Hormone-refractory Prostate Cancer Research Articles

REST is a crucial regulator for acquiring EMT-like and stemness phenotypes in hormone-refractory prostate cancer

Castration-resistance prostate cancer (CRPC), also known as hormone-refractory prostate cancer (HRPC), requires immediate attention since it is not only resistant to androgen ablation, chemo- and radiotherapy, but also highly metastatic. Increasing evidence suggests that enrichment of neuroendocrine (NE) cells is associated with CRPC. Here, combined RNA-seq and ChIP-seq analysis reveals that REST is involved in epithelial-mesenchymal transition (EMT) and stemness acquisition in NE differentiated prostate cancer (PCa) cells via direct transcriptional repression of Twist1 and CD44. Specifically we show that short-term knockdown of REST induces NE differentiation of LNCaP cells. Long-term REST knockdown enhanced the expression of Twist1 and CD44, cell migration and sphere formation. Overexpression of REST in hormone-refractory CWR22Rv1 PCa cells significantly reduces Twist1 and CD44 expression, cell migration and sphere formation. Collectively, our study uncovers REST in regulating EMT and stemness properties of NE PCa cells and suggests that REST is a potential therapeutic target for CRPC.

Antitumor activity of interferon-β1a in hormone refractory prostate cancer with neuroendocrine differentiation.

Type I interferons (IFN-α and IFN-β) are a class of cytokines that exert several biological activities, such as modulation of cell proliferation and differentiation and of the immune system. Although these cytokines interact with a common receptor complex, IFN-β showed a more potent antitumor activity than IFN-α in several tumor models. New recombinant human IFN-β products, such as IFN-β1a and IFN-β1b, have been produced in order to improve the stability and bioavailability of natural IFN-β. In this report, we analyzed the effects of recombinant IFN-β1a on the cell proliferation of two human androgen-resistant prostate cancer cell lines with neuroendocrine differentiation (DU-145, PC-3) and related mechanisms of action. The effects of IFN-β1a on the cell growth proliferation, cell cycle, and apoptosis have been evaluated in DU-145 and PC-3 cells through MTT assay, DNA flow cytometry with propidium iodide, and Annexin V-FITC/propidium iodide staining, respectively. Moreover, the expression of neuron-specific enolase (NSE), cleaved caspase-3, caspase-8, and PARP was evaluated through Western blotting. IFN-β1a showed a significant anti-proliferative activity in both androgen-resistant cell lines. This effect was related to cell cycle perturbation and induction in apoptosis, as shown by flow cytometric analysis, the activation of caspase-3 and caspase-8 and PARP cleavage during incubation with IFN-β1a. Moreover, this cytokine reduced the expression of NSE in both cell lines. Recombinant IFN-β1a (Rebif) showed a potent in vitro anti-proliferative activity in androgen-resistant prostate cancer cells, and it could represent a promising tool for the treatment of this tumor.

New gonadotropin-releasing hormone glycolipids with direct antiproliferative activity and gonadotropin-releasing potency

Gonadotropin-releasing hormone (GnRH) is an endogenous peptide with a short biological half-life. Although GnRH analogs (eg. triptorelin) are developed with enhanced stability compared to the native peptide, they still suffer from poor biological stability and pharmacokinetic properties. Furthermore, they are only effective in the treatment of hormone-dependent reproductive cancers. In this study we applied lipidation and glycosylation along with D-amino acid substitution at position 6 (D-Trp 6 ) to improve the stability, permeability, and consequently the potency of the GnRH peptide and triptorelin. We showed that the conjugation of GnRH with a lipid moiety and carbohydrates made all modified constructs ( 1– 8 ) more stable than the parent peptide against enzymatic degradation (5.5–6.5 times). Two of the lactose-modified glycolipopeptides, 3 and 6 , showed 27 and 16 times higher membrane permeability than the parent GnRH, respectively. All analogs with D-Trp 6 -substitution ( 4–6 ) exerted GnRH receptor-mediated antiproliferative activity in prostate and ovarian GnRH-receptor positive cell lines. They were more potent than triptorelin in the hormone-independent prostate cancer cell line: DU145. Compound 6 (lactose-modified) was the most potent analog for stimulating the release of luteinizing hormone (LH) and follicle stimulating hormone (FSH) gonadotropins from rat pituitary cells in vitro . The same glycolipopeptide exhibited a higher efficacy and duration of action in stimulating the release of LH than triptorelin in a preclinical mouse model. The superior activity of lipid- and carbohydrate-substituted triptorelin analog 6 made it a promising candidate for the development of new GnRH agonists to treat both hormone-dependent and hormone-refractory prostate cancer.

Association of endothelin-1 gene single-nucleotide polymorphisms and haplotypes with risk of hormone refractory prostate cancer.

Androgen deprivation is often the treatment of choice for patients with a new diagnosis of metastatic or locally advanced prostate cancer (CaP). However, most CaP patients showing a first response to androgen deprivation will progress to a hormone refractory phase of the disease (HRPC) with a much poorer prognosis. Accumulating evidence suggests that endothelin-1 (ET-1) plays an important role in CaP progression. Singlenucleotide polymorphisms (SNPs) of the ET-1 gene reportedly have been associated with cancer progression and chemoresistance. In the present study, we explored the association of SNPs and haplotypes of the ET-1 gene with the risk of HRPC. We genotyped three SNPs (rs1800541, rs2070699 and rs5370) in the ET-1 gene in a case-control study; 234 CaP patients who developed HRPC within six years after androgen deprivation therapy was used as HRPC cases, and 234 age- and primary therapy-matched CaP patients who had not developed HRPC within six years after androgen deprivation therapy were used as non-HRPC controls. Our results revealed that the G allele at rs1800541 and the G allele at rs2070699 were respectively associated with reduced and increased risk of HRPC at borderline statistical significance (p=0.047 and p=0.058, respectively). With adjustment for potential confounders including body mass index, initial Gleason score at diagnosis of CaP, and post-treatment nadir serum PSA level, we found that rs1800541-rs2070699 TG haplotype was significantly associated with increased risk of HRPC (p=0.033; adjusted OR, 2.10; 95% CI, 1.37-5.04). In conclusion, this study provides the first evidence that a 2-SNP haplotype of the ET-1 gene is associated with increased risk of HRPC, which adds new insights into early identification of CaP patients who are likely to develop HRPC in a later stage of the disease.

Identification of mitoxantrone as a new inhibitor of ROS1 fusion protein in non-small cell lung cancer cells

Mitoxantrone, an FDA-approved drug for multiple sclerosis and hormone refractory prostate cancer, is identified as a potent inhibitor of ROS1 fusion protein by in silico screening in non-small cell lung cancer cells. Mitoxantrone can suppress the phosphorylation of ROS1 and subsequently inhibit its downstream signaling pathway and thus induce cell apoptosis.

Analysis of Fascin-1 in Relation to Gleason Risk Classification and Nuclear ETS-Related Gene Status of Human Prostate Carcinomas: An Immunohistochemical Study of Clinically Annotated Tumours From the Wales Cancer Bank.

Although prostate-specific antigen (PSA) testing can identify early-stage prostate cancers, additional biomarkers are needed for risk stratification. In one study, high levels of the actin-bundling protein, fascin-1, were correlated with lethal-phase, hormone-refractory prostate cancer. Analyses of independent samples are needed to establish the value of fascin-1 as a possible biomarker. We examined fascin-1 by immunohistochemistry in tumour specimens from the Wales Cancer Bank in comparison with nuclear-located ETS-related gene (ERG), an emerging marker for aggressive prostate cancer. Fascin-1 was elevated in focal areas of a minority of tumours, yet fascin-1-positivity did not differentiate tumours of low-, intermediate-, or high-risk Gleason scores and did not correlate with PSA status or biochemical relapse after surgery. Stromal fascin-1 correlated with high Gleason score. Nuclear ERG was upregulated in tumours but not in stroma. The complexities of fascin-1 status indicate that fascin-1 is unlikely to provide a suitable biomarker for prediction of aggressive prostate cancers.

Determination of Cabazitaxel (An Anti-prostate cancer agent) by reverse phase liquid chromatography

Cabazitaxel is used in the treatment of hormone-refractory prostate cancer. It is a semisynthetic taxane that can be used as a precursor molecule obtained from yew tree needles. The authors have developed a stability indicating liquid chromatographic method for the determination of Cabazitaxel in pharmaceutical products. Shimadzu Model CBM-20A/20 Alite HPLC system (PDA detector) with Zorbax SB C18 column (150 mm × 4.6 mm i.d., 3.5 µm particle size) was selected for the quantification of Cabazitaxel. A mixture of tetra butyl ammonium hydrogen sulphate and methanol was used as the mobile phase with a flow rate of 1.0 mL/min (UV detection at 210 nm). The proposed analytical method was statistically validated and forced degradation studies were conducted. Cabazitaxel has shown linearity over the concentration range 0.1-200 µg/mL with regression equation y = 26145x + 22943 (r2=0.9997) and considerable degradation was observed in acidic, alkaline and oxidation conditions. The method is specific as the resolution of Cabazitaxelwas good in presence of its degradation products. This validated stability indicating liquid chromatographic method can be used for the determination of Cabazitaxel in biological studies as well as for the pharmaceutical products.

Cabazitaxel in Metastatic Castration-Resistant Prostate Cancer Patients Progressing after Docetaxel: A Prospective Single-Center Study

Purpose: The present study aims to evaluate the efficacy of cabazitaxel in combination with prednisone treatment in Italian patients affected by hormone-refractory metastatic castration-resistant prostate cancer (mCRPC) previously treated with docetaxel plus prednisone. Methods: Thirty patients with mCRPC were enrolled between June 2013 and January 2016 (the last follow-up was in January 2016). Cabazitaxel was used according to the summary of product characteristics and administered at a dose of 25 mg/m² every 3 weeks plus oral prednisone at a dose of 5-mg tablets twice a day continuously. The reduction in serum prostate-specific antigen (PSA) was the primary endpoint while reducing pain, safety, progression-free survival, response rate and overall survival (OS) were secondary endpoints. Results: Cabazitaxel was well tolerated, showing a manageable toxicity profile, associated with a modest objective response rate and a good reduction in PSA levels. Only 12 patients (40%) had a partial response, 10 patients (33%) showed stabilization of disease and 8 (27%) experienced disease progression. The median OS was 14.8 months (95% CI: 11.6-19.8). The linear regression analysis revealed that PSA response was an important predictor of OS, showing a positive correlation with OS (β = 0.377, p < 0.01). Conclusions: Three-week treatment with cabazitaxel was found to be valid and was a well-tolerated treatment option for patients with mCRPC after a first-line docetaxel treatment.

Role of Colloidal Drug Delivery Carriers in Taxane-mediated Chemotherapy: A Review.

Chemotherapy is one of the most frequently employed and reliable treatment options for the management of a variety of cancers. Taxanes (paclitaxel, docetaxel and cabazitaxel) are frequently prescribed to treat breast cancer, hormone refractory prostate cancer, non-small cell lung cancer and ovarian cancer. Most of the commercial products of taxanes are available as injectables, which are not patient compliant and are associated with frequent side effects like ototoxicity, baldness and neurotoxicity. Most of these concerns are ascribable to the presence of toxic solvents in these commercial formulations, which are used to solubilize these drug(s). However, there have been several attempts to develop toxic solvent free taxane formulations, especially employing novel drug delivery systems (NDDS). These systems have been reported to result in the advancement of anticancer activity, therapeutic index, stability, biocompatibility, tissue or organ targeting, encapsulation capacity, tissue permeability, oral bioavailability, reduced toxicity and reduced incidences of abnormal reactions, sustained and controlled release in comparison to the conventional solvent-based formulations. The review is an attempt to analyze the potential of NDDS-mediated taxane delivery for safer and effective cancer chemotherapy.

Re: Reevaluating PSA Testing Rates in the PLCO Trial

available at http://www.ncbi.nlm.nih.gov/pubmed/27262168 Editorial Comment: The role of circulating tumor cells (CTCs) in predicting prostate cancer stage and prognosis has been studied literally since I was a third year resident in the early 1990s. Initial studies were neither conclusive nor provocative, and the use of CTCs really never caught on as a standard modality. Through the years the science has improved in many ways. CTCs can be more readily and reliably identified. CTCs can be accurately quantified through automated methods. And now, most importantly, CTCs can be well characterized at the cell surface and the intracellular protein level. In this study the authors use methods of characterizing CTCs as a means of determining the presence of an androgen receptor mutation, the AR-V7 splice variant. This mutation has previously been demonstrated as a potential mechanism of enzalutamide resistance and is known to be present in a significant proportion of men with progression on enzalutamide therapy. The authors were able to determine the presence of nuclear AR-V7 protein in CTCs in a series of men undergoing therapy for castration resistant prostate cancer (CRPC). Men with expression of nuclear AR-V7 protein were more commonly found among those who had previously been treated with 1 or more therapies for CRPC, and the splice variant was rare in those not previously treated. Men with nuclear AR-V7 protein expression were more likely to do poorly on AR directed therapies compared to those without AR-V7 protein expression, and they were more likely to fare better with a taxane than an AR targeting agent. The use of these elegant molecular techniques may allow direction in the often unclear practice of sequencing therapeutic agents in men with CRPC. Samir S. Taneja, MD Suggested Reading Mejean A, Vona G, Nalpas B et al: Detection of circulating prostate derived cells in patients with prostate adenocarcinoma is an independent risk factor for tumor recurrence. J Urol 2000; 163: 2022. Okegawa T, Nutahara K and Higashihara E: Prognostic significance of circulating tumor cells in patients with hormone refractory prostate cancer. J Urol 2009; 181: 1091. Small AC, Gong Y, Oh WK et al: The emerging role of circulating tumor cell detection in genitourinary cancer. J Urol 2012; 188: 21. Re: Addition of Docetaxel, Zoledronic Acid, or Both to First-Line Long-Term Hormone Therapy in Prostate Cancer (STAMPEDE): Survival Results from an Adaptive, Multiarm, Multistage, Platform Randomised Controlled Trial N. D. James, M. R. Sydes, N. W. Clarke, M. D. Mason, D. P. Dearnaley, M. R. Spears, A. W. Ritchie, C. C. Parker, J. M. Russell, G. Attard, J. de Bono, W. Cross, R. J. Jones, G. Thalmann, C. Amos, D. Matheson, R. Millman, M. Alzouebi, S. Beesley, A. J. Birtle, S. Brock, R. Cathomas, P. Chakraborti, S. Chowdhury, A. Cook, T. Elliott, J. Gale, S. Gibbs, J. D. Graham, J. Hetherington, R. Hughes, R. Laing, F. McKinna, D. B. McLaren, J. M. O’Sullivan, O. Parikh, C. Peedell, A. Protheroe, A. J. Robinson, N. Srihari, R. Srinivasan, J. Staffurth, S. Sundar, S. Tolan, D. Tsang, J. Wagstaff and M. K. Parmar

Non-immunosuppressive triazole-based small molecule induces anticancer activity against human hormone-refractory prostate cancers: the role in inhibition of PI3K/AKT/mTOR and c-Myc signaling pathways.

A series of triazole-based small molecules that mimic FTY720-mediated anticancer activity but minimize its immunosuppressive effect have been produced. SPS-7 is the most effective derivative displaying higher activity than FTY720 in anti-proliferation against human hormone-refractory prostate cancer (HRPC). It induced G1 arrest of cell cycle and subsequent apoptosis in thymidine block-mediated synchronization model. The data were supported by a decrease of cyclin D1 expression, a dramatic increase of p21 expression and an associated decrease in RB phosphorylation. c-Myc overexpression replenished protein levels of cyclin D1 indicating that c-Myc was responsible for cell cycle regulation. PI3K/Akt/mTOR signaling pathways through p70S6K- and 4EBP1-mediated translational regulation are critical to cell proliferation and survival. SPS-7 significantly inhibited this translational pathway. Overexpression of Myr-Akt (constitutively active Akt) completely abolished SPS-7-induced inhibitory effect on mTOR/p70S6K/4EBP1 signaling and c-Myc protein expression, suggesting that PI3K/Akt serves as a key upstream regulator. SPS-7 also demonstrated substantial anti-tumor efficacy in an in vivo xenograft study using PC-3 mouse model. Notably, FTY720 but not SPS-7 induced a significant immunosuppressive effect as evidenced by depletion of marginal zone B cells, down-regulation of sphingosine-1-phosphate receptors and a decrease in peripheral blood lymphocytes. In conclusion, the data suggest that SPS-7 is not an immunosuppressant while induces anticancer effect against HRPC through inhibition of Akt/mTOR/p70S6K pathwaysthat down-regulate protein levels of both c-Myc and cyclin D1, leading to G1 arrest of cell cycle and subsequent apoptosis. The data also indicate the potential of SPS-7 since PI3K/Akt signalingis responsive for the genomic alterations in prostate cancer.

Evaluation of the palliative benefit and toxicity of Ra-223 treatment of men with hormone refractory prostate cancer in a community setting.

225 Background: The ALSYMCA (Alpharadin in Symptomatic Prostate Cancer) trial was a phase III, placebo controlled, randomized trial in which 921 men with bone metastasis from hormone refractory prostate cancer (HRPC) were randomly assigned to receive radium-223 (Ra-223) or placebo. Ra-223 produced a 30% survival benefit, with a median survival of 14.9 months compared to 11.3 months for patients treated with a placebo, which led to FDA approval in 2013. Methods: We identified through the nuclear medicine records 11 patients who started Ra-223 between March 15, 2013 and December 10, 2015. The Wilcoxon signed rank test was used to compare the published results of the ALSYMPCA patients with those from our institution. Results: The Hodges-Lehman estimate of the median survival of our patients from the date of the first Ra-223 infusion was 7.8 months. The 95% confidence interval (CI) was (2.8, 14.7; p = 0.0122) indicating our patients had a significantly shorter survival. Our patients did not have a statistically significant worse rate of anemia, neutropenia, or thrombocytopenia. Only 27.3% (95% CI: 6.0, 61.0%) of our patients completed all 6 planned infusions significantly less than 63% for the ALSYMPCA patients treated with Ra-223 (p = 0.0239), but not statistically different than the placebo patients (p = 0.236). The median survival from the last Ra-223 was 3.53 months. We used 3 measures of treatment effectiveness: (1) reduction in the pain scores, (2) reduction in the serum PSA, and (3) reduction in the alkaline phosphatase. Compared to the pre-treatment values, numerical reductions were seen at the last follow-up evaluation for both the pain scores and the alkaline phosphatase levels, but the reductions were not statistically significant. Conclusions: Not all patients with castration resistant prostate cancer benefit from Ra-223 to the same extent as the ALSYMPCA patients. It is important to identify patients with a sufficient life expectancy to benefit from this treatment.

Glyoxalase 2 Is Involved in Human Prostate Cancer Progression as Part of a Mechanism Driven By PTEN/PI3K/AKT/mTOR Signaling With Involvement of PKM2 and ERα.

Glyoxalase 2 (Glo2), together with glyoxalase 1 (Glo1), forms the main scavenging system of methylglyoxal, a potent pro-apoptotic agent mainly generated by glycolysis. An increased rate of glycolysis is a well known signature of cancer cells. As a survival strategy, Glo1 is overexpressed in many human malignant cells, including prostate cancer (PCa), where it plays a crucial role in progression. No information is available on the role of Glo2 in the same ambit. PCa is the most common malignancy affecting men in the western world. Progression to a lethal hormone-refractory PCa represents the major concern in this pathology. Therefore, a deeper understanding of the molecular mechanisms underlying PCa invasiveness and metastasis is urgently needed in order to develop novel therapeutic targets for this incurable state of the malignancy. Glo2 and Glo1 expression was examined in clinical samples of PCa by immunohistochemistry and in different PCa cell models by western blotting and quantitative real-time polymerase chain reaction. Gene silencing/overexpression and scavenging/inhibitory agents were used for functional analyses. We demonstrated that Glo2, together with Glo1, represents a novel mechanism in PCa progression as part of a pathway driven by PTEN/PI3K/AKT/mTOR signaling with involvement of PKM2 and ERα. Importantly, Glo1/Glo2 silencing did not alter the behavior of benign cells. Targeting glyoxalases metabolic pathway may represent a strategy to selectively inhibit advanced PCa. Prostate 77:196-210, 2017. © 2016 Wiley Periodicals, Inc.

Abstract 925: IL-4 / IL-13 mediated cell-to-cell fusion in prostate cancer progress

Abstract Poorly understood interactions between prostate cancer (PCa) cells and their microenvironment direct the epithelial to mesenchymal transition (EMT) during disease progression. Cell-to-cell fusion, such as cell fusion in muscles and placenta, is one of the ways in which cells can drastically change their properties. Cell fusion has been proposed to promote tumor cell diversity and the ability to metastasize. Metastatic disease has been also suggested to depend on the interleukin 4 (IL-4) signaling. Patients with hormone-refractory PCa have elevated levels of IL-4 and it has been proposed that targeting IL4 -receptor interactions limits metastatic disease. Here, to mimic conditions at the interphase between rhabdosphincter myofibers and apical anterior regions of prostatic gland we explored interactions of PC3 cells (human PCa cell line) with skeletal muscle cells. Co-culturing of these cells resulted in an elevated concentration of related cytokines IL-4 and/or IL-13 in the tissue culture medium from the co-cultured cells but not from muscle cells cultured on their own. The co-culturing (i); the application of the conditioned medium from the co-cultured cells (ii); and treating PC3 cells with recombinant IL-4 (iii) resulted in a robust fusion between PC3 cells, in a significant increase in the percentage of PC3 cells expressing stem cell marker CD133, in the drug resistance, in an increase of the expression of mesenchymal-characteristic markers pAKT, MMP9, desmin, and in the loss of E-cadherin that is another marker for EMT. The described effects required co-culturing of the PC3 cells and muscle cells. Moreover, the co-culturing and recombinant IL-4 application also upregulated the expression of the two proteins - annexin A5 and syncytin that play important role in several cell-cell fusion processes. Significantly, application of either (i) IL-4-neutralizing antibodies or (ii) peptide inhibitors of syncytin; and (iii) lowering annexin A5 expression suppressed cell proliferation and fusion. Our findings substantiate a hypothesis that IL-4 and IL-13 in the microenvironment of PCa cells promote the EMT and raise metastatic potential of PCa cells by their fusion mediated by upregulated syncytin- and annexin A5. Citation Format: Berna Uygur, Evgenia Leikina, Leonid Chernomordik. IL-4 / IL-13 mediated cell-to-cell fusion in prostate cancer progress. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 925.

Abstract 4731: Targeted therapies for prostate cancer: Strategies for efficient combinatorial approaches

Abstract Metastasis-associated protein 1(MTA1) is a cancer progression- related epigenetic regulator, which is overexpressed in hormone-refractory and metastatic prostate cancer (PCa). MTA1/HDAC unit is a part of the multi-protein nucleosome remodeling and deacetylation (NuRD) complex. In our previous studies we found that MTA1 expression is significantly increased in prostate-specific Pten-null model, and that potent natural analog of resveratrol, pterostilbene (PTER), exerts its anti-tumorigenic effects by blocking MTA1-associated inactivation (deacetylation) of tumor suppressors. SAHA (suberoylanilide hydroxamine, vorinostat) is a histone deacetylase (HDAC) inhibitor that has been shown to be an effective inhibitor of tumor cell growth. We hypothesize that targeting MTA1/HDAC unit of NuRD complex using PTER in combination with SAHA could act additively or synergistically to block prostate tumor progression in vivo with higher efficacy and lower toxicity. In the current study, we utilized the prostate-specific Pten-null mouse model to evaluate the MTA1/HDAC mediated anti-cancer efficacy of combinatorial approach for dietary PTER and clinically approved HDAC inhibitor, SAHA. After a series of carefully designed breeding strategies and genotyping, we collected 30 prostate-specific luciferase expressing Pten knockout (Pten f/f; Rosa26Luc/+; Pb-Cre4) male mice for our experiments. Prostate-specific luciferase expression allowed non-invasive monitoring of prostate tumor growth in these animals. Mice were randomized into four groups: Vehicle control (10% DMSO); PTER (10 mg/kg bw) alone, SAHA (50 mg/kg bw) alone, and PTER + SAHA. Compounds were injected daily, i.p., starting at 8 weeks of age. Mice were sacrificed at week 18. Histopathological (H&amp;E, SMA, CK-8), immunohistochemical (Ki-67, cleaved caspase-3, CD31) and molecular evaluation (MTA1, pAkt, AR) of prostate tissues showed beneficial effects of treatments alone and more so in combination compared to the control group. Citation Format: Nasir A. Butt, Swati Dhar, Avinash Kumar, Agnes M. Rimando, Xu Zhang, Anait S. Levenson. Targeted therapies for prostate cancer: Strategies for efficient combinatorial approaches. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4731.

Abstract 427: Integrated PDEF and Twist1 expression distinguishes lethal prostate cancer from an indolent disease

Abstract Introduction: Prostate cancer (PCa) is the third most commonly diagnosed cancer in the world. Advanced genomic studies have characterized it as a molecularly heterogeneous disease with a multiple clinical spectrum ranging from indolent to highly aggressive. Conventional therapies produce a high rate of cure for patients with localized PCa, but there is no effective treatment for metastatic PCa. These facts underline the urgent, yet unmet, need for identification and characterization of new targets that can help distinguish metastatic PCa from an indolent disease, and pave a way for novel mechanism based anti-metastasis therapies against PCa. Our previous studies have shown that loss of PDEF, a putative tumor suppressor, could lead to more invasive phenotype in PCa cell lines through promoting Epithelial to Mesenchymal transition (EMT). In this study, we evaluate the role of PDEF and Twist1 in PCa through NCBI omnibus and The Cancer Genome Atlas. We also evaluated the mechanism by which PDEF is regulated epigenetically. Methods: PDEF expression was monitored by immunohistochemistry using tissue microarray. Western blot was employed to measure the PDEF level in PCa cell lines. PDEF and Twist1 gene expression was measured by real time PCR. The PDEF promoter was cloned and methylation specific PCR was performed. PDEF methylation in clinical samples was extracted from TCGA database and PDEF/Twist1 microarray data was extracted from GSE16560 in NCBI gene expression omnibus with R language. GraphPad prism was used to generate figure and statistical analysis. P &amp;lt; 0.05 is considered significant Results: IHC staining of PDEF on PCa patient samples and in commonly used PCa cell lines suggested an inverse correlation between the level of PDEF and Twist1. Over-expression of PDEF in PC3 cells inhibits Twist1 expression. DNA Methylation status near the promoter region of PDEF was negatively associated with the expression levels of PDEF in established PCa cells. These results suggest that PDEF levels are regulated in part by promoter methylation. Using TCGA data we identified 12 methylation site and the methylation level of multiple site correlates with the increased of Gleason Score (GS). Analysis of gene expression data from GSE16560 revealed that low expression of PDEF and high expression of Twist1 were independently associated with poor survival in PCa patients. Integrated PDEF and Twist1 expression can distinguished a high-risk group of people for hormone refractory PCa along with short median survival time. Conclusions: Loss of PDEF combined with gain of Twist1 expression can serve as a potential biomarker set for distinguishing aggressive PCa from an indolent disease. PDEF expression is epigenetically regulated in part by promoter hyper-methylation. Acknowledgement: Carroll W. Feist Endowed Chair Funds. Citation Format: Fengtian Wang, Sweaty Koul, Parveen K. Jaiswal, Runhua Shi, Glenn Mills, Hari K. Koul. Integrated PDEF and Twist1 expression distinguishes lethal prostate cancer from an indolent disease. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 427.

Abstract 23: Caloric restriction slows tumor growth and metastases in both hormone-sensitive and hormone-resistant prostate cancers

Abstract Introduction: The purpose of this study is to assess the effect of caloric restriction (CR) on prostate cancer (PCa) tumor burden, proliferation, and overall survival with and without radiation treatment (RT). Additionally, we determined if the beneficial effect of CR noted are due to a reduction in pro-inflammatory markers hypothesized to enhance PCa tumorgenesis. Methods: To assess the effect of CR in vivo, 40 male 12 week-old NCRNu-M mice were injected with LNCaP or PC3 tumor cells. Once tumors were palpable, mice were randomly assigned to one of four treatment groups in cohorts of 10: ad libitum (AL) diet, 6.5Gy of radiation (RT), 30% reduction in caloric intake (CR), or CR+RT. Tumor growth and proliferation rate were measured 3 times per week via calipers and live bioluminescent imaging. Additionally, PCa tumor tissue were analyzed to determine if CR can exert its effect on tumor growth and metastases via IGF-1R signaling pathway. Results: Adding CR to RT decreased tumor progression. In the PC3 murine model, when compared to AL, RT reduced tumor size by 22%, 77% with CR, and 80% with CR+RT. In the LNCaP murine model, compared with AL, CR reduced tumor size by 49% and a 55% reduction with CR+RT. Primary tumor formation began 9 weeks post tumor injection in the radiated cohort and was delayed to 15 weeks post tumor injection in the CR and CT+ RT cohorts. Additionally, time to metastasis was delayed with CR (86 days to metastasis in AL, 93 with RT, and 108 when combining CR+RT). Molecularly, CR decreased multiple members of the IGF-1R signaling pathway. The total IGF-1 and IGF-1R levels exhibited 50% reduction with CR and CR+RT but total INSR levels. CR also induced a significant decrease of pGSK3β and pAKT levels. Conclusions: For the first time, we have shown that decreasing calories by 30% in both hormone-sensitive and hormone-refractory prostate cancer models, enhance the efficacy of radiation. Our experiments show that even CR alone and in combination with RT can improve PCa tumor proliferation rate, tumor burden, time to metastasis, and overall survival. We hypothesize that these changes are in part, due to the decrease of the IGF-1R signaling pathway. We propose that CR may be used as a novel therapeutic intervention to enhance outcomes of radiation treatment by altering the molecular profile of prostate tumors. Citation Format: Robert S. Gitman, Meredith LaRose, Edouard J. Trabulsi, Ajay Palagani, Tiziana DeAngelis, William K. Kelly, Leonard G. Gomella, Nicole L. Simone. Caloric restriction slows tumor growth and metastases in both hormone-sensitive and hormone-resistant prostate cancers. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 23.

Bioactive natural products for chemoprevention and treatment of castration-resistant prostate cancer.

Prostate cancer (PCa), a hormonally-driven cancer, ranks first in incidence and second in cancer related mortality in men in most Western industrialized countries. Androgen and androgen receptor (AR) are the dominant modulators of PCa growth. Over the last two decades multiple advancements in screening, treatment, surveillance and palliative care of PCa have significantly increased quality of life and survival following diagnosis. However, over 20% of patients initially diagnosed with PCa still develop an aggressive and treatment-refractory disease. Prevention or treatment for hormone-refractory PCa using bioactive compounds from marine sponges, mushrooms, and edible plants either as single agents or as adjuvants to existing therapy, has not been clinically successful. Major advancements have been made in the identification, testing and modification of the existing molecular structures of natural products. Additionally, conjugation of these compounds to novel matrices has enhanced their bio-availability; a big step towards bringing natural products to clinical trials. Natural products derived from edible plants (nutraceuticals), and common folk-medicines might offer advantages over synthetic compounds due to their broader range of targets, as compared to mostly single target synthetic anticancer compounds; e.g. kinase inhibitors. The use of synthetic inhibitors or antibodies that target a single aberrant molecule in cancer cells might be in part responsible for emergence of treatment refractory cancers. Nutraceuticals that target AR signaling (epigallocatechin gallate [EGCG], curcumin, and 5α-reductase inhibitors), AR synthesis (ericifolin, capsaicin and others) or AR degradation (betulinic acid, di-indolyl diamine, sulphoraphane, silibinin and others) are prime candidates for use as adjuvant or mono-therapies. Nutraceuticals target multiple pathophysiological mechanisms involved during cancer development and progression and thus have potential to simultaneously inhibit both prostate cancer growth and metastatic progression (e.g., inhibition of angiogenesis, epithelial-mesenchymal transition (EMT) and proliferation). Given their multi-targeting properties along with relatively lower systemic toxicity, these compounds offer significant therapeutic advantages for prevention and treatment of PCa. This review emphasizes the potential application of some of the well-researched natural compounds that target AR for prevention and therapy of PCa.

Radiosensitization by the investigational NEDD8-activating enzyme inhibitor MLN4924 (pevonedistat) in hormone-resistant prostate cancer cells.

Salvage radiotherapy (SRT) is the first-line treatment for prostate cancer patients with biochemical recurrence following radical prostatectomy, and new specific radiosensitizers are in urgent need to enhance SRT effect. MLN4924 (also known as Pevonedistat), a specific inhibitor of NEDD8-activating enzyme, has recently entered phase I/II clinical trials in several malignancies. By inhibiting cullin neddylation, MLN4924 inactivates Cullin-RING ligases (CRL), which have been validated as an attractive radiosensitizing target. In our study, we demonstrate that MLN4924 can be used as a potent radiosensitizer in hormone-resistant prostate cancer cells. We found that MLN4924 inhibited cullin neddylation and sensitized prostate cancer cells to irradiation (IR). Mechanistically, MLN4924 enhanced IR-induced G2 cell-cycle arrest, by inducing accumulation of WEE1/p21/p27, three well-known CRL substrates. Importantly, siRNA knockdown of WEE1/p21/p27 partially abrogated MLN4924-induced G2 cell-cycle arrest, indicating a causal role of WEE1/p21/p27 in MLN4924-induced radiosensitization. Further mechanistic studies revealed that induction of DNA damage and apoptosis also contributed to MLN4924 radiosensitization in hormone-resistant prostate cancer cells. Our findings lay the foundation for future application of MLN4924 as a potential radiosensitizer in hormone refractory prostate cancer (HRPC).

Anti prostate cancer using PEGylated bombesin containing, cabazitaxel loading nano-sized drug delivery system

Context: Prostate cancer (PCa) is the second most-frequently diagnosed cancer in men. Cabazitaxel was approved for the treatment of patients with hormone-refractory metastatic prostate cancer previously treated with a docetaxel-containing regimen.Objective: In this study, bombesin (BN), a ligand reported to specifically target GRP overexpressing prostate tumor, was applied for the construction of lipid-polymer hybrid nanoparticles (LPNs), and used for the targeted delivery of cabazitaxel (CAB) to prostate cancer.Methods: BN-polyethylene glycol-1,2-Distearoyl-sn-glycero-3-phosphoethanolamine (BN-PEG-DSPE) was synthesized. CAB loaded, BN-PEG-DSPE contained LPNs (BN-CAB-LPNs) were prepared. Their particle size, zeta potential and drug encapsulation efficiency (EE) were evaluated. In vitro cytotoxicity study of BN-CAB-LPNs was tested in LNCaP human prostatic cancer cell line (LNCaP cells). In vivo anti-tumor efficacy of the carriers was evaluated on mice bearing prostate cancer model.Results: The optimum BN-CAB-LPNs formulations had a particle size of 184.9 nm and a 26.5 mV positive surface charge. The growth of LNCaP cells in vitro was obviously inhibited. BN-CAB-LPNs also displayed better anti-tumor activity than the other formulations in vivo.Conclusion: The results demonstrated that BN-CAB-LPNs can sufficiently deliver CAB to the cancer cells and enhance the anti-tumor capacity. Thus, BN-CAB-LPNs can be proved to be a superior nanomedicine which can achieve better therapeutic efficacy of prostate tumor.