SOCS2 correlates with malignancy and exerts growth-promoting effects in prostate cancer

Deregulation of cytokine and growth factor signaling due to an altered expression of endogenous regulators is well recognized in prostate cancer (PCa) and other cancers. Suppressor of cytokine signaling 2 (SOCS2) is a key regulator of the GH, IGF, and prolactin signaling pathways that have been implicated in carcinogenesis. In this study, we evaluated the expression patterns and functional significance of SOCS2 in PCa. Protein expression analysis employing tissue microarrays from two independent patient cohorts revealed a significantly enhanced expression in tumor tissue compared with benign tissue as well as association with Gleason score and disease progression. In vitro and in vivo assays uncovered the involvement of SOCS2 in the regulation of cell growth and apoptosis. Functionally, SOCS2 knockdown inhibited PCa cell proliferation and xenograft growth in a CAM assay. Decreased cell growth after SOCS2 downregulation was associated with cell-cycle arrest and apoptosis. In addition, we proved that SOCS2 expression is significantly elevated upon androgenic stimulation in androgen receptor (AR)-positive cell lines, providing a possible mechanistic explanation for high SOCS2 levels in PCa tissue. Consequently, SOCS2 expression correlated with AR expression in the malignant tissue of patients. On the whole, our study linked increased SOCS2 expression in PCa with a pro-proliferative role in vitro and in vivo.

Long-term follow up of renal anastomosing hemangioma mimicking renal angiosarcoma

Anastomosing hemangioma of the kidney is a very rare neoplasm, currently 19 cases have been reported in the literature. First described in 2009, histopathologically anastomosing hemangioma is similar to aggressive angiosarcoma. No long-term follow-up data of anastomosing hemangioma have been described yet. Here, we present the case of a healthy 56-year-old man diagnosed in 2002 with a 7 × 5-cm anastomosing hemangioma mimicking an aggressive renal angiosarcoma. The patient underwent nephrectomy and has been followed up disease free for 13 years.

IL6 sensitizes prostate cancer to the antiproliferative effect of IFNα2 through IRF9

Development and progression of prostate cancer (PCa) are associated with chronic inflammation. The cytokine interleukin 6 (IL6) can influence progression, differentiation, survival, and angiogenesis of PCa. To identify novel pathways that are triggered by IL6, we performed a gene expression profiling of two PCa cell lines, LNCaP and MDA PCa 2b, treated with 5 ng/ml IL6. Interferon (IFN) regulatory factor 9 (IRF9) was identified as one of the most prevalent IL6-regulated genes in both cell lines. IRF9 is a mediator of type I IFN signaling and acts together with STAT1 and 2 to activate transcription of IFN-responsive genes. The IL6 regulation of IRF9 was confirmed at mRNA and protein levels by quantitative real-time PCR and western blot respectively in both cell lines and could be blocked by the anti-IL6 antibody Siltuximab. Three PCa cell lines, PC3, Du-145, and LNCaP-IL6+, with an autocrine IL6 loop displayed high expression of IRF9. A tissue microarray with 36 PCa tissues showed that IRF9 protein expression is moderately elevated in malignant areas and positively correlates with the tissue expression of IL6. Downregulation and overexpression of IRF9 provided evidence for an IFN-independent role of IRF9 in cellular proliferation of different PCa cell lines. Furthermore, expression of IRF9 was essential to mediate the antiproliferative effects of IFNα2. We concluded that IL6 is an inducer of IRF9 expression in PCa and a sensitizer for the antiproliferative effects of IFNα2.

Stromal insulin-like growth factor binding protein 3 (IGFBP3) is elevated in the diseased human prostate and promotes ex vivo fibroblast-to-myofibroblast differentiation

Dysregulation of the IGF axis is implicated in the development of benign prostatic hyperplasia (BPH) and prostate cancer (PCa), 2 of the most common diseases affecting elderly males. PCa is the second leading cause of male-related cancer death in Western societies. Although distinct pathologies, BPH and PCa are both characterized by extensive stromal remodeling, in particular fibroblast-to-myofibroblast differentiation, thought to be induced by elevated local production of TGFβ1. We previously showed that TGFβ1-mediated fibroblast-to-myofibroblast differentiation of primary human prostatic stromal cells resulted in the dsyregulation of several components of the IGF axis, including the induction of IGF binding protein 3 (IGFBP3). Using isoform-specific lentiviral-mediated knockdown, we demonstrate herein that IGFBP3 is essential for TGFβ1-mediated differentiation. Although recombinant human IGFBP3 alone was not sufficient to induce differentiation, IGFBP3 synergistically potentiated TGFβ1-mediated stromal remodeling predominantly via an IGF-independent mechanism. Consistent with these in vitro findings, IGFBP3 immunohistochemistry revealed elevated levels of IGFBP3 in the hyperplastic fibromuscular stroma of BPH specimens and in the tumor-adjacent stroma of high-grade PCa. Collectively these data indicate that the dysregulation of the stromal IGF axis, in particular elevated IGFBP3, plays a crucial role in fibroblast-to-myofibroblast differentiation in the diseased prostatic stroma and indicate the therapeutic potential of inhibiting stromal remodeling and the resulting dysregulation of the stromal IGF axis as a novel strategy for the treatment of advanced PCa and BPH.

Enhanced inhibition of prostate tumor growth by dual targeting the androgen receptor and the regulatory subunit type iα of protein kinase a in vivo

Progression to castration resistance is a major problem in the treatment of advanced prostate cancer and is likely to be driven by activation of several molecular pathways, including androgen receptor (AR) and cyclic AMP-dependent protein kinase A (PKA). In this study, we examined the therapeutic efficacy of a combined inhibition of the AR and the regulatory subunit type Iα (RIα) of protein kinase A with second generation antisense oligonucleotides (ODNs) in androgen-sensitive LNCaP and castration-resistant LNCaPabl tumors in vivo. We found that targeting the AR alone inhibited LNCaP, as well as LNCaPabl tumors. Combined inhibition resulted in an improved response over single targeting and even a complete tumor remission in LNCaPabl. Western blot analysis revealed that both ODNs were effective in reducing their target proteins when administered alone or in combination. In addition, treatment with the ODNs was associated with an induction of apoptosis. Our data suggest that dual targeting of the AR and PKARIα is more effective in inhibiting LNCaP and LNCaPabl tumor growth than single treatment and may give a treatment benefit, especially in castration-resistant prostate cancers.

Unrecognized paraganglioma of the urinary bladder as a cause for basilar-type migraine

Extra-adrenal paraganglioma with isolated localization in the urinary bladder is a rare neuroendocrine tumor. Although the typical symptoms like headache, nausea, weight loss, flushing, heart palpitation or paroxysmal hypertension during micturition are well established, we present an unusual case of bladder paraganglioma, 'misdiagnosed' with basilar-type migraine due to headache for the past 8 years. As urologists linked the presence of a tumor (by CT) and symptoms connected with micturition, no cystoscopy and no transurethral resection of the bladder was performed prior to detailed diagnostic workup. After diagnosis of an extra-adrenal paraganglioma, the patient was scheduled for open partial cystectomy. In consideration of the fact that bladder paraganglioma is an infrequent genitourinary cancer, this case report clearly points out the importance of an exact anamnesis and clinical examination to minimize the probability of misdiagnosis with possible fatal consequences in any case with clinical suspicion of bladder paraganglioma.

Bcl-2 associated athanogene 5 (Bag5) is overexpressed in prostate cancer and inhibits ER-stress induced apoptosis

Background

The Bag (Bcl-2 associated athanogene) family of proteins consists of 6 members sharing a common, single-copied Bag domain through which they interact with the molecular chaperone Hsp70. Bag5 represents an exception in the Bag family since it consists of 5 Bag domains covering the whole protein. Bag proteins like Bag1 and Bag3 have been implicated in tumor growth and survival but it is not known whether Bag5 also exhibits this function.

Methods

Bag5 mRNA and protein expression levels were investigated in prostate cancer patient samples using real-time PCR and immunoblot analyses. In addition immunohistological studies were carried out to determine the expression of Bag5 in tissue arrays. Analysis of Bag5 gene expression was carried out using one-way ANOVA and Bonferroni’s Multiple Comparison test. The mean values of the Bag5 stained cells in the tissue array was analyzed by Mann-Whitney test. Functional studies of the role of Bag5 in prostate cancer cell lines was performed using overexpression and RNA interference analyses.

Results

Our results show that Bag5 is overexpressed in malignant prostate tissue compared to benign samples. In addition we could show that Bag5 levels are increased following endoplasmic reticulum (ER)-stress induction, and Bag5 relocates from the cytoplasm to the ER during this process. We also demonstrate that Bag5 interacts with the ER-resident chaperone GRP78/BiP and enhances its ATPase activity. Bag5 overexpression in 22Rv.1 prostate cancer cells inhibited ER-stress induced apoptosis in the unfolded protein response by suppressing PERK-eIF2-ATF4 activity while enhancing the IRE1-Xbp1 axis of this pathway. Cells expressing high levels of Bag5 showed reduced sensitivity to apoptosis induced by different agents while Bag5 downregulation resulted in increased stress-induced cell death.

Conclusions

We have therefore shown that Bag5 is overexpressed in prostate cancer and plays a role in ER-stress induced apoptosis. Furthermore we have identified GRP78/BiP as a novel interaction partner of Bag5.

Characterization of transcriptional changes in ERG rearrangement-positive prostate cancer identifies the regulation of metabolic sensors such as neuropeptide Y

ERG gene rearrangements are found in about one half of all prostate cancers. Functional analyses do not fully explain the selective pressure causing ERG rearrangement during the development of prostate cancer. To identify transcriptional changes in prostate cancer, including tumors with ERG gene rearrangements, we performed a meta-analysis on published gene expression data followed by validations on mRNA and protein levels as well as first functional investigations. Eight expression studies (n = 561) on human prostate tissues were included in the meta-analysis. Transcriptional changes between prostate cancer and non-cancerous prostate, as well as ERG rearrangement-positive (ERG+) and ERG rearrangement-negative (ERG−) prostate cancer, were analyzed. Detailed results can be accessed through an online database. We validated our meta-analysis using data from our own independent microarray study (n = 57). 84% and 49% (fold-change>2 and >1.5, respectively) of all transcriptional changes between ERG+ and ERG− prostate cancer determined by meta-analysis were verified in the validation study. Selected targets were confirmed by immunohistochemistry: NPY and PLA2G7 (up-regulated in ERG+ cancers), and AZGP1 and TFF3 (down-regulated in ERG+ cancers). First functional investigations for one of the most prominent ERG rearrangement-associated genes - neuropeptide Y (NPY) - revealed increased glucose uptake in vitro indicating the potential role of NPY in regulating cellular metabolism. In summary, we found robust population-independent transcriptional changes in prostate cancer and first signs of ERG rearrangements inducing metabolic changes in cancer cells by activating major metabolic signaling molecules like NPY. Our study indicates that metabolic changes possibly contribute to the selective pressure favoring ERG rearrangements in prostate cancer.

Potentials and limitations of real-time elastography for prostate cancer detection: a whole-mount step section analysis

Objectives. To evaluate prostate cancer (PCa) detection rates of real-time elastography (RTE) in dependence of tumor size, tumor volume, localization and histological type. Materials and Methods. Thirdy-nine patients with biopsy proven PCa underwent RTE before radical prostatectomy (RPE) to assess prostate tissue elasticity, and hard lesions were considered suspicious for PCa. After RPE, the prostates were prepared as whole-mount step sections and were compared with imaging findings for analyzing PCa detection rates. Results. RTE detected 6/62 cancer lesions with a maximum diameter of 0–5 mm (9.7%), 10/37 with a maximum diameter of 6–10 mm (27%), 24/34 with a maximum diameter of 11–20 20 mm (70.6%), 14/14 with a maximum diameter of >20 mm (100%) and 40/48 with a volume ≥0.2 cm³ (83.3%). Regarding cancer lesions with a volume ≥ 0.2 cm³ there was a significant difference in PCa detection rates between Gleason scores with predominant Gleason pattern 3 compared to those with predominant Gleason pattern 4 or 5 (75% versus 100%; P = 0.028). Conclusions. RTE is able to detect PCa of significant tumor volume and of predominant Gleason pattern 4 or 5 with high confidence, but is of limited value in the detection of small cancer lesions.

Adverse pathological findings in needle biopsy gleason score 6 prostate cancers with low and intermediate preoperative PSA levels following radical prostatectomy

AIM

We retrospectively analyzed the risk associated with undergrading Gleason score 6 (GS6) prostate cancer (PCa) at biopsy, in patients with preoperative PSA levels of 2-3,99 and 4-10 ng/ml.

PATIENTS AND METHODS

A total of 674 patients with needle biopsy-diagnosed GS6 PCa, who underwent radical prostatectomy (RP) between 1995 and 2011, were evaluated. Patients were stratified by preoperative PSA levels into low PSA (2-3,99 ng/ml) and an intermediate PSA of 4-10 ng/ml. Subsequently, the percentage of patients with extracapsular disease (pathological stage ≥pT3a) and/or positive surgical margins was determined among those whose RP GS was still 6 and compared to undergraded cases.

RESULTS

Out of 674 patients with needle biopsy-diagnosed GS6 PCa, 36.2% had no difference between biopsy and RP GS while 11.4% had been overgraded and 52.4% of patients were undergraded at biopsy. Stratified according to preoperative PSA levels, there was a significantly higher incidence of undergrading in the intermediate PSA group. Among those with ≥pT3a tumors, 74.1 % were undergraded in needle biopsy, out of which 67.7% had intermediate PSA levels and 32.3% low PSA levels. Among patients with R1 resections 75.1 % were underdiagnosed, out of which 75.9% had intermediate PSA levels. Stratifying these data according to preoperative PSA levels, ≥pT3a tumors and R1 resection were found significantly more often in the intermediate-PSA group.

CONCLUSION

The incidence of adverse pathological findings, including extraprostatic extension and positive surgical margins, is significantly higher in patients with undergraded biopsy GS6. Low preoperative PSA levels improved the correlation between primary and final GS and led to the reduction of unfavorable pathological findings.

Epithelial-to-mesenchymal transition leads to docetaxel resistance in prostate cancer and is mediated by reduced expression of miR-200c and miR-205

Docetaxel is a standard chemotherapy for patients with metastatic prostate cancer. However, the response is rather limited and not all of the patients benefit from this treatment. To uncover key mechanisms of docetaxel insensitivity in prostate cancer, we have established docetaxel-resistant sublines. In this study, we report that docetaxel-resistant cells underwent an epithelial-to-mesenchymal transition during the selection process, leading to diminished E-cadherin levels and up-regulation of mesenchymal markers. Screening for key regulators of an epithelial phenotype revealed a significantly reduced expression of microRNA (miR)-200c and miR-205 in docetaxel-resistant cells. Transfection of either microRNA (miRNA) resulted in re-expression of E-cadherin. Functional assays confirmed reduced adhesive and increased invasive and migratory abilities. Furthermore, we detected an increased subpopulation with stem cell-like properties in resistant cells. Tissue microarray analysis revealed a reduced E-cadherin expression in tumors after neoadjuvant chemotherapy. Low E-cadherin levels could be linked to tumor relapse. The present study uncovers epithelial-to-mesenchymal transition as a hallmark of docetaxel resistance. Therefore, we suggest that this mechanism is at least in part responsible for chemotherapy failure, with implications for the development of novel therapeutics.

Real-time sonoelastography for the evaluation of testicular lesions

PURPOSE

To evaluate the feasibility of using real-time sonoelastography (RTE) for the differentiation and characterization of testicular lesions.

MATERIALS AND METHODS

Institutional review board approval was obtained for this retrospective study, and the requirement to obtain informed consent was waived. Fifty patients (mean age, 42 years; age range, 18-81 years) with testicular lesions detected with gray-scale ultrasonography (US) and color and/or power Doppler US were evaluated with RTE between December 2004 and August 2010 to assess tissue elasticity of the testes. Stiff or "hard" lesions were suspected of being malignant. Testicular lesions with normal or decreased tissue stiffness ("soft" lesions) were considered benign. Findings from surgery and histopathologic examination were used as the reference standard in 34 cases, and findings from clinical and US follow-up were used as the reference standard in 16 cases. Sensitivity, specificity, negative predictive value, positive predictive value, and diagnostic accuracy were calculated.

RESULTS

Thirty-four of the 50 lesions (68%) were testicular tumors and 16 (32%) were of nontumorous origin. RTE showed the presence of hard lesions in all cases of testicular tumors and three cases of nontumorous lesions. Four lesions with an uncertain diagnosis when tested with gray-scale US and color and/or power Doppler US alone were soft at RTE and showed nontumorous character at follow-up. RTE showed a sensitivity of 100%, a specificity of 81%, a negative predictive value of 100%, a positive predictive value of 92%, and an accuracy of 94% in the diagnosis of testicular tumors.

CONCLUSION

RTE demonstrated all testicular tumors as lesions with increased tissue stiffness. Because of its higher specificity, RTE can provide additional information in cases with indeterminate US findings.

Abstract A38: Maternal embryonic leucine zipper kinase (MELK) is upregulated in high-grade prostate cancer

Loss of cell cycle control is a prerequisite for cancer onset and progression. In prostate cancer, increased activity of cell cycle proliferating genes has been associated with prognostic parameters such as biochemical relapse and survival. The identification of novel oncogenic and druggable targets in patient subgroups with poor prognosis may help to develop targeted therapy approaches.

We analyzed prostate cancer and corresponding benign tissues (n = 98) using microarrays. The comparison of high and low grade tumors (Gleason score ≥ 4+3 vs. ≤ 3+4) revealed 144 differentially expressed genes (p < 0.05), which are associated with a severe disease course. Out of these, 15 genes are assigned to cell cycle process. The gene maternal embryonic leucine zipper kinase (MELK) was identified to be highly correlated with cell cycle and prostate cancer associated genes like UBE2C, TOP2A, CCNB2 and AURKB, and was therefore further included into validation and functional experiments. The association between MELK gene expression and high-risk prostate cancer was validated in an independent patient cohort (p < 0.005, n = 79). Furthermore, our finding was supported by a public microarray dataset showing a higher MELK expression in prostate cancer patients with biochemical relapse. Immunohistochemical analysis using a tissue microarray (n = 94) revealed increased MELK protein expression in prostate cancer tissues of high Gleason scores. Knockdown of MELK decreased cell viability in PC3 and LNCaP cells. Microarray analysis upon MELK knockdown experiments revealed downstream processes like chromatin modification, embryonic development and cell migration. Our findings indicate that the protein serine/threonine kinase MELK represents a promising marker for advanced prostate cancer disease.

Citation Format: Ruprecht Kuner, Holger Sültmann, Maria Fälth, Nicole Chui Pressinotti, Jan Christoph Brase, Sabrina Balaguer-Puig, Georg Schäfer, Georg Bartsch, Eberhard Steiner, Helmut Klocker. Maternal embryonic leucine zipper kinase (MELK) is upregulated in highgrade prostate cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr A38.

Abstract A26: Changes in gene expression in ERG-rearrangement positive prostate cancer are related to signaling, adhesion, and defense response

Since 2005 we know that around 50% of all prostate cancers harbor a genetic gene rearrangement. This gene rearrangement is formed by fusion of 5′ regulatory elements of an androgen-regulated gene to the coding region of a member of the E twenty-six (ETS) gene family of transcription factors. The major ETS transcription factor involved in the genetic rearrangement is the erythroblastosis virus E26 oncogene homolog gene (ERG). So far little is known about the cellular changes following ERG-rearrangement in prostate cancer.

We performed a meta-analysis on published gene expression data to identify ERG-rearrangement associated changes in gene expression. Six independent studies investigating 252 prostate cancer tissues were implemented in our analysis. ERG-rearrangement results in ERG overexpression. No information was available on the ERG-rearrangement status of the meta-analysis samples; thus we grouped the samples according to their ERG expression status. The comparative meta-analysis revealed 109 up-regulated and 58 down-regulated genes (fold-change >1.5; corrected p-value <0.1) in ERG-overexpressing compared to non ERG-overexpressing prostate cancers. The differentially regulated genes were related to the functional clusters signaling (extracellular signaling peptides and hormone signaling); adhesion (cell adhesion and extracellular matrix proteins) and defense response (wound healing and inflammatory response).

For meta-analysis validation we used data from an independent expression study performed on 57 prostate cancer tissues from the Innsbruck Prostate Cancer Biobank (independent patient cohort). In this study the ERG-rearrangement status was analyzed by fluorescent in situ hybridization. 76.6% of all genes found to be differentially regulated between ERG-rearrangement positive and ERG-rearrangement negative prostate cancers in the meta-analysis were verified in the validation study. The good overlap between the meta-analysis and the validation study demonstrates that our meta-analysis generated very stable results, which were independent of sample cohort, sample assignment and gene expression technology.

In summary we characterized changes in gene expression in ERG-rearrangement positive prostate cancer using published gene expression data. These data give new insights into the biology of prostate cancer. Furthermore our study demonstrates that published gene expression data are, beyond their initial scope, of great value to investigate new research questions.

Citation Format: Petra Massoner, Karl Kugler, Helmut Klocker, Georg Schäfer, Laurin Müller, Huajie Bu, Ruprecht Kuner, Maria Faelth, Holger Sültmann, Mark A. Rubin, Armin Graber. Changes in gene expression in ERG-rearrangement positive prostate cancer are related to signaling, adhesion, and defense response [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr A26.

Lamin A/C protein is overexpressed in tissue-invading prostate cancer and promotes prostate cancer cell growth, migration and invasion through the PI3K/AKT/PTEN pathway

Prostate cancer (PC) remains the second most common cause of cancer-related death in Western countries. A previous proteomics study suggested that the nuclear membrane protein lamin A/C to be a maker to discriminate low- and high-Gleason score tumors and to identify high-risk cancers. To characterize its function in PC cells, we performed a detailed expression analysis in PC tissue and explored the consequences of down or upregulation of lamin A/C in PC cells. Our results confirm an increased lamin A/C protein expression in high-risk cancers and show association of expression with tumor cell formations at the invasion fronts of tumors and in invasion 'spearheading' tumor cell clusters. In the prostate tumor cell lines, LNCaP, DU145, and PC3 small hairpin RNA knockdown or overexpression of lamin A/C resulted in inhibition or stimulation, respectively, of cell growth, colony formation, migration and invasion. Further mechanism studies suggested that the lamin A/C-related malignant behavior is regulated through modulation of the phosphoinositide 3-kinase (PI3K)/AKT/PTEN signaling pathway. Western blot results indicated that knockdown or overexpression of lamin A/C decreased or increased, respectively, protein levels of the PI3K subunits p110 and p85 in all three cell lines; phosphor-AKT in the PTEN-negative cell lines LNCaP and PC3, and, increased or decreased, respectively, PTEN protein levels in PTEN-positive DU145 cells. Together, our data suggest that lamin A/C proteins are positively involved in malignant behavior of PC cells through the PI3K/AKT/PTEN pathway. Lamin A/C may represent a new oncogenic factor and a novel therapeutic target for PC.

Expression of the IGF axis is decreased in local prostate cancer but enhanced after benign prostate epithelial differentiation and TGF-β treatment

The insulin-like growth factor (IGF) axis is a molecular pathway intensively investigated in cancer research. Clinical trials targeting the IGF1 receptor (IGF1R) in different tumors, including prostate cancer, are under way. Although studies on the IGF axis in prostate cancer have already entered into clinical trials, the expression and functional role of the IGF axis in benign prostate and in prostate cancer needs to be better defined. We determined mRNA expression levels of the IGF axis in microdissected tissue specimens of local prostate cancer using quantitative PCR. All members of the IGF axis, including IGF1, IGF2, IGF binding proteins 1 through 6, and insulin receptor, were measured in both the stromal and epithelial compartments of the prostate. IGF1, IGF2, IGF1R, and insulin receptor were down-regulated in local prostate cancer tissue compared with matched benign tissue, suggesting that the IGF axis is not induced during prostate cancer development. Using a new prostate epithelial differentiation model, we demonstrate that the expression of the IGF axis is enhanced during normal prostate epithelial differentiation and regulated by tumor growth factor (TGF)-β. Our data reveal a functional role of the IGF axis in prostate differentiation, underscoring the importance of the IGF axis in normal development and emphasizing the importance of accurate target validation before moving to advanced clinical trials.

Comparison of real-time sonoelastography with T2-weighted endorectal magnetic resonance imaging for prostate cancer detection

OBJECTIVES

The purpose of this study was to compare the value of real-time sonoelastography with T2-weighted endorectal magnetic resonance imaging (MRI) for prostate cancer detection.

METHODS

Thirty-three patients with an elevated prostate-specific antigen level were investigated with real-time sonoelastography and T2-weighted endorectal MRI for prostate cancer diagnosis before systematic prostate biopsy. Real-time sonoelastography was performed to assess prostate tissue elasticity, and hard areas were considered suspicious for prostate cancer. Low-signal intensity nodules on T2-weighted endorectal MRI were considered suspicious for prostate cancer. Imaging findings were assigned to 6 areas of the peripheral zone (sextants), and their cancer detection rates were compared.

RESULTS

Overall, prostate cancer was detected in 13 of 33 patients (39.4%). Both real-time sonoelastography and T2-weighted endorectal MRI detected 11 cancer-positive patients (84.6%). Real-time sonoelastography showed 27 suspicious lesions in 198 sextants, and 15 (55.6%) were cancer positive. T2-weighted endorectal MRI showed 31 suspicious lesions in 198 sextants, and 13 (40.6%) were cancer positive. These findings resulted in sensitivity rates and negative predictive values per patient of 84.6% and 86.7%, respectively, for sonoelastography and 84.6% and 83.3% for MRI. The per-sextant analysis showed sensitivity rates and negative predictive values of 57.7% and 93.6% for sonoelastography and 50.0% and 92.2% for MRI.

CONCLUSIONS

Real-time sonoelastography showed comparable results as T2-weighted endorectal MRI for prostate cancer detection.

The anterior gradient 2 (AGR2) gene is overexpressed in prostate cancer and may be useful as a urine sediment marker for prostate cancer detection

BACKGROUND

AGR2 is a member of the endoplasmatic reticulum protein disulphide isomerase gene family implicated in tumor metastasis. Its expression pattern, function, and utility as a marker remains to be further investigated.

METHODS

Using real-time RT-PCR and immunohistochemistry, changes of expression in different tumor stages were explored in microdissected tumor samples. AGR2 transcript level in urine sediments was scrutinized for suitability as a tumor marker. AGR2 androgen regulation and function were analyzed in cellular prostate cancer models.

RESULTS

AGR2 is highly expressed in prostate cancer compared to benign tissue in particular also in low-grade tumors and PIN lesions. AGR2 transcripts were detected in urine sediments of patients undergoing prostate biopsy with significantly higher levels in tumor patients. The urine AGR2/PSA transcript ratio allowed much better discrimination between cancer and benign patients than serum total PSA or %freePSA. Prostate tumor cells express and secrete variable amounts of AGR2 protein, the highest level was found in PC3 cells. In androgen receptor-positive cell lines AGR2 is upregulated by androgens. Increased expression enhanced the migratory and invasive potential but decreased growth and proliferation in vitro and in vivo.

CONCLUSION

AGR2 enhances the invasion phenotype of prostate cancer cells while at the same time attenuating cell-cycle progression. This function, its expression pattern and the increased level of AGR transcripts in urine sediments of prostate cancer patients call for further exploration as a prostate cancer marker and a modulator of tumor growth and invasion.

Somatic mutations throughout the entire mitochondrial genome are associated with elevated PSA levels in prostate cancer patients

The genetic etiology of prostate cancer, the most common form of male cancer in western countries, is complex and the interplay of disease genes with environmental factors is far from being understood. Studies on somatic mitochondrial DNA (mtDNA) mutations have become an important aspect of cancer research because these mutations might have functional consequences and/or might serve as biosensors for tumor detection and progression. We sequenced the entire mitochondrial genome (16,569 bp) from 30 prospectively collected pairs of macrodissected cancerous and benign cells from prostate cancer patients and compared their genetic variability. Given recent concerns regarding the authenticity of newly discovered mtDNA mutations, we implemented a high-quality procedure for mtDNA whole-genome sequencing. In addition, the mitochondrial genes MT-CO2, MT-CO3, MT-ATP6, and MT-ND6 were sequenced in further 35 paired samples from prostate cancer patients. We identified a total of 41 somatic mutations in 22 out of 30 patients: the majority of these mutations have not previously been observed in the human phylogeny. The presence of somatic mutations in transfer RNAs (tRNAs) was found to be associated with elevated PSA levels (14.25 ± 5.44 versus 7.15 ± 4.32 ng/ml; p = 0.004). The level and degree of heteroplasmy increased with increasing tumor activity. In summary, somatic mutations in the mitochondrial genome are frequent events in prostate cancer. Mutations mapping to mitochondrial tRNAs, ribosomal RNAs, and protein coding genes might impair processes that occur within the mitochondrial compartment (e.g., transcription, RNA processing, and translation) and might finally affect oxidative phosphorylation.

Proteomics profiling of microdissected low- and high-grade prostate tumors identifies Lamin A as a discriminatory biomarker

Proteomics screening methods for the identification of diagnostic and prognostic biomarkers in cancer are still lagging behind DNA- or RNA-based analysis. We used two-dimensional differential gel electrophoresis (2D-DIGE) in combination with laser capture microdissection (LCM) and MALDI-TOF/TOF mass spectrometry to determine differentially abundant proteins and candidate biomarkers in prostate cancer. Paired (benign and tumor) samples were isolated from 23 Gleason Score 6 (GS 6) and 23 Gleason Score 8 and higher (GS 8+) radical prostatectomy specimens and subjected to 2D-DIGE analysis. Minimal fluorescent dye labeling was applied and electrophoresis performed with triple samples (paired benign and tumor; internal control) for each case of tumor. Nineteen differently abundant proteins were identified by mass spectrometry and further validated. One half of them were associated with glycolysis and the Warburg effect; these were upregulated in tumors. The upregulation correlated with tumor dedifferentiation and might be relevant for selection of therapeutic strategies. Among the other proteins, heat shock protein 60 (HSP60) was significantly upregulated in tumor tissue compared to its benign counterpart. Furthermore, lamin A was statistically highly discriminatory between low and high Gleason score tumors and might serve as a new biomarker of tumor differentiation and prognosis.