Sarah Minner

Genomic Deletion of PTEN Is Associated with Tumor Progression and Early PSA Recurrence in ERG Fusion-Positive and Fusion-Negative Prostate Cancer

The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) gene is often altered in prostate cancer. To determine the prevalence and clinical significance of the different mechanisms of PTEN inactivation, we analyzed PTEN deletions in TMAs containing 4699 hormone-naïve and 57 hormone-refractory prostate cancers using fluorescence in situ hybridization analysis. PTEN mutations and methylation were analyzed in subsets of 149 and 34 tumors, respectively. PTEN deletions were present in 20.2% (458/2266) of prostate cancers, including 8.1% heterozygous and 12.1% homozygous deletions, and were linked to advanced tumor stage (P < 0.0001), high Gleason grade (P < 0.0001), presence of lymph node metastasis (P = 0.0002), hormone-refractory disease (P < 0.0001), presence of ERG gene fusion (P < 0.0001), and nuclear p53 accumulation (P < 0.0001). PTEN deletions were also associated with early prostate-specific antigen recurrence in univariate (P < 0.0001) and multivariate (P = 0.0158) analyses. The prognostic impact of PTEN deletion was seen in both ERG fusion-positive and ERG fusion-negative tumors. PTEN mutations were found in 4 (12.9%) of 31 cancers with heterozygous PTEN deletions but in only 1 (2%) of 59 cancers without PTEN deletion (P = 0.027). Aberrant PTEN promoter methylation was not detected in 34 tumors. The results of this study demonstrate that biallelic PTEN inactivation, by either homozygous deletion or deletion of one allele and mutation of the other, occurs in most PTEN-defective cancers and characterizes a particularly aggressive subset of metastatic and hormone-refractory prostate cancers.

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

Purpose: 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. Experimental Design: 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. Results: 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. Conclusions: 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. Clin Cancer Res; 17(18); 5878–88. ©2011 AACR.

Clinical significance of p53 alterations in surgically treated prostate cancers

Despite the high number of previous studies, the role of p53 alterations in prostate cancer is not clearly defined. To address the role of p53 alterations in prostate cancer biology, a total of 2514 cancers treated by radical prostatectomy were successfully analyzed by immunohistochemistry in a tissue microarray format. Overall a low rate of p53-positive tumors was found (2.5%). A significant underestimation of p53-positive cases was excluded by subsequent large section analyses and direct sequencing of the p53 gene in subsets of our patients. Large section analysis of 23 cases considered negative on the tissue microarray yielded only one weakly p53-positive tumor. Only 4 out of 64 (6.4%) high-grade tumors, that were considered negative for p53 by immunohistochemistry, presented exon 5–8 mutations. These data suggest a high sensitivity of our immunohistochemistry approach and confirm the overall low frequency of p53 alterations in clinically localized prostate cancer. A positive p53 immunostaining was strongly associated with presence of exon 5–8 mutations (P<0.0001), advanced pT-stage (P<0.0001), high Gleason grade (P<0.0001), positive surgical margins (P=0.03) and early biochemical tumor recurrence (P<0.0001). A higher rate of positive p53 immunostaining was detected in late-stage diseases including metastatic prostate cancer (P=0.0152) and hormone-refractory tumors (P=0.0003). Moreover, p53 expression was identified as an independent predictor of biochemical tumor recurrence in the subgroup of low- and intermediate-grade cancers. In summary, the results of this study show that p53 mutations characterize a small biologically aggressive subgroup of prostate cancers with a high risk of progression after prostatectomy. The rate of p53 alterations increases with prostate cancer progression.

CHD1 is a 5q21 tumor suppressor required for ERG rearrangement in prostate cancer

Deletions involving the chromosomal band 5q21 are among the most frequent alterations in prostate cancer. Using single-nucleotide polymorphism (SNP) arrays, we mapped a 1.3 megabase minimally deleted region including only the repulsive guidance molecule B (RGMB) and chromodomain helicase DNA-binding protein 1 (CHD1) genes. Functional analyses showed that CHD1 is an essential tumor suppressor. FISH analysis of 2,093 prostate cancers revealed a strong association between CHD1 deletion, prostate-specific antigen (PSA) biochemical failure (P = 0.0038), and absence of ERG fusion (P < 0.0001). We found that inactivation of CHD1 in vitro prevents formation of ERG rearrangements due to impairment of androgen receptor (AR)-dependent transcription, a prerequisite for ERG translocation. CHD1 is required for efficient recruitment of AR to responsive promoters and regulates expression of known AR-responsive tumor suppressor genes, including NKX3-1, FOXO1, and PPARγ. Our study establishes CHD1 as the 5q21 tumor suppressor gene in prostate cancer and shows a key role of this chromatin remodeling factor in prostate cancer biology.

O-GlcNAc transferase integrates metabolic pathways to regulate the stability of c-MYC in human prostate cancer cells.

Metabolic disruptions that occur widely in cancers offer an attractive focus for generalized treatment strategies. The hexosamine biosynthetic pathway (HBP) senses metabolic status and produces an essential substrate for O-linked β-N-acetylglucosamine transferase (OGT), which glycosylates and thereby modulates the function of its target proteins. Here, we report that the HBP is activated in prostate cancer cells and that OGT is a central regulator of c-Myc stability in this setting. HBP genes were overexpressed in human prostate cancers and androgen regulated in cultured human cancer cell lines. Immunohistochemical analysis of human specimens (n = 1987) established that OGT is upregulated at the protein level and that its expression correlates with high Gleason score, pT and pN stages, and biochemical recurrence. RNA interference-mediated siliencing or pharmacologic inhibition of OGT was sufficient to decrease prostate cancer cell growth. Microarray profiling showed that the principal effects of OGT inhibition in prostate cancer cells were related to cell-cycle progression and DNA replication. In particular, c-MYC was identified as a candidate upstream regulator of OGT target genes and OGT inhibition elicited a dose-dependent decrease in the levels of c-MYC protein but not c-MYC mRNA in cell lines. Supporting this relationship, expression of c-MYC and OGT was tightly correlated in human prostate cancer samples (n = 1306). Our findings identify HBP as a modulator of prostate cancer growth and c-MYC as a key target of OGT function in prostate cancer cells.

Low Level Her2 Overexpression Is Associated with Rapid Tumor Cell Proliferation and Poor Prognosis in Prostate Cancer

Purpose: The HER2 oncogene is involved in the biology of many different tumor types and serves as a prognostic marker and a therapeutic target in breast cancer. In contrast to breast cancer, studies on Her2 overexpression and gene amplification in prostate cancer have yielded different results. The purpose of this study was to learn more on the prevalence and clinical significance of HER2 amplification and overexpression in prostate cancer. Experimental Design: A tissue microarray containing >2,000 prostate cancers with follow-up data was used. Tissue microarray sections were analyzed on protein and DNA level using two different antibodies (HercepTest, DAKO; Novocastra NCL-CB11) and fluorescence in situ hybridization. Results: Immunohistochemical analyses showed highly similar results for both antibodies. Detectable Her2 immunostaining was observed in 17.2% for the HercepTest and in 22.5% for the Novocastra antibody with the vast majority of cases showing 1+ or 2+ staining. For both antibodies (HercepTest/Novocastra), significant associations were found between positive staining and high Gleason grade (P < 0.0001, both), advanced pT stage (P < 0.0001/P = 0.0015), rapid tumor cell proliferation (P = 0.0004/P = 0.0071), and tumor recurrence (P < 0.0001, both). HER2 amplification was only found in 1 of 2,525 analyzable cases (0.04%). Conclusions: Low-level Her2 overexpression occurs at relevant frequency in prostate cancer and in the absence of gene amplification. Increased Her2 expression may potentially lead to an aggressive behavior of tumor cells through the stimulation of tumor cell proliferation because Her2 staining was shown to be significantly associated with Ki67 labeling index. These data argue for reconsidering anti-Her2 therapy, possibly with modified approaches. Clin Cancer Res; 16(5); 1553–60

High level PSMA expression is associated with early PSA recurrence in surgically treated prostate cancer.

Prostate specific membrane antigen (PSMA) is a suggested target for antibody‐based therapy of prostate cancer potentially involved in the regulation of cell migration. This study was undertaken, to gain more insight on the role of PSMA in early prostate cancer and its distribution in various normal tissues.

Neurovascular Structure-adjacent Frozen-section Examination (NeuroSAFE) Increases Nerve-sparing Frequency and Reduces Positive Surgical Margins in Open and Robot-assisted Laparoscopic Radical Prostatectomy: Experience After 11 069 Consecutive Patients

BACKGROUND Intraoperative frozen-section analysis allows real-time histologic assessment of surgical margins (SMs) and identification of candidates for nerve-sparing (NS) procedures. OBJECTIVE To examine the efficacy and oncologic safety of a systematic neurovascular structure-adjacent frozen-section examination (NeuroSAFE) during NS radical prostatectomy (RP). DESIGN, SETTING, AND PARTICIPANTS From January 2002 to June 2011, 11 069 consecutive RPs were performed at the University Medical Center Hamburg-Eppendorf. Of these, 5392 (49%) were conducted with NeuroSAFE. SURGICAL PROCEDURE Our NeuroSAFE approach included the whole laterorectal circumference of the prostate to determine the SM status of the complete neurovascular tissue-corresponding prostatic surface. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS The impact of NeuroSAFE on NS frequency, SM status, and biochemical recurrence (BCR) was analyzed by chi-square test, and by Kaplan-Meier analyses in propensity score-based matched cohorts. RESULTS AND LIMITATIONS Positive SMs (PSMs) were detected in 1368 (25%) NeuroSAFE RPs, leading to a secondary resection of the ipsilateral neurovascular tissue. Secondary wide resection resulted in conversion to a definitive negative SM (NSM) status in 1180 (86%) patients. In NeuroSAFE RPs, frequency of NS was significantly higher (all stages: 97% vs 81%; pT2: 99% vs 92%; pT3a: 94% vs 72%; pT3b: 88% vs 40%; p<0.0001) and PSM rates were significantly lower (all stages: 15% vs 22%; pT2: 7% vs 12%; pT3a: 21% vs 32%; p<0.0001) than in the matched non-NeuroSAFE RPs. In propensity score-based comparisons, NeuroSAFE had no negative impact on BCR (pT2, p=0.06; pT3a, p=0.17, pT3b, p=0.99), and BCR-free survival of patients with conversion to NSM did not differ significantly from patients with primarily NSM (pT2, p=0.16; pT3, p=0.26). The accuracy of our NeuroSAFE approach was 97% with a false-negative rate of 2.5%. The major limitations of this study are its retrospective nature and relatively short follow-up. CONCLUSIONS NeuroSAFE enables real-time histologic monitoring of the oncologic safety of a NS procedure. Systematic NeuroSAFE significantly increases NS frequencies and reduces PSMs. Patients with a NeuroSAFE-detected PSM could be converted to a prognostically more favorable NSM status by secondary wide resection.

Prognostic Role and HER2 Expression of Circulating Tumor Cells in Peripheral Blood of Patients Prior to Radical Cystectomy: A Prospective Study

BACKGROUND Preliminary research has suggested the potential prognostic value of circulating tumor cells (CTC) in patients with advanced nonmetastatic urothelial carcinoma of the bladder (UCB). OBJECTIVE Prospectively analyze the clinical relevance and human epidermal growth factor receptor 2 (HER2) expression of CTC in patients with clinically nonmetastatic UCB. DESIGN, SETTING, AND PARTICIPANTS Blood samples from 100 consecutive UCB patients treated with radical cystectomy (RC) were investigated for the presence (CellSearch system) of CTC and their HER2 expression status (immunohistochemistry). HER2 expression of the corresponding primary tumors and lymph node metastasis were analyzed using fluorescence in situ hybridization. INTERVENTION Blood samples were taken preoperatively. Patients underwent RC with lymphadenectomy. MEASUREMENTS Outcomes were assessed according to CTC status. HER2 expression of CTC was compared with that of the corresponding primary tumor and lymph node metastasis. RESULTS AND LIMITATIONS CTC were detected in 23 of 100 patients (23%) with nonmetastatic UCB (median: 1; range: 1-100). Presence, number, and HER2 status of CTC were not associated with clinicopathologic features. CTC-positive patients had significantly higher risks of disease recurrence and cancer-specific and overall mortality (p values: ≤ 0.001). After adjusting for effects of standard clinicopathologic features, CTC positivity remained an independent predictor for all end points (hazard ratios: 4.6, 5.2, and 3.5, respectively; p values ≤ 0.003). HER2 was strongly positive in CTC from 3 of 22 patients (14%). There was discordance between HER2 expression on CTC and HER2 gene amplification status of the primary tumors in 23% of cases but concordance between CTC, primary tumors, and lymph node metastases in all CTC-positive cases (100%). The study was limited by its sample size. CONCLUSIONS Preoperative CTC are already detectable in almost a quarter of patients with clinically nonmetastatic UCB treated with RC and were a powerful predictor of early disease recurrence and cancer-specific and overall mortality. Thus CTC may serve as an indication for multimodal therapy. Molecular characterization of CTC may serve as a liquid biopsy to guide individual targeted therapy in future clinical trials.

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.