ERG-positive Cancers Research Articles

ERG expression in prostate cancer: the prognostic paradox.

TMPRSS2/ERG fusion resulting in ERG overexpression occurs in 30 to 50% of prostate cancer (PCa) in Caucasian patients, but its prognostic relevance remains controversial. In the present study, we investigated ERG expression in all stages of PCa progression, and evaluated the prognostic impact of ERG status in clinically localized PCa (CLC) and in castration resistant disease (CRPC). ERG and AR expressions were evaluated by immunohistochemistry on tissue microarrays containing samples of high grade PIN (n = 57), CLC surgically treated (n = 299, including 185 Caucasians and 114 African-Caribbeans), metastases (n = 17), and CRPC (n = 41). In Caucasians, ERG expression significantly increased from high grade PIN (17.5%) to pT2 (27%) and pT3 CLC (43%), then to metastases (53%). In CLC, stainings for ERG and AR were correlated, and ERG expression was less frequent in African-Caribbeans compared to Caucasians (11.5% vs. 33%). In Caucasians CLC, ERG was associated with longer recurrence free survival, after adjusting for classical prognostic markers. In CRPC, ERG was expressed in 29% of cases, and was associated with a longer overall survival. Our results confirm that ERG expression is less frequent in PCa from patients of African descent. Although ERG expression increases during PCa natural history, positive ERG status is associated with better outcome in both CLC and CRPC. This paradox could be explained in part by the fact that ERG expression is AR dependant, then ERG positive cancers are likely to progress in a rich androgen environment, with a better response to androgen suppression.

TMPRSS2-ERG Fusions Are Strongly Linked to Young Patient Age in Low-grade Prostate Cancer

Based on next-generation sequencing of early-onset prostate cancer (PCa), we earlier demonstrated that PCa in young patients is prone to rearrangements involving androgen-regulated genes—such as transmembrane protease, serine 2 (TMPRSS2)–v-ets avian erythroblastosis virus E26 oncogene homolog (ERG) fusion—and provided data suggesting that this situation might be caused by increased androgen signaling in younger men. In the same study, an accumulation of chromosomal deletions was found in cancers of elderly patients. To determine how age-dependent molecular features relate to cancer phenotype, an existing data set of 11 152 PCas was expanded by additional fluorescence in situ hybridization analyses of phosphatase and tensin homolog (PTEN), 6q15 and 5q21. The results demonstrate that the decrease in TMPRSS2–ERG fusions with increasing patient age is limited to low-grade cancers (Gleason ≤3+4) and that the significant increase in the deletion frequency with age was strictly limited to ERG-negative cancers for 6q15 and 5q21 but to ERG-positive cancers for PTEN. These data suggest that the accumulation of non–androgen-linked genomic alterations with advanced patient age may require an appropriate microenvironment, such as a positive or negative ERG status. The strong link of ERG activation to young patient age and low-grade cancers may help to explain a slight predominance of low-grade cancers in young patients.

Saccharomyces cerevisiae-like 1 overexpression is frequent in prostate cancer and has markedly different effects in Ets-related gene fusion-positive and fusion-negative cancers.

The cytosolic factor Saccharomyces cerevisiae-like 1 (SEC14L1) is a regulator of lipid metabolism and signaling pathways that has been suggested to play a role in cancer. To learn more about its relevance for prostate cancer, SEC14L1 expression was analyzed on a tissue microarray containing samples from 11152 prostate cancer patients. In benign prostate glands, SEC14L1 immunostaining was absent or weak. In prostate cancer, SEC14L1 positivity was found in 80% of 9876 interpretable tumors including 9% with strong, 38% with moderate, and 32% with weak immunostaining. SEC14L1 expression was more frequent in Transmembrane Protease, Serine 2 (TMPRSS2):Ets-related gene (ERG) fusion-positive (89%) than in TMPSSR2:ERG-negative cancers (73%, P < .0001). Comparative analysis of SEC14L1 expression in TMPSSR2:ERG-positive and -negative cancers suggested a different role of SEC14L1 in the 2 subsets: in TMPSSR2:ERG-negative cancers, strong SEC14L1 expression was associated with early prostate-specific antigen recurrence (P = .0270), advanced tumor stage (P = .0042), high Gleason score (P < .0001), and high preoperative prostate-specific antigen levels (P = .0035). In TMPSSR2:ERG-positive cancers, strong SEC14L1 staining was linked to a prolonged recurrence-free interval (P = .0023) and absence of lymph node metastases (P = .0002). Strong associations of high SEC14L1 levels with chromosomal deletions (5q, 6q, phosphatase and tensin homolog gene, 3p13; P < .0001) and a high Ki-67 labeling index (P < .0001) were seen in TMPSSR2:ERG-negative but not TMPSSR2:ERG-positive cancers. A direct or indirect role of SEC14L1 in maintenance of genomic integrity and regulating cell proliferation may thus exclusively exist in TMPSSR2:ERG-negative cancers. In conclusion, our data suggest a markedly different role of SEC14L1 in TMPSSR2:ERG-negative and TMPSSR2:ERG-positive prostate cancers.

NY-ESO-1 expression is tightly linked to TMPRSS2-ERG fusion in prostate cancer.

NY-ESO-1 has been suggested as therapeutic cancer vaccine in prostate cancer. This study was undertaken to explore the relationship of NY-ESO-1 with tumor phenotype, biochemical recurrence, and molecular subgroups in hormone-naive prostate cancers. NY-ESO-1 immunohistochemistry was analyzed on a tissue microarray containing 11,152 prostate cancer samples. Results were compared to clinically follow-up data, ERG status, and deletions on PTEN, 3p13, 5q21, and 6q15. NY-ESO-1 expression was absent in benign prostate glands. In prostate cancer, NY-ESO-1 positivity was found 8.8% of our 8,761 interpretable tumors including 5.8% with weak, 2.5% with moderate, and 0.5% with strong expression. There was a threefold higher rate of NY-ESO-1 expression in ERG fusion positive tumors than in ERG negative cancers (P < 0.0001). There was a significant association with early PSA recurrence, which was largely limited to ERG positive cancers. Within the ERG positive subgroup, high NY-ESO-1 expression was associated with early biochemical recurrence (P = 0.0002) and high Gleason grade (P < 0.0001). In ERG negative cancers, NY-ESO-1 expression was also linked to PTEN (P = 0.0012) and 6q15 deletions (P = 0.0005). Our observations indicate a tight link of NY-ESO-1 expression to ERG activation and (to a lesser extent) PTEN- and 6q15-deletions in prostate cancer. The impact of these interactions on the likelihood of response to immunotherapy is unclear. The prognostic impact of NY-ESO-1 expression is little and not independent of histologic variables.

The prognostic impact of high Nijmegen breakage syndrome (NBS1) gene expression in ERG-negative prostate cancers lacking PTEN deletion is driven by KPNA2 expression

The Nijmegen breakage syndrome (NBS1) gene was suggested as a prostate cancer susceptibility gene. This study was undertaken to determine, whether NBS1 expression is linked to clinically or molecularly relevant subgroups of prostate cancer. NBS1 expression was analyzed by immunohistochemistry on a tissue microarray containing 11,152 prostate cancer specimens. NBS1 expression was absent or only weakly detectable in benign prostate. In prostate cancers, NBS1 expression was found in 81.3% of interpretable tumors and was considered strong in 41.3% of cases. NBS1 upregulation was tightly linked to ERG-positive cancers (p<0.0001). Within ERG-negative cancers, strong NBS1 immunostaining was linked to advanced pathological tumor stage, high Gleason grade, and positive nodal status (p<0.0001 each), while high NBS1 immunostaining was only weakly associated with advanced pathological tumor stage in ERG-positive cancers (p=0.0099). A comparison with chromosomal deletions revealed a strong NBS1 upregulation in PTEN-deleted cancers, while deletions of 3p13, 5q21 and 6q15 did not affect NBS1 expression. High NBS1 expression was linked to biochemical recurrence in ERG-negative and PTEN non-deleted cancers (p<0.0001), which was largely driven by high KPNA2 karyopherin alpha 2 expression. In conclusion, our study identifies an association of NBS1 expression with surrogates of genomic instability in prostate cancer including TMPRSS2-ERG rearrangements and PTEN deletion. The prognostic impact of NBS1 expression in ERG-negative, PTEN non-deleted cancers was dependent of the expression status of its interaction partner KPNA2.

βIII-Tubulin Overexpression Is an Independent Predictor of Prostate Cancer Progression Tightly Linked to ERG Fusion Status and PTEN Deletion

Evidence suggests that class III β-tubulin (βIII-tubulin) may represent a prognostic and predictive molecular marker in prostate cancer. βIII-Tubulin expression was determined by IHC in 8179 prostate cancer specimens in a TMA format. Results were compared with tumor phenotype, biochemical recurrence, v-ets avian erythroblastosis virus E26 oncogene homolog (ERG) status, and deletions on PTEN, 3p13, 5q21, and 6q15. βIII-Tubulin expression was detectable in 25.6% of 8179 interpretable cancers. High βIII-tubulin expression was strongly associated with both TMPRSS2:ERG rearrangement and ERG expression (P<0.0001 each). High βIII-tubulin expression was tightly linked to high Gleason grade, advanced pT stage, and early prostate-specific antigen (PSA) recurrence in all cancers (P<0.0001 each), but also in the subgroups of ERG-negative and ERG-positive cancers. When all tumors were analyzed, the prognostic role of βIII-tubulin expression was independent of Gleason grade, pT stage, pN stage, surgical margin status, and preoperative PSA. Independent prognostic value became even more evident if the analysis was limited to preoperatively available features, such as biopsy specimen Gleason grade, preoperative PSA, cT stage, and βIII-tubulin expression (P<0.0001 each). βIII-Tubulin expression was associated with PTEN (P<0.0001) when all tumors were analyzed, but also in the subgroups of ERG-negative and ERG-positive cancers. βIII-Tubulin expression is an independent prognostic parameter. The significant associations with key genomic alterations of prostate cancer, such as TMPRSS2:ERG fusions and PTEN deletions, suggest interactions with several pivotal pathways involved in prostate cancer.

Reduced CD147 expression is linked to ERG fusion-positive prostate cancers but lacks substantial impact on PSA recurrence in patients treated by radical prostatectomy

The extracellular matrix metalloproteinase inducer CD147 has been suggested as a prognostic marker in prostate cancer. CD147 expression was analyzed by immunohistochemistry on a tissue microarray containing 11,152 prostate cancer specimens. Results were compared to tumor phenotype, biochemical recurrence, ERG status and deletions on PTEN, 3p13, 6q15 and 5q21. CD147 expression was strong in benign prostatic glands and often reduced in prostate cancers. CD147 immunostaining was found in 71.7% of 7628 interpretable cases. CD147 staining was considered strong in 34.6%, moderate in 24.3% and weak in 12.8% of cancers while 28.3% did not show any CD147 reactivity. Reduced CD147 staining was strongly associated with both TMPRSS2-ERG-rearrangement and ERG expression (p<0.0001 each). Within the subgroups of ERG positive and negative cancers, deletions of PTEN, 3p13, 6q15 and 5q21 were unrelated to the CD147 expression status. Decreased CD147 expression was significantly linked to high preoperative PSA values, high Gleason grade, advanced tumor stage (p<0.0001 each), and positive lymph node involvement (p=0.0026) in all cancers. There was a marginal, but statistically significant, association of reduced CD147 expression with early biochemical recurrence (p=0.0296). The significant reduction of CD147 expression in ERG positive prostate cancer provides further evidence for marked biological differences between “fusion type” and “non-fusion type” prostate cancer. Despite a weak association with PSA recurrence, CD147 cannot be considered a relevant prognostic biomarker.

High lysophosphatidylcholine acyltransferase 1 expression independently predicts high risk for biochemical recurrence in prostate cancers

Lysophosphatidylcholine acyltransferase 1 (LPCAT1) has been suggested to play a role in cancer. To assess its role in prostate cancer, LPCAT1 expression was analyzed on a tissue microarray containing samples from 11,152 prostate cancer patients. In benign prostate glands, LPCAT1 immunostaining was absent or weak. In prostate cancer, LPCAT1 positivity was found in 73.8% of 8786 interpretable tumors including 29.2% with strong expression. Increased LPCAT1 expression was associated with advanced tumor stage (pT3b/T4) (p < 0.0001), high Gleason score (≥4 + 4) (p < 0.0001), positive nodal involvement (p = 0.0002), positive surgical margin (p = 0.0005), and early PSA recurrence (p < 0.0001). High LPCAT1 expression was strongly linked to ERG-fusion type prostate cancer. Strong LPCAT1 staining was detected in 45.3% of ERG positive but in only 16.7% of ERG negative tumors (p < 0.0001). Within ERG negative cancers, LPCAT1 staining was strongly increased within the subgroup of PTEN deleted cancers (p < 0.0001). Further subgroup analyses revealed that associations of high LPCAT1 expression with PSA recurrence and unfavorable tumor phenotype were largely driven by ERG negative cancers (p < 0.0001) while these effects were substantially mitigated in ERG positive cancers (p = 0.0073). The prognostic impact of LPCAT1 expression was independent of histological and clinical parameters. It is concluded, that LPCAT1 measurement, either alone or in combination, may be utilized for better clinical decision-making. These data also highlight the potentially important role of lipid metabolism in prostate cancer biology.

SPINK1 expression is tightly linked to 6q15- and 5q21-deleted ERG-fusion negative prostate cancers but unrelated to PSA recurrence

The serine peptidase inhibitor, Kazal type 1 (SPINK1) has been suggested to define an aggressive molecular subtype of ERG-fusion negative prostate cancer. It was the aim of this study to further study the clinical relevance of SPINK1 expression and its relationship with other key genomic alterations of prostate cancer. A tissue microarray containing more than 10,000 prostate cancers with clinical follow-up was used for immunohistochemical SPINK1 analysis. Data on ERG status as well as PTEN, 6q, 5q, and 3p deletions were available for comparison. SPINK1 expression was absent in benign prostate glands and detectable in 5.9% of 9,503 interpretable prostate cancers. Presence of SPINK1 expression was markedly more frequent in ERG negative (10.4%) than in ERG positive cancers (0.3%; P < 0.0001). However, SPINK1 expression was unrelated to tumor phenotype and biochemical recurrence in all cancers and in the subgroup of ERG negative cancers. Further subgroup analyses revealed, however, that--within ERG negative cancers--SPINK1 expression was significantly linked to deletions at 6q15 (P < 0.0001) and 5q21 (P = 0.0042). Our results exclude SPINK1 as a relevant prognostic prostate cancer biomarker. However, the data demonstrate that SPINK1 overexpression is tightly linked to the small subsets of 6q15- and 5q21-deleted ERG negative prostate cancers. These findings support the concept of molecularly defined subtypes of prostate cancers.

Genomic deletion of MAP3K7 at 6q12-22 is associated with early PSA recurrence in prostate cancer and absence of TMPRSS2:ERG fusions

6q12-22 is the second most commonly deleted genomic region in prostate cancer. Mapping studies have described a minimally deleted area at 6q15, containing MAP3K7/TAK1, which was recently shown to have tumor suppressive properties. To determine prevalence and clinical significance of MAP3K7 alterations in prostate cancer, a tissue microarray containing 4699 prostate cancer samples was analyzed by fluorescence in situ hybridization. Heterozygous MAP3K7 deletions were found in 18.48% of 2289 interpretable prostate cancers. MAP3K7 deletions were significantly associated with advanced tumor stage (P<0.0001), high Gleason grade (P<0.0001), lymph node metastasis (P<0.0108) and early biochemical recurrence (P<0.0001). MAP3K7 alterations were typically limited to the loss of one allele as homozygous deletions were virtually absent and sequencing analyses revealed no evidence for MAP3K7 mutations in 15 deleted and in 14 non-deleted cancers. There was a striking inverse association of MAP3K7 deletions and TMPRSS2:ERG fusion status with 26.7% 6q deletions in 1125 ERG-negative and 11.1% 6q deletions in 1198 ERG-positive cancers (P<0.0001). However, the strong prognostic role of 6q deletions was retained in both ERG-positive and ERG-negative cancers (P<0.0001 each). In summary, our study identifies MAP3K7 deletion as a prominent feature in ERG-negative prostate cancer with strong association to tumor aggressiveness. MAP3K7 alterations are typically limited to one allele of the gene. Together with the demonstrated tumor suppressive function in cell line experiments and lacking evidence for inactivation through hypermethylation, these results indicate MAP3K7 as a gene for which haploinsufficency is substantially tumorigenic.

Cysteine-rich secretory protein 3 overexpression is linked to a subset of PTEN-deleted ERG fusion-positive prostate cancers with early biochemical recurrence

The aim of this study was to determine whether cysteine-rich secretory protein 3 (CRISP3) expression is linked to clinically or molecularly relevant subgroups of prostate cancer. A tissue microarray representing samples from >10 000 prostate cancers from radical prostatectomy specimens with clinical follow-up data were analyzed for CRISP3 expression by immunohistochemistry. CRISP3 expression was also compared with key genomic alterations of prostate cancer. CRISP3 staining was found as weak in 15%, moderate in 8.5%, and strong in 7.2% of prostate cancers, whereas no expression was detected in normal prostate. Strong CRISP3 expression was linked to advanced tumor stage, high Gleason score, and positive surgical margin status (P<0.0001 each). There was a marked accumulation of high CRISP3 expression in PTEN-deleted ERG-positive tumors (P<0.0001). A total of, 21.7% of ERG-positive and PTEN-deleted cancers had strong CRISP3 expression, but only 10.4% of ERG-positive cancers without PTEN deletion (P<0.0001). The rate of high CRISP3 expression was 2.5% in ERG-negative cancers (P=0.0001; vs ERG-positive cancers). Accordingly, CRISP3 overexpression was associated with early prostate-specific antigen recurrence in all tumors (P=0.0013) as well as in ERG-negative (P=0.004) and ERG-positive cancers (P=0.0318). CRISP3 expression did not retain prognostic significance in models also involving PTEN deletions. Strong CRISP3 expression is associated with unfavorable tumor phenotype and early recurrence in prostate cancers. The tight link of strong CRISP3 expression to the ERG fusion-positive prostate cancers with PTEN deletions provides further evidence for the existence of molecularly distinct subgroups of prostate cancers.

Abstract 1972: Clinical impact of 6q deletion patterns in prostate cancer.

Abstract Deletions of chromosome 6q12-22 represent the second common deletion in prostate cancer. Although most of these deletions are large and span &amp;gt; 50 megabases, a minimal deleted region containing 3-4 megabases was described at 6q15. MAP3K7 (at 6q15) was suggested as a potential target gene in this area. Based on the hypothesis, that large 6q deletions compromising a multitude of genes may have a different impact on the biology of prostate cancer cells than small circumscribed 6q15 deletions, a tissue microarray (TMA) containing over 7000 prostate cancers was analyzed by fluorescence in situ hybridization (FISH). All cancers were analyzed with probes for 6q12, 6q14, 6q15 (MAP3K7), 6q16, and 6q22. 3888 tumors were interpretable for all 5 probes including 463 (10.6%) showing a 6q deletion. 6q deletions were tightly linked to a negative ERG status with 15.6% deletions in ERG negative and 5.8% deletions in ERG positive cancers (p&amp;lt;0.0001). The frequency of 6q deletions increased with Gleason grade and pT stage. 6q deletions were found in 5.4% of ≤3+3, 10.6% of 3+4, 19.6% of 4+3, and 18.8% of ≥4+4 cancers (p&amp;lt;0.0001). 6q deletions occurred in 9.6% of pT2, 11.5% of pT3a, and 14.8% of pT3b carcinomas (p=0.0160). 6q deletions were also linked to early PSA recurrence (p&amp;lt;0.0001). Remarkably, the clinical outcome varied markedly with deletion size. PSA recurrence was more likely in cancers with 6q12-22 deletions as compared to tumors with 6q14-16 deletions (p&amp;lt;0.0001). Twelve genes located within 6q14-16 were functionally evaluated applying colony formation assays to prostate cell lines BPH1, DU-145, and PC-3. These analyses failed to identify a cell behavior consistent with a role as a tumor suppressor gene for MAP3K7, as well as RRAGD, ANKRD6, LYRM2, MDN1, CASP8AP2, BACH2, COQ3, MANEA, RNGTT, SLC35A1, and MMS22L. In conclusion, the strong impact of the deletion size suggests, that multiple genes on chromosome 6q12-22 might have a tumor suppressive role in prostate cancer and that alterations of more than one of these has an additive adverse effect to cells. Our data do not confirm MAP3K7 as the main target of 6q deletions in prostate cancer Citation Format: Martina Kluth, Nina Amschler, Anna Heinl, Simon Jung, Ronald Simon, Thorsten Schlomm, Guido Sauter, Sarah Jane Pauline Minner. Clinical impact of 6q deletion patterns in prostate cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1972. doi:10.1158/1538-7445.AM2013-1972

Abstract 2176: Deletion of 3p14 is linked to ERG-fusion positive prostate cancers and harbors the FOXP1 tumor suppressor gene

Abstract Genetic rearrangements involving 3p14 are frequent alterations in prostate cancer, affecting approximately 15-20% of tumors. Both the clinical significance and the tumor suppressor at 3p14 locus are currently unknown. We performed SNP array analysis of 72 primary prostate cancers and show a commonly deleted region at 3p14 in 14 (19%) of the tumors. Our data indicate the existence of a small, recurrent deletion in a significant fraction of prostate cancers harboring 8 genes only. Ten of 14 tumors with 3p14 deletions detected in our study included the FOXP1 locus. To estimate the prevalence and clinical significance of FOXP1 deletions, we analyzed a tissue microarray containing 4,699 prostate cancers with histopathological and clinical follow-up data. Heterozygous FOXP1 deletions were found in 15% of tumors, and were strongly associated with ERG-fusion positive cancers (p&amp;lt;0.0001). No homozygous deletions were detected. FOXP1 deletions were unrelated to tumor stage or Gleason grade. FOXP1 deletions were linked to early PSA recurrence in ERG-positive cancers (p=0.0576) but not in ERG negative tumors (p=0.5425). To better understand the association between ERG fusion and FOXP1 expression, we performed FOXP1 immunohistochemistry on our TMA. FOXP1 expression was found in virtually all (95%) prostate cancers, and was particularly strong in ERG-fusion positive tumors. This finding argues for an important role of FOXP1 in prostate cancer in general and for ERG fusion positive tumors in particular. Since FOXP1 is a transcriptional repressor, we hypothesized that upregulation might be a consequence of ERG activation in order to control transcription of ERG target genes. However, neither expression of ERG in LNCaP cells, or depletion of ERG in VCaP cells had an effect on FOXP1 mRNA levels, strongly arguing against a direct link between ERG and FOXP1 at least in the tested cell lines. In addition neither the transcription nor the steady state levels of FOXP1 protein were modulated by activation of AR signaling. Finally, colony formation assays in both benign and malignant prostate cell lines revealed that FOXP1 may act as a tumor suppressor. In summary, our study demonstrates that FOXP1 functions as one of the tumor suppressor genes in prostate cancer that is targeted by genomic deletions at 3p14. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2176. doi:1538-7445.AM2012-2176

Association of nuclear accumulation of p53 with ERG fusion and poor prognosis in prostate cancer.

124 Background: We have previously shown that nuclear accumulation of p53 is rare in prostate cancer but strongly linked to early biochemical recurrence (Schlomm et al., Modern Pathology, 2008). The current study was designed to study the association between ERG fusion and p53 in a large series of prostate cancers. Methods: A prostate cancer tissue microarray (TMA) was constructed from 4,699 radical prostatectomie specimens with histological, pathological, and clinical follow-up data. Immunohistochemistry was applied to detect nuclear p53 accumulation as a marker for defective p53 and to detect ERG expression as a surrogate for ERG gene fusion. Results: Nuclear accumulation of p53 was detected in 62/3,667 (1.7%) analyzable tissue spots. Positive staining was significantly linked to advanced tumor stage (p&lt;0.0001), high Gleason score (p&lt;0.0001), presence of lymph node metastases (p=0.0005), and early PSA recurrence (p&lt;0.0001) in all cancers. ERG expression was found in 1,990/4,266 (46.6%) analyzable cancers, but was unrelated to tumor phenotype or patient prognosis. Results of both p53 and ERG were available from 3,392 tumors. Presence of nuclear p53 staining was linked to ERG fusion positive cancers: 40 (2.7%) of 1,491 ERG-positive cancers, but only 20 (1.1%) of 1,901 ERG-negative tumors showed nuclear p53 staining (p=0.0004). A Kaplan-Meier survival analysis of p53 in the subsets of 1,699 ERG positive and 1,280 ERG negative cancers revealed that nuclear p53 accumulation was strongly linked to early PSA recurrence in both subsets (p&lt;0.0001 each). Conclusions: These data demonstrate that the poor prognosis of prostate cancer patients with nuclear p53 accumulation is independently from the ERG fusion status, but suggest a distinct biological role of p53 inactivation in ERG fusion positive cancers. The very high number of prostate cancer samples included in the TMA used in this study allows for analysis of rare events such as p53 alterations with high statistical power.

ERG Status Is Unrelated to PSA Recurrence in Radically Operated Prostate Cancer in the Absence of Antihormonal Therapy

About 50% of prostate cancers have TMPRSS2-ERG fusions with concurrent ERG overexpression. The aim of this study was to determine whether clinical differences exist between ERG-positive and ERG-negative cancers in surgically treated patients not exposed to antihormonal therapy. A secondary aim was to search for differences between these tumor classes. A tissue microarray containing samples from more than 2,800 prostate cancers with clinical data was analyzed for ERG alterations by immunohistochemistry and FISH. Results were compared with tumor phenotype, biochemical recurrence, and molecular features considered important for prostate cancer. The effect of ERG on androgen receptor (AR)-dependent transcription was analyzed in cell lines. ERG expression was found in 52.4% of 2,805 cancers with a 95% concordance between ERG expression and ERG gene rearrangement detected by FISH. ERG expression was unrelated to clinical outcome and tumor phenotype. Differences in AMACR, Annexin A3, Bcl2, CD10, ALCAM, chromogranin A, epidermal growth factor receptor, HER2, mTOR, p53, and synaptophysin status were significant but minimal in absolute numbers. The most striking difference was found for AR expression, which was markedly higher in ERG-positive cancers. In vitro studies showed ERG-dependent impairment of AR-mediated transcriptional activity. The striking similarities between these two types of prostate cancers rules out a major impact of ERG on tumor aggressiveness in early, not hormonally treated cancer. The marked difference in AR levels between ERG-positive and -negative cancers supports a systematic difference in potential response to hormonal therapy as previously observed in clinical trials.

Abstract 4840: DNA methylation patterns and transcript isoform regulation in prostate cancer

Abstract In cancer, the genome undergoes global DNA methylation changes, which contributes to disease progression. We mapped the global DNA methylation patterns in prostate tissues and cells (n=19) from fifty nanograms of genomic DNA. The methylated regions enriched by Methylplex technology, were subjected -Next Generation Sequencing (M-NGS). A total of 28 lanes of next generation sequencing yielded approximately 530 million sequence reads. The reads uniquely mapped to human genome were analyzed by H-Peak program to identify 1.8 million methylated regions from the 28 runs. While twenty percent of all CpG islands (CGIs) (68,508) were methylated in tissues, the promoter CGI methylation gradually increased from ∼12.6% in benign samples to 19.3% and 21.8% in localized and metastatic cancer tissues. However surprisingly, the total methylation events in intergenic/intronic regions between benign adjacent and cancer tissues were largely comparable. We found distinct patterns in promoter methylation around transcription start sites where methylation occurred directly on the CGIs, flanking regions and on CGI sparse promoters. Among the 6,691 methylated promoters in prostate tissues, 2481 differentially methylated regions (DMRs) were cancer specific and several previously studied targets were among them. A novel cancer specific DMR in WFDC2 promoter showed 77% methylation in cancer (17/22), 100% methylation in transformed prostate cell lines (6/6), none in the benign tissues (0/10) and normal PrEC cells. Integration of LNCaP DNA methylation and H3K4me3 data suggested a role for DNA methylation in alternate transcription start site utilization. Specifically, we detail the regulation of RASSF1, a gene previously reported to be silenced through DNA methylation in PCa and NDRG2. We show that variant-1 of RASSF1, but not variant-2 or -3, is specifically silenced in LNCaP through promoter methylation, and normal cells do not exhibit this phenomenon. Treatment with 5-Aza-2-deoxycytidine preferentially induced re-expression of variant-1 of RASSF1 in LNCaP, confirming transcriptional regulation of this isoform through DNA methylation. The methylated promoters lacking CGIs showed sparse H3K4me3 modification, interestingly methylated promoters containing CGIs showed a mutually exclusive H3K4me3/DNA methylation marks. Finally, we observed a difference in the methylation of LINE-1 elements between transcription factor ERG positive and negative cancers. The comprehensive methylome map presented here will further our understanding of epigenetic regulation of the prostate cancer genome. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4840. doi:10.1158/1538-7445.AM2011-4840

Abstract 3809: TMPRSS2-ERG gene fusion is strongly associated with elevated androgen receptor expression in early prostate cancer

Abstract Introduction and Objective: About 50% of prostate cancers have TMPRSS2-ERG fusions resulting in ERG overexpression. The aim of this study was to determine whether prostate cancer of “fusion-type” differs from “non-fusion” prostate cancer both clinically and molecularly. Methods: A prostate cancer tissue microarray (TMA) consisting of over 2,500 cancer samples was analyzed for ERG protein expression and TMPRSS2-ERG gene fusion by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). Results were compared with tumor phenotype, clinical outcome, and molecular features previously determined in studies using the same TMA. Furthermore, a fresh frozen prostate cancer TMA containing 41 “fusion-type” and 21 “non-fusion” prostate cancers was analyzed by MALDI (Matrix Assisted Laser Desorption/Ionisation) mass spectrometric imaging, a technology analyzing proteomic patterns directly on tissue sections. Functional analyses included comparisons of androgen receptor (AR) mRNA levels in LNCaP cells before and after induced ectopic ERG overexpression through lentiviral vectors. Results: Detectable ERG protein expression was found in 52% of 2818 interpretable cancers on our TMA and TMPRSS2-ERG fusion was observed by FISH in 42% of 947 interpretable cases. The data did not reveal any clinical or prognostic significance of ERG protein expression and TMPRSS2-ERG fusion. However, several molecular features differed between “”fusion-type” and “non-fusion” prostate cancers, including AR, AMACR, Annexin A3, Bcl2, CD10, CD166, Chromogranin A, EGFR, HER2 and mTOR. The strongest difference was found for AR expression, which was considered strong in 62.9% of ERG negative but in 81.0% of ERG positive cancers. In the LNCaP cell line, ectopic ERG overexpression lead to a marked downregulation of androgen receptor dependent transcription. MALDI imaging identified several additional masses that differed significantly between “fusion-type” and “non-fusion” tumors. Conclusions: There is no particular clinical behavior of “fusion-type” and “non-fusion” cancers in surgically treated patients. The TMPRSS2-ERG fusion determines a distinct subgroup of prostate cancers, which strongly differ on the molecular level as detected by immunohistochemistry and MALDI imaging. Furthermore, our data indicate that ERG modulates the transcription of AR-dependent genes in prostate cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3809. doi:10.1158/1538-7445.AM2011-3809