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.     

Molecular evidence that invasive adenocarcinoma can mimic prostatic intraepithelial neoplasia (PIN) and intraductal carcinoma through retrograde glandular colonization

Prostate cancer often manifests as morphologically distinct tumour foci and is frequently found adjacent to presumed precursor lesions such as high‐grade prostatic intraepithelial neoplasia (HGPIN). While there is some evidence to suggest that these lesions can be related and exist on a pathological and morphological continuum, the precise clonal and temporal relationships between precursor lesions and invasive cancers within individual tumours remain undefined. Here, we used molecular genetic, cytogenetic, and histological analyses to delineate clonal, temporal, and spatial relationships between HGPIN and cancer lesions with distinct morphological and molecular features. First, while confirming the previous finding that a substantial fraction of HGPIN lesions associated with ERG‐positive cancers share rearrangements and overexpression of ERG, we found that a significant subset of such HGPIN glands exhibit only partial positivity for ERG. This suggests that such ERG‐positive HGPIN cells either rapidly invade to form adenocarcinoma or represent cancer cells that have partially invaded the ductal and acinar space in a retrograde manner. To clarify these possibilities, we used ERG expression status and TMPRSS2–ERG genomic breakpoints as markers of clonality, and PTEN deletion status to track temporal evolution of clonally related lesions. We confirmed that morphologically distinct HGPIN and nearby invasive cancer lesions are clonally related. Further, we found that a significant fraction of ERG‐positive, PTEN‐negative HGPIN and intraductal carcinoma (IDC‐P) lesions are most likely clonally derived from adjacent PTEN‐negative adenocarcinomas, indicating that such PTEN‐negative HGPIN and IDC‐P lesions arise from, rather than give rise to, the nearby invasive adenocarcinoma. These data suggest that invasive adenocarcinoma can morphologically mimic HGPIN through retrograde colonization of benign glands with cancer cells. Similar clonal relationships were also seen for intraductal carcinoma adjacent to invasive adenocarcinoma. These findings represent a potentially undervalued indicator of pre‐existing invasive prostate cancer and have significant implications for prostate cancer diagnosis and risk stratification. Copyright © 2015 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.     

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.     

Infrequent genetic alterations of the PTEN gene in Japanese patients with sporadic prostate cancer

Prostate cancer is a major cause of cancer death among elderly men in America, Europe, and Japan. However, the molecular mechanism of carcinogenesis is not yet well characterized. Frequent loss of heterozygosity (LOH) on chromosome 10q was reported in prostate cancer, and a candidate tumor suppressor gene, PTEN, was isolated on chromosome band 10q23.3. To investigate the genetic alterations of PTEN, we examined 45 primary prostate cancer specimens. LOH at the PTEN locus was observed in two (11.1%) of 18 tumors. However, no mutations were observed in any of the primary prostate cancers. These data suggest that mutation of the PTEN gene does not play a major role in prostate carcinogenesis of Japanese patients. Received: February 6, 1998 / Accepted: July, 3, 1998     

Incidence of intraductal carcinoma,multifocality and bilateral significant disease in radical prostatectomy specimens from Japan and United States

Significant differences, including epidemiologic, clinical, pathologic and genetic, exist between Asian and Caucasian prostate cancer. Detailed pathologic data are, however, scarce. We studied in detail and compared the pathological features of prostate cancer in radical prostatectomy specimens in 228 patients (117 Japan, 111 US). Japanese prostate cancer had a higher Gleason grade group (mean 2.67 vs. 2.42 US, P < 0.05), but lower pathological stage (72 % pT2 and 28 % pT3 vs 55 % pT2 and 45 % pT3 US, P < 0.05). Japanese cancer showed significantly more tumor foci (3.8 vs 2.9 US, P < 0.05), and higher incidence of bilateral significant disease (81.3 % vs. 66.7 % US, P < 0.05). The dominant tumor nodules in Japanese cases had higher Gleason grade group (mean 2.73 vs. 2.40 US, P < 0.05). The incidence of intraductal carcinoma was significantly higher in Japanese patients (35.3 % vs. 12.6 % US, P < 0.01), which was independent of Gleason score (7: 30.9 % Japan vs 11.8 % US, P < 0.01; ≥ 8: 87.5 % Japan vs 28.6 % US, P < 0.01) and tumor stage (pT2: 24.1 % Japan vs 6.6 % US, P < 0.01; pT3: 62.9 % Japan vs 20 % US, P < 0.01). These findings demonstrate distinct pathological features in prostate cancer between Japanese and Caucasian patients, and may have important diagnostic and therapeutic implications.     

前列腺癌PTEN表达的丢失与病理分级、分期关系

目的 探讨前列腺癌组织中抑癌基因PTEN蛋白的表达丢失情况及临床病理意义。方法 应用免疫组化SP法检测了38例前列腺癌及其相应的癌旁组织中PTEN蛋白的表达情况，同时结合肿瘤病理分级及分期进行分析。结果 阳性信号定位于上皮细胞胞质中，呈棕色颗粒状物，所有良性前列腺上皮均阳性着色。所有肿瘤细胞均出现颗粒状胞质着色为阳性组，瘤细胞阳性与阴性共存为混合组，肿瘤组织完全不着色为阴性。其中阳性4例(10．52％)，混合27例(71．05％)，阴性7例(18．42％)。PTEN表达的丢失与Gleason分级相关且与高分级(Ⅳ、Ⅴ级)及高分期(进展期癌T3b、T4)相关。结论 前列腺癌的进展中PTEN基因失活可能起重要作用，PTEN表达的丢失可能与前列腺癌的不良预后有关。     

Association of intraductal carcinoma of the prostate detected by initial histological specimen and neuroendocrine prostate cancer: A report of three cases

We present three cases of neuroendocrine prostate cancer (NEPC) and histologically investigate the association of intraductal carcinoma of the prostate (IDC-P) and NEPC. Case 1 was a 76-year-old man who had NEPC identified by repeated biopsy specimens when his prostate-specific antigen (PSA) level became elevated 8 years after the initiation of androgen deprivation therapy (ADT). Case 2 was a 70-year-old man who had NEPC detected when multiple bone metastases were found 3 years after the initiation of ADT. Case 3 was a 70-year-old man who was diagnosed with NEPC based on histological examination of transurethral resected specimens. The histological findings in these three cases showed mixed neuroendocrine carcinoma–acinar adenocarcinoma with various proportions of both components. In all three cases, the neuroendocrine carcinoma components were positive for synaptophysin and chromogranin A, whereas the adenocarcinoma components were positive for PSA and NKX3.1. When we retrospectively reviewed the initial hematoxylin and eosin-stained slides, IDC-P was detected in all three cases. Furthermore, we collected nine additional cases of NEPC and found that all six cases with initial biopsy specimens available had an IDC-P component. Detecting IDC-P on initial histological specimens of the prostate may predict transformation to NEPC.     

The PTEN gene in locally progressive prostate cancer is preferentially inactivated by bi-allelic gene deletion

PTEN is frequently inactivated during the development of many cancers, including prostate cancer, and both bi-allelic and mono-allelic PTEN inactivation may contribute to tumorigenesis. PTEN mutations in clinical cancer specimens can easily be recorded but mono- or bi-allelic gene deletions are often difficult to assess. We performed a comprehensive study to detect PTEN inactivation in 40 locally progressive clinical prostate cancer specimens obtained by transurethral resection of the prostate, utilizing a variety of complementary technical approaches. The methods to detect PTEN deletion included allelotype analysis, dual-colour FISH and array-based CGH. We also applied a novel semi-quantitative approach, assessing the PTEN-WT (wild-type): PTEN-Psi (pseudogene) ratio (WPR). Structural analysis of PTEN was performed by single-strand conformational polymorphism (PCR-SSCP) and sequencing. PTEN protein expression was assessed by immunohistochemistry. Our data predict complete PTEN inactivation in 12 samples (30%), nine of these by bi-allelic deletion. Loss of one PTEN copy was also detected by several methodologies but the number could not be accurately assessed. Immunohistochemistry indicated the absence of PTEN protein in 15 samples, and heterogeneous expression of the protein in eight tumours. Taken together, these data show that bi-allelic deletion is a major mechanism of PTEN inactivation in locally progressive prostate cancer.     

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.     

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.     

PTEN deletion and heme oxygenase-1 overexpression cooperate in prostate cancer progression and are associated with adverse clinical outcome

Overexpression of the pro-survival protein heme oxygenase-1 (HO-1) and loss of the pro-apoptotic tumour suppressor PTEN are common events in prostate cancer (PCA). We assessed the occurrence of both HO-1 expression and PTEN deletion in two cohorts of men with localized and castration-resistant prostate cancer (CRPC). The phenotypic cooperation of these markers was examined in preclinical and clinical models. Overall, there was a statistically significant difference in HO-1 epithelial expression between benign, high-grade prostatic intraepithelial neoplasia (HGPIN), localized PCA, and CRPC (p < 0.0001). The highest epithelial HO-1 expression was noted in CRPC (2.00 ± 0.89), followed by benign prostate tissue (1.49 ± 1.03) (p = 0.0003), localized PCA (1.20 ± 0.95), and HGPIN (1.07 ± 0.87) (p < 0.0001). However, the difference between HGPIN and PCA was not statistically significant (p = 0.21). PTEN deletions were observed in 35/55 (63.6%) versus 68/183 (37.1%) cases of CRPC and localized PCA, respectively. Although neither HO-1 overexpression nor PTEN deletions alone in localized PCA showed a statistically significant association with PSA relapse, the combined status of both markers correlated with disease progression (log-rank test, p = 0.01). In a preclinical model, inhibition of HO-1 by shRNA in PTEN-deficient PC3M cell line and their matched cells where PTEN is restored strongly reduced cell growth and invasion in vitro and inhibited tumour growth and lung metastasis formation in mice compared to cells where only HO-1 is inhibited or PTEN is restored. In summary, we provide clinical and experimental evidence for cooperation between epithelial HO-1 expression and PTEN deletions in relation to the PCA patient's outcome. These findings could potentially lead to the discovery of novel therapeutic modalities for advanced PCA.     

PTEN allelic loss is an important mechanism in the late stage of development of oral leucoplakia into oral squamous cell carcinoma

Aim

The aim of this study was to analyse allelic loss of the phosphatase and tensin homologue deleted on chromosome 10 (PTEN) gene and its protein immuno‐expression in dysplastic oral lesions and oral squamous cell carcinomas (OSCCs).

Methods and results

Samples were collected from 153 patients [20 ranulas used as a control (C); 30 leucoplakias with mild dysplasia (MD); 30 leucoplakias with moderate to severe dysplasia (MSD); 73 oral squamous cell carcinoma (OSCC)]. PTEN protein expression was investigated using immunohistochemistry, and PTEN allelic loss was analysed by fluorescence in‐situ hybridisation (FISH). Differences among groups were evaluated using the χ² test. PTEN expression was higher in MSD (P = 0.002) and OSCC (P = 0.0259) compared with the C group; additionally, a higher expression was observed in MSD (P = 0.0035) and OSCC (P = 0.049) than MD. Regarding FISH analysis, a higher hemizygous (single copy) loss was observed in OSCC than in C (P = 0.0467) and in OSCC than in MD (P = 0.0175), as well as a higher homozygous deletion in OSCC compared with C (P = 0.0159) and OSCC than MD (P = 0.0145).

Conclusion

The results of this work suggest that PTEN allelic loss is an important mechanism in the late stage of the development of oral potentially malignant lesions into oral 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.     

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.     

PTEN loss and KRAS activation leads to the formation of serrated adenomas and metastatic carcinoma in the mouse intestine

Mutation or loss of the genes PTEN and KRAS have been implicated in human colorectal cancer (CRC), and have been shown to co‐occur despite both playing a role in the PI3' kinase (PI3'K) pathway. We investigated the role of these genes in intestinal tumour progression in vivo, using genetically engineered mouse models, with the aim of generating more representative models of human CRC. Intestinal‐specific deletion of Pten and activation of an oncogenic allele of Kras was induced in wild‐type (WT) mice and mice with a predisposition to adenoma development (Apc^fl/+). The animals were euthanized when they became symptomatic of a high tumour burden. Histopathological examination of the tissues was carried out, and immunohistochemistry used to characterize signalling pathway activation. Mutation of Pten and Kras resulted in a significant life‐span reduction of mice predisposed to adenomas. Invasive adenocarcinoma was observed in these animals, with evidence of activation of the PI3'K pathway but no metastasis. However, mutation of Pten and Kras in WT animals not predisposed to adenomas led to perturbed homeostasis of the intestinal epithelium and the development of hyperplastic polyps, dysplastic sessile serrated adenomas and metastasizing adenocarcinomas with serrated features. These studies demonstrate synergism between Pten and Kras mutations in intestinal tumour progression, in an autochthonous and immunocompetent murine model, with potential application to preclinical drug testing. In particular, they show that Pten and Kras mutations alone predispose mice to the spectrum of serrated lesions that reflect the serrated pathway of CRC progression in humans. Published by John Wiley & Sons, Ltd. www.pathsoc.org.uk