PSA Transcription Research Articles

Identification of Clinically Significant Prostate Cancer by Combined PCA3 and AMACR mRNA Detection in Urine Samples.

PurposePreclinical evaluation of PCA3 and AMACR transcript simultaneous detection in urine to diagnose clinical significant prostate cancer (prostate cancer with Gleason score ≥7) in a Russian cohort.Patients and MethodsWe analyzed urine samples of patients with a total serum PSA ≥2 ng/mL: 31 men with prostate cancer scheduled for radical prostatectomy, 128 men scheduled for first diagnostic biopsy (prebiopsy cohort). PCA3, AMACR, PSA and GPI transcripts were detected by multiplex reverse transcription quantitative polymerase chain reaction, and the results were used for scores for calculation and statistical analysis.ResultsThere was no significant difference between clinically significant and nonsignificant prostate cancer PCA3 scores. However, there was a significant difference in the AMACR score (patients scheduled for radical prostatectomy p=0.0088, prebiopsy cohort p=0.029). We estimated AUCs, optimal cutoffs, sensitivities and specificities for PCa and csPCa detection in the prebiopsy cohort by tPSA, PCA3 score, PCPT Risk Calculator and classification models based on tPSA, PCA3 score and AMACR score. In the clinically significant prostate cancer ROC analysis, the PCA3 score AUC was 0.632 (95%CI: 0.511–0.752), the AMACR score AUC was 0.711 (95%CI: 0.617–0.806) and AUC of classification model based on the PCA3 score, the AMACR score and total PSA was 0.72 (95%CI: 0.58–0.83). In addition, the correlation of the AMACR score with the ratio of total RNA and RNA of prostate cells in urine was shown (tau=0.347, p=6.542e–09). Significant amounts of nonprostate RNA in urine may be a limitation for the AMACR score use.ConclusionThe AMACR score is a good predictor of clinically significant prostate cancer. Significant amounts of nonprostate RNA in urine may be a limitation for the AMACR score use. Evaluation of the AMACR score and classification models based on it for clinically significant prostate cancer detection with larger samples and a follow-up analysis is promising.

The p14ARF tumor suppressor restrains androgen receptor activity and prevents apoptosis in prostate cancer cells.

Prostate cancer (PCa) is characterized by a unique dependence on optimal androgen receptor (AR) activity where physiological androgen concentrations induce proliferation but castrate and supraphysiological levels suppress growth. This feature has been exploited in bipolar androgen therapy (BAT) for castrate resistant malignancies. Here, we investigated the role of the tumor suppressor protein p14ARF in maintaining optimal AR activity and the function of the AR itself in regulating p14ARF levels. We used a tumor tissue array of differing stages and grades to define the relationships between these components and identified a strong positive correlation between p14ARF and AR expression. Mechanistic studies utilizing CWR22 xenograft and cell culture models revealed that a decrease in AR reduced p14ARF expression and deregulated E2F factors, which are linked to p14ARF and AR regulation. Chromatin immunoprecipitation studies identified AR binding sites upstream of p14ARF. p14ARF depletion enhanced AR-dependent PSA and TMPRSS2 transcription, hence p14ARF constrains AR activity. However, p14ARF depletion ultimately results in apoptosis. In PCa cells, AR co-ops p14ARF as part of a feedback mechanism to ensure optimal AR activity for maximal prostate cancer cell survival and proliferation.

P-34 - Assessment of percentage free PSA and urinary transcripts in decision-making for the prostate biopsy

P-34 - Assessment of percentage free PSA and urinary transcripts in decision-making for the prostate biopsy

Association of AR-V7 and Prostate-Specific Antigen RNA Levels in Blood with Efficacy of Abiraterone Acetate and Enzalutamide Treatment in Men with Prostate Cancer

We evaluated the association of PSA and androgen receptor splice variant-7 (AR-V7) transcript levels in patients' blood with time to treatment failure (TTF) and overall survival (OS) with abiraterone acetate and/or enzalutamide treatment in castration-resistant prostate cancer (CRPC) patients. RNA levels of AR-V7 and PSA in peripheral blood collected before treatment were quantified using droplet digital-PCR in retrospective cohorts treated with abiraterone acetate (N = 81) or enzalutamide (N = 51) for CRPC. Multivariable Cox regression adjusted for known prognostic factors was used for analyses. PSA transcripts were detected in 57% of abiraterone acetate-treated patients and in 63% of enzalutamide-treated patients. PSA-positive patients had a shorter TTF than PSA-negative patients [adjusted HR = 2.27 (95% confidence interval (CI) 1.26-4.10) and 2.60 (95% CI, 1.19-5.69); P = 0.006 and 0.017 in abiraterone acetate and enzalutamide cohorts, respectively]. Patients with a higher-AR-V7 transcript level had a shorter TTF with abiraterone acetate and enzalutamide in univariate analysis (median 8.0 months vs. 15.6 months, P = 0.046 in abiraterone acetate-cohort and 3.6 months vs. 5.6 months; P = 0.050 in enzalutamide cohort). In multivariable models, the association with TTF remained significant in the enzalutamide cohort (adjusted HR = 2.02; 95% CI, 1.01-4.05; P = 0.048), but statistically insignificant in the abiraterone acetate cohort. In both cohorts, we observed potential prognostic value of both PSA and AR-V7 RNA expression on OS; patients with detectable PSA transcripts and high AR-V7 predicted the poorest OS. PSA and AR-V7 transcripts in blood potentially serve as biomarkers predicting TTF and OS with abiraterone acetate or enzalutamide treatment. If validated prospectively, their detection could be facilitated without isolation of circulating tumor cells. Clin Cancer Res; 23(3); 726-34. ©2016 AACR.

Androgen Receptor Overexpression in Mantle Cell Lymphoma: Potential Novel Therapeutic Implications

BACKGROUND: Mantle cell lymphoma (MCL) represents approximately 5-10% of all non-Hodgkin lymphoma (NHL) diagnosed annually in the US and Europe. In contrast to the slight male predominance of other non-Hodgkin lymphomas, most series report that approximately 80% of MCL patients are male. While the pathobiology underlying this gender-distribution imbalance is unknown, sex-related differences in androgen receptor (AR) expression in the hematopoietic system have been described, leading us to hypothesize that the gender imbalance in MCL may be mediated via differential sex-related effects on AR activity. Enzalutamide is a potent inhibitor of the AR axis, binding to the AR with high selectivity, and targeting multiple steps in AR signaling, including inhibition of AR ligand binding, AR nuclear translocation, and AR-mediated DNA binding.OBJECTIVE: To evaluate AR expression in MCL cell lines and human specimens and explore the effect of AR-axis blockade with enzalutamide on MCL tumor cell proliferation.METHODS: MCL cell lines (JVM-13, Maver-1, Jeko-1, Rec-1, JVM-2, Granta and Mino), non-MCL cell lines (SUDHL4, FL18 and Ramos) and prostate cancer cell lines (LNCaP, VCaP, PC3 and Du-145) were obtained from American Type Culture Collection (Rockville, Maryland, USA) and cultured in accordance with supplier recommended methods. Buffy coat specimens from three MCL patients with circulating tumor cells were utilized for RNA isolation and analysis of AR transcript expression. Additionally, formalin fixed samples from nine archival MCL tumor specimens were obtained for immunohistochemistry (IHC) analysis of AR staining. RNA was isolated and prepared for quantitative real time PCR (qRT-PCR) using primers for AR and PSA. All qRT-PCR experiments were performed in triplicate, and the housekeeping gene RPL13A was used as an endogenous control. Proliferation assays were carried out with cells brought up in serum free media, incubated under standard culture conditions for 24 hours, then plated in triplicate with the AR antagonist enzalutamide (10uM), the synthetic AR agonist R1881 (1nM), or the combination for 96 hours. Following the incubation period, cells were transferred to a flat-bottomed 96-well plate and proliferation was quantified using the CyQUANTTM Assay Kit.RESULTS: The median expression of AR transcript was significantly higher in MCL lines than in non-MCL B-NHL lines (normalized to the difference in cycle threshold (dCT) of the housekeeping gene RPL13A). The median dCT for AR was -12 in MCL lines (range -11 to -15) vs. -18 in non-MCL lines (p=0.006; Figure 1A), representing a 64 fold difference in transcript expression. Additionally, the tight correlation between the canonical AR-regulated target gene PSA and AR (r=.715, p=0.001; Figure 1B) suggests that AR expression within these MCL lines is functionally active and capable of driving transactivation of target genes. These findings were also observed in a limited number of frozen, patient-derived MCL tumors; where 2 of 3 samples demonstrated AR and PSA transcripts at levels similar to those observed in the MCL cell lines (Figure 1C). Staining of formalin fixed human MCL tumor cells for AR expression by IHC demonstrated a spectrum of expression; including tumors with no staining, tumors with predominantly cytoplasmic AR staining, and tumors with evidence of scattered nuclear AR staining. Proliferation assays of four different AR+ MCL lines (Granta, Jeko, Maver, Rec-1) with the AR agonist R1881, enzalutamide, or the combination demonstrated somewhat limited stimulation by agonist but consistent and statistically significant suppression of proliferation by enzalutamide (Figure 2). The magnitude of suppression in several of the MCL lines (eg, Granta and Jeko) was comparable to that observed in the AR+ LNCaP PCa cell line.CONCLUSION: Functional AR transcript is overexpressed in both MCL cell lines and human tumor samples. Blockade of the AR-axis by enzalutamide effects consistent and reproducible suppression of MCL tumor growth, even in the presence of AR agonist R1881. These results have led to the conception and recent initiation of an NCCN funded phase II clinical trial evaluating the safety and clinical efficacy of enzalutamide as a novel therapy for patients with relapsed or refractory MCL (NCT02489123). [Display omitted] [Display omitted] DisclosuresGopal:Paid Consultancy- Gilead, Janssen, Seattle Genetics, Spectrum, Research funding- Gilead, Janssen, Pfizer, BMS, Merck, Teva, Takeda, Spectrum, Seattle Genetics: Consultancy, Honoraria, Research Funding.

Abstract 366: A novel transcript variant of androgen receptor identified in circulating tumor cells from castration-resistant prostate cancer patients as a potentially prognostic biomarker

Abstract Circulating tumor cells (CTCs) are rare cancer cells in the bloodstream thought to have a key role in cancer metastasis. There are enormous interests in their analysis for castration-resistant prostate cancer (CRPC) due to their tendency to metastasize to bone. In this study, we applied a surface marker-independent microfluidic device for CTCs capture and retrieval that is based on cell size and deformability. Our device was able to capture 90% and recover 30% of tumor cells in spike experiments. We also developed and validated assays capable of detecting the transcript levels of selected molecular markers in single cells prepared with C1TM Single-Cell AutoPrep System. Blood samples drawn from 34 CRPC patients and 10 primary prostate cancer patients (PPC) were preceded for CTC isolation and molecular characterization. We found that 73% CRPC patients and 10% PPC patients were positive for EpCAM, and only about half of the EpCAM-positive CRPC cases were PSA or AR positive. It is interesting that while there is a strong association between AR and PSA expression in CTC samples, there is no correlation between AR or PSA transcripts in CTCs and serum PSA protein levels in CRPC patients. The positive detection of AR or PSA, but not EpCAM is statistically associated with poor prognosis of the CRPC patients. Very intriguingly, we identified a novel androgen receptor (AR) transcript variant -ARv from four CRPC patients’ CTCs. This ARv lacks a 554bp sequence region in the ligand binding domain (LBD), resulting in a loss of the entire LBD. Clinical data analysis revealed that the ARv is significantly associated with worse survival of CRPC patients (p<0.0001). In vitro functional studies showed this novel ARv is constitutively active in the absence of testosterone. Our findings suggest that this AR variant might contribute to the late stage progression of the diseases and could be used as a potential indicator for alternative therapies. In summary, our new fluidic device is capable of isolating CTC to enable molecular marker analysis, providing value in prognosis and guidance to therapy. Citation Format: Zhigang Kang, Avani Shah, Yunkai Yu, Yuelin Zhu, Ali Asgar Bhagat, Kyra Zhao, Andrew Wu, James Gao, Ravi Madan, James Gulley, William Dahut, Paul Meltzer, Liang Cao. A novel transcript variant of androgen receptor identified in circulating tumor cells from castration-resistant prostate cancer patients as a potentially prognostic biomarker. [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 366. doi:10.1158/1538-7445.AM2015-366

MP37-17 DISTINCT EXPRESSION FEATURES OF PMEPA1 AND ITS ISOFORM STAG1 IN PROSTATE CANCER

You have accessJournal of UrologyProstate Cancer: Basic Research I1 Apr 2015MP37-17 DISTINCT EXPRESSION FEATURES OF PMEPA1 AND ITS ISOFORM STAG1 IN PROSTATE CANCER Hua Li, Lakshmi Ravindranath, Yongmei Chen, David McLeod, Isabell Sesterhenn, Albert Dobi, Shiv Srivastava, and Gyorgy Petrovics Hua LiHua Li More articles by this author , Lakshmi RavindranathLakshmi Ravindranath More articles by this author , Yongmei ChenYongmei Chen More articles by this author , David McLeodDavid McLeod More articles by this author , Isabell SesterhennIsabell Sesterhenn More articles by this author , Albert DobiAlbert Dobi More articles by this author , Shiv SrivastavaShiv Srivastava More articles by this author , and Gyorgy PetrovicsGyorgy Petrovics More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.1280AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Our earlier studies defined PMEPA1, a NEDD4 E3 ubiquitin ligase binding protein, as an androgen regulated gene with decreased or absent PMEPA1 transcripts in 65% of prostate cancer (CaP). Solid tumor associated gene 1 (STAG1) is an isoform of PMEPA1 upregulated in several solid tumors. STAG1 has an alternative first exon and a predicted alternative promoter compared to PMEPA1. In order to better understand STAG1 and its relation to PMEPA1 in CaP, this study focuses on comparative analyses of STAG1 and PMEPA1 expression in human CaP. METHODS Tumor and benign epithelial cells were laser capture microdissected (LCM) from frozen OCT embedded prostate tissue. Total RNA was isolated from the LCM samples and converted to cDNA. Quantitative gene expression analysis was performed by TaqMan-based QRT-PCR. A total of 117 matched normal and prostate tumor specimens (N=234) were assayed for STAG1, PMEPA1, AR and PSA transcripts. Correlation of the gene expression data with clinical and pathological characteristics were examined by Kaplan-Meier survival and Cox proportional hazard model analyses. Biochemical recurrence (BCR) was defined as two consecutive post-operative PSA > 0.2 ng/mL 2 months after surgery. RESULTS STAG1 mRNA levels did not have significant correlation with transcript levels of PMEPA1, AR or PSA. Patients with increased tumor / normal STAG1 mRNA level had a shorter time to BCR in a Kaplan-Meier analysis (P=0.018). The correlation of increased STAG1 expression in tumor cells with increased chance for BCR was supported by multivariable Cox proportional hazard model (P=0.0015; HR=4.3). CONCLUSIONS In contrast to PMEPA1, STAG1 expression does not appear to be androgen regulated. Surprisingly, STAG1 expression was an independent predictor of BCR after radical prostatectomy. Based on our findings further mechanistic evaluation of STAG1 and PMEPA1 in CaP is warranted. © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e444 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Hua Li More articles by this author Lakshmi Ravindranath More articles by this author Yongmei Chen More articles by this author David McLeod More articles by this author Isabell Sesterhenn More articles by this author Albert Dobi More articles by this author Shiv Srivastava More articles by this author Gyorgy Petrovics More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Abstract 2123: Tetrandrine impairs prostate cancer cell survival in part by inhibiting AR signaling pathway.

Abstract Prostate cancer (PCa) is the second leading cause of cancer deaths in men, and the majority of prostate cancer deaths are a result of emergence of castrate resistant phenotype. Our previous studies indicated that Tetrandrine (TET), a bis-benzylisoquinoline alkaloid isolated from the root of Stephania tetrandra inhibited cell cycle progression and promoted growth arrest at lower concentrations and promoted apoptosis at higher concentrations and at longer time points. AR signaling is known to play a critical role in androgen responsive prostate cancer cells. In the present studies we evaluated the effects of TET on AR signaling in androgen dependent (LNCaP cells) as well as castrate resistant (C4 and C42B cells, castrate resistant lineages of LNCaP cells) prostate cancer cells. Exposure of LNCaP cells to Tet resulted in a dose and time dependent decrease in PSA protein (cell associated as well as secreted PSA). Further analysis revealed that Tet also decreased PSA mRNA as well as PSA promoter activity, suggesting that Tet induced decrease in PSA was a result of inhibition of PSA transcription. Since PSA is known to be an AR responsive gene, these results led us to investigate the effects of Tet on AR signaling. Results from these studies revealed that Tet inhibited AR activity as measured by TARP promoter assay. Taken together these studies suggest that Tet targets AR signaling pathway effectively blocking AR target genes. In summary our results suggest that Tet by inhibiting AR signaling pathway may work as an effective therapeutic agent in prostate cancer, for which there is no cure to date. Grant Support: Studies supported in part by VA Merit Award-01BX001258 (HK), NIH/NCI R01CA161880 (HK) and Department of Surgery, School of Medicine chair commitment (HK). Citation Format: Sweaty Koul, Hari K. Koul. Tetrandrine impairs prostate cancer cell survival in part by inhibiting AR signaling pathway. [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 2123. doi:10.1158/1538-7445.AM2013-2123

Abstract 174: MicroRNA signatures of castration resistant human prostate cancer

Abstract Androgen-dependent (AD) prostate cancer (CaP) typically progresses to castration resistant prostate cancer (CRPC) after after some duration of androgen deprivation therapy (ADT). The mechanisms of this transition are at the beginning to be understood. MicroRNAs (miRs) are non-coding small RNAs (19-25nt) that play an important role in the regulation of gene expression. So far, only a few studies have looked at prostate cancer-specific miRNA signatures relevant to the development and progression of CaP. By performing genome-wide expression profiling of miRs, we found 7 miRs (miR-221, miR-222, miR-15a, miR-16-1, miR-203, miR-23b and miR-27b) differentially expressed in the AD prostate cancer LNCaP cell line and the LNCaP derived CRPC cell line- LNCaP-Abl. In particular miR-221 and miR-222, were most dramatically increased in the CRPC cell lines. Over-expression of miR-221 or -222 in LNCaP or another AD cell line, LAPC-4 significantly reduced the level of the dihydrotestosterone (DHT) induced up-regulation of PSA expression and increased androgen independent (AI) growth of LNCaP cells. Knocking down the expression level of miR-221 and -222 with antagonist miRs in the LNCaP-Abl cell line restored the response to DHT induction of PSA transcription and also increased the growth response of LNCaP-Abl cells to androgen. To determine the clinical relevance of the differential expression patterns of these miRs, we compared the expression levels of these 7 miRs in 86 normal prostate tissues, 34 localized hormone naïve primary tumors and 17 bone metastatic CRPC samples. Despite of the anticipated heterogeneity of CRPCs within each individual or among patients, surprisingly ∼90% of analyzed CRPC tumors can be characterized by significant up-regulation of miR-221/-222 and down-regulation of miR-23b/-27b. This finding suggests that the signature of altered miR-221/-222 and miR-23b/-27b expression is associated with the development of CRPC in human tumors. 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 174. doi:10.1158/1538-7445.AM2011-174

131 BIOBANKING OF TISSUE OBTAINED FROM ROBOTIC-ASSISTED RADICAL PROSTATECTOMY CAN BE SUCCESSFULLY IMPLEMENTED WITHOUT COMPROMISING RNA INTEGRITY

cific antigen (PSA) and cytokeratin 18 (CK18) genes was measured by quantitative RT/PCR, and we have optimized this method by using SABiosciences qPCR Master Mix. We also employ an additional technique of immunomagnetic precipitation to extract RNA from CTCs. Specifically, we coat Dynabeads® (Invitrogen) with equal amounts of antibody to epithelial cell adhesion molecule (EpCAM) and to prostate specific membrane antigen (PSMA). RESULTS: Using a specific primer/probe set, we demonstrate that our qRT/PCR assay is linear over a wide range, and that we can detect PSA transcript in RNA from 1 LNCaP cell. When LNCaP cells are spiked into peripheral blood mononuclear cells (PBMNCs) from men without PCa, we demonstrate that we can detect 1 human prostate cell per 10 7 PBMNCs. In our phase II clinical trial we successfully detected CTCs in 13/17 (76.5%) patients. Our technique of dual antigen pull-down can detect 1 CTC per ml of whole blood of PCa patients. PSA transcripts have not been detected in negative control blood. CONCLUSIONS: We have developed a novel, rapid and sensitive assay suitable for the detection of CTCs in peripheral blood of PCa patients.

559 HUMAN HETEROCHROMATIN PROTEIN 1 ISOFORM HP1βASSOCIATED WITH METHYLATED LYS9 OF HISTONE H3 PROMOTES PROSTATE CANCER CELL GROWTH THROUGH ANDROGEN RECEPTOR ACTIVATION

You have accessJournal of UrologyProstate Cancer: Basic Research IV1 Apr 2010559 HUMAN HETEROCHROMATIN PROTEIN 1 ISOFORM HP1βASSOCIATED WITH METHYLATED LYS9 OF HISTONE H3 PROMOTES PROSTATE CANCER CELL GROWTH THROUGH ANDROGEN RECEPTOR ACTIVATION Masaki Shiota, YooHuang Song, Akira Yokomizo, Yasuhiro Tada, Junichi Inokuchi, Daisuke Masubuchi, Masatoshi Eto, Naohiro Fujimoto, Narihito Seki, and Seiji Naito Masaki ShiotaMasaki Shiota Fukuoka, Japan More articles by this author , YooHuang SongYooHuang Song Fukuoka, Japan More articles by this author , Akira YokomizoAkira Yokomizo Fukuoka, Japan More articles by this author , Yasuhiro TadaYasuhiro Tada Fukuoka, Japan More articles by this author , Junichi InokuchiJunichi Inokuchi Fukuoka, Japan More articles by this author , Daisuke MasubuchiDaisuke Masubuchi Fukuoka, Japan More articles by this author , Masatoshi EtoMasatoshi Eto Kumamoto, Japan More articles by this author , Naohiro FujimotoNaohiro Fujimoto Kitakyushu, Japan More articles by this author , Narihito SekiNarihito Seki Fukuoka, Japan More articles by this author , and Seiji NaitoSeiji Naito Fukuoka, Japan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2010.02.779AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES There are currently few successful therapies for castration-resistant prostate cancer (CRPC). CRPC results from augmented androgen/androgen receptor (AR) signaling pathway, which could be enhanced by AR cofactors. Recently, epigenetics have been known to play the important role in gene expression. Then, we searched new AR cofactor from the stand of epigenetics and evaluated the function of newly-identified AR cofactor. In addition, the possibility as therapeutic target was evaluated. METHODS Human prostate cancer PC-3, LNCaP cells and castration-resistant LNCaP derivatives which were established by us and named as CxR cells were used. Using these cells, we searched the AR cofactor relating to epigenetics by co-immunoprecipitation assay. Based on the identified AR cofactor, we performed luciferase reporter assay using PSA reporter plasmid to examine the role as AR cofactor. Further, we conducted chromatin-immunoprecipitation assay to evaluate AR binding ability to PSA promoter. In addition, immunohistochemistry was performed using prostate cancer tissues. Last, we evaluated the impact as a therapeutic target based on the identified AR cofactor by cell proliferation assay and flow cytometry. RESULTS We identified new AR co-factor, heterochromatin protein 1 isoform, HP1β. HP1β was shown to upregulate the PSA transcription via augmentation of binding to androgen-responsive elements (Fig. A). In addition, CxR cells expressed high levels of HP1β and AR protein. Immunohistochemistry of prostate cancer revealed that HP1β expression and tri-methylated lysine 9 of histone H3 level was elevated in cancer compared with normal prostate epithelium and HP1β expression correlated with Gleason score (Fig. B). Silencing of HP1β suppressed cell growth of LNCaP and CxR cells by inducing cell-cycle arrest (Fig. C). CONCLUSIONS This study indicated that HP1β is involved in proliferation of AR-expressing prostate cancer cells and progression to CRPC as an AR coactivator. Modulation of HP1β expression or function might be a useful strategy for developing novel therapeutics for prostate cancer, even in CRPC. © 2010 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 183Issue 4SApril 2010Page: e219-e220 Peer Review Report Advertisement Copyright & Permissions© 2010 by American Urological Association Education and Research, Inc.MetricsAuthor Information Masaki Shiota Fukuoka, Japan More articles by this author YooHuang Song Fukuoka, Japan More articles by this author Akira Yokomizo Fukuoka, Japan More articles by this author Yasuhiro Tada Fukuoka, Japan More articles by this author Junichi Inokuchi Fukuoka, Japan More articles by this author Daisuke Masubuchi Fukuoka, Japan More articles by this author Masatoshi Eto Kumamoto, Japan More articles by this author Naohiro Fujimoto Kitakyushu, Japan More articles by this author Narihito Seki Fukuoka, Japan More articles by this author Seiji Naito Fukuoka, Japan More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Preclinical antitumor activity of the oral platinum analog satraplatin

Satraplatin is an orally available platinum analog. The purpose of this study was to better characterize satraplatin's preclinical antitumor efficacy in a variety of sensitive and resistant human tumor cell lines and in a prostate cancer xenograft model and to evaluate the effect of satraplatin on PSA expression and/or secretion in a prostate cancer cell line. Satraplatin and its primary metabolite JM-118 were preclinically tested for their cytotoxic activity in a range of cancer cells including: human prostate, those forming the NCI drug screening panel, and those resistant to anti-cancer drugs. Also, the antiproliferative efficacy of satraplatin was tested in vivo in a human prostate cancer model. The effect of satraplatin and JM-118 on PSA transcription was measured by quantitative real time PCR. Satraplatin and JM-118 inhibited in vitro and in vivo the growth of prostate cancer cells in a dose-dependent fashion. The IC50 cytotoxicity values for satraplatin ranged from 1 to 3 microM for androgen-insensitive cells and was 11 microM for the androgen-sensitive cell line. Interestingly, JM-118 was up to 16-fold more potent than satraplatin. Oral administration of satraplatin to nude mouse PC-3 xenograft models inhibited the growth of these human tumors. Satraplatin had no direct effect on PSA transcription and the observed decrease in secreted PSA correlated with a decrease in cell number. When evaluated in the NCI drug-screening panel, satraplatin was most active in leukemia and small cell lung cancer cell lines. Both satraplatin and JM-118 were tested on cells resistant to chemotherapeutic agents. Satraplatin and JM-118 were equally active in the cisplatin-resistant A129cp80 ovarian carcinoma cell line, with activity comparable to that observed in the parent line. Neither expression of MDR1, BCRP, MRP1, nor altered tubulin or topoisomerase I were found to mediate resistance to satraplatin or JM-118. Although these resistance mechanisms contribute to drug resistance for a number of chemotherapeutics, they do not appear to play a role in satraplatin resistance. These results demonstrate that satraplatin and JM-118 have preclinical antitumor activity in human prostate cancer and other tumor types as well, including several cell lines displaying drug resistance to cisplatin, docetaxel and mitoxantrone. In addition, the results suggest that PSA should be further evaluated as a relevant marker of clinical response in patients with prostate cancer treated with satraplatin.

Methyl selenium metabolites decrease prostate-specific antigen expression by inducing protein degradation and suppressing androgen-stimulated transcription

Prostate-specific antigen (PSA) is widely used clinically for prostate cancer diagnostics and as an indicator of therapeutic efficacy and recurrence. Several human chemoprevention trials are being conducted to validate the prostate cancer prevention efficacy of selenium and PSA is used in these trials as a biomarker of response. A better understanding of the effects of selenium metabolites on the kinetics of PSA turnover and secretion in prostate cancer cells treated with selenium at concentrations which are achievable physiologically will be important for interpreting the results of these trials. This study addresses whether the putative active anticancer selenium metabolite methylselenol or its precursor methylseleninic acid (MSeA) specifically inhibits PSA expression in the androgen-responsive LNCaP prostate cancer cell model. The results show that exposure to sub-apoptotic concentrations of MSeA and methylselenol inhibited PSA protein expression and secretion, whereas sodium selenite and selenomethionine lacked inhibitory effect. The inhibition was detectable at 3 h of exposure and required a threshold level of MSeA to sustain. Turnover experiments showed that MSeA caused rapid PSA degradation, which was partially blocked by lysosomal inhibitors, but not by a proteasomal inhibitor. Furthermore, MSeA treatment reduced PSA mRNA level, down-regulated androgen receptor protein expression, and inhibited androgen-stimulated PSA promoter transcription. In summary, methylselenol or MSeA specifically and rapidly inhibited PSA expression through two mechanisms of action: inducing PSA protein degradation and suppressing androgen-stimulated PSA transcription. These findings may have important mechanistic implications for the prostate specific cancer chemopreventive action of selenium.

Plant-derived 3,3′-Diindolylmethane Is a Strong Androgen Antagonist in Human Prostate Cancer Cells

3,3'-Diindolylmethane (DIM) is a major digestive product of indole-3-carbinol, a potential anticancer component of cruciferous vegetables. Our results indicate that DIM exhibits potent antiproliferative and antiandrogenic properties in androgen-dependent human prostate cancer cells. DIM suppresses cell proliferation of LNCaP cells and inhibits dihydrotestosterone (DHT) stimulation of DNA synthesis. These activities were not produced in androgen-independent PC-3 cells. Moreover, DIM inhibited endogenous PSA transcription and reduced intracellular and secreted PSA protein levels induced by DHT in LNCaP cells. Also, DIM inhibited, in a concentration-dependent manner, the DHT-induced expression of a prostate-specific antigen promoter-regulated reporter gene construct in transiently transfected LNCaP cells. Similar effects of DIM were observed in PC-3 cells only when these cells were co-transfected with a wild-type androgen receptor expression plasmid. Using fluorescence imaging with green fluorescent protein androgen receptor and Western blot analysis, we demonstrated that DIM inhibited androgen-induced androgen receptor (AR) translocation into the nucleus. Results of receptor binding assays indicated further that DIM is a strong competitive inhibitor of DHT binding to the AR. Results of structural modeling studies showed that DIM is remarkably similar in conformational geometry and surface charge distribution to an established synthetic AR antagonist, although the atomic compositions of the two substances are quite different. Taken together with our published reports of the estrogen agonist activities of DIM, the present results establish DIM as a unique bifunctional hormone disrupter. To our knowledge, DIM is the first example of a pure androgen receptor antagonist from plants.

Increased transcriptional activity of prostate-specific antigen in the presence of TNP-470, an angiogenesis inhibitor.

Prostate-specific antigen, PSA, is regarded as a reliable surrogate marker for androgen-independent prostate cancer (AIPC). Concern has been raised that investigational agents may affect PSA secretion without altering tumour growth or volume. In a phase I trial, several patients with AIPC had elevated serum PSA levels while receiving TNP-470 that reversed upon discontinuation. TNP-470 inhibits capillary growth in several angiogenesis models. These observations prompted us to determine if TNP-470, or its metabolite, AGM-1883, altered PSA secretion. Intracellular protein and transcriptional levels of PSA and androgen receptor were also determined. The highest TNP-470 concentration produced a 40.6% decrease in cell number; AGM-1883 had minimal effects on cell viability. PSA secretion per cell was induced 1.1- to 1.5-fold following TNP-470 exposure. The same trend was observed for AGM-1883. PSA and AR were transcriptionally up-regulated within 30 min after exposure to TNP-470. PSA transcription was increased 1.4-fold, while androgen receptor (AR) transcription was induced 1.2-fold. The increased PSA transcriptional activity accounts for the increased PSA secretion. Increased AR transcription was also reflected at the protein level. In conclusion, TNP-470 and AGM-1883 both up-regulated PSA making clinical utilization of this surrogate marker problematic. © 1999 Cancer Research Campaign