Expression In Prostate Cancer Tissues Research Articles

MiR-34a inhibits cell proliferation in prostate cancer by downregulation of SIRT1 expression.

MicroRNA-34a (miR-34a) functions as a tumor suppressor gene and inhibits abnormal cell growth by regulating the expression of other genes. The role of miR-34a in regulating sirtuin 1 (SIRT1) in prostate cancer remains unclear. The objective of the present study was to investigate the biological function and molecular mechanisms of miR-34a regulation of SIRT1 in human prostate cancer samples and the human prostate cancer cell line, PC-3. Fresh prostate tissues were obtained from patients, and the miR-34a expression in prostate cancer tissues was measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). qPCR and western blotting were performed to assess the effects of miR-34a overexpression on SIRT1 regulation in PC-3 cells, and the cell growth was assessed by Cell Counting Kit-8 (CCK-8). Flow cytometry was used to assess the cell cycle status of the cells. The miR-34a expression levels in prostate cancer tissues were significantly reduced compared with adjacent normal prostate tissues (P<0.05). SIRT1 expression levels in PC-3 cells with over-expression of miR-34a were significantly reduced compared with those in the negative control (P<0.05). The over-expression of miR-34a inhibited PC-3 cells growth and resulted in increased cell cycle arrest compared with the negative control (P<0.05). In conclusion, miR-34a inhibits the human prostate cancer cell proliferation, in part, through the downregulation of SIRT1 expression.

PIAS1 is a determinant of poor survival and acts as a positive feedback regulator of AR signaling through enhanced AR stabilization in prostate cancer.

Novel drugs like Abiraterone or Enzalutamide, which target androgen receptor (AR) signaling to improve androgen deprivation therapy (ADT), have been developed during the past years. However, the application of these drugs is limited because of occurrence of inherent or acquired therapy resistances during the treatment. Thus, identification of new molecular targets is urgently required to improve current therapeutic prostate cancer (PCa) treatment strategies. PIAS1 (protein inhibitor of activated STAT1 (signal transducer and activator of transcription-1)) is known to be an important cell cycle regulator and PIAS1-mediated SUMOylation is essential for DNA repair. In this context, elevated PIAS1 expression has already been associated with cancer initiation. Thus, in the present study, we addressed the question of whether PIAS1 targeting can be used as a basis for an improved PCa therapy in combination with anti-androgens. We show that PIAS1 significantly correlates with AR expression in PCa tissue and in cell lines and demonstrate that high PIAS1 levels predict shorter relapse-free survival. Our patient data are complemented by mechanistic and functional in vitro experiments that identify PIAS1 as an androgen-responsive gene and a crucial factor for AR signaling via prevention of AR degradation. Furthermore, PIAS1 knockdown is sufficient to decrease cell proliferation as well as cell viability. Strikingly, Abiraterone or Enzalutamide treatment in combination with PIAS1 depletion is even more effective than single-drug treatment in multiple PCa cell models, rendering PIAS1 as a promising target protein for a combined treatment approach to improve future PCa therapies.

Survivin mRNA-circulating tumor cells are associated with prostate cancer metastasis.

Detection of circulating tumor cells (CTCs) has been made to develop reliable assays for early diagnosis of various cancers. Overexpression of survivin in cancer cells is strongly associated with tumor progression. Although upregulation of survivin is observed in various tumors, its expression profile in the peripheral blood of prostate cancer (PCa) patients has not yet been investigated. In this study, we validated the application of survivin as the tumor marker to detect CTC and assessed its utility for diagnosis of PCa distant metastasis. Immunohistochemistry and quantitative real-time PCR (QRT-PCR) were performed to confirm the levels of surviving expression in PCa tissues. In addition, CTC values in 3mL of peripheral blood from PCa patients, benign prostate hyperplasia (BPH) patients, and normal controls were also measured by the survivin-targeted PCR. Our results showed that surviving was overexpressed in PCa tissues. The median levels of blood surviving mRNA of PCa patients, BPH patients, and normal controls were 5.67 (range from 0 to 12.46), 2.24 (range from 0 to 6.55), and 1.85 (range from 0 to 3.82), respectively. The levels of survivin are positively associated with PCa distant metastasis. Our results concluded that quantitation of CTCs through survivin-PCR could be a promising marker for diagnosis of PCa metastasis.

Abstract 3: Mechanistic rationale for MCL1 inhibition during androgen deprivation therapy

Abstract The cellular consequences of androgen deprivation therapy (ADT), a first-line therapy for locally advanced and metastatic prostate cancer (PCa), are induction of apoptosis or G1 cell cycle arrest. Inability of PCa cells to induce apoptosis is the starting point of development of castration resistance. Hence, an improved therapy should target the cell cycle-arrested cells in a combinatorial approach together with currently applied ADT. Here we set out to analyze whether MCL1, a pro-survival member of the BCL2 family and known mediator of chemotherapy resistance regulates the cellular response to androgen withdrawal. Analysis of MCL1 protein and mRNA expression in PCa tissue and primary cell culture specimens of luminal and basal origin, respectively, reveals higher expression in cancerous tissue compared to benign origin. Using PCa cellular models in vitro and in vivo we show that MCL1 expression is regulated through the action of androgens and upregulated in androgen-sensitive PCa cells when grown under steroid-deprived conditions. Analysis of the underlying mechanism suggests that regulation of MCL1 through the AR signaling axis is indirectly mediated via a cell cycle-dependent mechanism. Using constructs downregulating or overexpressing MCL1 we demonstrate that expression of MCL1 prevents induction of apoptosis when androgen-sensitive PCa cells are grown under steroid-deprived conditions. The BH3-mimetic Obatoclax induces apoptosis and decreases MCL1 expression in androgen-sensitive PCa cells, while castration-resistant PCa cells are less sensitive and react with an upregulation of MCL1 expression. Synergistic effects of Obatoclax with androgen receptor inactivation can be observed in androgen-sensitive cells. In addition, Obatoclax efficiently inhibits clonogenicity of primary basal PCa cells. Altogether, our results suggest that MCL1 is a key molecule deciding over the fate of PCa cells upon inactivation of androgen receptor signaling and provide a mechanistic rationale for a clinical assessment of a MCL1-targeting therapy adjuvant to ADT. Citation Format: Frédéric R. Santer, Holger H.H. Erb, Su Jung Oh, Florian Handle, Gertrud E. Feiersinger, Birgit Luef, Huajie Bu, Georg Schäfer, Christian Ploner, Martina Egger, Jayant K. Rane, Norman J. Maitland, Helmut Klocker, Iris E. Eder, Zoran Culig. Mechanistic rationale for MCL1 inhibition during androgen deprivation therapy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3. doi:10.1158/1538-7445.AM2015-3

Upregulation of Serine/arginine- rich splicing factor 1 is correlated with prostate caner progression and prognosis

Objective Serine/arginine- rich splicing factor 1(ASF/SF2, also known as SRSF1)is an oncogenic splicing factor in various malignancies.The aim of this study is to investigate the expression of ASF/SF2,and its clinicalpathological significance in prostate cancer(PCa). Methods Immunohistochmistry was conducted to analyze the expression of ASF/SF2 in 103 PCa samples and 20 benign prostate samples.The associations of ASF/SF2 expression with clinicopathological features and prognosis in PCa patients were analyzed by various statistical methods,such as chi- square test, Kaplan- Meier method and Log- rank test. Re-sults The positive rate of ASF/SF2 was 51.0%(52/102)in prostate cancer group, and 20.0%(5/20)in benign group(P< 0.05).In addition, ASF/SF2 expression in PCa tissues was significantly associated with pathological stage(P<0.05).Moreover, Kaplan- Meier survival analysis showed that the higher expression of ASF/SF2 was correlated with shorter biochemical recurrence- free survival(P<0.05).The multivariate analysis revealed that ASF/SF2 was an independent prognostic predictor for biochemical recurrence- free survival in patients with PCa(Hazard ratio= 2.943,P<0.05). Conclusion Our study demonstrates the overexpression of ASF/SF2 is associated with PCa progression,and it may serve as potential therapeutic target.Further study is needed to identify the potential link between ASF/SF2 and mammalian target of rapamycin (mTOR)pathway in PCa. Key words: Prostate cancer; Serine/arginine- rich splicing factor 1; Recurrence

MP66-19 REDUCED AUTOPHAGY LEVELS ARE ASSOCIATED WITH A HIGHER GLEASON SCORE, TUMOR STAGE AND AN INCREASED RATE OF PROSTATE CANCER SPECIFIC DEATH

You have accessJournal of UrologyProstate Cancer: Basic Research V1 Apr 2015MP66-19 REDUCED AUTOPHAGY LEVELS ARE ASSOCIATED WITH A HIGHER GLEASON SCORE, TUMOR STAGE AND AN INCREASED RATE OF PROSTATE CANCER SPECIFIC DEATH Ashkan Mortezavi, Souzan Salemi, Niels Rupp, Thomas Hermanns, Tullio Sulser, Peter J. Wild, and Daniel Eberli Ashkan MortezaviAshkan Mortezavi More articles by this author , Souzan SalemiSouzan Salemi More articles by this author , Niels RuppNiels Rupp More articles by this author , Thomas HermannsThomas Hermanns More articles by this author , Tullio SulserTullio Sulser More articles by this author , Peter J. WildPeter J. Wild More articles by this author , and Daniel EberliDaniel Eberli More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.2372AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Autophagy is a catabolic cellular process used for degradation of cytoplasmic organelles and preservation of cell viability. Data regarding the role of autophagy in treatment naive prostate cancer (PCa) is sparse. Therefore we aimed to analyze the level of autophagy in benign and malignant prostate tissue and to evaluate the prognostic properties for patients with PCa. METHODS A Tissue microarray containing 479 formalin-fixed, paraffin-embedded prostate tissue cores was stained immunohistochemically for major autophagy proteins ATG5, Beclin1 and LC3b: 41 normal prostate tissues, 382 primary adenocarcinomas (ADC) and 56 prostate cancer metastases or castration resistant prostate cancers. Immunoreactivity was semiquantitatively scored and correlated with pathologic and clinical parameters including survival. RESULTS LC3b expression was significantly upregulated in PCa, especially in metastatic and castration-resistant prostate cancer samples compared to normal prostate tissue (p=0.002). Evaluation of expression in ADCs revealed an inverse association with preoperative serum PSA level (p=0.047), pT-stage (0.033) and Gleason Score (p=0.026). Negative LC3b expression was identified as a novel predictor of prostate cancer specific death after radical prostatectomy (p=0.02). A significant association of ATG-5 and Beclin1 with LC3b expression could be noticed, but no link with clincopathologic parameters. CONCLUSIONS A lower LC3b expression in prostate cancer tissue is significantly associated with a higher rate of prostate cancer specific death. Furthermore, there is a significant association of a lower expression in tumors with extraprostatic extension and higher Gleason Scores. This is the first report evaluating autophagy expression levels and their association with the clinical course in prostate cancer patients. © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e823 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ashkan Mortezavi More articles by this author Souzan Salemi More articles by this author Niels Rupp More articles by this author Thomas Hermanns More articles by this author Tullio Sulser More articles by this author Peter J. Wild More articles by this author Daniel Eberli More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

173 Reduced autophagy levels are associated with a higher Gleason score, tumour stage and an increased rate of prostate cancer specific death

INTRODUCTION AND OBJECTIVES: Autophagy is a catabolic cellular process used for degradation of cytoplasmic organelles and preservation of cell viability. Data regarding the role of autophagy in treatment naive prostate cancer (PCa) is sparse. Therefore we aimed to analyze the level of autophagy in benign and malignant prostate tissue and to evaluate the prognostic properties for patients with PCa. METHODS: A Tissue microarray containing 479 formalin-fixed, paraffin-embedded prostate tissue cores was stained immunohistochemically for major autophagy proteins ATG5, Beclin1 and LC3b: 41 normal prostate tissues, 382 primary adenocarcinomas (ADC) and 56 prostate cancer metastases or castration resistant prostate cancers. Immunoreactivity was semiquantitatively scored and correlated with pathologic and clinical parameters including survival. RESULTS: LC3b expression was significantly upregulated in PCa, especially in metastatic and castration-resistant prostate cancer samples compared to normal prostate tissue (p1⁄40.002). Evaluation of expression in ADCs revealed an inverse association with preoperative serum PSA level (p1⁄40.047), pT-stage (0.033) and Gleason Score (p1⁄40.026). Negative LC3b expression was identified as a novel predictor of prostate cancer specific death after radical prostatectomy (p1⁄40.02). A significant association of ATG-5 and Beclin1 with LC3b expression could be noticed, but no link with clincopathologic parameters. CONCLUSIONS: A lower LC3b expression in prostate cancer tissue is significantly associated with a higher rate of prostate cancer specific death. Furthermore, there is a significant association of a lower expression in tumors with extraprostatic extension and higher Gleason Scores. This is the first report evaluating autophagy expression levels and their association with the clinical course in prostate cancer patients.

Mechanistic rationale for MCL1 inhibition during androgen deprivation therapy.

Androgen deprivation therapy induces apoptosis or cell cycle arrest in prostate cancer (PCa) cells. Here we set out to analyze whether MCL1, a known mediator of chemotherapy resistance regulates the cellular response to androgen withdrawal. Analysis of MCL1 protein and mRNA expression in PCa tissue and primary cell culture specimens of luminal and basal origin, respectively, reveals higher expression in cancerous tissue compared to benign origin. Using PCa cellular models in vitro and in vivo we show that MCL1 expression is upregulated in androgen-deprived PCa cells. Regulation of MCL1 through the AR signaling axis is indirectly mediated via a cell cycle-dependent mechanism. Using constructs downregulating or overexpressing MCL1 we demonstrate that expression of MCL1 prevents induction of apoptosis when PCa cells are grown under steroid-deprived conditions. The BH3-mimetic Obatoclax induces apoptosis and decreases MCL1 expression in androgen-sensitive PCa cells, while castration-resistant PCa cells are less sensitive and react with an upregulation of MCL1 expression. Synergistic effects of Obatoclax with androgen receptor inactivation can be observed. Moreover, clonogenicity of primary basal PCa cells is efficiently inhibited by Obatoclax. Altogether, our results suggest that MCL1 is a key molecule deciding over the fate of PCa cells upon inactivation of androgen receptor signaling.

CtBP2 overexpression is associated with tumorigenesis and poor clinical outcome of prostate cancer.

IntroductionThe aim of the study was to evaluate the expression of CtBP2 in prostate cancer and to determine its relationship with clinicopathologic parameters.Material and methodsThe expression of CtBP2 in 119 prostate cancer tissues and 41 normal tissues was examined by qPCR and Western blot analysis, and the results were correlated with clinicopathologic parameters.ResultsCtBP2 expression in prostate cancer tissues was higher than that in normal samples. CtBP2 overexpression was closely correlated with serum prostatic specific antigen (PSA) (p = 0.018), advanced tumor stage (T3) (p = 0.025), higher Gleason scores (p = 0.019), positive extraprostatic extension (p = 0.012), positive vascular invasion (p = 0.011) and perineural invasion (p = 0.035). However, no significant association was found between CtBP2 abnormal expression and other parameters, including age (p = 0.776), positive lymph node (p = 0.872) and positive surgical margin (p = 0.37). Moreover, CtBP2 overexpression was significantly associated with poor clinical outcome of prostate cancer (p = 0.0168).ConclusionsCtBP2 is overexpressed in prostate cancer, and its increased expression is closely associated with tumor progression and the outcome of prostate cancer.

Expression and significance of S100P, CD147, and OCT4 in different prostate cancer tissue TNM stages.

The aim of this project was to investigate the expression and significance of S100P, CD147, and OCT4 in prostate cancer tissue at different TNM stages. We enrolled 54 patients with prostate cancer, 40 with benign prostatic hyperplasia, and 20 subjects with normal prostates. S100P, CD147, and OCT4 were detected by immunohistochemistry. The positive rate of S100P detection was 18.52% in prostate cancer tissues, significantly lower than in normal and benign prostate hyperplasia tissues (P ˂ 0.05). The positive expression rate of CD147 and OCT4 were 100 and 77.38% in prostate cancer tissue, respectively, both markedly higher than in normal and benign prostate hyperplasia tissue (P ˂ 0.05). The positive rate of S100P in stage V was 0, which was significantly lower than in stages I (37.50%) and II (35.71%) (P ˂ 0.05). OCT4 expression in stages III (86.67%) and V (94.12%) was higher than in stage I (37.50%). The positive rate of S100P in patients with distant metastasis was 4%, which was significantly lower than that in patients without metastases (P ˂ 0.05). In contrast, the positive rate of OCT4 in patients with distant metastasis was 92%. S100P, CD147, and OCT4 expression in prostate cancer patients with different degrees of differentiation had no significant difference (P > 0.05). Overall, our results demonstrated that S100P expression in prostate cancer tissue was significantly decreased, whereas CD147 and OCT4 expression was increased. Their expression levels were closely associated with TNM stage and distant metastasis, but were not related to the degree of differentiation.

Urinary miR-183 and miR-205 do not surpass PCA3 in urine as predictive markers for prostate biopsy outcome despite their highly dysregulated expression in prostate cancer tissue.

MicroRNAs (miRNAs) have shown to be promising novel biomarkers in various cancers. We aimed to translate the results of an own previous tissue-based miRNA profile of prostate carcinoma (PCa) with upregulated miR-183 and downregulated miR-205 into a urine-based testing procedure for diagnosis of PCa. Urine sediments were prepared from urine samples collected after a standardized digital-rectal examination (DRE) of patients undergoing prostate biopsy with PSA (prostate-specific antigen) values <20 μg/L in consecutive order. According to the sample-size calculation (α=0.05, power=0.95), 38 patients each with PCa and without PCa were randomly enrolled in this study. PCA3 (prostate cancer associated 3) in urine as Food and Drug Administration-approved assay was determined as reference standard for comparison. The miRNAs were measured by RT-qPCR using TaqMan assays and normalized using different approaches. Both miRNAs were correlated to the mRNA PSA concentrations in the sediments indicating a relationship to the released prostate cells after DRE. However, they had no discriminating capacity between patients with and without PCa. In contrast, PCA3 clearly differentiated between these two patients groups. There was also no significant correlation between miRNAs and standard clinicopathologic variables like Gleason score and serum PSA. The data of our study show that miR-183 and miR-205 failed to detect early and aggressive PCa despite their highly dysregulated expression in cancer tissue. Our results and the critical evaluation of the few data of other studies raise serious doubts concerning the capability of urinary miRNAs to replace or improve PCA3 as predictive marker for prostate biopsy outcome.

Identification of prostate cancer LncRNAs by RNA-Seq.

To identify prostate cancer lncRNAs using a pipeline proposed in this study, which is applicable for the identification of lncRNAs that are differentially expressed in prostate cancer tissues but have a negligible potential to encode proteins. We used two publicly available RNA-Seq datasets from normal prostate tissue and prostate cancer. Putative lncRNAs were predicted using the biological technology, then specific lncRNAs of prostate cancer were found by differential expression analysis and co-expression network was constructed by the weighted gene co-expression network analysis. A total of 1,080 lncRNA transcripts were obtained in the RNA-Seq datasets. Three genes (PCA3, C20orf166-AS1 and RP11-267A15.1) showed a significant differential expression in the prostate cancer tissues, and were thus identified as prostate cancer specific lncRNAs. Brown and black modules had significant negative and positive correlations with prostate cancer, respectively. The pipeline proposed in this study is useful for the prediction of prostate cancer specific lncRNAs. Three genes (PCA3, C20orf166-AS1, and RP11-267A15.1) were identified to have a significant differential expression in prostate cancer tissues. However, there have been no published studies to demonstrate the specificity of RP11-267A15.1 in prostate cancer tissues. Thus, the results of this study can provide a new theoretic insight into the identification of prostate cancer specific genes.

CMTM5 is reduced in prostate cancer and inhibits cancer cell growth in vitro and in vivo.

A novel tumor suppressor CKLF-like MARVEL transmembrane domain-containing member 5 (CMTM5) is reduced or undetectable in many kinds of cancers and inhibits tumor cells' malignant features. To explore its role in prostate cancer (PCa), we detected its expression patterns in prostate tissues and PCa cells, and determined its anti-proliferation functions in PCa cells in vitro and in vivo. The expression of CMTM5 in prostate tissue microarray, specimens and cell lines was evaluated by immunohistochemistry and Western blot, respectively. After being transfected with CMTM5 adenovirus or vector, the proliferation and migration of DU145 cells were detected by MTT assay and transwell assay, respectively. Furthermore, the effects of CMTM5 on tumor growth were performed in nude mice xenograft in vivo. We found CMTM5 was reduced in PCa tissues and cells compared with BPH tissues, and its expression in PCa tissues was related to the Gleason score. Moreover, after being transfected with adenovirus, ectopic expression of CMTM5-v1 in DU145 cells led to significant inhibition of cell proliferation and migration compared with the control, which may be attributed to decreased Akt activity. Finally, restoration of CMTM5 significantly suppressed tumor growth in vivo. These results indicate that CMTM5 is down-regulated in PCa and exhibit tumor suppressor activities in androgen-independent PCa cells. Loss of CMTM5 protein may be contributed to the development of PCa and it is a potential therapeutic target for castration-resistant prostate cancer.

Abstract 39: Expression of uPA-system members correlate with the clinico-pathological parameters of PCa patients

Abstract Background: Members of the urokinase-type plasminogen activator (uPA) system play an important role in tumor progression and angiogenesis in different human malignancies including breast, kidney, colon, stomach and prostate cancer (PCa). The objective of this study was to determine the mRNA expression and protein levels of uPA system components in tissue specimens and serum samples, respectively, from patients with PCa, and to assess their potential association with clinic-pathological parameters and overall survival (OS). Material and methods: mRNA levels of uPA, its receptor (uPAR) and its inhibitor type 1 (PAI-1) were analyzed in corresponding malignant and adjacent non-malignant prostate tissue specimens from 132 PCa patients. Relative mRNA expression levels were determined by quantitative PCR and normalized to the reference gene TATA-box-binding protein. Pre-operative serum samples from 81 of the 132 PCa patients and 36 patients with benign prostatic hyperplasia (BPH) were analyzed for antigen levels of uPA system members by ELISA. Results: mRNA levels of the uPA system components displayed significant correlations with each other in the tumor tissues (uPA vs. uPAR: rs = 0.550; uPA vs. PAI-1: rs = 0.552; uPAR vs. PAI-1: rs = 0.643; all P &amp;lt; 0.001). A significantly decreased uPA mRNA expression in PCa tissue compared to the corresponding non-malignant tissue specimens was detected (data not shown). High mRNA expression of uPA and PAI-1 was significantly associated with a high Gleason score (P = 0.001 and P = 0.007, respectively; Fig. 2). Antigen levels of uPA and soluble uPAR (suPAR) in serum correlated weakly, but significantly, with each other (rs = 0.382, P &amp;lt; 0.001). A significant association was found between elevated suPAR concentrations in serum and poor OS of PCa patients (P = 0.022, log rank test). In multivariate Cox's regression analysis (adj. for age, lymph node status, tumor stage and Gleason sum) a high suPAR level was associated with a 7.12-fold increased risk of death (P=0.027). Conclusion: The observed association of high suPAR levels with poor survival of PCa patients is consistent with published data on patients afflicted with other types of solid cancer and strongly suggests a general prognostic impact of uPAR antigen levels in serum of cancer patients. Citation Format: Omar Al-Janabi, Helge Taubert, Andrea Lohse-Fischer, Michael Fröhner, Sven Wach, Robert Stöhr, Bastian Keck, Max Burger, Wolf Wieland, Kati Erdmann, Manfred P. Wirth, Bernd Wullich, Gustavo Baretton, Viktor Magdolen, Matthias Kotzsch, Susanne Füssel. Expression of uPA-system members correlate with the clinico-pathological parameters of PCa patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 39. doi:10.1158/1538-7445.AM2014-39

Monoamine oxidase A mediates prostate tumorigenesis and cancer metastasis

Tumors from patients with high-grade aggressive prostate cancer (PCa) exhibit increased expression of monoamine oxidase A (MAOA), a mitochondrial enzyme that degrades monoamine neurotransmitters and dietary amines. Despite the association between MAOA and aggressive PCa, it is unclear how MAOA promotes PCa progression. Here, we found that MAOA functions to induce epithelial-to-mesenchymal transition (EMT) and stabilize the transcription factor HIF1α, which mediates hypoxia through an elevation of ROS, thus enhancing growth, invasiveness, and metastasis of PCa cells. Knockdown and overexpression of MAOA in human PCa cell lines indicated that MAOA induces EMT through activation of VEGF and its coreceptor neuropilin-1. MAOA-dependent activation of neuropilin-1 promoted AKT/FOXO1/TWIST1 signaling, allowing FOXO1 binding at the TWIST1 promoter. Importantly, the MAOA-dependent HIF1α/VEGF-A/FOXO1/TWIST1 pathway was activated in high-grade PCa specimens, and knockdown of MAOA reduced or even eliminated prostate tumor growth and metastasis in PCa xenograft mouse models. Pharmacological inhibition of MAOA activity also reduced PCa xenograft growth in mice. Moreover, high MAOA expression in PCa tissues correlated with worse clinical outcomes in PCa patients. These findings collectively characterize the contribution of MAOA in PCa pathogenesis and suggest that MAOA has potential as a therapeutic target in PCa.

A safety study of trebananib (AMG 386) and abiraterone in metastatic castration-resistant prostate cancer (mCRPC).

5074 Background: Trebananib is an angiopeptide angiopoietin1/2 peptibody antagonist . Androgens stimulate expression of VEGF via activation of hypoxia inducible factor-a (HIFa). Androgen deprivation therapy (ADT) is associated with lower HIF1a gene expression in prostate cancer tissue. Dual targeting of the androgen and angiogenic axis represents a potential synergistic anti-angiogenic therapeutic approach in mCRPC. In this preliminary safety study we hypothesize that trebananib in combination with abiraterone will have a favorable tolerability and efficacy profile. Methods: Patients(pts) with mCRPC were treated with abiraterone 1000mg daily and prednisone 5 mg twice daily. Trebananib was administered intravenously every week, in escalating doses from 15mg/kg to 30mg/kg on days 1, 8, 15 and 22 every 28-days. Results: A total of 9 pts were enrolled. Three of nine pts had prior chemotherapy. The median age was 63.8 (63-71yrs). No dose limiting toxicities were observed. The most common grade ≥2 toxicities included limb edema (3/9), hyperglycemia (1/9), gastrointestinal (2/9), fatigue (2/9), hypertension (1/9), confusion (1/9), weight gain (1/9) and insomnia (2/9). 5/9 of pts had an overall PSA decline of >30%. 8/9 pts were evaluable for response. Pts previously treated with chemotherapy were on study for 1and 3 months, respectively. Chemotherapy-naïve pts were treated for 1, 6, 9, 10, 10, and 21 months, respectively. Conclusions: Trebananib in combination with abiraterone is well tolerated and displayed an acceptable safety profile in pts with mCRPC. Based on this safety data a randomized phase II study randomizing chemotherapy-naïve mCRPC pts to either abiraterone/prednisone plus AMG 386 at 30mg/kg or abiraterone/prednisone is currently accruing at the NCI. Clinical trial information: NCT01553188.

Identification of miR-133b and RB1CC1 as Independent Predictors for Biochemical Recurrence and Potential Therapeutic Targets for Prostate Cancer

We aimed to investigate the contribution of microRNA-133b (miR-133b) in prostate cancer cell proliferation, cell cycle, and apoptosis. We also examined expression of miR-133b in prostate cancer tissues, and evaluated the prognostic significance of miR-133b, as well as its target gene RB1CC1 in patients with prostate cancer after radical prostatectomy. miR-133b mimics (miR-133bm) and anti-miR-133b were transfected into LNCaP and PC-3 cells. CCK-8 was used to look at cell proliferation, flow cytometric analysis was carried out to study cell cycle, and apoptosis was determined by caspase-3 activity. miR-133b expression was assessed by real-time reverse transcription PCR and in situ hybridization in prostatic cell lines and 178 prostate tissue samples, respectively. The protein level of RB1CC1 was examined by Western blot and immunohistochemistry in prostatic cell lines and prostate tissue samples, respectively. Overexpression of miR-133b in LNCaP cells boosted cell proliferation and cell-cycle progression, but inhibited apoptosis; in contrast, miR-133bm promoted cell apoptosis, but suppressed cell proliferation and cell-cycle progression in PC-3 cells. In LNCaP cells, silencing of RB1CC1, a target of miR-133b, inhibited cell apoptosis, and promoted cell-cycle progression. Moreover, miR-133b expression was significantly inversely correlated with RB1CC1 expression in prostate cancer tissues. Multivariate Cox analysis indicated that miR-133b and RB1CC1 might be two independent prognostic factors of biochemical recurrence. miR-133b might enhance tumor-promoting properties in less aggressive LNCaP cells, whereas this miR may act as a tumor suppressor in more aggressive PC-3 cells. miR-133b and RB1CC1 were independent prognostic indicators for prostate cancer.

Deregulation of an imprinted gene network in prostate cancer

Multiple epigenetic alterations contribute to prostate cancer progression by deregulating gene expression. Epigenetic mechanisms, especially differential DNA methylation at imprinting control regions (termed DMRs), normally ensure the exclusive expression of imprinted genes from one specific parental allele. We therefore wondered to which extent imprinted genes become deregulated in prostate cancer and, if so, whether deregulation is due to altered DNA methylation at DMRs. Therefore, we selected presumptive deregulated imprinted genes from a previously conducted in silico analysis and from the literature and analyzed their expression in prostate cancer tissues by qRT-PCR. We found significantly diminished expression of PLAGL1/ZAC1, MEG3, NDN, CDKN1C, IGF2, and H19, while LIT1 was significantly overexpressed. The PPP1R9A gene, which is imprinted in selected tissues only, was strongly overexpressed, but was expressed biallelically in benign and cancerous prostatic tissues. Expression of many of these genes was strongly correlated, suggesting co-regulation, as in an imprinted gene network (IGN) reported in mice. Deregulation of the network genes also correlated with EZH2 and HOXC6 overexpression. Pyrosequencing analysis of all relevant DMRs revealed generally stable DNA methylation between benign and cancerous prostatic tissues, but frequent hypo- and hyper-methylation was observed at the H19 DMR in both benign and cancerous tissues. Re-expression of the ZAC1 transcription factor induced H19, CDKN1C and IGF2, supporting its function as a nodal regulator of the IGN. Our results indicate that a group of imprinted genes are coordinately deregulated in prostate cancers, independently of DNA methylation changes.

A safety study of trebananib (AMG 386) and abiraterone in metastatic castration-resistant prostate cancer.

218 Background: Trebananib is an angiopoietin1/2 antagonist peptibody. Androgens stimulate expression of VEGF via activation of hypoxia inducible factor-a (HIFa). Androgen deprivation therapy (ADT) is associated with lower HIF1a gene expression in prostate cancer tissue. Dual targeting of the androgen and angiogenic axis represents a potential synergistic anti-angiogenic therapeutic approach in metastatic castration resistant prostate cancer (mCRPC). In this preliminary safety study we hypothesize that trebananib in combination with abiraterone will have a favorable tolerability and efficacy profile. Methods: Patients with mCRPC were treated with abiraterone 1000mg daily and prednisone 5 mg twice daily. Trebananib was administered intravenously every week, in escalating doses from 15mg/kg to 30mg/kg on days 1, 8, 15, and 22 every 28-days. Results: A total of 9 patients were enrolled. Three of nine patients had prior chemotherapy. The median age was 63.8 (63-71yrs). No dose limiting toxicities were observed. The most common grade ≥ 2 toxicities included limb edema (3/9), hyperglycemia (1/9), gastrointestinal (2/9), fatigue (2/9), hypertension (1/9), confusion (1/9), weight gain (1/9) and insomnia (2/9). 5/9 of patients had an overall PSA decline of &gt;30%. 8/9 patients were evaluable for response. Prior chemotherapy patients were on study for 1 and 3 months. No prior chemotherapy patients were treated for 1, 6, 9, 10, 10, and 17 months. Conclusions: Trebananib in combination with abiraterone is well tolerated and displayed an acceptable safety profile in patients with mCRPC. Based on this safety data a randomized phase II study randomizing chemotherapy-naïve mCRPC patients to either abiraterone/prednisone plus AMG 386 at 30mg/kg or abiraterone/prednisone is currently accruing at the NCI. Clinical trial information: NCIT01553188.

Expression patterns of candidate susceptibility genes HNF1β and CtBP2 in prostate cancer: Association with tumor progression

ObjectivesGenome-wide association studies have identified variants at multiple loci associated with prostate cancer (PCa) risk. Some of these loci include candidate susceptibility genes, such as MSMB, HNF1β, and C-terminal-binding protein (CtBP2). Except for MSMB, the clinicopathological significance of these genes has not been investigated. We therefore aimed to analyze their expression in PCa tissues, in relation with tumor progression and aggressiveness. Methods and materialsProtein expression was evaluated by immunohistochemistry on tissue microarrays containing samples from normal prostate (NL, n = 91), high-grade prostatic intraepithelial neoplasia (PIN, n = 61), clinically localized PCa (CLC, n = 434), PCa metastases (M, n = 28), and castration-resistant PCa (CRC, n = 49). Moreover, mRNA expression for each marker was assessed by quantitative real-time polymerase chain reaction, on 53 frozen samples of NL, CLC, and CRC. ResultsThese genes were differentially expressed at the different stages of PCa natural history. MSMB expression decreased with disease development and progression. In contrast, nuclear HNF1β and CtBP2 staining significantly increased in the CRC and M groups when compared with CLC, together with the transcripts levels. In patients with CLC, HNF1β and CtBP2 nuclear expressions were strongly associated with cancer cell proliferation. After adjusting for the Gleason score and the pathological stage, none of the candidate genes was significantly predictive of recurrence after radical prostatectomy. In patients with CRC, CtBP2 nuclear staining was associated with shorter overall survival. ConclusionsThe decrease of MSMB expression during tumor progression strongly supports its role as a tumor-suppressor gene. Although its functions remain to be clarified in PCa cells, HNF1β and CtBP2 are associated with cancer cell proliferation, tumor progression, and castration-resistant disease.