Expression of ERG protein in prostate cancer: variability and biological correlates

Morphological and Immunocytochemical Characterization of Tumor Spheroids in Ascites from High-Grade Serous Carcinoma

Tumor spheroids in the ascites of high-grade serous carcinoma (HGSC) are poorly described. Our objective was to describe their morphological features, cellular composition, PD-1 and PD-L1 expression, and survival correlation of these parameters. The density and size of spheroids were assessed in Giemsa-stained smears; the cell composition of spheroids, including tumor cells, immune cells, capillaries, and myofibroblasts, as well as PD-1 and PD-L1 expression on tumor and immune cells was assessed in immunocytochemically stained cell block sections. Forty-seven patients with primary HGSC and malignant ascites were included. A cut-off value for a spheroid density of 10% was established, which significantly predicted overall survival. However, spheroid size did not correlate with survival outcomes. Spheroids were primarily composed of tumor cells, but the presence of lymphocytes and macrophages was also confirmed. Moreover, capillaries were present in the spheroids of three patients, but the presence of myofibroblasts was not confirmed. PD-1 was expressed on lymphocytes but not on tumor cells. PD-L1 expression was seen on both tumor and immune cells, assessed by 22C3 and SP263 antibody clones but not by the SP142 clone. Our results highlight the potential of routine cytopathological techniques to analyze spheroids in HGSC ascites as a valuable tool to investigate their potential as prognostic markers.

Cytokine-Mediated Degradation of the Transcription Factor ERG Impacts the Pulmonary Vascular Response to Systemic Inflammatory Challenge

Background

During infectious diseases, pro-inflammatory cytokines transiently destabilize interactions between adjacent vascular endothelial cells (ECs) to facilitate the passage of immune molecules and cells into tissues. However, in the lung the resulting vascular hyperpermeability can lead to organ dysfunction. Previous work identified the transcription factor ERG as a master regulator of endothelial homeostasis. Here we investigate whether the sensitivity of pulmonary blood vessels to cytokine-induced destabilization is due to organotypic mechanisms affecting the ability of endothelial ERG to protect lung ECs from inflammatory injury.

Methods

Cytokine-dependent ubiquitination and proteasomal degradation of ERG was analyzed in cultured Human Umbilical Vein ECs (HUVECs). Systemic administration of TNFα or the bacterial cell wall component lipopolysaccharide (LPS) was used to cause a widespread inflammatory challenge in mice; ERG protein levels were assessed by immunoprecipitation, immunoblot, and immunofluorescence. Murine Erg deletion was genetically induced in ECs ( Erg fl/fl ;Cdh5(PAC)Cre ERT2 ), and multiple organs were analyzed by histology, immunostaining, and electron microscopy.

Results

In vitro, TNFα promoted the ubiquitination and degradation of ERG in HUVECs, which was blocked by the proteasomal inhibitor MG132. In vivo, systemic administration of TNFα or LPS resulted in a rapid and substantial degradation of ERG within lung ECs, but not ECs of the retina, heart, liver, or kidney. Pulmonary ERG was also downregulated in a murine model of influenza infection. Erg fl/fl ;Cdh5(PAC)-Cre ERT2 mice spontaneously recapitulated aspects of inflammatory challenges, including lung-predominant vascular hyperpermeability, immune cell recruitment, and fibrosis. These phenotypes were associated with a lung-specific decrease in the expression of Tek , a gene target of ERG previously implicated in maintaining pulmonary vascular stability during inflammation.

Conclusions

Collectively, our data highlight a unique role for ERG in pulmonary vascular function. We propose that cytokine-induced ERG degradation and subsequent transcriptional changes in lung ECs play critical roles in the destabilization of pulmonary blood vessels during infectious diseases.

Differences in Prostate Cancer Transcriptomes by Age at Diagnosis: Are Primary Tumors from Older Men Inherently Different?

Older age at diagnosis is consistently associated with worse clinical outcomes in prostate cancer. We sought to characterize gene expression profiles of prostate tumor tissue by age at diagnosis. We conducted a discovery analysis in The Cancer Genome Atlas prostate cancer dataset (n = 320; 29% of men >65 years at diagnosis), using linear regressions of age at diagnosis and mRNA expression and adjusting for TMPRSS2:ERG fusion status and race. This analysis identified 13 age-related candidate genes at FDR < 0.1, six of which were also found in an analysis additionally adjusted for Gleason score. We then validated the 13 age-related genes in a transcriptome study nested in the Health Professionals Follow-up Study and Physicians' Health Study (n = 374; 53% of men >65 years). Gene expression differences by age in the 13 candidate genes were directionally consistent, and age at diagnosis was weakly associated with the 13-gene score. However, the age-related genes were not consistently associated with risk of metastases and prostate cancer-specific death. Collectively, these findings argue against tumor genomic differences as a main explanation for age-related differences in prostate cancer prognosis.

PREVENTION RELEVANCE

Older age at diagnosis is consistently associated with worse clinical outcomes in prostate cancer. This study with independent discovery and validation sets and long-term follow-up suggests that prevention of lethal prostate cancer should focus on implementing appropriate screening, staging, and treatment among older men without expecting fundamentally different tumor biology.

ETS-related Gene (ERG) is Differentially Expressed in Dermatofibroma (Fibrous Histiocytoma) as Compared With Dermatofibrosarcoma Protuberans and Hypertrophic Scars: A Pilot Immunohistochemical Study

Immunohistochemical staining can be of great utility in differentiating various cutaneous spindle cell neoplasms, particularly when the histomorphologic appearance of the lesions is inconclusive. Nuclear staining for ETS-related gene (ERG), a highly sensitive endothelial cell marker, has seldom been studied in the context of cutaneous spindle cell neoplasms. Little is known about its specificity for vascular differentiation. In this pilot study, immunohistochemical analysis for ERG was performed on 15 dermatofibromas (DF), 10 keloids, and 9 dermatofibrosarcoma protuberans (DFSP) tumors. Consistent nuclear expression of ERG was found in DF [100% (15/15) of the lesions demonstrated >50% labeling of tumor cells with moderate to strong intensity]. However, ERG expression was largely absent in DFSP [89% (8/9) of the lesions demonstrating <50% labeling staining, generally of mild intensity] and hypertrophic scars-keloids [80% (8/10) without expression]. On the basis of the results of this pilot study, immunohistochemical staining for ERG may prove useful in helping to differentiate DF from DFSP and hypertrophic scars in the context of partial biopsy sampling. If replicated in a larger number of samples, this finding could mitigate the use of costly sequencing panels and potentially avoid unnecessary reexcisions in certain contexts.

Prostate cancer histopathology using label-free multispectral deep-UV microscopy quantifies phenotypes of tumor aggressiveness and enables multiple diagnostic virtual stains

Identifying prostate cancer patients that are harboring aggressive forms of prostate cancer remains a significant clinical challenge. Here we develop an approach based on multispectral deep-ultraviolet (UV) microscopy that provides novel quantitative insight into the aggressiveness and grade of this disease, thus providing a new tool to help address this important challenge. We find that UV spectral signatures from endogenous molecules give rise to a phenotypical continuum that provides unique structural insight (i.e., molecular maps or “optical stains") of thin tissue sections with subcellular (nanoscale) resolution. We show that this phenotypical continuum can also be applied as a surrogate biomarker of prostate cancer malignancy, where patients with the most aggressive tumors show a ubiquitous glandular phenotypical shift. In addition to providing several novel “optical stains” with contrast for disease, we also adapt a two-part Cycle-consistent Generative Adversarial Network to translate the label-free deep-UV images into virtual hematoxylin and eosin (H&E) stained images, thus providing multiple stains (including the gold-standard H&E) from the same unlabeled specimen. Agreement between the virtual H&E images and the H&E-stained tissue sections is evaluated by a panel of pathologists who find that the two modalities are in excellent agreement. This work has significant implications towards improving our ability to objectively quantify prostate cancer grade and aggressiveness, thus improving the management and clinical outcomes of prostate cancer patients. This same approach can also be applied broadly in other tumor types to achieve low-cost, stain-free, quantitative histopathological analysis.

Fusion Genes in Prostate Cancer: A Comparison in Men of African and European Descent

Simple Summary

Men of African origin have a 2–3 times greater chance of developing prostate cancer than those of European origin, and of patients that are diagnosed with the disease, men of African descent are 2 times more likely to die compared to white men. Men of African origin are still greatly underrepresented in genetic studies and clinical trials. This, unfortunately, means that new discoveries in cancer treatment are missing key information on the group with a greater chance of mortality. A fusion gene is a hybrid gene formed from two previously independent genes. Fusion genes have been found to be common in all main types of human cancer. The objective of this study was to increase our knowledge of fusion genes in prostate cancer using computational approaches and to compare fusion genes between men of African and European origin. This identified novel gene fusions unique to men of African origin and suggested that this group has a greater number of fusion genes.

Abstract

Prostate cancer is one of the most prevalent cancers worldwide, particularly affecting men living a western lifestyle and of African descent, suggesting risk factors that are genetic, environmental, and socioeconomic in nature. In the USA, African American (AA) men are disproportionately affected, on average suffering from a higher grade of the disease and at a younger age compared to men of European descent (EA). Fusion genes are chimeric products formed by the merging of two separate genes occurring as a result of chromosomal structural changes, for example, inversion or trans/cis-splicing of neighboring genes. They are known drivers of cancer and have been identified in 20% of cancers. Improvements in genomics technologies such as RNA-sequencing coupled with better algorithms for prediction of fusion genes has added to our knowledge of specific gene fusions in cancers. At present AA are underrepresented in genomic studies of prostate cancer. The primary goal of this study was to examine molecular differences in predicted fusion genes in a cohort of AA and EA men in the context of prostate cancer using computational approaches. RNA was purified from prostate tissue specimens obtained at surgery from subjects enrolled in the study. Fusion gene predictions were performed using four different fusion gene detection programs. This identified novel putative gene fusions unique to AA and suggested that the fusion gene burden was higher in AA compared to EA men.

Epigenetic loss of heterogeneity from low to high grade localized prostate tumours

Identifying precise molecular subtypes attributable to specific stages of localized prostate cancer has proven difficult due to high levels of heterogeneity. Bulk assays represent a population-average, which mask the heterogeneity that exists at the single-cell level. In this work, we sequence the accessible chromatin regions of 14,424 single-cells from 18 flash-frozen prostate tumours. We observe shared chromatin features among low-grade prostate cancer cells are lost in high-grade tumours. Despite this loss, high-grade tumours exhibit an enrichment for FOXA1, HOXB13 and CDX2 transcription factor binding sites, indicating a shared trans-regulatory programme. We identify two unique genes encoding neuronal adhesion molecules that are highly accessible in high-grade prostate tumours. We show NRXN1 and NLGN1 expression in epithelial, endothelial, immune and neuronal cells in prostate cancer using cyclic immunofluorescence. Our results provide a deeper understanding of the active gene regulatory networks in primary prostate tumours, critical for molecular stratification of the disease.

Correlation of integrated ERG/PTEN assessment with biochemical recurrence in prostate cancer

INTRODUCTION

Prostate cancer is a heterogeneous disease, with a complex molecular landscape that evolves throughout disease progression. Common alterations in genes such as ERG and PTEN have been attributed to worse prognosis. This study aimed to further examine the clinical relevance of PTEN and ERG expression in a cohort of patients with prostate cancer post radical prostatectomy.

METHODS

Tissue microarrays were constructed from 132 patients with prostate cancer from the Irish Prostate Cancer Research Consortium and University Hospital of Orebro, Sweden. Patients were divided into three groups - Group 1: biochemical recurrence, Group 2: no biochemical recurrence and Group 3: immediate progression after surgery. PTEN and ERG immunohistochemical analysis was performed and the association between expression levels and clinical parameters were compared.

RESULTS

Pathological stage pT3 tumours were more common at borderline significantly higher levels amongst patients who biochemically recurred when compared to patients who did not recur after radical prostatectomy (p = 0.05). ERG and PTEN expression levels were compared separately and concurrently across all three patient groups. Lack of ERG expression was strongly associated with immediate progression after surgery (p = 0.029). Loss of/low PTEN trended towards an association with immediate progression, however this was not statistically significant (p = 0.066).

CONCLUSION

In this study, negative ERG expression was strongly associated with immediate biochemical progression after radical prostatectomy. Moreover, a trend towards a relationship between aberrant PTEN expression and progression was observed. Additional studies with long-term follow up data may provide further clinical insight into the genomic heterogeneity in this population.

Noninvasive Precision Screening of Prostate Cancer by Urinary Multimarker Sensor and Artificial Intelligence Analysis

Screening for prostate cancer relies on the serum prostate-specific antigen test, which provides a high rate of false positives (80%). This results in a large number of unnecessary biopsies and subsequent overtreatment. Considering the frequency of the test, there is a critical unmet need of precision screening for prostate cancer. Here, we introduced a urinary multimarker biosensor with a capacity to learn to achieve this goal. The correlation of clinical state with the sensing signals from urinary multimarkers was analyzed by two common machine learning algorithms. As the number of biomarkers was increased, both algorithms provided a monotonic increase in screening performance. Under the best combination of biomarkers, the machine learning algorithms screened prostate cancer patients with more than 99% accuracy using 76 urine specimens. Urinary multimarker biosensor leveraged by machine learning analysis can be an important strategy of precision screening for cancers using a drop of bodily fluid.

Comparative study of immunohistochemical expression of ERG and MAGI2 in prostatic carcinoma

Diagnosis of Prostatic adenocarcinoma (PAC) is still a problematic issue. The objective of this study was to evaluate the diagnostic and prognostic value of ERG immunohistochemical (IHC) expression compared to MAGI2.

MATERIALS AND METHODS

This study was conducted on 56 cases of PAC and 29 cases of nodular prostatic hyperplasia (NPH). IHC staining for ERG and MAGI2 was applied to archival formalin-fixed paraffin-embedded blocks. Semi-quantitative scoring was compared and correlated with clinicopathologic parameters and the Ki-67 index.

RESULTS

Revealed positive ERG in 51.8% of PAC while all NPH cases were negative. On the other hand, MAGI2 was detected in 91.1% of PAC versus 17.2% of NPH. Using ROC curve, the ERG showed 53.6% sensitivity, 100% specificity, 76.5% diagnostic accuracy (DA) and area under the ROC curve 0.768 in comparison to MAGI2 that showed (91.1%, 86.2%, 88.25% and 0.948 respectively). Analysis of the combined use of the two markers revealed 95% sensitivity, 100% specificity, and 94% DA when tested synchronously. Moreover, a statistically significant inverse relationship could be detected between ERG expression and the Gleason grading group (P = 0.01) and Ki-67 index (P < 0.001). In addition, high-grade prostatic intraepithelial neoplasia (HGPIN) adjacent to carcinoma; showed positive expressions in (1/11 cases, 9.11%) for ERG and (6/11 cases, 54%) for MAGI2.

CONCLUSION

This study recommends using both ERG and MAGI2 in a cocktail for better diagnostic validity of PAC. Only ERG expression could be a good prognostic indicator.

Prostate Carcinogenesis: Insights in Relation to Epigenetics and Inflammation

Prostate cancer is a multifactorial disease that mainly occurs due to the accumulation of somatic, genetic, and epigenetic changes, resulting in the inactivation of tumor-suppressor genes and activation of oncogenes. Mutations in genes, specifically those that control cell growth and division or the repair of damaged DNA, make the cells grow and divide uncontrollably to form a tumor. The risk of developing prostate cancer depends upon the gene that has undergone the mutation. Identifying such genetic risk factors for prostate cancer poses a challenge for the researchers. Besides genetic mutations, many epigenetic alterations, including DNA methylation, histone modifications (methylation, acetylation, ubiquitylation, sumoylation, and phosphorylation) nucleosomal remodeling, and chromosomal looping, have significantly contributed to the onset of prostate cancer as well as the prognosis, diagnosis, and treatment of prostate cancer. Chronic inflammation also plays a major role in the onset and progression of human cancer, via modifications in the tumor microenvironment by initiating epithelialmesenchymal transition and remodeling the extracellular matrix. In this article, the authors present a brief history of the mechanisms and potential links between the genetic aberrations, epigenetic changes, inflammation, and inflammasomes that are known to contribute to the prognosis of prostate cancer. Furthermore, the authors examine and discuss the clinical potential of prostate carcinogenesis in relation to epigenetics and inflammation for its diagnosis and treatment..

Endothelial Cells Promote Docetaxel Resistance of Prostate Cancer Cells by Inducing ERG Expression and Activating Akt/mTOR Signaling Pathway

Docetaxel is a first-line chemotherapy for the treatment of patients with castration-resistant prostate cancer (CRPC). Despite the good initial response of docetaxel, drug resistance will inevitably occur. Mechanisms underlying docetaxel resistance are not well elaborated. Endothelial cells (ECs) have been implicated in the progression and metastasis of prostate cancer. However, little attention has been paid to the role of endothelial cells in the development of docetaxel resistance in prostate cancer. Here, we sought to investigate the function and mechanism of endothelial cells involving in the docetaxel resistance of prostate cancer. We found that endothelial cells significantly promoted the proliferation of prostate cancer cells and decreased their sensitivity to docetaxel. Mechanistically, basic fibroblast growth factor (FGF2) secreted by endothelial cells leads to the upregulation of ETS related gene (ERG) expression and activation of the Akt/mTOR signaling pathway in prostate cancer cells to promote docetaxel resistance. In summary, these findings demonstrate a microenvironment-dependent mechanism mediating chemoresistance of prostate cancer and suggest that targeting FGF/FGFR signaling might represent a promising therapeutic strategy to overcome docetaxel resistance.

Assessing COVID-19 susceptibility through analysis of the genetic and epigenetic diversity of ACE2-mediated SARS-CoV-2 entry

There is considerable variation in disease course among individuals infected with SARS-CoV-2. Many of them do not exhibit any symptoms, while some others proceed to develop COVID-19; however, severity of COVID-19 symptoms greatly differs among individuals. Focusing on the early events related to SARS-CoV-2 entry to cells through the ACE2 pathway, we describe how variability in (epi)genetic factors can conceivably explain variability in disease course. We specifically focus on variations in ACE2, TMPRSS2 and FURIN genes, as central components for SARS-CoV-2 infection, and on other molecules that modulate their expression such as CALM, ADAM-17, AR and ESRs. We propose a genetic classifier for predicting SARS-CoV-2 infectivity potential as a preliminary tool for identifying the at-risk-population. This tool can serve as a dynamic scaffold being updated and adapted to validated (epi)genetic data. Overall, the proposed approach holds potential for better personalization of COVID-19 handling.

PTEN and ERG expression in MRI-ultrasound guided fusion biopsy correlated with radical prostatectomy findings in men with prostate cancer

BACKGROUND

Conventional systematic prostate biopsies (SBx) have multiple limitations, and magnetic resonance imaging (MRI)-ultrasound fusion targeting is increasingly applied (fusion biopsies [FBx]). In our previous studies, we have shown that loss of the tumor suppressor gene phosphatase and tensin homolog (PTEN) in radical prostatectomy (RP) specimens predicts poor disease-specific survival, and in active surveillance (AS), PTEN loss in SBx predicts an adverse AS outcome, although SBx PTEN status does not correlate well with the corresponding RP status. Here, we have hypothesized that PTEN and erythroblast transformation-specific related gene (ERG) status in FBx correlate better with RP than they would in SBx.

METHODS

A total of 106 men, who had undergone FBx and subsequent RP in a single center between June 2015 and May 2017 were included. Fifty-three of the men had concomitant or previous SBx's. All biopsy and RP specimens were collected, and tissue microarrays (TMA) were constructed from RP specimens. Immunohistochemical stainings for PTEN and ERG expression were conducted on biopsies and RP TMAs and results were compared by using Fisher's exact test.

RESULTS

The immunohistochemical predictive power of FBx, determined by the concordance of biopsy PTEN and ERG status with RP, is superior to SBx (77.6% vs 66.7% in PTEN, 92.4% vs 66.6% in ERG). FBx was superior to SBx in correlation with RP Gleason Grade Groups and MRI prostate imaging reporting and data system scores.

CONCLUSION

FBx grading correlates with RP histology and MRI findings and predicts the biomarker status in the RP specimens more accurately than SBx. A longer follow-up is needed to evaluate if this translates to better prediction of disease outcomes, especially in AS and radiation therapy where prostatectomy specimens are not available for prognostication.

A Method to Reuse Archived H&E Stained Histology Slides for a Multiplex Protein Biomarker Analysis

Archived Hematoxylin and Eosin (H&E) stained pathology slides are routinely stored to index formalin-fixed paraffin-embedded (FFPE) sample tissue blocks. FFPE blocks are clinically annotated human tumor specimens that can be valuable in studies decades after the tissue is collected. If stored properly, they have the potential to yield a valuable number of serial sectioned slides for diagnostic or research purposes. However, some retrospective studies are limited in scope because the tissue samples have been depleted or not enough material is available in stored blocks for serial sections. The goal of these studies was to determine if archived H&E-stained slides can be directly reutilized by optimizing methods to de-stain and then re-stain the H&E stained slides to allow the detection of several biomarkers of interest using a conjugated antibody with chromogen multiplex immunohistochemistry procedure. This simple but innovative procedure, combined with image analysis techniques, demonstrates the ability to perform precise detection of relevant markers correlated to disease progression in initially identified tumor regions in tissue. This may add clinical value in retaining H&E slides for further use.

Comparative analysis of p16 expression among African American and European American prostate cancer patients

BACKGROUND

Expression of p16 is increased in a number of malignancies, including prostate cancer (PCa). Recent studies in a European cohort showed that expression of p16 is correlated with expression of the TMPRSS2/ERG (T/E) fusion protein. The T/E fusion is significantly less common in PCas in African American (AA) men. Thus, it would be predicted that p16 expression should be less common in PCas in AA men. We, therefore, sought to compare the expression of p16 in benign prostate and PCas from AA and European American (EA) men.

METHODS

Immunohistochemistry for p16 and ERG was performed on tissue microarrays constructed from radical prostatectomies performed on AA and EA veterans. Staining was scored and the scores compared with demographic, clinical and pathological parameters. Percent of West African ancestry in the AA cohort was assessed using ancestry informative markers.

RESULTS

Contrary to our predictions, p16 expression was similar in the cancers in the AA and EA cohorts. Consistent with prior reports, expression of p16 was quite low in benign prostate tissues from EA patients but surprisingly was significantly higher in benign tissues from AA patients. Expression of p16 was significantly associated with a family history of PCa in AA men. In addition, p16 was associated with ERG expression in AA PCa.

CONCLUSIONS

While overall expression of p16 is similar in PCas from the two racial groups, the expression of p16 in benign tissues from a subset of AA men and the stronger correlation with ERG expression implies that there are different mechanisms for p16 overexpression in PCas from the two racial groups.

Fibroblast growth factor receptor signaling plays a key role in transformation induced by the TMPRSS2/ERG fusion gene and decreased PTEN

Prostate cancer is the most common visceral malignancy and the second leading cause of cancer deaths in US men. Correlative studies in human prostate cancers reveal a frequent association of the TMPRSS2/ERG (TE) fusion gene with loss of PTEN and studies in mouse models reveal that ERG expression and PTEN loss synergistically promote prostate cancer progression. To determine the mechanism by which ERG overexpression and PTEN loss leads to transformation, we overexpressed the TE fusion gene and knocked down PTEN in an immortalized but non-transformed prostate epithelial cell line. We show that ERG overexpression in combination with PTEN loss can transform these immortalized but non-tumorigenic cells, while either alteration alone was not sufficient to fully transform these cells. Expression microarray analysis revealed extensive changes in gene expression in cells expressing the TE fusion with loss of PTEN. Among these gene expression changes was increased expression of multiple FGF ligands and receptors. We show that activation of fibroblast growth factor receptor signaling plays a key role in transformation induced by TE fusion gene expression in association with PTEN loss. In addition, in vitro and in silico analysis reveals PTEN loss is associated with widespread increases in FGF ligands and receptors in prostate cancer. Inhibitors of FGF receptor signaling are currently entering the clinic and our results suggests that FGF receptor signaling is a therapeutic target in cancers with TE fusion gene expression and PTEN loss.

Intrafocal heterogeneity of ERG protein expression and gene fusion pattern in prostate cancer

BACKGROUND

Prostate cancer is considered to be highly heterogeneous, with various morphologic features and biologic behaviors. The TMPRSS2-ERG gene fusion is the most frequently observed genetic aberration in prostate cancer. The aim of this study was to elucidate the intrafocal heterogeneity of ERG gene fusion status.

METHODS

ERG immunohistochemistry (IHC) was performed in samples from 168 prostate cancer patients who had undergone radical prostatectomy, and 40 cases showing ERG-positive IHC staining were selected for tissue microarray (TMA) construction. Two to six representative cores were selected from each tumor focus. In the cases with heterogeneous ERG IHC staining intensity, the areas showing different intensities were separately selected. Using the TMA blocks, IHC and fluorescence in situ hybridization (FISH) were conducted to evaluate the heterogeneity of ERG protein expression and ERG fusion gene patterns, respectively, in a single tumor focus. Heterogeneity of ERG IHC staining was defined as the simultaneous presence of negative and positive cores in the same tumor focus. Heterogeneity of ERG FISH was defined by the presence of cores with positive and negative FISH signals or cores with break-apart and interstitial deletion FISH signals in the same tumor focus.

RESULTS

A total of 202 TMA cores were isolated from 40 ERG-positive cases. Of the 202 total cores, 19 were negative for ERG IHC staining, and 46 showed 1+, 52 showed 2+, and 85 showed 3+ ERG staining intensity. Eleven cores were negative for ERG FISH signal, 119 cores showed ERG break-apart FISH signals, and the remaining 72 cores revealed interstitial deletion. Intrafocal heterogeneity of ERG IHC staining was found in 20% (8/40) of cases, and intrafocal heterogeneity of ERG gene fusion pattern was found in 32.5% (13/40) of cases.

CONCLUSIONS

In summary, this study showed significantly frequent intrafocal heterogeneity of ERG protein expression, gene fusion status and fusion pattern. This heterogeneity can be caused by the development of subclones during cancer progression or the intermingling of different tumors.

Vitamin D receptor activation reduces VCaP xenograft tumor growth and counteracts ERG activity despite induction of TMPRSS2:ERG

Whether vitamin D is chemopreventive and/or has potential therapeutically in prostate cancer is unresolved. One confounding factor is that many prostate cancers express a TMPRSS2:ERG fusion gene whose expression is increased both by androgens and by vitamin D receptor (VDR) activation. Two challenges that limit VDR agonist use clinically are hypercalcemia and the cooperation of VDR with ERG to hyper-induce the 1α,25-dihydroxyvitamin D3 metabolizing enzyme, CYP24A1, thus reducing VDR activity. Using the VCaP TMPRSS2:ERG positive cell line as a model, we found that a nonsecosteroidal CYP24A1 resistant VDR agonist, VDRM2, substantially reduces growth of xenograft tumors without inducing hypercalcemia. Utilizing next generation RNA sequencing, we found a very high overlap of 1,25D(OH)2D3 and VDRM2 regulated genes and by drawing upon previously published datasets to create an ERG signature, we found activation of VDR does not induce ERG activity above the already high basal levels present in VCaP cells. Moreover, we found VDR activation opposes 8 of the 10 most significant ERG regulated Hallmark gene set collection pathways from Gene Set Enrichment Analysis (GSEA). Thus, a CYP24A1 resistant VDR agonist may be beneficial for treatment of TMPRSS2:ERG positive prostate cancer; one negative consequence of TMPRSS2:ERG expression is inactivation of VDR signaling.

Concurrent nuclear ERG and MYC protein overexpression defines a subset of locally advanced prostate cancer: Potential opportunities for synergistic targeted therapeutics

BACKGROUND

Recurrent ERG gene fusions, the most common genetic alterations in prostate cancer, drive overexpression of the nuclear transcription factor ERG, and are early clonal events in prostate cancer progression. The nuclear transcription factor MYC is also frequently overexpressed in prostate cancer and may play a role in tumor initiation and/or progression. The relationship between nuclear ERG and MYC protein overexpression in prostate cancer, as well as the clinicopathologic characteristics and prognosis of ERG-positive/MYC high tumors, is not well understood.

METHODS

Immunohistochemistry (IHC) for ERG and MYC was performed on formalin-fixed, paraffin-embedded tissue from prostate cancer tissue microarrays (TMAs), and nuclear staining was scored semi-quantitatively (IHC product score range = 0-300). Correlation between nuclear ERG and MYC protein expression and association with clinicopathologic parameters and biochemical recurrence after radical prostatectomy was assessed.

RESULTS

29.1% of all tumor nodules showed concurrent nuclear ERG and MYC protein overexpression (i.e., ERG-positive/MYC high), including 35.0% of secondary nodules. Overall, there was weak positive correlation between ERG and MYC expression across all tumor nodules (rpb  = 0.149, P = 0.045), although this correlation was strongest in secondary nodules (rpb  = 0.520, P = 0.019). In radical prostatectomy specimens, ERG-positive/MYC high tumors were positively associated with the presence of extraprostatic extension (EPE), relative to all other ERG/MYC expression subgroups, however, there was no significant association between concurrent nuclear ERG and MYC protein overexpression and time to biochemical recurrence.

CONCLUSIONS

Concurrent nuclear ERG and MYC protein overexpression is common in prostate cancer and defines a subset of locally advanced tumors. Recent data indicates that BET bromodomain proteins regulate ERG gene fusion and MYC gene expression in prostate cancer, suggesting possible synergistic targeted therapeutics in ERG-positive/MYC high tumors. Prostate 76:845-853, 2016. © 2016 Wiley Periodicals, Inc.

Spheroid culture of LuCaP 136 patient-derived xenograft enables versatile preclinical models of prostate cancer

LuCaP serially transplantable patient-derived xenografts (PDXs) are valuable preclinical models of locally advanced or metastatic prostate cancer. Using spheroid culture methodology, we recently established cell lines from several LuCaP PDXs. Here, we characterized in depth the features of xenografts derived from LuCaP 136 spheroid cultures and found faithful retention of the phenotype of the original PDX. In vitro culture enabled luciferase transfection into LuCaP 136 spheroids, facilitating in vivo imaging. We showed that LuCaP 136 spheroids formed intratibial, orthotopic, and subcutaneous tumors when re-introduced into mice. Intratibial tumors responded to castration and were highly osteosclerotic. LuCaP 136 is a realistic in vitro-in vivo preclinical model of a subtype of bone metastatic prostate cancer.

Correlation of ERG immunohistochemistry with molecular detection of TMPRSS2-ERG gene fusion

Aims

TMPRSS2/E26 transformation-specific (ETS) family gene fusion in prostate carcinoma (PCa) can be detected by several methods including immunohistochemistry (IHC) for ETS-related gene (ERG), the diagnostic utility of which has not been clearly defined.

Methods

We explored TMPRSS2-ERG gene rearrangement status in 132 patients with PCa with four detection methods including fluorescence in situ hybridisation for TMPRSS2-ERG fusion, real-time reverse transcription PCR (RT-qPCR) for ERG and TMPRSS-ERG fusion transcript mRNA and IHC for ERG.

Results

Concordant results were found in 126 cases for the four detection methods and the remaining six cases showed discrepancy in one method: two cases in IHC, three cases in RT-qPCR for ERG and one case in RT-qPCR for fusion transcript. In discordant cases, the majority results were determined as final fusion status. Analysis of discrepancy cases for ERG IHC showed that weak immunoreactivity for ERG should be regarded as equivocal and that even strong immunoreactivity can be false positive. The overall incidence of TMPRSS-ERG gene fusion was 24%.

Conclusions

ERG IHC is a useful surrogate test for the detection of TMPRSS2-ERG gene fusion, but it needs to be interpreted with caution and definite judgement should not be based on IHC alone. A relatively low incidence of TMPRSS2-ERG gene fusion was demonstrated in this Korean cohort.