Strategy For Prostate Cancer Therapy Research Articles

The potential role of purinergic signaling in cancer therapy: perspectives on anti-CD73 strategies for prostate cancer.

Purines and pyrimidines are signaling molecules in the tumor microenvironment that affect cancer immunity. The purinergic signaling pathways have been shown to play an important role in the development and progression of cancer. CD39 and CD73 are ectonucleotidases responsible for breaking down ATP or ADP into adenosine, which regulates immunosuppression in various types of cancer. These enzymes have been studied as a potential therapeutic target in immunotherapy, and recent research suggests a correlation between ectonucleotidases and clinical outcomes in cancer.Prostate cancer is the most diagnosed cancer in men, after non-melanoma skin tumors, and is the second leading cause of death in men in the world. Despite having long survival periods, patients often receive excessive or insufficient treatment. Within this complex landscape, the adenosine/CD73 pathway plays a crucial role. Therefore, this review aims to highlight new findings on the potential role of purinergic signaling in cancer treatment and emphasizes the importance of anti-CD73 as a pharmacological strategy for prostate cancer therapy.

Aptamer-modified Nanocarrier(s) for the Management of Prostate Cancer

Abstract: Prostate cancer remains a significant global health concern, necessitating the development of innovative therapeutic approaches. This editorial provides an overview of the current state of research on aptamer-modified nanocarriers as a novel strategy for prostate cancer therapy. Aptamers, known for their high specificity and affinity, have drawn much attention in both research and the pharmaceutical industry. The Systematic Evolution of Ligands by the Exponential Enrichment (SELEX) technique has enabled the development of aptamers that can selectively bind to target ligands based on their unique three-dimensional structures. Notably, the A10 aptamer, modified to target PSMA (Prostate-Specific Membrane Antigen), has demonstrated strong binding affinity and specificity to prostate cancer cells, offering promise as an efficient drug-delivery system. Additionally, biosensors, like the innovative apta-sensor targeting MUC1, have utilized aptamers to detect cancer through electrochemical signals. Additionally, aptamers have improved the pharmacological attributes of chemotherapeutic agents for prostate cancer treatment. Aptamer-- mediated drug delivery has offered enhanced drug delivery, targeting, cellular uptake, and minimizing side effects.

RGD-decorated nanoliposomes for combined delivery of arsenic trioxide and curcumin to prostate cancer cells.

Nanotechnology and drug co-delivery offera novel avenue in drug delivery research liposome-based co-delivery of anticancer drugs targeting the apoptosis pathway as a promising new approach to treat cancer. In this study, a co-delivery system of liposomes (arsenic trioxide/curcumin) modified with RGD peptide was designed to aim for enhancing the treatment of prostate cancer cells (PC3 cell line). Liposomal co-loaded curcumin and arsenic trioxide modified by RGD peptide (NLPs-RGD-Cur-ATO) were prepared by thin-layer lipid hydration techniques for the treatment of prostate cancer. The stability of the NLPs-RGD-Cur-ATO was evaluated by particle size analysis through dynamic light scattering (DLS) analysis and transmission electron microscopy (TEM). The percentage of cytotoxicity and apoptotic effect in PC3 cells treated with NLPs-RGD-Cur-ATO were detected by MTT and Annexin V-FITC (fluorescein isothiocyanate)/PI affinity assay, respectively. The particle size of NLPs-RGD-Cur-ATO was approximately 100nm, with an encapsulation efficiency of about 99.52% and 70.61%, for ATO and Cur, respectively. Besides, NLPs-RGD-Cur-ATO displayed an enhanced anti-proliferative effect, increased the percentage of apoptotic cells 98 ± 1.85% (p < 0.0001), and significantly reduced EGFR gene expression level (p < 0.001) in the cell line tested. These results indicated that our NLPs-RGD-Cur-ATO co-delivery system was a promising strategy for prostate cancer therapy.

Management of prostate cancer by targeting 3βHSD1 after enzalutamide and abiraterone treatment

SummaryNovel strategies for prostate cancer therapy are required to overcome resistance to abiraterone and enzalutamide. Here, we show that increasing 3βHSD1 after abiraterone and enzalutamide treatment is essential for drug resistance, and biochanin A (BCA), as an inhibitor of 3βHSD1, overcomes drug resistance. 3βHSD1 activity increases in cell lines, biopsy samples, and patients after long-term treatment with enzalutamide or abiraterone. Enhanced steroidogenesis, mediated by 3βHSD1, is sufficient to impair enzalutamide function. In patients, accelerated abiraterone metabolism results in a decline of plasma abiraterone as disease progresses. BCA inhibits 3βHSD1 and suppresses prostate cancer development alone or together with abiraterone and enzalutamide. Daidzein, a BCA analog of dietary origin, is associated with higher plasma abiraterone concentrations and prevented prostate-specific antigen (PSA) increases in abiraterone-resistant patients. Overall, our results show that 3βHSD1 is a promising target to overcome drug resistance, and BCA suppresses disease progression as a 3βHSD1 inhibitor even after abiraterone and enzalutamide resistance.

The marine factor 3,5-dihydroxy-4-methoxybenzyl alcohol suppresses growth, migration and invasion and stimulates death of metastatic human prostate cancer cells: targeting diverse signaling processes.

Prostate cancer is metastatic cancer and is the second leading cause of cancer-related death in men. It is needed to develop more effective treatment for metastatic prostate cancer. The present study investigates whether the novel factor 3,5-dihydroxy-4-methoxybenzyl alcohol (DHMBA), which was isolated from marine oyster, suppresses the activity of metastatic human prostate cancer PC-3 or DU-145 cells. Culture of DHMBA (1 or 10 µM) suppressed colony formation and growth of PC-3 or DU-145 cells in vitro. Suppressive effects of DHMBA on cell proliferation were not occurred by culturing with intracellular signaling inhibitors. Mechanistically, DHMBA (10 µM) reduced the levels of key proteins linked to promotion of cell growth, including Ras, PI3K, Akt, MAPK, and mTOR in PC-3 cells. Interestingly, DHMBA increased the levels of cancer suppressor p53, p21, Rb, and regucalcin. Moreover, culture of DHMBA simulated the death of PC-3 and DU-145 cells. This effect was implicated to caspase-3 activation in cells. Interestingly, the effects of DHMBA on cell proliferation and death were blocked by culturing with an inhibitor of aryl hydrocarbon receptor linked to transcriptional regulation. Furthermore, culture of DHMBA inhibited production of reactive oxygen species in PC-3 or DU-145 cells. Of note, DHMBA blocked migration and invasion by diminishing their related protein levels, including NF-κB 65, caveolin-1 and integrin β1. The novel marine factor DHMBA was demonstrated to suppress metastatic prostate cancer cells via targeting diverse signaling pathways. This study may provide a new strategy for prostate cancer therapy with DHMBA.

Tumor irradiation combined with minimally invasive surgery (vascular-targeted photodynamic therapy) enhances anti-tumour effects in preclinical prostate cancer

Hanna T Sjoberg, Yiannis Philippou, Anette L Magnussen, Iain DC Tullis, Esther Bridges, Andrea Chatrian, Joel Loefebvre, Ka Ho Tam, Emma A Murphy, Jens Rittscher, Dina Preise, Lilach Agemy, Tamar Yechezkel, Sean C Smart, Paul Kinchesh, Stuart Gilchrist, Danny P Allen, David A Scheiblin, Stephen J Lockett, David A Wink, Alastair D Lamb, Ian G Mills, Adrian Harris, Ruth J Muschel, Boris Vojnovic, Avigdor Scherz, Freddie C Hamdy, Richard J Bryant.&#x0D; &#x0D; Introduction There is an important clinical need to improve the treatment of high risk localised and locally advanced prostate cancer (PCa), and to reduce the side effects of these treatments. We hypothesised that multi-modality therapy combining radiotherapy and vascular-targeted photodynamic therapy (VTP) could PCa tumour control compared against monotherapy with each of these treatments alone. This could provide proof-of-concept to take to the clinic. VTP is a minimally invasive focal surgical therapy for localised PCa, which rapidly destroys targeted tumours through vascular disruption. Tumour vasculature is characterised by vessel immaturity, increased permeability, aberrant branching and inefficient flow. Fractionated radiotherapy (FRT) alters the tumour microenvironment and promotes transient vascular normalisation.&#x0D; Materials and Methods We investigated whether sequential delivery of FRT followed by VTP 7 days later improves PCa tumour control compared to monotherapy with FRT or VTP alone.&#x0D; Results FRT induced vascular normalisation changes in PCa flank tumour allografts, improving vascular function as demonstrated using dynamic contrast enhanced magnetic resonance imaging. FRT followed by VTP significantly delayed tumour growth in flank PCa allograft pre-clinical models, compared with monotherapy with FRT or VTP alone, and improved overall survival.&#x0D; Conclusion Taken together, these results suggest that combining FRT and VTP could become a promising multimodal clinical strategy in PCa therapy. This provides proof-of-concept for this multi-modality therapy approach to take forward to early phase clinical trials.

PSMA-targeted arsenic nanosheets: a platform for prostate cancer therapy via ferroptosis and ATM deficiency-triggered chemosensitization.

Ferroptosis, a newly recognized form of non-apoptotic cell death, has recently been introduced for effective cancer therapy. The reported ferroptosis-inducing nanomaterials mainly consisted of metal-based components. Herein, we designed an inorganic metal-free nanoplatform, PSMA-targeted arsenic nanosheets (PMANs), which simultaneously increased glutathione (GSH) consumption, suppressed solute carrier family 7 member 11 (SLC7A11) and glutathione-dependent peroxidase 4 (GPX4) expression, and promoted the generation of reactive oxygen species (ROS) and lipid peroxides (LPO). In addition, owing to the large surface area, PMANs efficiently transported doxorubicin (DOX) to prostate cancer for synergistic therapy. Surprisingly, we found that PMANs could sensitize prostate cancer cells to DOX through downregulating the expression of ataxia telangiectasia mutated (ATM), which further augmented the GPX4 downregulation-mediated ferroptotic tumoricidal effect. Given that arsenic trioxide has been routinely and successfully used in the clinical treatment of leukemia for a long time, we anticipate that PMANs will offer a promising strategy for prostate cancer therapy.

Macrophages expedite cell proliferation of prostate intraepithelial neoplasia through their downstream target ERK.

The risk factors for prostate cancer include a high-fat diet and obesity, both of which are associated with an altered cell environment including increased inflammation. It has been shown that chronic inflammation due to a high-fat diet or bacterial infection has the potential to accelerate prostate cancer as well as its precursor, prostatic intraepithelial neoplasia (PIN), development. However, the underlying mechanism of how chronic inflammation promotes prostate cancer development, especially PIN, remains unclear. In this study, we showed that more macrophages were present in PIN areas as compared to the normal areas of human prostate. When co-culturing PIN cells with macrophages in 3D, more PIN cells had nuclear localized cyclin D1, indicating that macrophages enhanced PIN cell proliferation. We identified ICAM-1 and CCL2 as chemoattractants expressed by PIN cells to recruit macrophages. Furthermore, we discovered that macrophage-secreted cytokines including C5a, CXCL1, and CCL2 were responsible for increased PIN cell proliferation. These three cytokines activated ERK and JNK signaling in PIN cells through a ligand-receptor interaction. However, only blockade of ERK abolished macrophage cytokines-induced cell proliferation of PIN. Overall, our results provide a mechanistic view on how macrophages activated through chronic inflammation can expedite PIN progression during prostate cancer development. The information from our work can facilitate a comprehensive understanding of prostate cancer development, which is required for improvement of current strategies for prostate cancer therapy.

Combination Therapy of Prostate Cancer by Oncolytic Adenovirus Harboring Interleukin 24 and Ionizing Radiation.

Prostate cancer is a common malignant tumor and the second leading cause of cancer-related death in men. Radiation therapy is a curative treatment for localized prostate cancer and has a limited effect for castration-resistant prostate cancer (CRPC). Interleukin 24 (IL-24) has a radiosensitizing effect in cancer cells. Our previous studies showed that ZD55-IL-24, an oncolytic adenovirus harboring IL-24, had better anti-tumor effect with no toxicity to normal cells. In this study, we evaluated the synergistic anti-tumor effect of oncolytic adenovirus ZD55-IL-24 combined with radiotherapy in prostate cancer. In Vitro and In Vivo experiments showed that the combined therapy significantly inhibited the growth of prostate cancer and provoked apoptosis of prostate cancer cells. In conclusion, the combination of ionizing radiation and oncolytic adenovirus expressing IL24 could achieve synergistic anti-tumor effect on prostate cancer, and is a promising strategy for prostate cancer therapy.

A Novel Fully Human Antibody targeting Extracellular Domain of PSMA Inhibits Tumor Growth in Prostate Cancer.

Prostate cancer is the most commonly diagnosed malignancy in men and the second leading cause of cancer-related death. It is of vital importance to develop new strategies for prostate cancer therapy. PSMA (prostate-specific membrane antigen) is specifically expressed in prostate cancer and the neovasculature of certain cancer types, thus is considered to be an ideal target for cancer therapy. In our previous study, we have obtained a PSMA-specific single-chain variable fragment (scFv), named gy1, from a large yeast display naïve human scFv library. In this study, we reconstructed the PSMA scFv into a fully human antibody (named PSMAb) and evaluated its characterization both in vitro and in vivo We showed that PSMAb can specifically bind with and internalize into PSMA+ cells. The binding affinity of PSMAb is measured to be at nanomolar level, and PSMAb has very good thermostability. In vivo study showed that near IR dye-labeled PSMAb can specifically localize at PSMA+ tumors, and the application of PSMAb in vivo significantly inhibited the growth of PSMA+ tumors, but not PSMA- tumors. At the studied doses, no obvious toxicity was observed when applied in vivo, as shown by the relative normal liver and kidney function and normal structure of important organs, shown by hematoxylin and eosin staining. In addition, PSMAb may inhibit tumor growth through antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity mechanisms. Our results indicated that the novel fully human antibody, PSMAb, deserve further study for PSMA-targeted diagnosis and therapy for prostate cancer and other cancer types with vascular PSMA expression.

Functional Silencing of HSD17B2 in Prostate Cancer Promotes Disease Progression.

Steroidogenic enzymes are essential for prostate cancer development. Enzymes inactivating potent androgens were not investigated thoroughly, which leads to limited interference strategies for prostate cancer therapy. Here we characterized the clinical relevance, significance, and regulation mechanism of enzyme HSD17B2 in prostate cancer development. HSD17B2 expression was detected with patient specimens and prostate cancer cell lines. Function of HSD17B2 in steroidogenesis, androgen receptor (AR) signaling, and tumor growth was investigated with prostate cancer cell lines and a xenograft model. DNA methylation and mRNA alternative splicing were investigated to unveil the mechanisms of HSD17B2 regulation. HSD17B2 expression was reduced as prostate cancer progressed. 17βHSD2 decreased potent androgen production by converting testosterone (T) or dihydrotestosterone (DHT) to each of their upstream precursors. HSD17B2 overexpression suppressed androgen-induced cell proliferation and xenograft growth. Multiple mechanisms were involved in HSD17B2 functional silencing including DNA methylation and mRNA alternative splicing. DNA methylation decreased the HSD17B2 mRNA level. Two new catalytic-deficient isoforms, generated by alternative splicing, bound to wild-type 17βHSD2 and promoted its degradation. Splicing factors SRSF1 and SRSF5 participated in the generation of new isoforms. Our findings provide evidence of the clinical relevance, significance, and regulation of HSD17B2 in prostate cancer progression, which might provide new strategies for clinical management by targeting the functional silencing mechanisms of HSD17B2.See related commentary by Mostaghel, p. 1139.

Design, synthesis, and biological evaluation of 2-(5-methyl-1H-pyrazol-1-yl) acetamide derivatives as androgen receptor antagonists

Androgen receptor (AR) signaling is often activated in prostate cancer (PCa) cells, and blockage of this signaling by AR antagonists is an important strategy in PCa therapy. In this study, we designed and synthesized a series of 2-(5-methyl-1H-pyrazol-1-yl) acetamide derivatives, and evaluated their biological activities. AR luciferase reporter assay revealed compound 6f (59.7%) as a potent AR antagonist. Some compounds in this series showed higher anti-proliferative activity against LNCaP cells than Bicalutamide (IC50 = 35.0 μM), especially 6g with IC50 value of 13.6 μM.

Abstract 4863: Targeting the NFAT1-MDM2-MDMX network for prostate cancer therapy

Abstract The MDM2 and MDMX oncogenes are overexpressed in human prostate cancer, promoting tumor growth and metastasis. We recently demonstrate that the transcription factor NFAT1 activates MDM2 oncogene, independent of p53. The present study was designed to examine the effectiveness of targeting the NFAT1-MDM2-MDMX network for prostate cancer therapy. We identified a natural product NFAT1-MDM2 inhibitor, Inulanolide A (InuA) in the present study. The anticancer activity of InuA and its effects on the expression and stability of NFAT1, MDM2, and MDMX were examined in human prostate cancer cell lines with different genetic background, including LNCaP (p53 wild-type, AR positive), PC3 (p53 null, AR negative) and DU145 (p53 mutant, AR negative) cells. Our molecular docking studies predicted the binding ability and binding sites of InuA on NFAT1, MDM2, and MDMX. Its binding affinity and specificity were investigated using recombinant proteins and biotinylated InuA. To further demonstrate the specificity of InuA in targeting NFAT1-MDM2-MDMX network and the importance of NFAT1-MDM2-MDMX network in InuA's anticancer activity, the transient overexpression (OE) and knockdown (KD) experiments of these genes, as well as the pharmacological activators and inhibitors of NFAT1 signaling, were used. Our results indicated that InuA directly bound to the DNA binding domain of NFAT1, leading to a marked inhibition of MDM2 transcription. The compound also bound to the RING domains of MDM2 and MDMX with high affinity, inhibited the MDM2-MDMX binding, and enhanced MDM2 protein degradation. InuA inhibited the proliferation, migration, and invasion of prostate cancer cells, regardless of their p53 status and AR responsiveness. The expression of NFAT1, MDM2, and MDMX were important for InuA's anticancer activity, as demonstrated using the cancer cell lines with transient OE and KD of these genes. In conclusion, InuA represents a novel class of NFAT1-MDM2-MDMX inhibitor, and inhibiting the NFAT1-MDM2-MDMX network may be a promising strategy for prostate cancer therapy. (Supported by NIH R01 CA186662 and R01CA214019 and ACS RSG-15-009-01-CDD.) Citation Format: Jiang-Jiang Qin, Xin Li, Wei Wang, Ruiwen Zhang. Targeting the NFAT1-MDM2-MDMX network for prostate cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4863.

Activation of p53 and destabilization of androgen receptor by combinatorial inhibition of MDM2 and MDMX in prostate cancer cells.

Castration-resistant prostate cancer (CRPC) frequently develops after initial standard radiation and androgen deprivation therapy, leaving patients with limited further treatment options. Androgen receptor (AR) is a transcription factor that plays a key role in the initiation and progression of prostate cancer. p53, a major tumor suppressor that is rarely mutated in early-stages of prostate cancer, is often deregulated during prostate cancer progression. Here, we report an unusual co-amplification of MDM2 and MDMX, two crucial negative regulators of p53, in CRPC datasets. We demonstrate that combinatorial inhibition of MDM2 and MDMX, with nutlin-3 and NSC207895 respectively, has a profound inhibitory effect on cell proliferation of androgen-responsive, wild-type TP53 gene carrying prostate cancer cells LNCaP and 22Rv1. We further show that the combinatorial inhibition of MDM2 and MDMX not only activates p53, but also decreases cellular levels of AR and represses its function. Additionally, co-expression of MDM2 and MDMX stabilizes AR. Together, our results indicate that combinatorial inhibition of MDM2 and MDMX may offer a novel compelling strategy for prostate cancer therapy.

Autophagy activated by the c-Jun N-terminal kinase-mediated pathway protects human prostate cancer PC3 cells from celecoxib-induced apoptosis.

The aim of the present study was to investigate the role of autophagy in celecoxib-induced apoptosis in human hormone-insensitive prostate cancer cell line PC3 cells and to explore the underlying molecular mechanism leading to autophagic activation. A cell viability assay was applied to investigate the effect of various concentrations of celecoxib (0, 40, 60, 80, 100 and 120 µmol/l) on PC3 cells for 24 and 48 h, respectively. The 50% inhibitory concentration of celecoxib for 24 h was chosen for subsequent experiments. Annexin V-fluorescein isothiocyanate/propidium iodide double staining flow cytometry, as well as caspase 3 and poly (ADP-ribose) polymerase proteins detected by western blotting, were applied to analyze cellular apoptosis induced by celecoxib. Ultrastructural cellular changes observed by transmission electron microscopy and the level of LC-3 II and P62 detected by western blotting were used to determine the activation of autophagy. It was demonstrated that celecoxib induced apoptosis and activated autophagy in PC3 cells in a dose- and time-dependent manner. Furthermore, flow cytometry and western blotting were applied to elucidate whether the role of autophagy in celecoxib-induced apoptosis is protective or destructive. Blockade of autophagy markedly increased apoptosis, suggesting that celecoxib-activated autophagy was cytoprotective. Additionally, c-jun-N-terminal kinase (JNK) was demonstrated to have a role in autophagic activation, and suppression of JNK was able to reduce autophagy and increase apoptosis. In conclusion, the results of the present study indicate that celecoxib induces apoptosis in PC3 cells; however, celecoxib also activates JNK-mediated autophagy, which exerts cytoprotective effects in prostate cancer PC3 cells. Blockade of autophagy via the JNK-mediated pathway may provide a promising strategy for prostate cancer therapy.

Multi-drug loaded micelles delivering chemotherapy and targeted therapies directed against HSP90 and the PI3K/AKT/mTOR pathway in prostate cancer.

BackgroundAdvanced prostate cancers that are resistant to all current therapies create a need for new therapeutic strategies. One recent innovative approach to cancer therapy is the simultaneous use of multiple FDA-approved drugs to target multiple pathways. A challenge for this approach is caused by the different solubility requirements of each individual drug, resulting in the need for a drug vehicle that is non-toxic and capable of carrying multiple water-insoluble antitumor drugs. Micelles have recently been shown to be new candidate drug solubilizers for anti cancer therapy.MethodsThis study set out to examine the potential use of multi-drug loaded micelles for prostate cancer treatment in preclinical models including cell line and mouse models for prostate cancers with Pten deletions. Specifically antimitotic agent docetaxel, mTOR inhibitor rapamycin, and HSP90 inhibitor 17-N-allylamino-17-demethoxygeldanamycin were incorporated into the micelle system (DR17) and tested for antitumor efficacy.ResultsIn vitro growth inhibition of prostate cancer cells was greater when all three drugs were used in combination compared to each individual drug, and packaging the drugs into micelles enhanced the cytotoxic effects. At the molecular level DR17 targeted simultaneously several molecular signaling axes important in prostate cancer including androgen receptor, mTOR, and PI3K/AKT. In a mouse genetic model of prostate cancer, DR17 treatment decreased prostate weight, which was achieved by both increasing caspase-dependent cell death and decreasing cell proliferation. Similar effects were also observed when DR17 was administered to nude mice bearing prostate cancer cells xenografts.ConclusionThese results suggest that combining these three cancer drugs in multi-drug loaded micelles may be a promising strategy for prostate cancer therapy.

Cytoplasmic, full length and novel cleaved variant, TBLR1 reduces apoptosis in prostate cancer under androgen deprivation.

TBLR1/TBL1XR1, a core component of the nuclear receptor corepressor (NCoR) complex critical for the regulation of multiple nuclear receptors, is a transcriptional coactivator of androgen receptor (AR) and functions as a tumor suppressor when expressed in the nucleus in prostate. Subcellular localization of a protein is critical for its function, and although TBLR1, as a transcriptional cofactor, has been primarily viewed as a nuclear protein, many cells also express variable levels of cytoplasmic TBLR1 and its cytoplasmic specific functions have not been studied. Prostate cancer (PCa) cells express moderately higher level of cytoplasmic TBLR1 compared to benign prostate cells. When comparing androgen-dependent (AD) to androgen-independent (AI) PCa, AI cells contain very high levels of TBLR1 cytoplasmic expression and low levels of nuclear expression. Overexpression of cytoplasmic TBLR1 in AD cells inhibits apoptosis induced by androgen deprivation therapy, either in an androgen free condition or in the presence of bicalutamide. Additionally, we identified a cytoplasmic specific isoform of TBLR1 (cvTBLR1) approximately 5 kDa lower in molecular weight, that is expressed at higher levels in AI PCa cells. By immunoprecipitation, we purified cvTBLR1 and using mass spectrometry analysis combined with N-terminal TMPP labeling and Edman degradation, we identified the cleavage site of cvTBLR1 at amino acid 89, truncating the first 88 amino acids of the N-terminus of the full length protein. Functionally, cvTBLR1 expressed in the cytoplasm reduced apoptosis in PCa cells and promoted growth, migration, and invasion. Finally, we identified a nuclear export signal sequence for TBLR1 cellular localization by deletion and site-directed mutagenesis. The roles of TBLR1 and cvTBLR1 provide novel insights into the mechanism of castration resistance and new strategies for PCa therapy.

DUP1 peptide modified micelle efficiently targeted delivery paclitaxel and enhance mitochondrial apoptosis on PSMA-negative prostate cancer cells.

Prostate tumor cell targeted peptide fragment conjugated to the nano drug delivery system is a promising strategy for prostate cancer therapy. In this work, an amphiphilic copolymer Chol–PEG–DUP1 (PEG–cholesterol conjugated with DUP1 peptide) has been synthesized and characterized by proton nuclear magnetic resonance spectrum (1H NMR). The paclitaxel (PTX) was encapsulated into the Chol–PEG–DUP1 micelles to obtain aqueous formulation with small particle size (within 200 nm) and high drug encapsulating efficiency. The DUP1 modified PTX micelle significantly enhanced the cytotoxicity of paclitaxel to PSMA negative prostate tumor cells (PC-3 cell) as demonstrated by MTT (IC50 = 15.8 μg/mL compared to 68.7 μg/mL of free PTX). Flow cytometry analysis and fluorescence images revealed the DUP1 peptide fragments on the surface of micelles increased drug uptake (2.08-fold) by PC-3 cells. Flow cytometry and immunoblotting analysis showed the DUP1 modified PTX micelle enhanced the mitochondrial apoptosis-inducing capacity of PTX to PC-3 cells. In conclusion, Chol–PEG–DUP1 modified micelle was a reasonable, facile, and economic drug delivery system to target the PSMA-negative prostate cancer.

A specific aptamer-cell penetrating peptides complex delivered siRNA efficiently and suppressed prostate tumor growth in vivo

ABSTRACTSpecific and efficient delivery of siRNA into intended tumor cells remains as a challenge, even though RNAi has been exploited as a new strategy for prostate cancer therapy. This work aims to address both specificity and efficiency of SURVIVIN-siRNA delivery by constructing a therapeutic complex using combinatorial strategies. A fusion protein STD was first expressed to serve as a backbone, consisting of streptavidin, a cell-penetrating peptide called Trans-Activator of Transcription (TAT) and a double-stranded RNA binding domain. A biotinylated Prostate Specific Membrane Antigen (PSMA) specific aptamer A10 and SURVIVIN-siRNA were then linked to STD protein to form the therapeutic complex. This complex could specifically targeted PSMA+ tumor cells. Compared to lipofectamine and A10-siRNA chimera, it demonstrated higher efficiency in delivering siRNA into target cells by 19.2% and 59.9%, and increased apoptosis by 16.8% and 26.1% respectively. Upon systemic administration, this complex also showed significant efficacy in suppressing tumor growth in athymic mice (p <0.001). We conclude that this therapeutic complex could specifically and efficiently deliver SURVIVIN-siRNA to target cells and suppressed tumor growth in vivo, which indicates its potential to be used as a new strategy in prostate cancer therapy

MP49-04 ROLE OF NUCLEAR AND CYTOPLASMIC TBLR1 IN PROSTATE CANCER

You have accessJournal of UrologyProstate Cancer: Basic Research IV1 Apr 2014MP49-04 ROLE OF NUCLEAR AND CYTOPLASMIC TBLR1 IN PROSTATE CANCER Garrett Daniels, Yirong Li, Lan Lin Gellert, Jonathan Melamed, Xinyu Wu, David Zhang, Daniel Meruelo, Susan Logan, Ross Basch, and Peng Lee Garrett DanielsGarrett Daniels More articles by this author , Yirong LiYirong Li More articles by this author , Lan Lin GellertLan Lin Gellert More articles by this author , Jonathan MelamedJonathan Melamed More articles by this author , Xinyu WuXinyu Wu More articles by this author , David ZhangDavid Zhang More articles by this author , Daniel MerueloDaniel Meruelo More articles by this author , Susan LoganSusan Logan More articles by this author , Ross BaschRoss Basch More articles by this author , and Peng LeePeng Lee More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.1105AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail Introduction and Objectives TBLR1, a core component of the nuclear receptor corepressor (NCoR) complex, shows both co-repressor and co-activator activities on nuclear receptors, although little is known about its effects on Androgen Receptor (AR). AR coactivators have primarily been viewed as pro-proliferative, however increasing evidence shows the importance of AR coactivators in regulating growth suppressive AR target genes. Cofactors may also have different functions depending on their cellular localization, switching from tumor suppressors to oncogenes or vice versa. In our study, we aim to assess the cofactor TBLR1 function, expression, and localization in prostate cancer. Methods Dual luciferase assays were performed using a reporter plasmid containing 4X androgen response elements. pBabe vector containing TBLR1 fusion proteins with the strong NLS(PKKKRKV) or NES (MLQKKLEELE) fused to the N-terminus was used to create stable cell lines and proliferation was measured by WST-1 assay. RNA levels were measured using quantitative RT-PCR and protein levels were measured by western blotting. ChIP was performed to determine the activation of AR target genes by TBLR1. Immunohistochemistry using TBLR1 antibody was performed on prostate cancer tissue microarray. Results We showed TBLR1 functions as a coactivator of AR in prostate cancer cells and the activation is both phosphorylation and 19S proteosome dependent. TBLR1 primarily localizes in the nucleus in benign prostate cell lines and tissue. In contrast, there is a significant reduction in nuclear TBLR1 expression in prostate cancer (PCa) cell lines and human tissue. Serum starvation induced growth arrest in cancer cells leads to translocation of TBLR1 expression from cytoplasmic to nuclear. Stable ectopic expression of nuclear TBLR1 leads to in vitro and in vivo growth suppression in AR-positive LNCaP cells by activation of androgen regulated genes responsible for differentiation/growth suppression of the prostate (e.g. NKX3.1, KRT18). Interestingly however, TBLR1 expressed in the cytoplasm promotes growth and growth in androgen free conditions. Conclusions There are distinct tumor suppressor and oncogenic functions of nuclear TBLR1 and cytoplasmic TBLR1 respectively. Nuclear TBLR1 selectively activates AR target genes important for growth suppression, whereas cytoplasmic TBLR1 plays a role in promoting growth in the absence of androgens. Further characterizing the role of TBLR1 in prostate could provide novel insights in developing strategies for prostate cancer therapy. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e503 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Garrett Daniels More articles by this author Yirong Li More articles by this author Lan Lin Gellert More articles by this author Jonathan Melamed More articles by this author Xinyu Wu More articles by this author David Zhang More articles by this author Daniel Meruelo More articles by this author Susan Logan More articles by this author Ross Basch More articles by this author Peng Lee More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...