Purpose: About 50% of prostate cancers have TMPRSS2-ERG fusions with concurrent ERG overexpression. The aim of this study was to determine whether clinical differences exist between ERG-positive and ERG-negative cancers in surgically treated patients not exposed to antihormonal therapy. A secondary aim was to search for differences between these tumor classes.Experimental Design: A tissue microarray containing samples from more than 2,800 prostate cancers with clinical data was analyzed for ERG alterations by immunohistochemistry and FISH. Results were compared with tumor phenotype, biochemical recurrence, and molecular features considered important for prostate cancer. The effect of ERG on androgen receptor (AR)-dependent transcription was analyzed in cell lines.Results: ERG expression was found in 52.4% of 2,805 cancers with a 95% concordance between ERG expression and ERG gene rearrangement detected by FISH. ERG expression was unrelated to clinical outcome and tumor phenotype. Differences in AMACR, Annexin A3, Bcl2, CD10, ALCAM, chromogranin A, epidermal growth factor receptor, HER2, mTOR, p53, and synaptophysin status were significant but minimal in absolute numbers. The most striking difference was found for AR expression, which was markedly higher in ERG-positive cancers. In vitro studies showed ERG-dependent impairment of AR-mediated transcriptional activity.Conclusions: The striking similarities between these two types of prostate cancers rules out a major impact of ERG on tumor aggressiveness in early, not hormonally treated cancer. The marked difference in AR levels between ERG-positive and -negative cancers supports a systematic difference in potential response to hormonal therapy as previously observed in clinical trials.

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Background: Expression levels of mRNA and protein by cell types exhibit a range of correlations for different genes. In this study, we compared levels of mRNA abundance for several cluster designation (CD) genes determined by gene arrays using magnetic sorted and laser-capture microdissected human prostate cells with levels of expression of the respective CD proteins determined by immunohistochemical staining in the major cell types of the prostate -basal epithelial, luminal epithelial, stromal fibromuscular, and endothelial -and for prostate precursor/ stem cells and prostate carcinoma cells. Immunohistochemical stains of prostate tissues from more than 50 patients were scored for informative CD antigen expression and compared with cell-type specific transcriptomes.

To examine the role of intercellular interaction on cell differentiation and gene expression in human prostate, we separated the two major epithelial cell populations and studied them in isolation and in combination with stromal cells. The epithelial cells were separated by f low cytometry using antibodies against differentially expressed cell-surface markers CD44 and CD57.

Cluster designation (CD) antigens are cell surface markers that can be used to identify constituent cell populations of an organ. We have previously determined the CD phenotype of normal prostate parenchymal cells and are now extending this analysis to prostate cancer. Since expression of CD antigens is associated with cellular differentiation, cancer cells may differ from their normal counterpart in their CD profile. Compared with luminal secretory cells, prostate adenocarcinoma cells are frequently negative for CD10 and CD13, express increased levels of the cell activation molecule CD24, and decreased levels of the apoptosis-associated multifunctional enzyme CD38. Expression of CD57, CD63, CD75s, CD107a, CD107b, CD164, and CD166 by cancer cells is similar to that of secretory cells. Prostate basal epithelial cells do not express the CD antigens characteristic of prostate secretory cells; and the basal cell CD markers, CD29, CD44, CD49b, CD49f, CD104, and nerve growth factor receptor (NGFR) are not expressed by cancer cells. The preferential expression of secretory cell-associated CD markers by prostate cancer cells suggests a closer lineage relationship between cancer cells and secretory cells than basal cells. Although the above cancer CD phenotype was the most frequently seen, some prostate cancers contained populations of CD10- and/or CD13-positive cells, and CD57-negative cells. Furthermore, the cancer phenotype of tumor metastasis is different. Despite its low frequency in primary tumors, CD10 is expressed by virtually all of the nodal metastases of prostate cancer. In addition, stromal fibromuscular cells associated with primary prostate cancer differ from stromal cells in benign prostate tissue by an increased level of expression of the cell activation molecule, CD90. In summary, our data show that the CD marker expression profile of prostate cancer cells most closely resembles that of secretory prostate epithelial cells and that some prostate cancers consist of heterogeneous cell populations as distinguished by CD-marker expression profiles.

We recently reported an antibody-free targeted protein quantification strategy, termed high-pressure, high-resolution separations with intelligent selection and multiplexing (PRISM) for achieving significantly enhanced sensitivity using selected reaction monitoring (SRM) mass spectrometry. Integrating PRISM with front-end IgY14 immunoaffinity depletion, sensitive detection of targeted proteins at 50–100 pg/mL levels in human blood plasma/serum was demonstrated. However, immunoaffinity depletion is often associated with undesired losses of target proteins of interest. Herein we report further evaluation of PRISM-SRM quantification of low-abundance serum proteins without immunoaffinity depletion. Limits of quantification (LOQ) at low ng/mL levels with a median coefficient of variation (CV) of ~12% were achieved for proteins spiked into human female serum. PRISM-SRM provided >100-fold improvement in the LOQ when compared to conventional LC-SRM measurements. PRISM-SRM was then applied to measure several low-abundance endogenous serum proteins, including prostate-specific antigen (PSA), in clinical prostate cancer patient sera. PRISM-SRM enabled confident detection of all target endogenous serum proteins except the low pg/mL-level cardiac troponin T. A correlation coefficient >0.99 was observed for PSA between the results from PRISM-SRM and immunoassays. Our results demonstrate that PRISM-SRM can successful quantify low ng/mL proteins in human plasma or serum without depletion. We anticipate broad applications for PRISM-SRM quantification of low-abundance proteins in candidate biomarker verification and systems biology studies.

BackgroundThe prostate stroma is a key mediator of epithelial differentiation and development, and potentially plays a role in the initiation and progression of prostate cancer. The tumor-associated stroma is marked by increased expression of CD90/THY1. Isolation and characterization of these stromal cells could provide valuable insight into the biology of the tumor microenvironment.MethodsProstate CD90+ stromal fibromuscular cells from tumor specimens were isolated by cell-sorting and analyzed by DNA microarray. Dataset analysis was used to compare gene expression between histologically normal and tumor-associated stromal cells. For comparison, stromal cells were also isolated and analyzed from the urinary bladder.ResultsThe tumor-associated stromal cells were found to have decreased expression of genes involved in smooth muscle differentiation, and those detected in prostate but not bladder. Other differential expression between the stromal cell types included that of the CXC-chemokine genes.ConclusionCD90+ prostate tumor-associated stromal cells differed from their normal counterpart in expression of multiple genes, some of which are potentially involved in organ development.

BackgroundProstate cancer cells in primary tumors have been typed CD10-/CD13-/CD24hi/CD26+/CD38lo/CD44-/CD104-. This CD phenotype suggests a lineage relationship between cancer cells and luminal cells. The Gleason grade of tumors is a descriptive of tumor glandular differentiation. Higher Gleason scores are associated with treatment failure.MethodsCD26+ cancer cells were isolated from Gleason 3+3 (G3) and Gleason 4+4 (G4) tumors by cell sorting, and their gene expression or transcriptome was determined by Affymetrix DNA array analysis. Dataset analysis was used to determine gene expression similarities and differences between G3 and G4 as well as to prostate cancer cell lines and histologically normal prostate luminal cells.ResultsThe G3 and G4 transcriptomes were compared to those of prostatic cell types of non-cancer, which included luminal, basal, stromal fibromuscular, and endothelial. A principal components analysis of the various transcriptome datasets indicated a closer relationship between luminal and G3 than luminal and G4. Dataset comparison also showed that the cancer transcriptomes differed substantially from those of prostate cancer cell lines.ConclusionsGenes differentially expressed in cancer are potential biomarkers for cancer detection, and those differentially expressed between G3 and G4 are potential biomarkers for disease stratification given that G4 cancer is associated with poor outcomes. Differentially expressed genes likely contribute to the prostate cancer phenotype and constitute the signatures of these particular cancer cell types.