Src tyrosine kinase (Src) is implicated in the development of bone metastasis and castration resistance of prostate cancer. Src inhibitors are currently being tested in clinical trials for such ...diseases. Understanding the molecular and cellular actions of Src inhibitors holds the key to future improvement of this line of therapy. Here we describe the microRNA expression profiles modulated by two Src inhibitors and demonstrate that the miR-30 family members are the most prominently induced species. Consistent with its tumor suppressor role, miR-30 is downmodulated by oncogenic signals such as epidermal growth factor (EGF) and hepatocyte growth factor, and is generally underexpressed in prostate cancer specimens. A number of epithelial-to-mesenchymal transition (EMT)-associated genes are predicted targets of miR-30. Among these genes the Ets-related gene (ERG) is the most frequently overexpressed oncogene in prostate cancer activated by genomic fusion events between promoter upstream sequences of the TMPRSS2 and coding sequences of ERG. We showed by ERG 3' untranslated region reporter and mutagenesis assays that ERG is a direct target of miR-30. Overexpression of miR-30 in prostate cancer cells suppresses EMT phenotypes and inhibits cell migration and invasion. It also inhibits the in vitro and in vivo growth of VCaP cells, which depends on TMPRSS2-ERG for proliferation. TMPRSS2-ERG is generally regulated by androgen at the transcriptional level. Our finding reveals a new post-transcriptional mechanism of TMPRSS2-ERG regulation by Src and growth signals via miR-30 providing a rationale for targeting ERG-positive castration-resistant tumors with Src inhibitors.
The high prevalence of TMPRSS2-ERG rearrangements ( approximately 60%) in prostate cancer (CaP) leads to androgenic induction of the ETS-related gene (ERG) expression. However, the biological ...functions of ERG overexpression in CaP remain to be understood. ERG knockdown in TMPRSS2-ERG expressing CaP cells induced striking morphological changes and inhibited cell growth both in cell culture and SCID mice. Evaluation of the transcriptome and specific gene promoters in ERG siRNA-treated cells and investigation of gene expression signatures of human prostate tumors revealed ERG-mediated activation of C-MYC oncogene and the repression of prostate epithelial differentiation genes (PSA and SLC45A3/Prostein). Taken together, these data combining cell culture and animal models and human prostate tumors reveal that ERG overexpression in prostate tumor cells may contribute to the neoplastic process by activating C-MYC and by abrogating prostate epithelial differentiation as indicated by prostate epithelial specific markers.
Gene fusions prevalent in prostate cancer (CaP) lead to the elevated expression of the ERG proto-oncogene. ERG activation present in 50-70% of prostate tumors underscores one of the most common ...oncogenic alterations in CaP. Despite numerous reports of gene fusions and mRNA expression, ERG oncoprotein status in CaP still remains to be defined. Furthermore, development of ERG protein-based assays may provide a new dimension to evaluation of gene fusions involving diverse androgen-regulated promoters and the ERG protein-coding sequence. Through exhaustive evaluations of 132 whole-mount prostates (261 tumor foci and over 200 000 benign glands) for the ERG oncoprotein nuclear expression, we demonstrated 99.9% specificity for detecting prostate tumor cells using a highly specific anti-ERG monoclonal antibody. The ERG oncoprotein expression correlated well with fusion transcript or gene fusion in randomly selected specimens. Strong concordance of ERG-positive foci of prostatic intraepithelial neoplasia (PIN) with ERG-positive carcinoma (82 out of 85 sections with PIN, 96.5%) affirms the biological role of ERG in clonal selection of prostate tumors in 65% (86 out of 132) of patients. Conversely, ERG negative PINs were associated with ERG-negative carcinoma. Taken together, the homogeneous and strong ERG expression detected in individual tumors establishes the potential for ERG oncoprotein-based stratification of CaP.
Overexpression of the ERG protein is highly prevalent in prostate cancer (PCa) and commonly results from gene fusions involving the ERG gene. Recently, N-terminal epitope-targeted mouse and a ...C-terminal epitope-targeted rabbit monoclonal anti-ERG antibody (ERG-MAbs) have been introduced for the detection of the ERG protein. Independent studies reported that immunohistochemistry (IHC) with both ERG-MAbs highly correlates with the underlying ERG gene rearrangement status. However, comparative studies of both antibodies are lacking. Here, we are among the first to compare the mouse ERG-MAb with the rabbit ERG-MAb for their concordance on the same PCa cohort. Furthermore, we assessed whether the ERG protein expression is conserved in lymph node and distant PCa metastases.
We evaluated tissue microarrays of 278 specimens containing 265 localized PCa, 29 lymph node, 30 distant metastases and 13 normal prostatic tissues. We correlated ERG protein expression with ERG rearrangement status using an ERG break-apart fluorescence in-situ hybridization assay and IHC of both ERG-MAbs.
ERG expression and ERG rearrangement status were highly concordant regardless of whether the mouse or rabbit ERG-MAb was used (97.8% versus 98.6%, respectively). Of interest, both ERG antibodies reliably detected the ERG expression in lymph node and distant PCa metastases, of which a subset underwent decalcification. Lymphocytes only revealed immunoreactivity using the rabbit ERG-MAb. If ERG protein expression was present in localized PCa, we observed the same pattern in the corresponding lymph node metastases.
By demonstrating a broad applicability of IHC to study ERG protein expression using either antibody, this study adds an important step toward a facilitated routine clinical application. Further, we demonstrate that the clonal nature of the ERG rearrangement is not restricted to the genomic level, but proceeds in the proteome. Together, our results simplify future efforts to further eliucidate the biological role of ERG in PCa.
Alteration of the AR functions due to amplification, overexpression and somatic mutation of the AR itself or altered interaction of AR with other cell growth regulatory proteins, may contribute to a ...significant subset of advanced prostate cancer (CaP). Very little is known about the pathways impacted by AR dysfunctions, although CaP associated AR alterations suggest the biological role of the AR dysfunction in disease progression. Comparative evaluations of wild type (wt) AR and mutant (mt) ARs in appropriate experimental models should provide a better understanding of the functional impact of AR alterations in CaP. Here, we provide direct evidence showing cell growth/cell survival promoting effects of the widely studied CaP associated AR mutation (T877A). In contrast to Ad-wtAR or Ad-control infected LNCaP or LAPC4 cells, Ad-mtAR (T877A) infected LNCaP or LAPC4 cells continued to grow in the androgen-deprived medium and exhibited an androgen independent AR-transcription factor activity. Further, Ad-mtAR (T877A) infected LNCaP or LAPC4 cells exhibited enhanced cell growth in the presence of lower concentrations of the synthetic androgen, R1881. Of note, Ad-mtAR (T877A) infected LNCaP cells showed striking resistance to cell growth inhibition/apoptosis mediated by the wt p53. Taken together, these findings provide novel insights into the AR dysfunctions resulting from the T877A mutation and functionally similar AR alterations may provide selective cell growth/survival advantage for CaP progression. These observations have important implications for developing biology-based prognostic biomarkers and therapeutic strategies for CaP showing such AR dysfunctions.
To determine whether prostate cancers detected in the anterior vs posterior zones impact clinicopathological features and patient outcomes. This information could potentially affect clinical ...management.
A retrospective pathological review of 1528 radical prostatectomy specimens submitted between 1989 and 2011 was completed. Specimens were characterized as anterior zone vs posterior zone based on index tumor and predominant tumor volume location. The chi-square test was used to determine associations between tumor location and categorical patient features. Kaplan-Meier unadjusted analysis was used to compare biochemical recurrence-free and overall survival.
Tumors occurred predominantly in the anterior location in 155 (10.1%) of specimens. There was no difference between mean age, body mass index, racial distribution, family history, number of previous biopsies, clinical Gleason sum or pathological stage in the two groups. Fewer patients had clinically palpable disease in the anterior tumor group, 28.8% vs 40.7% (P=0.0150). Pretreatment PSA was lower in the anterior tumor group. Total tumor volume did differ with anterior tumors having a mean 8.3 cc vs 5.6 cc (P<0.0001) size and a higher incidence of positive margins (P=0.0008). There were no differences in biochemical recurrence-free or overall survival.
Despite the potential for adverse pathological features in anterior-based disease, there appears to be no demographic predilection, notable delay in diagnosis or significant difference in survival outcomes.
Detection of krypton in xenon for dark matter applications Dobi, A.; Davis, C.; Hall, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2011, Letnik:
665
Journal Article
Recenzirano
Odprti dostop
We extend our technique for observing very small concentrations of impurities in xenon gas to the problem of krypton detection. We use a conventional mass spectrometer to identify the krypton content ...of the xenon, but we improve the sensitivity of the device by more than five orders of magnitude with a liquid nitrogen cold trap. We find that the absolute krypton concentration in the xenon can be inferred from the mass spectrometry measurements, and we identify krypton signals at concentrations as low as 0.5×10
−12
mol/mol (Kr/Xe). This technique simplifies the monitoring of krypton backgrounds for WIMP dark matter searches in liquid xenon.
Study of a zirconium getter for purification of xenon gas Dobi, A.; Leonard, D.S.; Hall, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2010, Letnik:
620, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Oxygen, nitrogen and methane purification efficiencies for a common zirconium getter are measured in 1050
Torr of xenon gas. Starting with impurity concentrations near 10
−6
g/g, the outlet impurity ...level is found to be less than 120 ×10
−12
g/g for O
2 and less than 950×10
−12
g/g for N
2. For methane we find residual contamination of the purified gas at concentrations varying over three orders of magnitude, depending on the purifier temperature and the gas flow rate. A slight reduction in the purifier's methane efficiency is observed after 13
mg of this impurity has been absorbed, which we attribute to partial exhaustion of the purifier's capacity for this species. We also find that the purifier's ability to absorb N
2 and methane can be extinguished long before any decrease in O
2 performance is observed, and slower flow rates should be employed for xenon purification due to the cooling effect that the heavy gas has on the getter.
Androgen receptor and prostate cancer Richter, E; Srivastava, S; Dobi, A
Prostate cancer and prostatic diseases,
05/2007, Letnik:
10, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Since the original observations of Huggins and Hodges that prostate cancers are androgen dependent, androgen ablation therapy has been the gold standard for the treatment of advanced prostate cancer ...(CaP). Androgen receptor (AR) is believed to play critical roles in the development and progression of CaP. Treatment for neoadjuvant, adjuvant and recurrent disease all center on the regulation and manipulation of the androgen pathway, in which AR plays an integral role. Recent discoveries that frequent overexpression of ETS-related proto-oncogenes may be driven by AR as a consequence of common genomic rearrangements can hold the key towards the understanding of early phases of prostate cancer. Furthermore, AR function evolves as the cell changes towards a clinically androgen depletion independent state. Comprehension of AR function, regulation and abnormalities are increasingly refined towards the understanding of the role of AR in CaP, and in therapeutic applications. Development of future therapy for CaP will be aided by improving the knowledge of dysfunctions of AR and its network in prostate cancer. This review focuses salient features of AR and on the recent advances addressing AR dysfunctions in prostate cancer.
The majority of prostate cancers (CaP) are detected in early stages with uncertain prognosis. Therefore, an intensive effort is underway to define early predictive markers of CaP with aggressive ...progression characteristics.
In order to define such prognostic markers, we performed comparative analyses of transcriptomes of well- and poorly differentiated (PD) tumor cells from primary tumors of patients (N=40) with 78 months of mean follow-up after radical prostatectomy. Validation experiments were carried out at transcript level by quantitative real-time reverse transcriptase-PCR (RT-PCR) (N=110) and at protein level by immunohistochemistry (N=53) in primary tumors from an independent patient cohort.
Association of a biochemical network of 12 genes with SPARC gene as a central node was highlighted with PD phenotype. Of note, there was remarkable enrichment of NKXH_NKXH_HOX composite regulatory elements in the promoter of the genes in this network suggesting a biological significance of this gene-expression regulatory mechanism in CaP progression. Further, quantitative expression analyses of SPARC mRNA in primary prostate tumor cells of 110 patients validated the association of SPARC expression with poor differentiation and higher Gleason score. Most significantly, higher SPARC protein expression at the time of prostatectomy was associated with the subsequent development of metastasis (P=0.0006, AUC=0.803).
In summary, we propose that evaluation of SPARC in primary CaP has potential as a prognostic marker of metastatic progression.
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