ERG oncoprotein expression in prostate cancer: clonal progression of ERG-positive tumor cells and potential for ERG-based stratification

Increased frequency of CHD1 deletions in prostate cancers of African American men is associated with rapid disease progression without inducing homologous recombination deficiency

We analyzed genomic data derived from the prostate cancer of African and European American men in order to identify differences that may contribute to racial disparity of outcome and that could also define novel therapeutic strategies. In addition to analyzing patient derived next generation sequencing data, we performed FISH based confirmatory studies of Chromodomain helicase DNA-binding protein 1 (CHD1) loss on prostate cancer tissue microarrays. We created CRISPR edited, CHD1 deficient prostate cancer cell lines for genomic, drug sensitivity and functional homologous recombination (HR) activity analysis. We found that subclonal deletion of CHD1 is nearly three times as frequent in prostate tumors of African American men than in men of European ancestry and it associates with rapid disease progression. We further showed that CHD1 deletion is not associated with homologous recombination deficiency associated mutational signatures in prostate cancer. In prostate cancer cell line models CHD1 deletion did not induce HR deficiency as detected by RAD51 foci formation assay or mutational signatures, which was consistent with the moderate increase of olaparib sensitivity. CHD1 deficient prostate cancer cells, however, showed higher sensitivity to talazoparib. CHD1 loss may contribute to worse outcome of prostate cancer in African American men. A deeper understanding of the interaction between CHD1 loss and PARP inhibitor sensitivity will be needed to determine the optimal use of targeted agents such as talazoparib in the context of castration resistant prostate cancer.

The potential role of the microbiota in prostate cancer pathogenesis and treatment

The human body hosts a complex and dynamic population of trillions of microorganisms - the microbiota - which influences the body in homeostasis and disease, including cancer. Several epidemiological studies have associated specific urinary and gut microbial species with increased risk of prostate cancer; however, causal mechanistic data remain elusive. Studies have associated bacterial generation of genotoxins with the occurrence of TMPRSS2-ERG gene fusions, a common, early oncogenic event during prostate carcinogenesis. A subsequent study demonstrated the role of the gut microbiota in prostate cancer endocrine resistance, which occurs, at least partially, through the generation of androgenic steroids fuelling oncogenic signalling via the androgen receptor. These studies present mechanistic evidence of how the host microbiota might be implicated in prostate carcinogenesis and tumour progression. Importantly, these findings also reveal potential avenues for the detection and treatment of prostate cancer through the profiling and modulation of the host microbiota. The latter could involve approaches such as the use of faecal microbiota transplantation, prebiotics, probiotics, postbiotics or antibiotics, which can be used independently or combined with existing treatments to reverse therapeutic resistance and improve clinical outcomes in patients with prostate cancer.

Development and characterization of an ETV1 rabbit monoclonal antibody for the immunohistochemical detection of ETV1 expression in cancer tissue specimens

BACKGROUND

Aberrant ETV1 overexpression arising from gene rearrangements or mutations occur frequently in prostate cancer, round cell sarcomas, gastrointestinal stromal tumors, gliomas, and other malignancies. The absence of specific monoclonal antibodies (mAb) has limited its detection and our understanding of its oncogenic function.

METHODS

An ETV1 specific rabbit mAb (29E4) was raised using an immunogenic peptide. Key residues essential for its binding were probed by ELISA and its binding kinetics were measured by surface plasmon resonance imaging (SPRi). Its selective binding to ETV1 was assessed by immunoblots and immunofluorescence assays (IFA), and by both single and double-immuno-histochemistry (IHC) assays on prostate cancer tissue specimens.

RESULTS

Immunoblot results showed that the mAb is highly specific and lacked cross-reactivity with other ETS factors. A minimal epitope with two phenylalanine residues at its core was found to be required for effective mAb binding. SPRi measurements revealed an equilibrium dissociation constant in the picomolar range, confirming its high affinity. ETV1 (+) tumors were detected in prostate cancer tissue microarray cases evaluated. IHC staining of whole-mounted sections revealed glands with a mosaic staining pattern of cells that are partly ETV1 (+) and interspersed with ETV1 (-) cells. Duplex IHC, using ETV1 and ERG mAbs, detected collision tumors containing glands with distinct ETV1 (+) and ERG (+) cells.

CONCLUSIONS

The selective detection of ETV1 by the 29E4 mAb in immunoblots, IFA, and IHC assays using human prostate tissue specimens reveals a potential utility for the diagnosis, the prognosis of prostate adenocarcinoma and other cancers, and the stratification of patients for treatment by ETV1 inhibitors.

PCA3 and TMPRSS2: ERG Urine Level as Diagnostic Biomarker of Prostate Cancer

Background

Prostate cancer is a highly prevalent urological carcinoma with an increasing incidence in Indonesia and all around the world. Early diagnosis can greatly affect treatment outcomes and increase life expectancy. Several biomarkers for detecting prostate cancer have been studied and showed great promise.

Purpose

This study aims to analyze prostate cancer antigen 3 (PCA3) as well as transmembrane serine protease 2:ERG (TMPRSS2:ERG) for diagnosing and serving as urine biomarkers in predicting prostate cancer incidences.

Methods

We conducted an analytical study to assess the utility of PCA3 and TMPRSS2:ERG for detecting prostate cancer. Thirty samples were included in this study to see the utilization of PCA3 and TMPRSS2:ERG as diagnostic biomarkers of prostate cancer. A urine sample was taken and the PCA3 test was performed using the PCA3 PROGENSA test, while the TMPRSS2:ERG was performed using the chemiluminescent DNA probe method with a hybridization protection test.

Results

The average age of the subject was 61.07±8.3 years. Based on calculations using the Mann-Whitney test, there was a significant relationship between prostate-Specific Antigen (PSA) overexpression (p<0.001), TMPRSS2:ERG (p=0.001), and PCA3 (p=0.003) with prostate cancer incidence. The sensitivity of PCA3 and TMPRSS2:ERG in detecting prostate cancer was 76.9% and 92.3%, respectively. Hence, TMPRSS2:ERG and PCA3 can be used as biomarkers for the occurrence of prostate cancer. We also performed a Kruskal-Wallis test; however, there was no significant relationship between PSA (p=0.236), TMPRSS2:ERG (p=0.801), and PCA3 (p=0.091) with the Gleason score.

Conclusion

There is a significant correlation between overexpression of PSA, TMPRSS2:ERG and PCA3 with the incidence of prostate cancer, and TMPRSS2:ERG and PCA3 can be used as biomarkers of prostate cancer.

Emerging Developments in ETS-Positive Prostate Cancer Therapy

Prostate cancer is a global health concern, which has a low survival rate in its advanced stages. Even though second-generation androgen receptor-axis inhibitors serve as the mainstay treatment options, utmost of the metastatic cases progress into castration-resistant prostate cancer after their initial treatment response with poor prognostic outcomes. Hence, there is a dire need to develop effective inhibitors that aim the causal oncogenes tangled in the prostate cancer initiation and progression. Molecular-targeted therapy against E-26 transformation-specific (ETS) transcription factors, particularly ETS-related gene, has gained wide attention as a potential treatment strategy. ETS rearrangements with the male hormone responsive transmembrane protease serine 2 promoter defines a significant number of prostate cancer cases and is responsible for cancer initiation and progression. Notably, inhibition of ETS activity has shown to reduce tumorigenesis, thus highlighting its potential as a clinical therapeutic target. In this review, we recapitulate the various targeted drug approaches, including small molecules, peptidomimetics, nucleic acids, and many others, aimed to suppress ETS activity. Several inhibitors have demonstrated ERG antagonist activity in prostate cancer, but further investigations into their molecular mechanisms and impacts on nontumor ETS-containing tissues is warranted.

Determination of ERG(+), EZH2, NKX3.1, and SPINK-1 subtypes to evaluate their association with clonal origin and disease progression in multifocal prostate cancer

BACKGROUND

The prognostic relevance of prostate cancer (PCa) molecular subtypes remains controversial, given the presence of multiple foci with the possibility of different subtypes in the same patient.

AIM

To determine the clonal origin of heterogeneity in PCa and its association with disease progression, SPOP, ERG(+), EZH2, NKX3.1, and SPINK-1 subtypes were analyzed.

METHODS

A total of 103 samples from 20 PCa patients were analyzed; foci of adjacent non-tumor prostate tissue, HGPIN, GL3, GL4, GL5, and LN were examined to determine the presence of the TMPRSS2-ERG fusion and ERG, EZH2, NKX3.1, and SPINK-1 expression levels, using RT-PCR. Mutations in exons 6 and 7 of the SPOP gene were determined by sequencing. The presence of subtypes and molecular patterns were identified by combining all subtypes analyzed. To establish the clonal origin of multifocal PCa, molecular concordance between different foci of the same patient was determined. Association of these subtypes with histopathological groups and time to biochemical recurrence (BCR) was assessed.

RESULTS

No mutation was found in SPOP in any sample. The ERG(+) subtype was the most frequent. The molecular pattern containing all four PCa subtypes was only detected in 3 samples (4%), all LN, but it was the most frequent (40%) in patients. Molecular discordance was the predominant status (55%) when all analyzed molecular characteristics were considered. It was possible to find all subtypes, starting as a preneoplastic lesion, and all but one LN molecular subtype were ERG(+) and NKX3.1 subtypes. Only the expression of the NKX3.1 gene was significantly different among the histopathological groups. No association was found between BCR time in patients and molecular subtypes or molecular concordance or between clinicopathological characteristics and molecular subtypes of ERG, EZH2, and SPINK-1.

CONCLUSION

The predominance of molecular discordance in prostatic foci per patient, which reflects the multifocal origin of PCa foci, highlights the importance of analyzing multiple samples to establish the prognostic and therapeutic relevance of molecular subtypes in a patient. All the subtypes analyzed here are of early onset, starting from preneoplastic lesions. NKX3.1 gene expression is the only molecular characteristic that shows a progression pattern by sample.

Monoamine oxidase A: An emerging therapeutic target in prostate cancer

Monoamine oxidase A (MAOA), a mitochondrial enzyme degrading biogenic and dietary amines, has been studied in the contexts of neuropsychiatry and neurological disorders for decades, but its importance in oncology, as best exemplified in prostate cancer (PC) to date, was only realized recently. PC is the most commonly diagnosed non-skin cancer and the second deadliest malignancy for men in the United States. In PC, the increased expression level of MAOA is correlated with dedifferentiated tissue microarchitecture and a worse prognosis. A wealth of literature has demonstrated that MAOA promotes growth, metastasis, stemness and therapy resistance in PC, mainly by increasing oxidative stress, augmenting hypoxia, inducing epithelial-to-mesenchymal transition, and activating the downstream principal transcription factor Twist1-dictated multiple context-dependent signaling cascades. Cancer-cell-derived MAOA also enables cancer-stromal cell interaction involving bone stromal cells and nerve cells by secretion of Hedgehog and class 3 semaphorin molecules respectively to modulate the tumor microenvironment in favor of invasion and metastasis. Further, MAOA in prostate stromal cells promotes PC tumorigenesis and stemness. Current studies suggest that MAOA functions in PC in both cell autonomous and non-autonomous manners. Importantly, clinically available monoamine oxidase inhibitors have shown promising results against PC in preclinical models and clinical trials, providing a great opportunity to repurpose them as a PC therapy. Here, we summarize recent advances in our understanding of MAOA roles and mechanisms in PC, present several MAOA-targeted strategies that have been nominated for treating PC, and discuss the unknowns of MAOA function and targeting in PC for future exploration.

Clonal relationships of adjacent Gleason pattern 3 and Gleason pattern 5 lesions in Gleason Scores 3+5=8 and 5+3=8

Genomic studies have demonstrated a high level of intra-tumoral heterogeneity in prostate cancer. There is strong evidence suggesting that individual tumor foci can arise as genetically distinct, clonally independent lesions. However, recent studies have also demonstrated that adjacent Gleason pattern (GP) 3 and GP4 lesions can originate from the same clone but follow divergent genetic and morphologic evolution. The clonal relationship of adjacent GP3 and GP5 lesions has thus far not been investigated. Here we analyzed a cohort of 14 cases-11 biopsy and 3 radical prostatectomy specimens-with a Gleason score of 3 + 5 = 8 or 5 + 3 = 8 present in the same biopsy or in a single dominant tumor nodule at radical prostatectomy. Clonal and subclonal relationships between GP3 and GP5 lesions were assessed using genetically validated immunohistochemical assays for ERG, PTEN, and P53. 9/14 (64%) cases showed ERG reactivity in both GP3 and GP5 lesions. Only 1/14 (7%) cases showed a discordant pattern with ERG staining present only in GP3. PTEN expression was lost in 2/14 (14%) cases with perfect concordance between GP5 and GP3. P53 nuclear reactivity was present in 1/14 (7%) case in both GP5 and GP3. This study provides first evidence that the majority of adjacent GP3 and GP5 lesions share driver alterations and are clonally related. In addition, we observed a lower-than-expected rate of PTEN loss in GP5 in the context of Gleason score 3 + 5 = 8 or 5 + 3 = 8 tumors.

Diagnostic utility of immunohistochemical markers alpha methyl acyl coA racemase (AMACR) and Ets related gene (ERG) in prostate cancer

OBJECTIVES

To study the sensitivity and specificity of IHC markers AMACR and ERG in prostatic adenocarcinoma.

METHODS

The study was a prospective one and samples were collected from August 2014 to June 2016. A total of 186 samples were obtained from the Department of Urology, in which 112 of these were benign prostatic hyperplasia (BPH), and 71 were prostatic adenocarcinoma. The adenocarcinoma cases were evaluated by two histopathologists, and appropriate Gleason score was given according to the modified ISUP Gleason grading system (2016). IHC markers AMACR & ERG were performed on the adenocarcinoma cases and their sensitivity and specificity were calculated.

RESULTS

AMACR was a highly sensitive and specific marker for detecting prostatic carcinoma with a sensitivity and specificity of 95.8% and 96.5% respectively. ERG was a very specific marker with poor sensitivity in detecting prostate cancer. The sensitivity and specificity of ERG were 35.2% and 100% respectively. ERG expression decreased with increasing Gleason grade, PSA level, and tumour volume, which was statistically significant while the association of AMACR with Gleason grade or with tumor volume was not significant.

CONCLUSION

ERG is a marker of early prostatic carcinogenesis and tumors may be positive or negative subtypes. Special histomorphologic features like perineural invasion, glomerulations, and intraluminal blue mucin were also studied. AMACR was a highly sensitive marker for detecting prostatic adenocarcinoma, while ERG was highly specific.

The evolving landscape of prostate cancer somatic mutations

BACKGROUND

The landscape of somatic mutations in prostate cancer (PCa) has quickly evolved over the past years.

RESULTS

This evolution was in part due to the improved quality and lower cost of genomic sequencing platforms available to an ever-larger group of clinicians and researchers. The result of these efforts is a better understanding of early and late mutations that are enriched or nearly exclusive to treated PCa. There are, however, some important limitations to the current knowledge. The expanding variety of next-generation sequencing (NGS) assays either capture a wide spectrum of mutations but at low coverage or are focused panels that cover a select number of genes, most often cancer-related, at a deep coverage. Both of these approaches have their advantages, but ultimately miss low-frequency mutations or fail to cover the spectrum of potential mutations. Additionally, some alterations, such as the common ETS gene fusions, require a mixture of DNA and RNA analysis to capture the true frequency. Finally, almost all studies rely on bulk PCa tumor samples, which fail to consider tumor heterogeneity. Given all these caveats, the true picture of the somatic landscape of PCa continues to develop.

SUMMARY

In this review, the focus will be on how the landscape of mutations evolves during disease progression considering therapy. It will focus on a select group of early and late mutations and utilize SPOP mutations to illustrate recurrent alterations that may have clinical implications.

Downstream Regulatory Network of MYBL2 Mediating Its Oncogenic Role in Melanoma

The transcription factor MYBL2 is widely expressed in proliferating cells. Aberrant expression of MYBL2 contributes to tumor malignancy and is associated with poor patient prognosis. However, the downstream transcriptional network that mediates its oncogenic properties remains elusive. In the present study, we observed that MYBL2 was overexpressed in malignant and metastatic melanoma patient samples and that the high expression level of MYBL2 was significantly associated with poor prognosis. A loss-of-function study demonstrated that MYBL2 depletion significantly decreased cell proliferation and migration and prevented cell cycle progression. We also determined that MYBL2 promoted the formation of melanoma stem-like cell populations, indicating its potential as a therapeutic target for treating resistant melanoma. Mechanistically, we constructed an MYBL2 regulatory network in melanoma by integrating RNA-seq and ChIP-seq data. EPPK1, PDE3A, and FCGR2A were identified as three core target genes of MYBL2. Importantly, multivariate Cox regression and survival curve analysis revealed that PDE3A and EPPK1 were negatively correlated with melanoma patient survival; however, FCGR2A was positively correlated with patient survival. Overall, our findings elucidate an MYBL2 regulatory network related to cell proliferation and cancer development in melanoma, suggesting that MYBL2 may be potentially targeted for melanoma diagnosis and treatment.

Focal p53 protein expression and lymphovascular invasion in primary prostate tumors predict metastatic progression

TP53 is one of the most frequently altered genes in prostate cancer. The precise assessment of its focal alterations in primary tumors by immunohistochemistry (IHC) has significantly enhanced its prognosis. p53 protein expression and lymphovascular invasion (LVI) were evaluated for predicting metastatic progression by IHC staining of representative whole-mounted prostate sections from a cohort of 189 radical prostatectomy patients with up to 20 years of clinical follow-up. Kaplan–Meier survival curves were used to examine time to distant metastasis (DM) as a function of p53 expression and LVI status. TP53 targeted sequencing was performed in ten tumors with the highest expression of p53 staining. Nearly half (49.8%) of prostate tumors examined showed focal p53 expression while 26.6% showed evidence of LVI. p53(+) tumors had higher pathologic T stage, Grade Group, Nuclear Grade, and more frequent LVI. p53 expression of > 5% and LVI, individually and jointly, are associated with poorer DM-free survival. TP53 mutations were detected in seven of ten tumors sequenced. Four tumors with the highest p53 expression harbored likely pathogenic or pathogenic mutations. High levels of p53 expression suggest the likelihood of pathogenic TP53 alterations and, together with LVI status, could enhance early prognostication of prostate cancer progression.

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.

Evaluation of ERG Expression in Prostate Adenocarcinoma and Its Prognostic Impact in Patients Survival Rate

Background & Objective:

Some certain markers, including prostatic specific antigen (PSA), are being used to screen prostate cancer (PC), but none of them have sufficient sensitivity and specificity for evaluation of prognosis. Currently, genetic variants have found their place in the prognosis of PC. ETS-related gene (ERG) expression and its intensity have contradictory evidence regarding ERG expression with PC incidence or associating outcome. Our purpose was to survey the relationship of ERG expression and its intensity with PC and relative clinical outcome.

Methods:

We studied the immunohistochemichal (IHC) expression of ERG in 101 radical prostatectomy specimens with PC of different histologic grades. All samples were chosen from pathology department of Sina hospital in Tehran-Iran from 2011 to 2018. Positive ERG expression and its association with Gleason score, preoperative PSA, metastasis status, stage and grade of tumors was evaluated.

Results:

In total, ERG expression was observed in 42 cases (41.58%) and of these, 7 (16.66%) were categorized as weak, 13 (30.95%) moderate and 22(52.38%) as strong. There was no significant correlation between ERG expression and age, preoperative PSA, Gleason score, lymph node involvement, metastatic pattern, stage, and grade of the tumor (P>0.05). ERG expression frequency in the two groups of survived and expired patients was 42.85% and 0%, respectively; despite the noticeable difference, it was not statistically significance (P=0.264).

Conclusion:

Evaluation of ERG expression and its intensity may have no essential role as an acceptable prognostic factor in Iranian’s population for anticipating whether PC itself or the outcomes accompanied. This relation is vigorously under the influence of geographical/ethnical features.

Gene fusions in tumourigenesis with particular reference to ovarian cancer

Gene fusion, a genomic event that generates a novel gene from two independent genes, has long been known to be implicated in tumourigenesis and cancer progression. It has thus served as a diagnostic and prognostic biomarker in cancer, as well as an ideal therapeutic target in cancer therapy. Gene fusion can arise from chromosomal rearrangement and alternative splicing of transcripts, resulting in deregulation of proto-oncogenes or creation of an oncogenic novel gene. Largely facilitated by next generation sequencing technologies, a plethora of novel gene fusions have been identified in a variety of cancers, which leaves us the challenge of functionally characterising these candidate gene fusions. In this review, we summarise the molecular mechanisms, the oncogenic consequences and the therapeutic implications of verified gene fusions. We also discuss recent studies on gene fusions in both common and rare subtypes of ovarian tumours and how these findings can be translated to cancer therapies to benefit patients carrying these gene fusions.

Oncogenic gene fusions in nonneoplastic precursors as evidence that bacterial infection can initiate prostate cancer

Prostate adenocarcinoma is the second most commonly diagnosed cancer in men worldwide, and the initiating factors are unknown. Oncogenic TMPRSS2:ERG (ERG+) gene fusions are facilitated by DNA breaks and occur in up to 50% of prostate cancers. Infection-driven inflammation is implicated in the formation of ERG+ fusions, and we hypothesized that these fusions initiate in early inflammation-associated prostate cancer precursor lesions, such as proliferative inflammatory atrophy (PIA), prior to cancer development. We investigated whether bacterial prostatitis is associated with ERG+ precancerous lesions in unique cases with active bacterial infections at the time of radical prostatectomy. We identified a high frequency of ERG+ non-neoplastic-appearing glands in these cases, including ERG+ PIA transitioning to early invasive cancer. These lesions were positive for ERG protein by immunohistochemistry and ERG messenger RNA by in situ hybridization. We additionally verified TMPRSS2:ERG genomic rearrangements in precursor lesions using tricolor fluorescence in situ hybridization. Identification of rearrangement patterns combined with whole-prostate mapping in three dimensions confirmed multiple (up to eight) distinct ERG+ precancerous lesions in infected cases. We further identified the pathogen-derived genotoxin colibactin as a potential source of DNA breaks in clinical cases as well as cultured prostate cells. Overall, we provide evidence that bacterial infections can initiate driver gene alterations in prostate cancer. In addition, our observations indicate that infection-induced ERG+ fusions are an early alteration in the carcinogenic process and that PIA may serve as a direct precursor to prostate cancer.

GSTP1 positive prostatic adenocarcinomas are more common in Black than White men in the United States

GSTP1 is a member of the Glutathione-S-transferase (GST) family silenced by CpG island DNA hypermethylation in 90-95% of prostate cancers. However, prostate cancers expressing GSTP1 have not been well characterized. We used immunohistochemistry against GSTP1 to examine 1673 primary prostatic adenocarcinomas on tissue microarrays (TMAs) with redundant sampling from the index tumor from prostatectomies. GSTP1 protein was positive in at least one TMA core in 7.7% of cases and in all TMA cores in 4.4% of cases. The percentage of adenocarcinomas from Black patients who had any GSTP1 positive TMA cores was 14.9%, which was 2.5 times higher than the percentage from White patients (5.9%; P < 0.001). Further, the percentages of tumors from Black patients who had all TMA spots positive for GSTP1 (9.5%) was 3-fold higher than the percentage from White patients (3.2%; P<0.001). In terms of association with other molecular alterations, GSTP1 positivity was enriched in ERG positive cancers among Black men. By in situ hybridization, GSTP1 mRNA expression was concordant with protein staining, supporting the lack of silencing of at least some GSTP1 alleles in GSTP1-positive tumor cells. This is the first report revealing that GSTP1-positive prostate cancers are substantially over-represented among prostate cancers from Black compared to White men. This observation should prompt additional studies to determine whether GSTP1 positive cases represent a distinct molecular subtype of prostate cancer and whether GSTP1 expression could provide a biological underpinning for the observed disparate outcomes for Black men.

Prognostic Features of Biochemical Recurrence of Prostate Cancer Following Radical Prostatectomy Based on Multiparametric MRI and Immunohistochemistry Analysis of MRI-guided Biopsy Specimens

Background Although prostate MRI is routinely used for the detection and staging of localized prostate cancer, imaging-based assessment and targeted molecular sampling for risk stratification are an active area of research. Purpose To evaluate features of preoperative MRI and MRI-guided biopsy immunohistochemistry (IHC) findings associated with biochemical recurrence (BCR) of prostate cancer after surgery. Materials and Methods In this retrospective case-control study, patients underwent multiparametric MRI before MRI-guided biopsy followed by radical prostatectomy between 2008 and 2016. Lesions were retrospectively scored with the Prostate Imaging Reporting and Data System (PI-RADS) (version 2) by radiologists who were blinded to the clinical-pathologic results. The IHC staining, including stains for the ETS-related gene, phosphatase and tensin homolog, androgen receptor, prostate specific antigen, and p53, was performed with targeted biopsy specimens of the index lesion (highest suspicion at MRI and pathologic grade) and scored by pathologists who were blinded to clinical-pathologic outcomes. Cox proportional hazards regression analysis was used to evaluate associations with recurrence-free survival (RFS). Results The median RFS was 31.7 months (range, 1-101 months) for 39 patients (median age, 62 years; age range, 47-76 years) without BCR and 14.6 months (range, 1-61 months) for 40 patients (median age, 59 years; age range, 47-73 years) with BCR. MRI features that showed a significant relationship with the RFS interval included an index lesion with a PI-RADS score of 5 (hazard ratio [HR], 2.10; 95% CI: 1.05, 4.21; P = .04); index lesion burden, defined as ratio of index lesion volume to prostate volume (HR, 1.55; 95% CI: 1.2, 2.1; P = .003); and suspicion of extraprostatic extension (EPE) (HR, 2.18; 95% CI: 1.1, 4.2; P = .02). Presurgical multivariable analysis indicated that suspicion of EPE at MRI (adjusted HR, 2.19; 95% CI: 1.1, 4.3; P = .02) and p53 stain intensity (adjusted HR, 2.22; 95% CI: 1.0, 4.7; P = .04) were significantly associated with RFS. Conclusion MRI features, including Prostate Imaging Reporting and Data System score, index lesion burden, extraprostatic extension, and preoperative guided biopsy p53 immunohistochemistry stain intensity are associated with biochemical relapse of prostate cancer after surgery. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Costa in this issue.

Prevalence and clinical application of TMPRSS2-ERG fusion in Asian prostate cancer patients: a large-sample study in Chinese people and a systematic review

Fusion between the transmembrane protease serine 2 and v-ets erythroblastosis virus E26 oncogene homolog (TMPRSS2-ERG fusion) is a common genetic alteration in prostate cancer among Western populations and has been suggested as playing a role in tumorigenesis and progression of prostate cancer. However, the prevalence of TMPRSS2-ERG fusion differs among different ethnic groups, and contradictory results have been reported in Asian patients. We aim to evaluate the prevalence and significance of TMPRSS2-ERG fusion as a molecular subtyping and prognosis indicator of prostate cancer in Asians. We identified the fusion status in 669 samples from prostate biopsy and radical prostatectomy by fluorescence in situ hybridization and/or immunohistochemistry in China. We examined the association of TMPRSS2-ERG fusion with clinicopathological characteristics and biochemical recurrence by Chi-square test and Kaplan–Meier analysis. Finally, a systematic review was performed to investigate the positive rate of the fusion in Asian prostate cancer patients. McNemar's test was employed to compare the positive rates of TMPRSS2-ERG fusion detected using different methods. The positive rates of TMPRSS2-ERG fusion were 16% in our samples and 27% in Asian patients. In our samples, 9.4% and 19.3% of cases were recognized as fusion positive by fluorescence in situ hybridization and immunohistochemistry, respectively. No significant association between the fusion and clinical parameters was observed. TMPRSS2-ERG fusion is not a frequent genomic alteration among Asian prostate cancer patients and has limited significance in clinical practices in China. Besides ethnic difference, detection methods potentially influence the results showing a positive rate of TMPRSS2-ERG fusion.

Genomic and phenotypic heterogeneity in prostate cancer

From a clinical, morphological and molecular perspective, prostate cancer is a heterogeneous disease. Primary prostate cancers are often multifocal, having topographically and morphologically distinct tumour foci. Sequencing studies have revealed that individual tumour foci can arise as clonally distinct lesions with no shared driver gene alterations. This finding demonstrates that multiple genomically and phenotypically distinct primary prostate cancers can be present in an individual patient. Lethal metastatic prostate cancer seems to arise from a single clone in the primary tumour but can exhibit subclonal heterogeneity at the genomic, epigenetic and phenotypic levels. Collectively, this complex heterogeneous constellation of molecular alterations poses obstacles for the diagnosis and treatment of prostate cancer. However, advances in our understanding of intra-tumoural heterogeneity and the development of novel technologies will allow us to navigate these challenges, refine approaches for translational research and ultimately improve patient care.

Case Report: Prostate Adenocarcinoma With Mucinous Features of Normal-Level Serum PSA, Atypical Imaging, Biopsy-Negative, and Peculiar Urethrocystoscopic Manifestation

Background

Mucinous tumors of the prostate are seen as rare morphological variants of prostate carcinoma. Misdiagnosis and missed diagnosis are frequent clinically, especially when the clinical performance appears atypical. Furthermore, there has not been reported about the urethrocystoscopic performance of mucinous adenocarcinoma growing into the prostatic urethra so far.

Case Presentation

The current case report describes a 48-year old Asian male who was hospitalized because of intermittent gross hematuria for more than two months. The patient was diagnosed as prostatic space occupying lesions and an examination of needle biopsy was conducted on him, which did not indicate a definite malignancy. Transurethral plasma kinetic resection of the prostate (TUPKP) was performed for the patient, but the postoperative pathology revealed prostatic adenocarcinoma with mucinous features. Specifically, two cord-like neoplasms, extending to the bladder neck, were found through urethrocystoscopy in the prostatic urethra, both of which grew pedicles. The pedicles were situated on the right side of the parenchyma of the prostate. Finally, the patient underwent radical prostatectomy three weeks later.

Conclusion

Here, we reported a case that prostatic adenocarcinoma with mucinous features was diagnosed after TUPKP. The patient had normal serum prostate-specific antigen levels with atypical images and negative biopsy result. This report lays stress on the vigilance of clinicians in prostate mucinous adenocarcinoma and makes a description of its peculiar urethrocystoscopic manifestation, typical imaging, and unique growth pattern for the first time.

Prognostic features of Annexin A2 expression in prostate cancer

ANXA2 (Annexin A2 or Annexin II) is a calcium dependent phospholipid binding protein with diverse cellular functions. While ANXA2 is either absent or expressed focally in the prostate epithelium of well and moderately differentiated tumours, it is highly expressed in a subset of poorly differentiated tumours. Here we examined the association between ANXA2 expression and tumour progression, with consideration of ERG expression status and patient race (Caucasian American and African American). We evaluated ANXA2 and ERG expression in index tumours by immunohistochemistry of whole mounted prostate sections and tissue microarrays derived from radical prostatectomies of 176 patients, matched for long term post-radical prostatectomy follow-up of up to 22 years (median 12.6 years), race and pathological stage. Expression of ERG and ANXA2 was analysed for correlation with grade group (GG), and pathological T (pT) stage. Kaplan-Meier estimation curves were used to examine associations between ANXA2 or ERG expression and biochemical recurrence (BCR) free survival, and distant metastasis free survival. Significant associations were found between ANXA2(+) index tumours and poorest grade groups (GG 4-5, p=0.0037), and worse pathological stage (pT 3-4, p=0.0142). Patients with ANXA2(+) prostate tumours showed trends towards earlier BCR and metastatic progression. ANXA2(+)/ERG(-) tumours were found to be associated with GG 4-5; ANXA2(-)/ERG(+) tumours, with GG 1-2 (p=0.0036). ANXA2 expression was not associated with patient race. The association between high ANXA2 expression and prostate tumours of higher grade (GG 4-5) and stage (pT 3-4) suggests a potential use for ANXA2 as a prognostic biomarker of aggressive prostate cancer.

Cellular and Molecular Progression of Prostate Cancer: Models for Basic and Preclinical Research

Simple Summary

The molecular progression of prostate cancer is complex and elusive. Biological research relies heavily on in vitro and in vivo models that can be used to examine gene functions and responses to the external agents in laboratory and preclinical settings. Over the years, several models have been developed and found to be very helpful in understanding the biology of prostate cancer. Here we describe these models in the context of available information on the cellular and molecular progression of prostate cancer to suggest their potential utility in basic and preclinical prostate cancer research. The information discussed herein should serve as a hands-on resource for scholars engaged in prostate cancer research or to those who are making a transition to explore the complex biology of prostate cancer.

Abstract

We have witnessed noteworthy progress in our understanding of prostate cancer over the past decades. This basic knowledge has been translated into efficient diagnostic and treatment approaches leading to the improvement in patient survival. However, the molecular pathogenesis of prostate cancer appears to be complex, and histological findings often do not provide an accurate assessment of disease aggressiveness and future course. Moreover, we also witness tremendous racial disparity in prostate cancer incidence and clinical outcomes necessitating a deeper understanding of molecular and mechanistic bases of prostate cancer. Biological research heavily relies on model systems that can be easily manipulated and tested under a controlled experimental environment. Over the years, several cancer cell lines have been developed representing diverse molecular subtypes of prostate cancer. In addition, several animal models have been developed to demonstrate the etiological molecular basis of the prostate cancer. In recent years, patient-derived xenograft and 3-D culture models have also been created and utilized in preclinical research. This review is an attempt to succinctly discuss existing information on the cellular and molecular progression of prostate cancer. We also discuss available model systems and their tested and potential utility in basic and preclinical prostate cancer research.

Proteomic Tissue-Based Classifier for Early Prediction of Prostate Cancer Progression

Although ~40% of screen-detected prostate cancers (PCa) are indolent, advanced-stage PCa is a lethal disease with 5-year survival rates around 29%. Identification of biomarkers for early detection of aggressive disease is a key challenge. Starting with 52 candidate biomarkers, selected from existing PCa genomics datasets and known PCa driver genes, we used targeted mass spectrometry to quantify proteins that significantly differed in primary tumors from PCa patients treated with radical prostatectomy (RP) across three study outcomes: (i) metastasis ≥1-year post-RP, (ii) biochemical recurrence ≥1-year post-RP, and (iii) no progression after ≥10 years post-RP. Sixteen proteins that differed significantly in an initial set of 105 samples were evaluated in the entire cohort (n = 338). A five-protein classifier which combined FOLH1, KLK3, TGFB1, SPARC, and CAMKK2 with existing clinical and pathological standard of care variables demonstrated significant improvement in predicting distant metastasis, achieving an area under the receiver-operating characteristic curve of 0.92 (0.86, 0.99, p = 0.001) and a negative predictive value of 92% in the training/testing analysis. This classifier has the potential to stratify patients based on risk of aggressive, metastatic PCa that will require early intervention compared to low risk patients who could be managed through active surveillance.

Association of germline genetic variants with TMPRSS2-ERG fusion status in prostate cancer

Introduction: Oncogenic activation of ERG resulting from TMPRSS2-ERG gene fusion is a key molecular genetic alteration in prostate cancer (CaP). The frequency of ERG fusion is variable by race; however, there are limited data available on germline polymorphisms associating with ERG fusion status. The goal of this study is to identify the inherited risk variants associating with ERG status of CaP.

Materials and Methods: SNP genotyping was performed on the Illumina platform using Infinium Oncoarray SNP chip on blood derived genomic DNA samples from 400 patients treated by radical prostatectomy at a single military institution. ERG status was determined in whole mounted prostate specimens by immuno-histochemistry (IHC) for ERG protein expression. Data analysis approaches included association analyses based on EMMAX and imputation by IMPUTE2. Imputed SNPs were validated by ddPCR.

Results: SNP genotyping analysis using imputation identified rs34349373 (p 4.68 × 10^-8) and rs2055272 (p 5.62 × 10^-8) in TBC1D22B to be significantly associated with ERG fusion status in index tumor and non-index tumor foci. Imputed SNP rs2055272 was further experimentally validated by ddPCR with 98.04% (100/102) concordance. Initial discovery analysis based on SNPs on Oncoarray SNP chip, showed significant (p 10^-5) association for SNPs (rs6698333, rs1889877, rs3798999, rs10215144, rs3818136, rs9380660 and rs1792695) with ERG fusion status. The study also replicated two previously known ERG fusion associated SNPs (rs11704416 in chromsome 22; rs16901979 in chromosome 8).

Conclusions: This study identified SNPs associated with ERG status of CaP.

Impact: The findings may contribute towards defining the underlying genetics of ERG positive and ERG negative CaP patients.

Merging new-age biomarkers and nanodiagnostics for precision prostate cancer management

The accurate identification and stratified treatment of clinically significant early-stage prostate cancer have been ongoing concerns since the outcomes of large international prostate cancer screening trials were reported. The controversy surrounding clinical and cost benefits of prostate cancer screening has highlighted the lack of strategies for discriminating high-risk disease (that requires early treatment) from low-risk disease (that could be managed using watchful waiting or active surveillance). Advances in molecular subtyping and multiomics nanotechnology-based prostate cancer risk delineation can enable refinement of prostate cancer molecular taxonomy into clinically meaningful and treatable subtypes. Furthermore, the presence of intertumoural and intratumoural heterogeneity in prostate cancer warrants the development of novel nanodiagnostic technologies to identify clinically significant prostate cancer in a rapid, cost-effective and accurate manner. Circulating and urinary next-generation prostate cancer biomarkers for disease molecular subtyping and the newest complementary nanodiagnostic platforms for enhanced biomarker detection are promising tools for precision prostate cancer management. However, challenges in merging both aspects and clinical translation still need to be overcome.

KPNA2/ERG Coexpression is Associated With Early Recurrence in Advanced Prostate Cancers

Most prostate cancers (PC) overexpress the ERG oncogene and karyopherin α 2 (KPNA2). These genes play a role in prostatic carcinogenesis, but their prognostic significance is still debated. The aim of this study was to determine the prognostic significance of ERG and KPNA2 expression, and their association to early prostate-specific antigen (PSA) biochemical recurrence in advanced PC with lymph node metastases. A series of 65 consecutive pN1 M0 R0 PC samples obtained by radical prostatectomy with lymphadenectomy has been analyzed for ERG and KPNA2 expression by immunohistochemistry. For each case, the following clinical data were collected: age, preoperative serum PSA levels, Gleason grade group, TNM stage, and follow-up. PC recurrence was investigated by serum PSA assay and defined by a PSA concentration >0.2 ng/mL after a nadir of <0.1 ng/mL following radical prostatectomy. ERG-positive staining was found in 25/65 cases (38%), and KPNA2 in 56/65 cases (86%); neither was detected in normal prostatic tissue. Immunohistochemical concordance was found between primary tumor and lymph node metastases in 24/25 (96%) of ERG and 53/56 (95%) of KPNA2-positive cases. The follow-up was known in all cases, and early PSA recurrence occurred in 25/65 cases (38%). ERG positivity, both alone and in conjunction with KPNA2 positivity, was strongly associated with early PSA recurrence [both ERG+ and KPNA+, odds ratio: 22.2 (95% confidence interval, 6.0-82.3); ERG+ alone odds ratio: 17.9 (95% confidence interval, 5.1-63.5); P<0.0001 for both]. KPNA2 expression was significantly associated with the tumor stage (P<0.00001). The results suggest that the ERG+ phenotype might be selected in metastasis-initiating clones. ERG and KPNA2 may have a prognostic value, and their positivity in PC might warrant more aggressive treatments.

Molecular profiling of radical prostatectomy tissue from patients with no sign of progression identifies ERG as the strongest independent predictor of recurrence

BACKGROUND

As a major cause of morbidity and mortality among men, prostate cancer is a heterogenous disease, with a vast heterogeneity in the biology of the disease and in clinical outcome. While it often runs an indolent course, local progression or metastasis may eventually develop, even among patients considered "low risk" at diagnosis. Therefore, biomarkers that can discriminate aggressive from indolent disease at an early stage would greatly benefit patients. We hypothesized that tissue specimens from early stage prostate cancers may harbor predictive signatures for disease progression.

METHODS

We used a cohort of radical prostatectomy patients with longitudinal follow-up, who had tumors with low grade and stage that revealed no signs of future disease progression at surgery. During the follow-up period, some patients either remained indolent (non-BCR) or progressed to biochemical recurrence (BCR). Total RNA was extracted from tumor, and adjacent normal epithelium of formalin-fixed-paraffin-embedded (FFPE) specimens. Differential gene expression in tumors, and in tumor versus normal tissues between BCR and non-BCR patients were analyzed by NanoString using a customized CodeSet of 151 probes.

RESULTS

After controlling for false discovery rates, we identified a panel of eight genes (ERG, GGT1, HDAC1, KLK2, MYO6, PLA2G7, BICD1 and CACNAID) that distinguished BCR from non-BCR patients. We found a clear association of ERG expression with non-BCR, which was further corroborated by quantitative RT-PCR and immunohistochemistry assays.

CONCLUSIONS

Our results identified ERG as the strongest predictor for BCR and showed that potential prognostic prostate cancer biomarkers can be identified from FFPE tumor specimens.

ERG Tumor Type is Less Frequent in High Grade and High Stage Prostate Cancers of Chinese Men

Background: The incidence of prostatic adenocarcinoma has been rapidly increasing among Chinese men. This alarming trend prompted evaluations of early causal genomic alterations known to drive prostate tumorigenesis. Recurrent activation of the ETS-Related Gene (ERG) by genomic rearrangements is the most recognized early event in prostate cancer. Following the initial detection of ERG rearrangement at gene expression and genomic and levels, development of diagnostic quality antibodies against ERG oncoprotein have streamlined the rapid assessment of ERG frequencies world-wide. Unexpectedly, these studies revealed highest frequencies of ERG among Caucasian descents, lower frequencies among African Americans and even lower prevalence of ERG among Asian men.

Objective: To asses in a prospective study ERG frequencies, clinico-pathological and prognostic associations of ERG among prostate cancer patients of the Dalian region of Northeast China, by an established immunohistochemical procedure that have been used in studies world-wide.

Methods: Formalin fixed paraffin embedded specimens donated by patients (N=50) diagnosed with prostatic adenocarcinoma who underwent transurethral resection of the prostate (TURP) between 2007 and 2012 were evaluated for ERG by immunohistochemistry.

Results: Of the 50 cases, 13/50 (26.0%) tumors were positive for ERG. In all cases, normal prostatic epithelial were ERG negative. ERG was more frequently detected in the lower Gleason score (≤7) and low T-stage. Consistent with reports from Asian countries the results of our study shows lower overall frequencies of ERG positive tumors when compared to reports from Western countries.

Conclusion: The intriguing association of even lower ERG frequencies with high Gleason scores and higher T-stages provides impetus for current driver gene discoveries focused on the predominantly ERG negative prostate cancers of Asian men.

Molecular Pathology of High-Grade Prostatic Intraepithelial Neoplasia: Challenges and Opportunities

A better understanding of the early stages of prostate cancer initiation, potentially arising from precursor lesions, may fuel development of powerful approaches for prostate cancer prevention or interception. The best-known candidate for such a precursor lesion has been referred to as high-grade prostatic intraepithelial neoplasia (HGPIN). Although there is significant evidence supporting the notion that such HGPIN lesions can give rise to invasive adenocarcinomas of the prostate, there are also numerous complicating considerations and evidence that cloud the picture in many instances. Notably, recent evidence has suggested that some fraction of such lesions that are morphologically consistent with HGPIN may actually be invasive carcinomas masquerading as HGPIN-a state that we term "postinvasive intraepithelial carcinoma" (PIC). Although the prevalence of such PIC lesions is not fully understood, this and other factors can confound the potential of identifying prostate precursors that can be targeted for disease prevention, interception, or treatment. Here, we review our current understanding of the morphological and molecular pathological features of prostate cancer precursor lesions.

The Genomics of Prostate Cancer: A Historic Perspective

The genomics of prostate cancer (PCA) has been difficult to study compared with some other cancer types for a multitude of reasons, despite significant efforts since the early 1980s. Overcoming some of these obstacles has paved the way for greater insight into the genomics of PCA. The advent of high-throughput technologies coming from the initial use of microsatellite and oligonucleotide probes gave rise to techniques like comparative genomic hybridization (CGH). With the introduction of massively parallel genomic sequencing, referred to as next-generation sequencing (NGS), a deeper understanding of cancer genomics in general has occurred. Along with these technologic advances, there has been the development of computational biology and statistical approaches to address novel large data sets characterized by single base resolution. This review will provide a historic perspective of PCA genomics with an emphasis on the cardinal mutations and alterations observed to be consistently seen in PCA for both hormone-naïve localized PCA and castration-resistant prostate cancer (CRPC). There will be a focus on alterations that have the greatest potential to play a role in disease progression and therapy management.

ERG oncoprotein expression in prostatic acinar adenocarcinoma; clinicopathologic significance

Objectives

T/E fusion results in constitutive expression of ERG oncoprotein resulting in enhanced proliferation and invasive potential of prostatic cancer cells. In the present study we aimed to evaluate the ERG overexpression in 78 cases prostate acinar adenocarcinoma and its association with other prognostic parameters.

Results

ERG protein expression was noted in 39.7% (31 cases), out of which 3 cases (3.8%) showed low ERG expression, 10 cases (12.8%) showed intermediate expression and 18 cases (23.1%) revealed high ERG expression. Significant association of ERG expression was noted with gleason score (p = 0.009), WHO grade group (p = 0.008) and perineural invasion (p = 0.043). We found a significant proportion of our patients of prostatic acinar adenocarcinoma to over-express ERG protein which can help in devising therapeutic protocols. Significant association of ERG protein expression with gleason score and perineural invasion signifies its prognostic significance in prostatic carcinoma. Moreover, we also suggest that molecular studies should be performed in patients with prostatic carcinoma to look for T/E fusion gene and its correlation with ERG protein expression.

Comparison of ERG and SPINK1 expression among incidental and metastatic prostate cancer in Japanese men

BACKGROUND

TMPRSS2:ERG fusion is the most common genetic event in prostate cancer (PCa). However, its association with prognosis is controversial. Overexpression of serine protease inhibitor Kazal-type 1 (SPINK1) was almost exclusively defined in ERG-negative PCa in most studies. This study aimed to determine the association between ERG and SPINK1 expression and the biological aggressiveness of PCa by analyzing their expression in incidental and metastatic cohorts.

METHODS

A total of 143 cystoprostatectomy specimens of invasive bladder cancer and 98 biopsy specimens from de novo metastatic PCa were analyzed. The prostate gland of cystoprostatectomy specimens was fixed and sliced in step sections. Immunohistochemistry of ERG and SPINK1 was conducted, and the results were correlated with the clinicopathological characteristics of the patients.

RESULTS

The overall prevalence of incidental cancer was 32.2% (46/143). The frequencies of both ERG and SPINK1 expression were not significantly different between incidental and metastatic cohorts (15.2% and 14.3%; P = 1.00, and 6.5% and 12.2%; P = 0.38, respectively). In the metastatic cohort, any pre-treatment factors were not significantly associated with the frequencies of ERG and SPINK1 expression. However, SPINK1 expression was significantly associated with a shorter time to castration-resistant PCa (CRPC) (P = 0.048). Meanwhile, overall survival was not significantly associated with the expression status of ERG and SPINK1 (P = 0.71).

CONCLUSIONS

ERG and SPINK1 expression may not have significant influence on the metastatic behavior of PCa. SPINK1 expression was significantly associated with a shorter time to CRPC in metastatic PCa. The expression profile of ERG and SPINK1 may be a useful predictor for effect of androgen deprivation therapy in patients with metastatic castration-sensitive PCa.

Head and Neck Squamous Cell Carcinoma Detection and Surveillance: Advances of Liquid Biomarkers

Head and neck squamous cell carcinomas are aggressive tumors that often present at advanced stage in difficult-to-biopsy regions of the head and neck. With the rapid move to analyze circulating tumor DNA (ctDNA) to either detect cancer or monitor disease progression and response to therapy, we have designed this article as a primer to understand the recent studies that support a transition to use these circulating biomarkers as a part of routine clinical care. Whereas some technical challenges still need to be overcome, the utility of ctDNA in cancer care is already evident from these early studies. Therefore, it is critical to understand recent advances in this area as well as emerging questions that need to be addressed as these biomarkers move closer to enhancing routine clinical care paradigms. Laryngoscope, 129:1836-1843, 2019.

High concordance of TMPRSS-ERG fusion between primary prostate cancer and its lymph node metastases

Approximately 50% of prostate cancer types harbor the transmembrane protease, serine 2: Erythroblast transformation-specific-related gene (ERG) fusion, resulting in oncogenic expression of the ERG transcription factor. ERG represents an attractive target for potential future anticancer therapy in advanced and metastatic prostate cancer. To better understand whether the analysis of the primary cancer is sufficient to estimate the ERG expression status of the lymph node metastases, the present study examined patterns of immunohistochemical ERG expression in a tissue microarray created from multiple primary and metastatic sites of 77 prostate cancer tissues. Among the identified tumor types, 80% were either entirely ERG-positive (38%) or ERG-negative (42%) across all (at least 9) analyzed different tumor sites. The results were heterogeneous in 20% of the tumor types and typically resulted from small ERG-negative areas within otherwise ERG-positive tumor types. Comparison of the ERG expression status in 51 primary cancer types with at least three interpretable lymph node metastases revealed an entirely identical ERG status in all tumor sites in 75% of the cases, including 16 ERG-positive and 22 ERG-negative cancer types. The remaining 13 cancer types exhibited ERG heterogeneity within the primary tumor, while all metastases had an identical (12 positive and 1 negative) ERG status. The results of the present study revealed a high degree of concordance of the ERG expression status between primary prostate cancer types and their lymph node metastases. Therefore, potential anti-ERG therapy may also be effective against lymph node metastases in the majority of cases of ERG-positive metastatic prostate cancer.

Systematic analysis reveals molecular characteristics of ERG-negative prostate cancer

The TMPRSS2:ERG gene fusion is the most prevalent early driver gene activation in prostate cancers of European ancestry, while the fusion frequency is much lower in Africans and Asians. The genomic characteristics and mechanisms for patients lacking ERG fusion are still unclear. In this study, we systematically compared the characteristics of gene fusions, somatic mutations, copy number alterations and gene expression signatures between 201 ERG fusion positive and 296 ERG fusion negative prostate cancer samples. Both common and group-specific genomic alterations were observed, suggesting shared and different mechanisms of carcinogenesis in prostate cancer samples with or without ERG fusion. The genomic alteration patterns detected in ERG-negative group showed similarities with 77.5% of tumor samples of African American patients. These results emphasize that genomic and gene expression features of the ERG-negative group may provide a reference for populations with lower ERG fusion frequency. While the overall expression patterns were comparable between ERG-negative and ERG-positive tumors, we found that genomic alterations could affect the same pathway through distinct genes in the same pathway in both groups of tumor types. Altogether, the genomic and molecular characteristics revealed in our study may provide new opportunities for molecular stratification of ERG-negative prostate cancers.

Identification of a Small Molecule That Selectively Inhibits ERG-Positive Cancer Cell Growth

Oncogenic activation of the ETS-related gene (ERG) by recurrent gene fusions (predominantly TMPRSS2-ERG) is one of the most validated and prevalent genomic alterations present in early stages of prostate cancer. In this study, we screened small-molecule libraries for inhibition of ERG protein in TMPRSS2-ERG harboring VCaP prostate cancer cells using an In-Cell Western Assay with the highly specific ERG-MAb (9FY). Among a subset of promising candidates, 1-[2-Thiazolylazo]-2-naphthol (NSC139021, hereafter ERGi-USU) was identified and further characterized. ERGi-USU selectively inhibited growth of ERG-positive cancer cell lines with minimal effect on normal prostate or endothelial cells or ERG-negative tumor cell lines. Combination of ERGi-USU with enzalutamide showed additive effects in inhibiting growth of VCaP cells. A screen of kinases revealed that ERGi-USU directly bound the ribosomal biogenesis regulator atypical kinase RIOK2 and induced ribosomal stress signature. In vivo, ERGi-USU treatment inhibited growth of ERG-positive VCaP tumor xenografts with no apparent toxicity. Structure-activity-based derivatives of ERGi-USU recapitulated the ERG-selective activity of the parental compound. Taken together, ERGi-USU acts as a highly selective inhibitor for the growth of ERG-positive cancer cells and has potential for further development of ERG-targeted therapy of prostate cancer and other malignancies.Significance: A highly selective small-molecule inhibitor of ERG, a critical driver of early stages of prostate cancer, will be imperative for prostate cancer therapy. Cancer Res; 78(13); 3659-71. ©2018 AACR.

Constructing Bayesian networks by integrating gene expression and copy number data identifies NLGN4Y as a novel regulator of prostate cancer progression

To understand the heterogeneity of prostate cancer (PCa) and identify novel underlying drivers, we constructed integrative molecular Bayesian networks (IMBNs) for PCa by integrating gene expression and copy number alteration data from published datasets. After demonstrating such IMBNs with superior network accuracy, we identified multiple sub-networks within IMBNs related to biochemical recurrence (BCR) of PCa and inferred the corresponding key drivers. The key drivers regulated a set of common effectors including genes preferentially expressed in neuronal cells. NLGN4Y—a protein involved in synaptic adhesion in neurons—was ranked as the top gene closely linked to key drivers of myogenesis subnetworks. Lower expression of NLGN4Y was associated with higher grade PCa and an increased risk of BCR. We show that restoration of the protein expression of NLGN4Y in PC-3 cells leads to decreased cell proliferation, migration and inflammatory cytokine expression. Our results suggest that NLGN4Y is an important negative regulator in prostate cancer progression. More importantly, it highlights the value of IMBNs in generating biologically and clinically relevant hypotheses about prostate cancer that can be validated by independent studies.

The Genomics of Prostate Cancer: emerging understanding with technologic advances

With the advent of next-generation sequencing technologies and large whole-exome and genome studies in prostate and other cancers, our understanding of the landscape of genomic alterations has dramatically been refined. In additional to well-known alterations in genomic regions involving 8p, 8q, 10q23, common ETS translocations and androgen receptor amplifications, newer technology have uncovered recurrent mutations in SPOP, FOXA1, MED12, IDH and complex large scale genomic alterations (eg, chromoplexy). This review surveys the enhanced landscape of genomic alterations in clinically localized and advanced prostate cancer.

TMPRSS2:ERG Gene Fusions in Prostate Cancer of West African Men and a Meta-Analysis of Racial Differences

The prevalence of fusions of the transmembrane protease, serine 2, gene (TMPRSS2) with the erythroblast transformation-specific-related gene (ERG), or TMPRSS2:ERG, in prostate cancer varies by race. However, such somatic aberration and its association with prognostic factors have neither been studied in a West African population nor been systematically reviewed in the context of racial differences. We used immunohistochemistry to assess oncoprotein encoded by the ERG gene as the established surrogate of ERG fusion genes among 262 prostate cancer biopsies from the Ghana Prostate Study (2004-2006). Poisson regression with robust variance estimation provided prevalence ratios and 95% confidence intervals of ERG expression in relation to patient characteristics. We found that 47 of 262 (18%) prostate cancers were ERG-positive, and being negative for ERG staining was associated with higher Gleason score. We further conducted a systematic review and meta-analysis of TMPRSS2:ERG fusions in relation to race, Gleason score, and tumor stage, combining results from Ghana with 40 additional studies. Meta-analysis showed the prevalence of TMPRSS2:ERG fusions in prostate cancer to be highest in men of European descent (49%), followed by men of Asian (27%) and then African (25%) descent. The lower prevalence of TMPRSS2:ERG fusions in men of African descent implies that alternative genomic mechanisms might explain the disproportionately high prostate cancer burden in such populations.

Rapid Loss of RNA Detection by In Situ Hybridization in Stored Tissue Blocks and Preservation by Cold Storage of Unstained Slides

OBJECTIVES

Recent commercialization of methods for in situ hybridization using Z-pair probe/branched DNA amplification has led to increasing adoption of this technology for interrogating RNA expression in formalin-fixed, paraffin-embedded (FFPE) tissues. Current practice for FFPE block storage is to maintain them at room temperature, often for many years.

METHODS

To examine the effects of block storage time on FFPE tissues using a number of RNA in situ probes with the Advanced Cellular Diagnostic's RNAscope assay.

RESULTS

We report marked reductions in signals after 5 years and significant reductions often after 1 year. Furthermore, storing unstained slides cut from recent cases (<1 year old) at -20°C can preserve hybridization signals significantly better than storing the blocks at room temperature and cutting the slides fresh when needed.

CONCLUSIONS

We submit that the standard practice of storing FFPE tissue blocks at room temperature should be reevaluated to better preserve RNA for in situ hybridization.

Ethnicity and ERG frequency in prostate cancer

Emerging observations emphasize a distinct biology of prostate cancer among men of different ethnicities and races, as demonstrated by remarkable differences in the frequency of ERG oncogenic activation, one of the most common and widely studied prostate cancer driver genes. Worldwide assessment of ERG alterations frequencies show consistent trends, with men of European ancestry having the highest rates of alteration and men of African or Asian ancestries having considerably lower alteration rates. However, data must be interpreted cautiously, owing to variations in assay platforms and specimen types, as well as ethnic and geographical classifications. Many opportunities and challenges remain in assessing cancer-associated molecular alterations at a global level, and these need to be addressed in order to realize the true potential of precision medicine for all cancer patients.

Correlation between ERG Fusion Protein and Androgen Receptor Expression by Immunohistochemistry in Prostate, Possible Role in Diagnosis and Therapy

Background: Recent discovery of gene rearrangements have brought a new look to the molecular pathogenesis of cancer. Gene fusions occur in nearly 60% of prostate adenocarcinoma, being the TMPRSS2-ERG one of the most common. Evidence supports the role of ERG fusion in tumorigenesis, progression and invasion via effecting pathways such as WNT, MYC, uPA, PI3K/AKT/PTEN, RAS/RAF/MAPF, NKX3.1, GST-pi and androgen receptor (AR) mediated signaling. Most of the ERG fusions involve 5'-partners androgen responsive. Therefore, we aimed to evaluate AR and ERG fusion protein expression on prostate tissue to find clinicopathological applications and possible role in therapy.

Methods: One hundred three samples, including prostate core biopsies and radical prostatectomy specimens, were evaluated for ERG and AR expression by immunohistochemistry (IHC). ERG rearrangement was done by fluorescence in situ hybridization (FISH) on 11 randomly selected cases and correlated with IHC results.

Results: From the total of 103 samples, eight (8/103) were benign, fourteen (14/103) had atypical glands, two (2/103) had prostatic intraepithelial neoplasia (PIN), and seventy nine (79/103) showed prostate adenocarcinoma. Forty four (44/79) tumor cases were Gleason score (GS) 6-7 (lower GS), and thirty five (35/79) were GS of 8-10 (higher GS). ERG immunoreaction was observed in 27.8% (22/79) of the tumor cases, showing higher expression in those with lower GS (68.2%, 15/22) compared to higher GS (31.8%, 7/22). Neither benign glands nor PIN stained with ERG. AR expression was observed in 75% of benign samples, 78.5% of atypical glands, 100% of PIN, and in 87.3% of tumor cases with no significant difference based on GS. Co-expression of ERG and AR was evaluated on all the tumor samples. ERG+/AR+ was seen in 77.3% (17/22) of the ERG+ tumor cases, with higher frequency in lower GS (64.7%, 11/17) compared to those with higher GS (35.3%, 6/17). All but five corresponding ERG+ tumor samples were negative for AR. Only 5 samples were ERG-/AR- corresponding to adenocarcinoma GS of 6. Presence or absence of ERG rearrangement was confirmed by FISH and correlated with IHC results.

Conclusions: Characterization of ERG status by IHC in prostate tissue has an excellent correlation with FISH. It may also assist in diagnosis since none of the benign glands stained with ERG. Co-expression of ERG+/AR+ in prostate tumor by IHC may suggest gene fusion between ERG and a 5'-partner driven by androgen signaling such as TMPRSS2, which it could represent an important ancillary test for clinical management and development of new therapeutic targets.

Precursor Lesions of Urologic Malignancies

CONTEXT

- Precursor lesions of urologic malignancies are established histopathologic entities, which are important not only to recognize for clinical purposes, but also to further investigate at the molecular level in order to gain a better understanding of the pathogenesis of these malignancies.

OBJECTIVE

- To provide a brief overview of precursor lesions to the most common malignancies that develop within the genitourinary tract with a focus on their clinical implications, histologic features, and molecular characteristics.

DATA SOURCES

- Literature review from PubMed, urologic pathology textbooks, and the 4th edition of the World Health Organization Classification of Tumours of the Urinary System and Male Genital Organs. All photomicrographs were taken from cases seen at Weill Cornell Medicine or from the authors' personal slide collections.

CONCLUSIONS

- The clinical importance and histologic criteria are well established for the known precursor lesions of the most common malignancies throughout the genitourinary tract, but further investigation is warranted at the molecular level to better understand the pathogenesis of these lesions. Such investigation may lead to better risk stratification of patients and potentially novel treatments.

Application of Immunohistochemistry in Undifferentiated Neoplasms: A Practical Approach

Context.—

Advances in interventional technology have enhanced the ability to safely sample deep-seated suspicious lesions by fine-needle aspiration procedures. These procedures often yield scant amounts of diagnostic material, yet there is an increasing demand for the performance of more ancillary tests, especially immunohistochemistry and, not infrequently, molecular assays, to increase diagnostic sensitivity and specificity. A systematic approach to conserving diagnostic material is the key, and our previously proposed algorithm can be applied aptly in this context.

Objective.—

To elaborate a simple stepwise approach to the evaluation of cytology fine-needle aspiration specimens and small biopsy tissue specimens, illustrating the algorithmic application of small panels of immunohistochemical stains in providing an accurate diagnosis with scant amounts of tissue, including the potential pitfalls that may arise while using immunohistochemical staining on small quantities of tissue.

Data Sources.—

The sources include literature (PubMed), the first Chinese American Pathologists Association Diagnostic Pathology Course material, and the review authors' research data as well as practice experience. Seven examples selected from the CoPath database at Geisinger Medical Center (Danville, Pennsylvania) are illustrated.

Conclusions.—

A stepwise approach to the evaluation of fine-needle aspiration and small biopsy tissue specimens in conjunction with a small panel of select immunohistochemical stains has been successful in accurately assessing the lineage/origin of the metastatic tumors of unknown primaries. The awareness of the common pitfalls of these biomarkers is essential in many instances.

Prostate cancer in Jordanian-Arab population: ERG status and relationship with clinicopathologic characteristics

TMPRSS2/ERG fusion was found to be the most common genetic event in prostate adenocarcinoma. There is a strong correlation between the fusion and ERG-positive immunostaining. Many studies showed racial variation in ERG expression in prostate cancer patients. There is no data however on the rate of ERG-positive cancer in Jordanian or Arab population. We evaluated the frequency and the significance of ERG fusion in Jordanian-Arab population using immunohistochemistry for ERG. The cohort included 193 prostate cancer specimens: 109 needle core biopsies, 45 radical prostatectomies, 37 transurethral resections of prostate, and 2 enucleation specimens. We found ERG reactivity in 64 (33.2%) of evaluated cases. The observed ERG frequency in the Jordanian-Arab population is lower than the one documented in North America, but it is higher than in Asian patient cohorts. The ERG positivity was significantly associated with lower baseline prostate-specific antigen but was unrelated to patient age, Gleason Score, or the novel Gleason Grade Groups. In the 45 prostatectomy cases, ERG did not correlate with the pathologic stage, margin, nodal status, and the biochemical recurrence, and it did not appear to represent an important prognosticator.

Predicting Prostate Cancer Progression as a Function of ETS-related Gene Status, Race, and Obesity in a Longitudinal Patient Cohort

BACKGROUND

ETS-related gene (ERG) oncogenic activation is the most common genomic alteration in prostate cancer (CaP) although it occurs less frequently in African American (AA) versus Caucasian (CA) patients, and the potential role of ERG as a prognostic marker has not been confirmed.

OBJECTIVE

This study was conducted to confirm strong racial variation in the prevalence of ERG oncoprotein expression and to examine ERG oncoprotein expression, race, and body mass index as independent and joint predictors of CaP biochemical recurrence (BCR) following radical prostatectomy (RP).

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study of CA and AA CaP patients enrolled at Walter Reed National Military Medical Center, who donated clinically annotated, whole-mounted, prostatectomy specimens between 1994 and 2014 following RP, was conducted.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Kaplan-Meier (KM) estimation curves and multivariable Cox proportional hazards models were used to examine time to BCR as a function of ERG status, patient race, and obesity.

RESULTS AND LIMITATIONS

Among 930 eligible patients (36.1% AA and 63.9% CA), with 155 (16.7%) BCR events and a median follow-up time of 5.1 yr, ERG oncoprotein expression was significantly less prevalent in index tumors of AA versus CA patients (23.2% vs 49.3%; p<0.0001). KM curves showed significantly poorer BCR-free survival for CA patients with ERG-negative index tumors but not for AA patients. Race-stratified multivariable analyses revealed a significant association between ERG-negative index tumors and poorer BCR-free survival among CA patients (hazards ratio=1.67, confidence interval=1.07, 2.61; p=0.024). Less heterogeneity in ERG expression among AA patients may reduce the ability to show its association with BCR.

CONCLUSIONS

Striking racial variation in ERG oncoprotein expression was confirmed. A novel observation was the importance of index tumor ERG-negative status in predicting CaP progression for CA patients.

PATIENT SUMMARY

ETS-related gene (ERG) typing of tumors may be useful in prognosticating prostate cancer aggressiveness.