Relevance of cohort design for studying the frequency of the ERG rearrangement in prostate cancer

Braun M, Scheble V J, Menon R, Scharf G, Wilbertz T, Petersen K, Beschorner C, Reischl M, Kuefer R, Schilling D, Stenzl A, Kristiansen G, Rubin M A, Fend F & Perner S
(2011) Histopathology 58 , 1028–1036
Relevance of cohort design for studying the frequency of the ERG rearrangement in prostate cancer Aims: ERG rearrangements, mostly resulting in TMPRSS2–ERG fusions, are frequentalterations in prostate cancer (PCa), with a frequency ranging from 15% to 78%. As the reason for this variability is unknown, our aim was to investigate the ERG rearrangement frequency with a cohort design. Methods and results: We assessed three well‐defined cohorts for ERG rearrangements, using fluorescence in situ hybridization (FISH). The first cohort comprised 119 prostatectomy specimens. The second and third cohorts included incidentally diagnosed PCa [71 cystoprostatectomy specimens, and 105 transurethral resection of the prostate (TURP) specimens]. Seventy of 119 (59%) cases of the prostatectomy cohort harboured ERG rearrangements. Regarding zonal origin, 2/11 (18%) transition zone (TZ) foci and 75/145 (52%) peripheral zone (PZ) foci harboured ERG rearrangements. Within the cystoprostatectomies, 24/71 (34%) cases harboured ERG rearrangements. Regarding zonal origin, 2/9 (22%) TZ foci and 26/86 (30%) PZ foci harboured ERG rearrangements. PCa incidentally identified by TURP harboured ERG rearrangements in 31/105 (29%) cases. Conclusions: ERG rearrangements occur in TZ PCa, although at a lower frequency than in PZ PCa. We confirmed that approximately half of all prostatectomies harbour ERG rearrangements. However, the frequency in incidentally diagnosed PCa cohorts was significantly lower, even if multifocality was considered. Consequently, zonal origin and cohort design are key for studying the clinical implications of ERG rearrangements.     

Nucleotide resolution analysis of TMPRSS2 and ERG rearrangements in prostate cancer

TMPRSS2–ERG rearrangements occur in approximately 50% of prostate cancers and therefore represent one of the most frequently observed structural rearrangements in all cancers. However, little is known about the genomic architecture of such rearrangements. We therefore designed and optimized a pipeline involving target capture of TMPRSS2 and ERG genomic sequences coupled with paired‐end next‐generation sequencing to resolve genomic rearrangement breakpoints in TMPRSS2 and ERG at nucleotide resolution in a large series of primary prostate cancer specimens (n = 83). This strategy showed > 90% sensitivity and specificity in identifying TMPRSS2–ERG rearrangements, and allowed identification of intra‐ and inter‐chromosomal rearrangements involving TMPRSS2 and ERG with known and novel fusion partners. Our results indicate that rearrangement breakpoints show strong clustering in specific intronic regions of TMPRSS2 and ERG. The observed TMPRSS2–ERG rearrangements often exhibited complex chromosomal architecture associated with several intra‐ and inter‐chromosomal rearrangements. Nucleotide resolution analysis of breakpoint junctions revealed that the majority of TMPRSS2 and ERG rearrangements (～88%) occurred at or near regions of microhomology or involved insertions of one or more base pairs. This architecture implicates non‐homologous end joining (NHEJ) and microhomology‐mediated end joining (MMEJ) pathways in the generation of such rearrangements. These analyses have provided important insights into the molecular mechanisms involved in generating prostate cancer‐specific recurrent rearrangements. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Expression of ERG oncoprotein is associated with a less aggressive tumor phenotype in Japanese prostate cancer patients

To investigate and characterize ERG oncoprotein expression in Japanese patients with prostate cancer (PCa), we evaluated 92 index tumors from Japanese patients who had undergone radical prostatectomy for PCa, using an antibody‐based detection method to determine ERG expression. Expression status was compared with clinicopathological findings including patient age, body mass index and preoperative prostate‐specific antigen (PSA) levels, specimen Gleason score, pathological stage, positive surgical margin, size of index tumor, prostatic volume, zonal origin of index tumor and biochemical failure. Overall, ERG protein was expressed in 16.3% (15/92) of the index tumors, but not in benign glands. Younger patient age, lower Gleason score and negative surgical margins were found to be independently associated with its expression in the multivariate analysis (P= 0.015, 0.003 and 0.038, respectively). ERG expression was not associated with biochemical failure. Though not statistically significant, ERG expression was more frequently observed in peripheral zone than in transition zone cancers (28.2% vs 10%, respectively). In conclusion, ERG protein was less frequently expressed in this Japanese PCa cohort compared with Western reports. ERG expression was associated with a less aggressive tumor phenotype, and its biological significance needs to be further investigated.     

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.     

Interactions and relationships of PTEN, ERG, SPINK1 and AR in castration-resistant prostate cancer

Bismar T A, Yoshimoto M, Duan Q, Liu S, Sircar K & Squire J A
(2012) Histopathology  60, 645–652
Interactions and relationships of PTEN, ERG, SPINK1 and AR in castration‐resistant prostate cancer Aims: Recently, ETS‐related gene (ERG) gene rearrangements, phosphatase tensin homologue (PTEN) deletions and serine protease inhibitor Kazal type 1 (SPINK1) overexpression were investigated as potential markers for molecularly subtyping prostate cancer (PCA). However, their incidence and co‐association in castration‐resistant PCA (CRPC) has not been characterized fully. Methods and results: A cohort of 59 CRPC patients was investigated for ERG rearrangements, PTEN deletions and androgen receptor (AR) amplification by fluorescence in‐situ hybridization. SPINK1 overexpression was assessed by immunohistochemistry. ERG rearrangements and PTEN deletions were detected in 22 of 53 (41.5%) and 35 of 55 (63.6%) of cases, with 15 of 22 (68.1%) of ERG rearrangements occurring through deletions. SPINK1 overexpression occurred in three of 51 (5.8%) of cases exclusively in non‐ERG rearranged and AR amplification was detected in 12 of 49 (24.4%) of cases. Only PTEN deletions showed intrafocal heterogeneity occurring in nine of 35 (25.7%) of cases. PTEN deletions were significantly associated with each of ERG rearrangements occurring by deletions only (P = 0.001), AR amplification (P = 0.002) and SPINK1 overexpression (P = 0.002). None of the SPINK1 overexpressing tumours showed AR amplification (P = 0.005) and all occurred in PTEN deleted foci (P = 0.002). Conclusion: The study supports the heterogeneous nature of CRPC and confirms a significant association between PTEN, ERG, AR and SPINK1. Characterizing combined markers will aid in defining PCA subgroups relevant to prognosis contributing to the design of improved therapeutic approaches for CRPC.     

NMR‐based evaluation of the metabolic profile and response to dichloroacetate of human prostate cancer cells

The aim of this study was to evaluate the metabolic profile of human prostate cancer cells that have different metastatic potential and to determine their response to dichloroacetate (DCA) using NMR technology. Two isogenic human prostate cancer cell lines, differing in their metastatic potential [LNCaP (poorly metastatic) and LNCaP‐LN3 (highly metastatic)], were studied. Metabolite ratios from NMR spectral integrals acquired at a field strength of 9.4 T using a 5‐mm broadband probe with an NMR‐compatible bioreactor were compared in the presence and absence of the pyruvate dehydrogenase kinase inhibitor DCA. Lactate dehydrogenase (LDH) isoenzymes were assessed by zymography. Following the treatment of cells with 50 mm DCA, there was a significant reduction in the lactate/choline, lactate/creatine, lactate/alanine and the combined lactate/(choline + creatine + alanine) ratios in LNCaP‐LN3 cells relative to LNCaP cells. No significant changes in metabolite ratios were found in LNCaP cells following DCA treatment. As expected, LDH zymography assays showed an absence of the LDH‐B subunit in LNCaP‐LN3 cells, whereas both LDH‐A and LDH‐B subunits were present in LNCaP cells. DCA was shown to significantly modify the metabolite ratios in highly metastatic LNCaP‐LN3 cells, but not in poorly metastatic LNCaP cells. This effect was probably related to the absence of the LDH‐B subunit in LNCaP‐LN3 cells, and could have a bearing on cancer treatment with DCA and related compounds. © 2014 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd.     

C‐type natriuretic peptide in prostate cancer

C‐type natriuretic peptide (CNP) is expressed in the male reproductive organs in pigs. To examine whether the human prostate also expresses the CNP gene, we measured CNP and N‐terminal proCNP in prostate cancer tissue extracts and performed immunohistochemical biopsy staining. Additionally, proCNP‐derived peptides were quantitated in plasma from patients with prostate cancer. Blood was collected from healthy controls and patients before surgery for localized prostate cancer. Tissue extracts were prepared from tissue biopsies obtained from radical prostatectomy surgery. N‐terminal proCNP, proCNP (1–50) and CNP were measured in plasma and tissue extracts. Biopsies were stained for CNP‐22 and N‐terminal proCNP. Tissue extracts from human prostate cancer contained mostly N‐terminal proCNP [median 5.3 pmol/g tissue (range 1.0–12.9)] and less CNP [0.14 pmol/g tissue (0.01–1.34)]. Immunohistochemistry demonstrated the presence of the peptides in prostatic epithelial cells. The N‐terminal proCNP concentrations in plasma were marginally lower in patients with localized prostate cancer compared with control subjects [13.8 pmol/l (11.0–17.2) vs. 15.1 pmol/l (10.4–23.2), p=0.002] but not enough to justify the use of N‐terminal proCNP as a cancer marker. Further research is needed to establish whether measurement of proCNP‐derived peptides may offer clinical information.     

外泌体在前列腺癌诊疗中的研究进展

前列腺癌(PCa)是男性常见的恶性肿瘤。外泌体是存在于人体多种体液中的双层膜囊泡,携带核酸、蛋白等物质,介导细胞间通讯。外泌体可以促进前列腺癌的生长,协助免疫逃逸及化学治疗耐药,诱导血管生成、上皮细胞间充质转化(EMT)并为转移前生态位的形成提供条件,进而促进前列腺癌的侵袭和转移。基于肿瘤细胞与正常细胞分泌的外泌体成分不同,外泌体可作为前列腺癌诊断、预测侵袭转移、评估患者预后及药物疗效的生物标志物,并有望作为药物运输载体,在肿瘤的精准治疗中具有广阔的前景。     

Upregulation of PTTG1 is associated with poor prognosis in prostate cancer

Pituitary tumor‐transforming gene 1 (PTTG1) is a regulator of chromosome stability. PTTG1 overexpression had been associated with tumor aggressiveness in several cancer types. To examine its prognostic utility in prostate cancer, a tissue microarray including 12 427 tumors with clinical and molecular data was analyzed by immunohistochemistry. PTTG1 immunostaining was largely absent in normal prostate epithelial cells. In cancers, staining was considered weak in 5.4%, moderate in 5.6% and strong in 0.8%. Strong staining was linked to advanced pT stage, high classical and quantitative Gleason grade, high Ki67‐labeling index (all P < 0.0001) and lymph node metastasis (P = 0.0083). The prognostic impact of PTTG1 expression was independent of established preoperative and postoperative prognostic features. Comparison with molecular features revealed that PTTG1 upregulation was associated with nine of 12 common genomic deletions (P < 0.05), p53 alterations and high androgen receptor levels (P < 0.001 each), but was unrelated to the TMPRSS2:ERG fusion status. In conclusion, these data identify PTTG1 as a strong and independent prognostic feature in prostate cancer. PTTG1 measurement, either alone or in combination with other biomarkers might be instrumental for determining prostate cancer aggressiveness.     

前列腺病理大切片技术的临床应用及价值

目的探讨前列腺病理大切片技术的临床应用及价值。方法回顾性分析我院行根治性前列腺切除术的155例患者的临床资料。所有患者术后均进行病理切片分析,根据病理切片方式将其分为大切片组(45例)和常规切片组(110例)。比较2组患者切片情况、术后病理特征及Gleason评分。结果2组切片均未见收缩或褶皱,结构完整,细胞形态清晰可见。其中大切片组可多层、全面地观察到前列腺病变情况,准确定位病灶,直观辨别微小病灶、前列腺切缘是否为阳性;常规切片组无法全面观察到前列腺病变情况及其与周围组织的关系,难以明确肿瘤与切缘的距离和切缘是否为阳性。大切片组切缘阳性、微小病灶、精囊侵犯检出率高于常规切片组(P<0.05),但2组病理分期检出率比较,差异无统计学意义(P>0.05)。2组手术前后Gleason评分比较,差异无统计学意义(P>0.05),但大切片组术后Gleason评分升高比例高于常规切片组(P<0.05)。结论前列腺病理大切片技术可以全面观察到前列腺组织,提高切缘阳性、微小病灶及精囊侵犯检出率,为前列腺癌患者术后局部精准治疗提供病理依据。     

Immunohistochemical ETS-related gene detection in a Japanese prostate cancer cohort: diagnostic use in Japanese prostate cancer patients

Chromosomal rearrangements that result in high expression levels of the ETS-related gene (ERG) present in approximately 50% of prostate cancer (PCa) patients, making this one of the most common oncogenic alterations in PCa. However, ERG overexpression at the protein level has not been rigorously evaluated in Japanese PCa patients. In this study, we evaluated ERG expression using antibody-based detection in 230 prostate specimens in a Japanese PCa cohort. Overall, we identified 20.1% ERG-positive PCa cases. ERG was not detected in benign glands. The specificity of ERG staining for detecting PCa was almost 100%; all of the ERG-positive samples were also diagnosed as PCa. The expression level of the ERG protein correlated with clinicopathological variables, including grade (P= 0.038), stage (P= 0.005), and metastatic status (P= 0.014). No correlation was observed with age (P= 0.196) or with preoperative prostate-specific antigen level (P= 0.322). Although the frequency of ERG-positive cases in Japanese PCa patients (20.1%) was lower than that reported in a PCa cohort in Western countries (approximately 50%), our study demonstrates that the clinical utility of ERG detection at the protein level can serve as an ancillary tool for diagnosing PCa in the Japanese population.     

Effect of Gleason scores of lymph node metastases on prognosis of patients with prostate cancer

The long-term mortality risk from prostate cancer increases in lymph node (LN) positive patients. This study was done to assess the effect of lymph node Gleason score (LNGS) on prognosis in patients with LN-positive prostate cancer. Among the 1,415 patients who received pelvic lymph node dissection (PLND), 117 (8.4%) patients had a positive LN. The PGS of the prostate specimens and the LNGS of the positive LNs were assessed by uropathologists. The median age of patients at surgery was 67 years (interquartile range [IQR], 62-71 years) and the median follow-up duration was 44.3 months (IQR, 27.0-78.5 months). Pathologic Gleason scores (PGS) of 6-9 included one (0.9%), 53 (49.5%), 22 (20.6%), and 31 (29.0%) patients. The median total number of retrieved LNs was 9.0 (IQR, 5.3-12.8). The median number of positive LNs was one (IQR, 1-2). Cancer architecture with a Gleason pattern and score were observed in LNs as in ordinary prostate specimens. LNGS 6-9 included nine (8.1%), 57 (51.4%), 31 (27.9%), and 14 (12.6%) patients. The speaman’s analysis showed the meaningful correlation between PGS and LNGS (P = 0.249, P = 0.011). The univariate analysis showed that the number of positive LNs and LNGS were significantly associated with prostate cancer-specific survival (P = 0.028; P = 0.005). The same architecture that is seen in the prostate was seen in positive LNs, and LNGS may be a significant prognostic factor in patients with LN-positive prostate cancer.     

Recurrent deletion of 3p13 targets multiple tumour suppressor genes and defines a distinct subgroup of aggressive ERG fusion‐positive prostate cancers

Deletion of 3p13 has been reported from about 20% of prostate cancers. The clinical significance of this alteration and the tumour suppressor gene(s) driving the deletion remain to be identified. We have mapped the 3p13 deletion locus using SNP array analysis and performed fluorescence in situ hybridization (FISH) analysis to search for associations between 3p13 deletion, prostate cancer phenotype and patient prognosis in a tissue microarray containing more than 3200 prostate cancers. SNP array analysis of 72 prostate cancers revealed a small deletion at 3p13 in 14 (19%) of the tumours, including the putative tumour suppressors FOXP1, RYBP and SHQ1. FISH analysis using FOXP1‐specific probes revealed deletions in 16.5% and translocations in 1.2% of 1828 interpretable cancers. 3p13 deletions were linked to adverse features of prostate cancer, including advanced stage (p < 0.0001), high Gleason grade (p = 0.0125), and early PSA recurrence (p = 0.0015). In addition, 3p13 deletions were linked to ERG⁺ cancers and to PTEN deletions (p < 0.0001 each). A subset analysis of ERG⁺ tumours revealed that 3p13 deletions occurred independently from PTEN deletions (p = 0.3126), identifying tumours with 3p13 deletion as a distinct molecular subset of ERG⁺ cancers. mRNA expression analysis confirmed that all 3p13 genes were down regulated by the deletion. Ectopic over‐expression of FOXP1, RYBP and SHQ1 resulted in decreased colony‐formation capabilities, corroborating a tumour suppressor function for all three genes. In summary, our data show that deletion of 3p13 defines a distinct and aggressive molecular subset of ERG⁺ prostate cancers, which is possibly driven by inactivation of multiple tumour suppressors. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Precursors of prostate cancer

High-grade prostatic intraepithelial neoplasia (PIN) is the only accepted precursor of prostatic adenocarcinoma, according to numerous studies of animal models and man; other proposed precursors include atrophy and malignancy-associated changes (with no morphologic changes). PIN is characterized by progressive abnormalities of phenotype and genotype that are intermediate between benign prostatic epithelium and cancer, indicating impairment of cell differentiation and regulatory control with advancing stages of prostatic carcinogenesis. The only method of detection of PIN is biopsy because it does not significantly elevate serum prostate-specific antigen concentration and cannot be detected by ultrasonography. The mean incidence of PIN in biopsies is 9% (range, 4%-16%), representing about 115,000 new cases of isolated PIN diagnosed each year in the United States. The clinical importance of PIN is its high predictive value as a marker for adenocarcinoma, and its identification warrants repeat biopsy for concurrent or subsequent carcinoma, especially when multifocal or observed in association with atypical small acinar proliferation (ASAP). Carcinoma develops in most patients with PIN within 10 years. Androgen deprivation therapy and radiation therapy decrease the prevalence and extent of PIN, suggesting that these forms of treatment may play a role in prevention of subsequent cancer. Multiple clinical trials to date of men with PIN have had modest success in delaying or preventing subsequent cancer.     

前列腺癌中TMPRSS2-ERG融合基因和ERG蛋白表达及其意义

目的 探讨前列腺癌(prostate cancer,PC)中TMPRSS2-ERG(T-E)融合基因和ERG蛋白表达及其与各临床病理参数和预后的关系.方法 采用FISH和免疫组化技术分别检测145例PC穿刺标本中T-E融合基因和ERG蛋白的表达,以癌旁正常腺体为内对照.结果 145例PC中37例(25.5％)T-E融合基因阳性.T-E融合基因表达与患者年龄、术前血清PSA水平、Gleason评分、肿瘤有无远处转移和生存期均无相关性(P＞0.05).PC中ERG蛋白阳性率为24.8％ (36/145).ERG蛋白与术前血清PSA水平具有相关性(P＜0.05);与患者年龄、Gleason评分、肿瘤有无远处转移和患者生存期均无相关性.结论 T-E融合基因和ERG蛋白表达仅出现在PC中,而不出现于正常前列腺腺体,T-E融合基因和ERG蛋白可作为PC的特异性标志物.仅ERG蛋白表达与PSA水平相关,而T-E融合基因与临床病理参数和预后均无相关性.