Expression of ERG protein, a prostate cancer specific marker, in high grade prostatic intraepithelial neoplasia (HGPIN): lack of utility to stratify cancer risks associated with HGPIN

ETS-related gene (ERG) undermines genome stability in mouse prostate progenitors via Gsk3β dependent Nkx3.1 degradation

21q22.2–3 deletion is the most common copy number alteration in prostate cancer (PCa). The genomic rearrangement results in the androgen-dependent de novo expression of ETS-related gene (ERG) in prostate cancer cells, a condition promoting tumor progression to advanced stages of the disease.

Interestingly, ERG expression characterizes 5–30% of tumor precursor lesions – High Grade Prostatic Intraepithelial Neoplasia (HGPIN) - where its role remains unclear.

Here, by combining organoids technology with Click-chemistry coupled Mass Spectrometry, we demonstrate a prominent role of ERG in remodeling the protein secretome of prostate progenitors. Functionally, by lowering autocrine Wnt-4 signaling, ERG represses canonical Wnt pathway in prostate progenitors, and, in turn, promotes the accumulation of DNA double strand breaks via Gsk3β-dependent degradation of the tumor suppressor Nkx3.1. On the other hand, by shaping extracellular paracrine signals, ERG strengthens the pro-oxidative transcriptional signature of inflammatory macrophages, which we demonstrate to infiltrate pre-malignant ERG positive prostate lesions.

These findings highlight previously unrecognized functions of ERG in undermining adult prostate progenitor niche through cell autonomous and non-autonomous mechanisms. Overall, by supporting the survival and proliferation of prostate progenitors in the absence of growth stimuli and promoting the accumulation of DNA damage through destabilization of Nkx3.1, ERG could orchestrate the prelude to neoplastic transformation.

•

Expression of ERG_M40 in mouse prostate organoids promotes their survival and growth in the absence of Egf.

•

ERG_M40 alters the extracellular signaling network of mouse prostate organoids.

•

Canonical Wnt pathway is substantially reduced in ERG + prostate organoids due to decreased autocrine signaling of Wnt4.

•

Gsk3b promotes Nkx3.1 proteolysis and, in turn, accumulation of double strand breaks in ERG + prostate organoids.

•

Paracrine signaling of ERG + prostate organoids modulates Arginase 1 expression in M1-polarized macrophages.

The current recommendation for the management of isolated high-grade prostatic intraepithelial neoplasia

OBJECTIVE

To analyse the current predictive value of isolated high-grade prostatic intraepithelial neoplasia (HGPIN) for clinically significant prostate cancer (csPCa) detection in repeat biopsies.

PATIENTS AND METHODS

A cohort of 293 men with isolated HGPIN detected in previous biopsies performed without multiparametric magnetic resonance imaging (mpMRI), and who underwent repeat biopsy within 1 to 3 years, was analysed. Pre-repeat biopsy mpMRI and guided biopsies to suspicious lesions (Prostate Imaging - Reporting and Data System [PI-RADS] ≥3) and/or and systematic biopsies were performed. Persistent prostate cancer (PCa) suspicion, defined as sustained serum prostate-specific antigen level >4 ng/mL and/or abnormal digital rectal examination, was present in 248 men (84.6%), and was absent in 45 men (15.4%). A control group of 190 men who had no previous HGPIN, atypical small acinar proliferation or HGPIN with atypia who were scheduled to undergo repeat biopsy due to persistent PCa suspicion were also analysed. csPCa was defined as tumours of Grade Group ≥2.

RESULTS

In the subset of 45 men with isolated HGPIN, in whom PCa suspicion disappeared, only one csPCa (2.2%) and one insignificant PCa (iPCa) were detected. csPCa was detected in 34.7% of men with persistent PCa suspicion and previous HGPIN, and in 28.4% of those without previous HGPIN (P =0.180). iPCa was detected in 12.1% and 6.3%, respectively (P =0.039). Logistic regression analysis showed that the risk of csPCa detection was not predicted by previous HGPIN: odds ratio (OR) 1.369 (95% confidence interval [CI] 0.894-2.095; P =0.149); however, previous HGPIN increased the risk of iPCa detection: OR 2.043 (95% CI 1.016-4.109; P =0.006).

CONCLUSION

The risk of csPCa in men with isolated HGPIN, in whom PCa suspicion disappears, is extremely low. Moreover, in those men in whom PCa suspicion persists, the risk of csPCa is not influenced by the previous finding of HGPIN. However, previous HGPIN increases the risk of iPCa detection. Therefore, repeat prostate biopsy should not be recommended solely because of a previous HGPIN.

In Search for risk predictors at the microscopic scenario of a negative biopsy. A systematic review

INTRODUCTION

In cases of persistent suspicion of prostate cancer (PC), repeat prostate biopsies (PB) are frequently performed in spite of their low yield. In the context of a negative PB, there is a microscopic scenario (MS), which we define as the group of recognizable non-neoplastic lesions. While some of these lesions seem to have a protective effect, the existence of others increases the risk of PC detection in posterior PB. The objective of this systematic review is to identify the lesions that may belong to the MS of a negative PB and analyse the current evidence of their association with the risk of detecting PC in subsequent PBs.

EVIDENCE ACQUISITION

Two independent reviewers conducted a literature search on Medline, Embase and Central Cochrane with the following search terms: small acinar proliferation, ASAP, prostatic intraepithelial neoplasia, HGPIN, adjacent small atypical glands, pinatyp, atrophy, proliferative inflammatory atrophy, pia, prostatic inflammation, prostatitis and prostate cancer. 1,015 references were first identified, and 57 original articles were included in the study, following the PRISMA declaration and the PICO selection principles.

EVIDENCE SYNTHESIS

Atypical small acinar proliferation is associated with PC detection in repeat PB with rates ranging between 32 and 48%. High-grade prostatic intraepithelial neoplasia (HGPIN) is related to PC in 13 to 42% of cases. Studies show that HGPIN, when multifocal, is a significant independent risk factor for PC. Prostatic atrophy, inflammatory proliferative atrophy and prostatic inflammation seem to act as protective factors on the detection of PC in repeat PB. On the other hand, the risk of PC detection reduces significantly in male patients with multifocal HGPIN and coexistent PIA.

CONCLUSIONS

The MS of a negative PB may include atypical small acinar proliferation, HGPIN, prostatic atrophy, inflammatory proliferative atrophy and prostatic inflammation lesions, since they all seem to be associated with the risk of PC detection in repeat PB. This review has led us to create the hypothesis that the MS of a negative PB might be a valuable and useful tool when considering repeat PB.

ERG expression in prostate cancer biopsies with and without high-grade prostatic intraepithelial neoplasia: a study in Jordanian Arab patients

Background: High-grade prostatic intraepithelial neoplasia (HGPIN) is the most likely precancerous lesion for prostatic adenocarcinoma (PCa). Recent molecular studies have shown that HGPIN can harbor TMPRSS2-ERG fusion, a genetic marker also associated with PCa, which may provide an additional risk stratification tool for HGPIN, especially when present as an isolated lesion. Our aim was to assess the frequency of HGPIN and ERG expression in a cohort of prostatic needle core biopsies from Jordanian-Arab patients with PCa.

Materials and methods: We studied 109 needle core biopsies from patients with PCa. Clinical data, including age and preoperative prostate specific antigen (PSA) level, were obtained from patients’ medical records.

Results: HGPIN was present in 31 (28.4 %) of the 109 cases. Of the HGPIN cases, 13 (41.9%) expressed ERG immunostain. ERG expression in HGPIN was independent of patient age at presentation (P=0.4), pre-operative PSA (P=0.9), and the grade, using the novel Grade Groups (P=0.5).

Conclusion: The frequency of HGPIN in our cohort appears similar to the one found in the Western patient populations and demonstrates a comparable frequency of ERG expression in these lesions.

Managing high-grade prostatic intraepithelial neoplasia (HGPIN) and atypical glands on prostate biopsy

Prostate biopsy is the gold standard for diagnosing prostate cancer and reliable pathological assessment is essential for guiding management. Research efforts over the past few years have aimed to establish a more universal approach to management according to pathological grading; however, high-grade prostatic intraepithelial neoplasia (HGPIN) and atypical glands suspicious for carcinoma are two diagnoses without standardized follow-up and treatment pathways. Much of this uncertainty is due to limited evidence describing the subsequent rates of cancer and high-grade cancer when HGPIN or atypical glands are detected on initial biopsy. Fortunately, data from the past decade have shed light on these phenomena, and an improved understanding of the implications of the presence of HGPIN and atypical glands on prostate biopsy means that clinical recommendations can be made for the management of patients with these diagnoses.

ERG and PTEN status of isolated high-grade PIN occurring in cystoprostatectomy specimens without invasive prostatic adenocarcinoma

High-grade prostatic intraepithelial neoplasia (HGPIN) is widely believed to represent a precursor to invasive prostatic adenocarcinoma. However, recent molecular studies have suggested that retrograde spread of invasive adenocarcinoma into pre-existing prostatic ducts can morphologically mimic HGPIN. Thus, previous molecular studies characterizing morphologically identified HGPIN occurring in radical prostatectomies or needle biopsies with concurrent invasive carcinoma may be partially confounded by intraductal spread of invasive tumor. To assess ERG and PTEN status in HGPIN foci likely to represent true precursor lesions in the prostate, we studied isolated HGPIN occurring without associated invasive adenocarcinoma in cystoprostatectomies performed at Johns Hopkins between 2009 and 2014. Of 344 cystoprostatectomies, 33% (115/344) contained invasive prostatic adenocarcinoma in the partially submitted prostate (10 blocks/case on average) and were excluded from the study. Of the remaining cases without sampled cancer, 32% (73/229) showed 133 separate foci of HGPIN and were immunostained for ERG and PTEN using genetically validated protocols. Of foci of HGPIN with evaluable staining, 7% (8/107) were positive for ERG. PTEN loss was not seen in any HGPIN lesion (0/88). Because these isolated HGPIN foci at cystoprostatectomy are unlikely to represent retrograde spread of invasive tumor, our study suggests that ERG rearrangement, but not PTEN loss, is present in a minority of potential neoplastic precursor lesions in the prostate.

ERG overexpression and multifocality predict prostate cancer in subsequent biopsy for patients with high-grade prostatic intraepithelial neoplasia

PURPOSE

The most important clinical significance of an isolated high-grade prostatic intraepithelial neoplasia (HGPIN) diagnosis is the risk of missed prostate cancer (PCa) in subsequent biopsies. Because most patients with HGPIN do not harbor or develop PCa, clinical, pathological, or molecular markers that predict of PCa risk are of clinical significance.

MATERIALS AND METHODS

Overall, 155 men with a diagnosis of isolated HGPIN, which was based on the results of extended biopsy, and who underwent at least one repeat biopsy were analyzed for ERG oncoprotein (ERG) expression and clinicopathological parameters to determine the risk of finding PCa in subsequent biopsies.

RESULTS

Of 155 patients diagnosed with HGPIN on initial biopsy, 39 (25%) had PCa on subsequent biopsies. For men with only one repeat biopsy, the cancer detection rate was 22%. Most (54%) PCas were detected in≤6 months of rebiopsy. ERG expression was present in 15 patients with HGPIN (9.6%). Patients with ERG expression in HGPIN were more likely to have PCa in repeat biopsy, with 9 (60%) ERG-positive and 30 (21%) of ERG-negative patients having PCa (P = 0.001). Multifocal involvement (P = 0.0001), cribriform morphology (P = 0.004), and bilaterality (P = 0.0075) of HGPIN were other significant risk factors. On multivariable analysis, only the presence of ERG positivity and multifocality remained significant parameters in detecting PCa on a repeat biopsy. The presence of ERG-negative focal HGPIN involving one core, which accounted for 46% of patients, had minimal (16%) PCa risk on subsequent biopsy. In total, 8 patients (89%) ERG-positive HGPIN had PCa identified at identical sites on subsequent biopsy, of which 5 (71%) were ERG positive.

CONCLUSIONS

The status of ERG expression in HGPIN along with other histological parameters stratifies patients into low- and high-risk groups for having PCa on subsequent biopsy. Our results further support molecular characterization of HGPIN as a means to improve risk stratification and optimize surveillance strategies.

ERG expression in intraductal carcinoma of the prostate: comparison with adjacent invasive prostatic adenocarcinoma

Intraductal carcinoma of the prostate is a growth pattern of prostatic adenocarcinoma that has not been well characterized from the molecular standpoint. It remains debatable whether intraductal carcinoma of the prostate represents colonization of benign glands by pre-existing conventional prostatic adenocarcinoma, or progression of high-grade prostatic intraepithelial neoplasia. TMPRSS2-ERG is the most common gene fusion in conventional prostatic adenocarcinoma, identified in about 40-70% of cases. In this study, we compared the expression of ERG in intraductal carcinoma of the prostate and adjacent conventional prostatic adenocarcinoma. Thirty-one confirmed cases of intraductal carcinoma of the prostate, with adjacent conventional prostatic adenocarcinoma and available tissue blocks, were identified at our institution. Immunohistochemical stains were performed for ERG using a rabbit anti-ERG monoclonal antibody. The ERG expression in the intraductal carcinoma of the prostate component was compared with that in the adjacent conventional prostatic adenocarcinoma. Mean patient age was 65 years (range: 48-79 years). Positive ERG expression was identified in 11/31 (35%) cases of intraductal carcinoma of the prostate. In all 11/11 (100%) cases with positive ERG expression in the intraductal carcinoma of the prostate component, ERG expression was also positive in the adjacent conventional prostatic adenocarcinoma. In the 20/31 cases with negative ERG expression in the intraductal carcinoma of the prostate component, ERG was also negative in the adjacent conventional prostatic adenocarcinoma. It is highly conceivable that based on the identical ERG expression (positive or negative) in intraductal carcinoma of the prostate and the adjacent conventional prostatic adenocarcinoma, intraductal carcinoma of the prostate most likely represents colonization of benign glands by adjacent pre-existing conventional prostatic adenocarcinoma.

ERG protein expression as a biomarker of prostate cancer

TMPRSS2-ERG is a recurrent rearrangement specific for prostate cancer, leading to the overexpression of a truncated ERG protein product that is amenable to immunohistochemical detection. Two monoclonal anti-ERG antibodies have currently been validated, with comparable sensitivity and specificity for detecting ERG rearrangement. ERG immunostaining has been applied in different settings to elucidate the role of ERG rearrangement and overexpression in prostate cancer tumorigenesis and progression, as well as to investigate potential diagnostic and prognostic applications. In this article we review the literature on the topic and suggest potential future applications.

TMPRSS2:ERG gene fusion predicts subsequent detection of prostate cancer in patients with high-grade prostatic intraepithelial neoplasia

PURPOSE

High-grade prostatic intraepithelial neoplasia (HGPIN) is considered a precursor lesion of prostate cancer (PCa). The predictive value of ERG gene fusion in HGPIN for PCa was interrogated as a post hoc analysis in the context of a randomized clinical trial.

PATIENTS AND METHODS

The GTx Protocol G300104 randomly assigned 1,590 men with biopsy-diagnosed HGPIN to receive toremifene or placebo for 3 years or until a diagnosis of PCa was made on prostate biopsy. As part of this phase III clinical trial, a central pathologist evaluated biopsies of patients with isolated HGPIN at baseline and 12, 24, and 36 months of follow-up. ERG immunohistochemistry was performed on biopsies from 461 patients and evaluated for protein overexpression.

RESULTS

ERG expression was detected in 11.1% of patients (51 of 461 patients) with isolated HGPIN. In the first year and during the 3-year clinical trial, 14.7% and 36.9% of 461 patients were diagnosed with PCa, respectively. Patients with ERG expression were more likely to develop PCa, with 27 (53%) of 51 ERG-positive and 143 (35%) of 410 ERG-negative patients experiencing progression to PCa (P = .014, Fisher's exact test). ERG expression was not associated with age, baseline PSA, Gleason score, or tumor volume.

CONCLUSION

This study underscores the necessity of more stringent follow-up for men with HGPIN that is also positive for ERG overexpression. Clinicians should consider molecular characterization of HGPIN as a means to improve risk stratification.

Heterogeneity of ERG expression in core needle biopsies of patients with early prostate cancer

Prostate cancer is a heterogeneous, frequently multifocal disease with a broad spectrum of clinical, pathologic, and molecular characteristics. The TMPRSS2-ERG gene rearrangement is highly specific for prostate cancer. We used immunohistochemistry as a surrogate marker of the TMPRSS2-ERG fusion to study the heterogeneity of ERG expression in 280 prostate core needle biopsy series from 256 patients with early prostate cancer defined as 3 or less positive cores with no more than 50% of cancer per biopsy and a Gleason score of 7 or lower (3 + 4). Among the 163 patients with 2 or 3 cancer-positive biopsies, we found a subset of 19 patients (11.7%) with heterogeneous ERG expression. Thirteen (68.4%) of these patients showed biopsies with distinct positive and negative ERG staining in separate cores. The remaining 6 patients showed a mixture of both positive and negative staining within 1 biopsy core. This was either caused by different cancer foci (n = 3) or by one single, ERG-heterogeneous cancer focus (n = 3) in 1 core. Furthermore, we observed a heterogeneous ERG staining pattern over time in 6 (2.3%) of the 256 patients, in biopsies taken at various time points. An interobserver study of 21 cases with 2 separate cancer foci revealed that heterogeneity of ERG status in different cancer foci can be suspected based on morphologic differences (κ = 0.44). We conclude that heterogeneity of ERG expression is detectable in 10% to 15% of core biopsies of early prostate cancer. Further studies are needed to explore the clinical impact of heterogeneous ERG status in this patient group.