD More articles by this author , Amina AliAmina Ali Washington, DC More articles by this author , Maryanne VaheyMaryanne Vahey Silver Spring, MD More articles by this author , Isabell SesterhennIsabell Sesterhenn Washington, DC More articles by this author , David McLeodDavid McLeod Washington, DC More articles by this author , Albert DobiAlbert Dobi Rockville, MD More articles by this author , and Shiv SrivastavaShiv Srivastava Rockville, MD More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2010.02.1122AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Expression of the ERG proto-oncogene is activated in 50-70% of prostate tumors by AR mediated signals due to the fusion of AR regulated promoters (primarily TMPRSS2 and to a lesser extent SLC45A3 and NDRG1) to the ERG protein coding sequence. Our previous studies of quantitative expression levels of ERG or TMPRSS2-ERG fusion transcripts have noted that relatively low or no ERG expression in prostate tumors significantly associated with progressive disease. Here, we have tested the hypothesis that ERG expression levels in prostate tumor cells reflect AR transcriptional regulatory function in a given biological context of the tumor progression. Therefore, tumors with lower ERG may represent a subset with attenuated AR signaling. METHODS From over 300 radical prostatectomy (RP) specimens archived in the CPDR Biospecimen Bank with 8-13 years follow-up, 40 frozen tissue specimens were selected for this study: 20 with well/moderately differentiated (WD) tumor and less aggressive clinical features, and 20 with poorly differentiated (PD) tumor and more aggressive clinical characteristics, all from patients with no prior androgen ablation treatment. Prostate epithelial cells with tumor and benign morphology were microdissected (LCM) and the extracted RNA was analyzed by GeneChip technology (Affymetrix) after linear amplification. A selected set of known androgen regulated genes was used as in vivo AR readout (androgen receptor function index = ARFI). Correlation of ERG with ARFI and with clinico-pathological parameters was analyzed by conventional statistical approaches. RESULTS Positive regulation of ERG in the TMPRSS2-ERG fusion context by functional androgen signaling was evident in the majority of human prostate tumors, while absence of ERG tightly correlated with deregulated expression of AR target genes. Overall, ERG expression pattern was similar to that of other AR regulated genes. Strikingly low frequency of ERG expression was noted in PD tumor cells (30%) in comparison to WD tumor cells (80%), suggesting for subdued AR function in a significant fraction of tumors with genomic alterations of ERG. CONCLUSIONS By integrating ERG into a panel of defined AR target genes, we developed a cumulative AR Function Index (ARFI), which if validated may have future potential in stratifying patients for targeted therapy on the basis of overall AR functional status in primary tumors. © 2010 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 183Issue 4SApril 2010Page: e551 Advertisement Copyright & Permissions© 2010 by American Urological Association Education and Research, Inc.MetricsAuthor Information Gyorgy Petrovics Rockville, MD More articles by this author Bungo Furusato Washington, DC More articles by this author Syed Shaheduzzaman Rockville, MD More articles by this author Yongmei Chen Rockville, MD More articles by this author Timothy Nydam Washington, DC More articles by this author Lakshmi Ravindranath Rockville, MD More articles by this author Amina Ali Washington, DC More articles by this author Maryanne Vahey Silver Spring, MD More articles by this author Isabell Sesterhenn Washington, DC More articles by this author David McLeod Washington, DC More articles by this author Albert Dobi Rockville, MD More articles by this author Shiv Srivastava Rockville, MD More articles by this author Expand All Advertisement Advertisement PDF DownloadLoading ...

NOTCH1/FBXW7 Mutations, but Not Low ERG/BAALC Expression, Identify a Major Subgroup of Adult T-ALL with a Favorable Outcome: a GRAALL Study.

Abstract 1568▪▪This icon denotes an abstract that is clinically relevant.Poster Board I-592Several somatic genetic abnormalities have been identified in T-ALL but therapeutic stratification still relies on clinical markers. NOTCH1 and/or FBXW7 (N/F) mutations both lead to activation of the NOTCH1 pathway and are amongst the most frequent mutations in T-ALL. We identified N/F mutations as a good prognostic marker, found in 70% of patients within the French LALA-94 and GRAALL-2003 prospective adult T-ALL trials, whereas the German GMALL group reported that low ERG and BAALC (E/B) transcript expression also predicts a highly favorable outcome in 41% of adult T-ALL (Baldus et al. J Clin Oncol. 2007 25(24):3739-45). In order to compare the predictive prognosis value of N/F mutations versus low E/B expression, we analyzed 189 adult T-ALL for both, including 107 previously reported cases and 82 unreported cases included within the ongoing GRAALL-2005 trial up to the first planned interim analysis.E/B were quantified by real time RT-PCR and the comparative cycle threshold (Ct) method was used to determine the relative expression levels for ERG and BAALC to ABL. T-ALL patients were classified as low E/B expressers (E/Blow) or high E/B expressers (E/Bhigh) as previously reported by Baldus et al. Despite the use of ABL rather than GPI as internal control, we observed the same incidence of E/Blow. 41% (n=77) of T-ALLs were classified as E/Blowand 59% (n=112) as E/Bhigh. 68% (n=128) of cases were mutated for NOTCH1 and/or FBXW7 (N/Fmut) and 32% (n=61) were germline for both (N/FGL). As expected E/Bhigh correlated with an immature phenotype (p<0.0001). There was no association between E/B expression level and F/Nmut (p=0.5) and no significant correlation for either N/F or E/B status with age and leucocytosis at diagnosis.There was no difference in overall survival (OS) and event free survival (EFS) between E/Bhigh and E/Blow (4-years OS: 57% v 55 %; 4-years EFS: 46% v 47%). In contrast, N/Fmut compared with N/FGL had a better OS (67% v 36%; P= .002) and EFS (56% v 32%; P=.008). When the LALA and GRAALL protocols were analyzed separately, N/Fmut retained their significant favorable outcome, including in the GRAALL-2003 and GRAALL-2005 trials, which give overall good results for T-ALL. E/B expression did not impact on prognosis in either the GRAALL trials (E/Bhigh OS =68% EFS= 64% v E/Blow OS= 62% EFS=50%) or the LALA trials (E/Bhigh OS =46% EFS= 30% v E/Blow OS= 39% EFS=29%) individually.Taken overall, our data demonstrate that N/Fmut, but not low E/B expression, identify a major subgroup (68%) of adult T-ALL with a highly favorable outcome that could justify individual therapeutic stratification for T-ALL. N/F mutation status is also better suited to individual patient stratification than the continuous spectrum of ERG and BAALC transcript expression. DisclosuresNo relevant conflicts of interest to declare.

Overexpression of Prostate-Specific TMPRSS2(exon 0)-ERG Fusion Transcripts Corresponds with Favorable Prognosis of Prostate Cancer

To gain insight in the mechanism and clinical relevance of TMPRSS2-ERG expression in prostate cancer, we determined the specific characteristics of fusion transcripts starting at TMPRSS2 exon 1 and at a more upstream and less characterized exon 0. We used quantitative PCR analysis to investigate expression of wild-type TMPRSS2(exon 0) and TMPRSS2(exon 1) and of ERG fusion transcripts. Expression was tested in normal tissue samples, in prostate cancer cell lines and xenografts, and in fresh-frozen clinical prostate cancer samples (primary tumors and recurrences). Expression in clinical samples was correlated with disease progression. TMPRSS2(exon 0) and TMPRSS2(exon 1) transcripts were similarly androgen regulated in prostate cancer cell lines, but the expression levels of TMPRSS2(exon 1) were much higher. Comparison of expression in different tissues showed TMPRSS2(exon 0) expression to be much more prostate specific. In androgen receptor-positive prostate cancer xenografts, TMPRSS2(exon 1) transcripts were expressed at similar levels, but TMPRSS2(exon 0) transcripts were expressed at very variable levels. The same phenomenon was observed for TMPRSS2-ERG fusion transcripts. In clinical prostate cancers, the expression of TMPRSS2(exon 0)-ERG was even more variable. Expression of TMPRSS2(exon 0)-ERG transcripts was detected in 55% (24 of 44) of gene fusion-positive primary tumors but only in 15% (4 of 27) of gene fusion-positive recurrences and at much lower levels. Furthermore, in primary tumors, expression of TMPRSS2(exon 0)-ERG transcripts was an independent predictor of biochemical progression-free survival. The expression of TMPRSS2(exon 0)-ERG fusion transcripts in prostate cancer is associated with a less-aggressive biological behavior.