Androgen-independent Cells Research Articles

MP83-15 A NOVEL THERAPY FOR CASTRATION-RESISTANT PROSTATE CANCER THROUGH INHIBITION OF ONCOGENIC MICRORNAS

You have accessJournal of UrologyProstate Cancer: Basic Research & Pathophysiology II1 Apr 2017MP83-15 A NOVEL THERAPY FOR CASTRATION-RESISTANT PROSTATE CANCER THROUGH INHIBITION OF ONCOGENIC MICRORNAS Tyler Sheetz, Dario Palmieri, Vincenzo Coppola, Anna Tessari, Joseph Mills, Ashley Braddom, Erika Reese, Claudia Foray, Kareesma Parbhoo, and Carlo M. Croce Tyler SheetzTyler Sheetz More articles by this author , Dario PalmieriDario Palmieri More articles by this author , Vincenzo CoppolaVincenzo Coppola More articles by this author , Anna TessariAnna Tessari More articles by this author , Joseph MillsJoseph Mills More articles by this author , Ashley BraddomAshley Braddom More articles by this author , Erika ReeseErika Reese More articles by this author , Claudia ForayClaudia Foray More articles by this author , Kareesma ParbhooKareesma Parbhoo More articles by this author , and Carlo M. CroceCarlo M. Croce More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.2583AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Recent studies have shed light on the role of microRNAs (miRs) in prostate cancer (PCa). miR-21 is among the most frequently deregulated miRs in cancer, and has been implicated in a castration-resistant prostate cancer (CRPC) phenotype. In addition to miR-21's many oncogenic effects, a positive feedback loop between miR-21 and the androgen receptor (AR) has been reported in PCa. Separately, miRs -221 and -222 have been shown to target tumor suppressor p27Kip1, leading to inhibition of apoptosis and aberrant proliferation. Nucleolin (NCL) is a multifunctional protein found in the nucleocytoplasm of most human cells, and is abnormally translocated to the cell membrane in cancer. One of the mechanisms by which NCL exerts its oncogenic activity is through the biogenesis of miRs -21, -221, and -222. 4LB5 is a novel single-chain fragment variable (scFv) antibody that binds preferentially to cancer cell membranes via the RNA-binding domain of NCL and inhibits production of these oncogenic miRs. The therapeutic and diagnostic potential of 4LB5 has been described in breast and hepatocellular carcinoma cells in previous studies. Given the supporting evidence, we aim to characterize the effects of 4LB5 on CRPC and compare its efficacy among androgen-dependent and androgen-independent cells. METHODS Levels of NCL expression in PCa cell lines DU145, PC3, and LNCaP were investigated with western blot (WB). Cell surface ELISA was performed to compare 4LB5 binding across PCa cell lines. Cell survival assay was performed using 50 nM 4LB5 or control buffer. Levels of mature and precursor forms of miRs in 4LB5-treated cells were assessed using quantitative real-time polymerase chain reaction. MDA-MB-231 cells were used a positive control in all experiments. RESULTS All cell lines expressed NCL as evidenced by WB, and downregulation of NCL was observed with siNCL transfection. ELISA results showed a strong exponential association between 4LB5 concentration and binding activity in DU145 (R2 = 0.9972), PC3 (R2 = 0.9887), and LNCaP (R2 = 0.9897) cells, with more binding units observed in PC3 and DU145 compared to LNCaP. 4LB5 significantly inhibited proliferation of DU145 (p = 0.000016) and PC3 (p = 0.0074) cells, but not LNCaP (p = 0.45). Treatment with 4LB5 caused downregulation of mature forms of miRs 21, 221, and 222 with expected upregulation of precursor forms in PC3 cells, but LNCaP cells exhibited the opposite effect. CONCLUSIONS 4LB5 binds CRPC cells and inhibits proliferation through abrogation of oncogenic miR production. 4LB5 could represent a novel therapeutic option in CRPC patients. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e1111-e1112 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Tyler Sheetz More articles by this author Dario Palmieri More articles by this author Vincenzo Coppola More articles by this author Anna Tessari More articles by this author Joseph Mills More articles by this author Ashley Braddom More articles by this author Erika Reese More articles by this author Claudia Foray More articles by this author Kareesma Parbhoo More articles by this author Carlo M. Croce More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

PD33-01 NON-CANONICAL ACTIVATION OF HEDGEHOG SIGNALING IN PROSTATE CANCER CELLS MEDIATED BY THE BINDING OF TRANSCRIPTIONALLY ACTIVE ANDROGEN RECEPTORS TO GLI TRANSCRIPTION FACTORS

You have accessJournal of UrologyProstate Cancer: Basic Research & Pathophysiology I1 Apr 2017PD33-01 NON-CANONICAL ACTIVATION OF HEDGEHOG SIGNALING IN PROSTATE CANCER CELLS MEDIATED BY THE BINDING OF TRANSCRIPTIONALLY ACTIVE ANDROGEN RECEPTORS TO GLI TRANSCRIPTION FACTORS Na Li, Sarah Truong, Mannan Nouri, Amy Anne Lubik, and Ralph Buttyan Na LiNa Li More articles by this author , Sarah TruongSarah Truong More articles by this author , Mannan NouriMannan Nouri More articles by this author , Amy Anne LubikAmy Anne Lubik More articles by this author , and Ralph ButtyanRalph Buttyan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.3315AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Canonical (smoothened-driven) Hedgehog signaling regulates the activities of Gli transcription factors and their ability to induce cell proliferation, motility and invasion. While there are numerous reports of constitutive Hedgehog/Gli activity in prostate cancer (PCa) cells, there is little evidence for a role of smoothened in this activity. Previously we showed that Gli proteins bind to full length- (FL-) and truncated- (t-) androgen receptors (ARs) at the N-terminal tau5 transactivation domain and that this binding co-activates AR transcriptional activity in PCa cells. Here we show, conversely, that transcriptionally active AR binds to a critical protein processing domain on Gli2/Gli3, alters their post-translational proteolytic processing and drives non-canonical Hedgehog signaling that facilitates androgen-independent growth of PCa cells. METHODS Site-specific mutations were introduced into the Gli2 C-terminal domain to identify the peptides involved in AR recognition. GST-pulldown was used to test binding of the mutated peptide to AR-tau5 peptide. Western blotting was used to quantify AR expression and the proteolytic states of Gli2 and 3 in LNCaP, LNCaP-AI, LN95 and VCaP cells. AR or Gli3 protein was knocked down with siRNAs. A Gli-luciferase reporter was used to measure functional Gli activity in cells and qPCR was used to determine how AR or Gli expression manipulation affected expressions of endogenous Gli-responsive genes. Proximity ligation assays with antibodies against AR and Gli3 was used to quantify the relative binding of these proteins in androgen-dependent and androgen-independent cell lines. RESULTS Mutations in a repeat serine/arginine-rich peptide in the C-terminal domain of Gli2 (aa820-836) blocked Gli2 binding to AR. This peptide encompasses the Gli protein processing domain that regulates a site-specific proteolysis that renders transcriptionally active Gli proteins into transcriptional repressors. Binding of liganded AR to this site blocked Gli proteolysis and maintained Gli in transcriptionally active states. Knockdown of AR in androgen growth-independent cell lines induced proteolytic inactivation of Gli in PCa cells. Knockdown of Gli3 in these cells induced a loss of AR protein. Proximity ligation assays showed that binding between Gli3 and AR was higher in androgen-independent cell lines. CONCLUSIONS Transcriptionally active AR protein binding to Gli proteins protects both from a natural degradation process and provides a non-canonical means to activate Hedgehog signaling in PCa cells. Since Gli proteins regulate the expressions of growth-promoting genes, our findings suggest that the growth effects of androgens on PCa cells are the results of a non-canonical Hedgehog activation process. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e593 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Na Li More articles by this author Sarah Truong More articles by this author Mannan Nouri More articles by this author Amy Anne Lubik More articles by this author Ralph Buttyan More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

MP83-06 COMBINATION THERAPY WITH EPI-002 AND PARP INHIBITOR FOR CASTRATION-RESISTANT PROSTATE CANCER

You have accessJournal of UrologyProstate Cancer: Basic Research & Pathophysiology II1 Apr 2017MP83-06 COMBINATION THERAPY WITH EPI-002 AND PARP INHIBITOR FOR CASTRATION-RESISTANT PROSTATE CANCER Yusuke Ito, C. Adriana Banuelos, and Marianne D. Sadar Yusuke ItoYusuke Ito More articles by this author , C. Adriana BanuelosC. Adriana Banuelos More articles by this author , and Marianne D. SadarMarianne D. Sadar More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.2574AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Following the results of the TOPARP-A Phase II trial, Olaparib, an oral PARP inhibitor was recently recognized as a FDA breakthrough therapy for metastatic castration recurrent prostate cancer (mCRPC) patients who have germline mutations in DNA repair genes. Although these results are noteworthy, the problem remains of how to treat the remaining mCRPC patients who do not have detectable germline mutations of DNA repair genes. Androgen receptor (AR) signaling regulates DNA repair in prostate cancer and AR modulating drugs induce DNA damage. Thus a combination approach using AR modulating drugs with a PARP inhibitor could be a promising option for the treatment of mCRPC. All currently approved AR modulating drugs, such as enzalutamide and abiraterone, either directly or indirectly target the AR C-terminus ligand-binding domain (LBD). Such drugs are often unsuccessful due to the emergence of AR splice variants (ARV-7, ARv567es) that are constitutively active and lack a LBD. EPI-002 is a first-in-class AR antagonist that targets both full-length AR and AR splice variants. Here we present data to support that a combination of Olaparib, a PARP inhibitor, and EPI-002 have beneficial effects in vitro. METHODS Combination therapy using EPI-002 and Olaparib were evaluated in vitro using human prostate cancer cells, LNCaP (androgen sensitive and expresses full-length AR) and LNCaP95, an androgen-independent cell line that expresses full-length AR and AR-V7 and is resistant to enzalutamide. The effects of monotherapy and combination therapy on cell cycle and DNA damage were analysed using FACS and Western blot. RESULTS Unexpectedly, EPI-002 caused an enormous decrease of Checkpoint kinase 1 (Chk1) protein levels in LNCaP and LNCaP95 cells. Chk1 is one of the important mediators in cell cycle checkpoint during the DNA damage response. Whereas, enzalutamide also decreased the expression of Chk1 in LNCaP, it had no effect on Chk1 levels in LNCaP95 cells. Consistent with these data, AR knockdown in LNCaP cells also decreased Chk1 levels. The PARP inhibitor, Olaparib, induced phosphorylation of Chk1. EPI-002 induced G1 cell cycle arrest whereas Olaparib induced G2/M cell cycle arrest. FACS analysis of γH2AX showed increased DNA damage with combination therapy compared to monotherapies. CONCLUSIONS EPI-002 decreased the expression of Chk1 in prostate cancer cells that expressed both full-length AR and AR-V7. Combination therapy of EPI-002 plus Olaparib may provide a therapeutic approach for prostate cancer that expresses AR-V7. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e1108 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Yusuke Ito More articles by this author C. Adriana Banuelos More articles by this author Marianne D. Sadar More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Astaxanthin Inhibits PC-3 Xenograft Prostate Tumor Growth in Nude Mice.

Prostate cancer (PCa), the most common malignancy in men, is a major cause of cancer deaths. A better understanding of the mechanisms that drive tumor initiation and progression may identify actionable targets to improve treatment of this patient group. As a dietary carotenoid, astaxanthin has been demonstrated to exert beneficial effects against inflammation, cardiovascular disease, oxidative damage, or different cancer sites. This study used intragastric administration of astaxanthin to detect its role on tumor proliferation, apoptosis, microRNA (miRNA) overexpression, and microbacteria composition change by establishing androgen-independent PCa cell PC-3 xenograft nude mice. Nude mice were inoculated with androgen-independent prostate cancer PC-3 cells subcutaneously. The intervention was started when tumors reached 0.5–0.6 cm in diameter. Mice were intragastrically administered 100 mg/kg astaxanthin (HA), 25 mg/kg astaxanthin (LA), or olive oil (TC). The results showed that 100 mg/kg astaxanthin significantly inhibited tumor growth compared to the TC group, with an inhibitory rate of 41.7%. A decrease of Ki67 and proliferating cell nuclear antigen (PCNA) as well as an increase of cleaved caspase-3 were observed in HA-treated tumors, along with increasing apoptotic cells, obtained by TUNEL assay. The HA significantly elevated the levels of tumor suppressors miR-375 and miR-487b in tumor tissues and the amount of Lactobacillus sp. and Lachnospiraceae in mice stools, while there was no significant difference between LA and TC groups. These results provide a promising regimen to enhance the therapeutic effect in a dietary supplement manner.

Inhibitory effect of a redox-silent analogue of tocotrienol on hypoxia adaptation in prostate cancer cells

Prostate cancer (PCa) is one of the most common cancers in Western countries and acquires a malignant phenotype, androgen-independent growth. PCa under hypoxia often has resistance to chemotherapy and radiotherapy. However, an effective therapy against PCa under hypoxia has not yet been established. In this report, we investigated the inhibitory effect of a redox-silent analogue of tocotrienol on the survival of a human androgen-independent PCa cell line (PC3) under hypoxia. We found that the redox-silent analogue exerted a cytotoxic effect on PC3 cells in a dose-dependent manner irrespective of either hypoxia or normoxia. Moreover, under hypoxia, the analogue dose dependently reduced the protein levels of hypoxia-inducible factor (HIF)-1α and HIF-2α. In addition, a specific inhibitor toward HIF-1α induced cytotoxicity on PC3 cells, whereas selective inhibition of HIF-2α exerted no effect. Furthermore, suppression of HIFs levels by the analogue in hypoxic PC3 cells was closely associated with the inactivation of Fyn, a member of the nonreceptor tyrosine kinase family, as confirmed by the action of a specific inhibitor toward the kinase (PP2). Taken together, these results suggest that the tocotrienol analogue could inhibit the survival of PC3 cells under hypoxia, mainly by the inhibition of Fyn/HIF-1α signaling, and this may lead to the establishment of a new effective therapy for androgen-independent PCa.

Oridonin induces G2/M cell cycle arrest and apoptosis via the PI3K/Akt signaling pathway in hormone-independent prostate cancer cells.

Oridonin is an active constituent isolated from the traditional Chinese herb Rabdosia rubescens, which exerts antitumor effects in experimental and clinical settings. However, its antitumor effects and underlying mechanisms on prostate cancer cells have not yet been clearly identified. In the present study, the androgen-independent prostate cancer PC3 and DU145 cell lines were used as models to investigate the effects and possible mechanisms of oridonin on cellular proliferation and apoptosis. Results demonstrated that oridonin inhibited cellular proliferation, and was able to significantly induce G2/M cell cycle arrest and apoptosis. Detailed signaling pathway analysis by western blotting demonstrated that the expression levels of p53 and p21 were upregulated, whereas the expression of cyclin-dependent kinase 1 was downregulated following oridonin treatment, which led to cell cycle arrest in the G2/M phase. Oridonin also upregulated the proteolytic cleaved forms of caspase-3, caspase-9 and poly (ADP-ribose) polymerase. Furthermore, the protein expression levels of B-cell lymphoma 2 were decreased and those of Bcl-2-associated X protein were increased following oridonin treatment. In addition, oridonin treatment significantly inhibited the expression of phosphoiniositide-3 kinase (PI3K) p85 subunit and the phosphorylation of Akt. The downstream gene murine double minute 2 was also downregulated, which may contribute to the elevated expression of p53 following oridonin treatment. In conclusion, the results of the present study suggested that oridonin is able to inactivate the PI3K/Akt pathway and activate p53 pathways in prostate cancer cells, resulting in the suppression of proliferation and the induction of caspase-mediated apoptosis.

Anti-androgen 2-hydroxyflutamide modulates cadherin, catenin and androgen receptor phosphorylation in androgen-sensitive LNCaP and androgen-independent PC3 prostate cancer cell lines acting via PI3K/Akt and MAPK/ERK1/2 pathways

This study aimed to investigate rapid effect of anti-androgen 2-hydroxyflutamide (HF) on cadherin/catenin complex and androgen receptor (AR) phosphorylation in prostate cancer cell lines. In addition, a role of PI3K/Akt and MAPK/ERK1/2 pathways in mediating these effects was explored. We have demonstrated that in androgen-sensitive LNCaP cells HF induced rapid increase of E-cadherin phosphorylation at Ser 838/840 (p<0.05) in MAPK/ERK1/2-dependent manner, whereas phosphorylation of β-catenin at Tyr 654 was unchanged. Concomitantly, the reduction of the level of AR phosphorylated at Ser210/213 was found (p<0.01). In androgen-independent PC3 cells HF decreased Tyr 860 N-cadherin and Tyr 645 β-catenin phosphorylation (p<0.01), acting via both MAPK/ERK1/2 and PI3K/Akt pathways. Further, we evidenced that MAPK/ERK1/2 and PI3K/Akt pathways were differentially influenced by HF in LNCaP and PC3 cells. In LNCaP cells, both Akt (p<0.01) and ERK1/2 (p<0.001) phosphorylation were negatively regulated and this effect was mediated by Raf-1 (p<0.05). In contrast, in PC3 cells HF stimulated Akt (p<0.001) and ERK1/2 (p<0.001) activation, but had no effect on the crosstalk between PI3K/Akt and MEK/ERK1/2 pathways at the Raf-1 kinase level. Our findings expand the role of anti-androgen into non-genomic signaling, creating a link between anti-androgen action and phosphorylation of adherens junction proteins in prostate cancer cells.

The natural flavonoid apigenin sensitizes human CD44+ prostate cancer stem cells to cisplatin therapy.

Prostate cancer (PCa) is the second most common type of cancer and the fifth leading cause of cancer-related death among men. Development of chemoresistance, tumor relapse and metastasis remain major barriers to effective treatment and all been identified to be associated with cancer stem cells (CSCs). Natural flavonoids such as apigenin have been shown to have the ability to improve the therapeutic efficacy of common chemotherapy agents through CSCs sensitization. Thus, the aim of this study was to evaluate the combination of apigenin with cisplatin on CD44+ PCa stem cell growth and migration. Platinum-based anti-neoplastic drugs have been used to treat a number of malignancies including PCa. However, acquired resistance and side effects unfortunately have limited cisplatin's use. A CD44+ subpopulation was isolated from human androgen-independent PC3 PCa cells by using human CD44-PE antibody. IC50 values were determined by MTT test. RT-qPCR, Western blot analyses and image-based cytometer were used to investigate apoptosis, cell cycle and their underlying molecular mechanisms. Cell migration was evaluated by wound healing test. The combination of the IC50 doses of apigenin (15μM) and cisplatin (7.5μM) for 48h significantly enhanced cisplatin's cytotoxic and apoptotic effects through downregulation of Bcl-2, sharpin and survivin; and upregulation of caspase-8, Apaf-1 and p53 mRNA expression. The combined therapy suppressed the phosphorylation of p-PI3K and p-Akt, inhibited the protein expression of NF-κB, and downregulated the cell cycle by upregulating p21, as well as cyclin dependent kinases CDK-2, -4, and -6. Apigenin significantly increased the inhibitory effects of cisplatin on cell migration via downregulation of Snail expression. In conclusion, our study showed the possible therapeutic approach of using apigenin to potentially increase the effects of cisplatin by targeting CSCs subset in prostate cancer.

Investigating the role of caveolin-2 in prostate cancer cell line

Prostate cancer is a worldwide problem. While the role of caveolin-1 has been extensively studied, little is known about the role of caveolin-2 (CAV2) in prostate cancer. Up-regulation of CAV2 in androgen independent PC3 cells compared to normal prostate cell line and androgen dependent prostate cancer cell lines has been observed. Recent studies suggest that up-regulation of CAV2 plays an important role in androgen independent prostate cancer. This study investigates whether CAV2 is important in mediating the aggressive phenotypes seen in androgen independent prostate cancer cells. The androgen independent prostate cancer cell line, PC3 was used that has been shown to express CAV2, and CAV2 knock down was performed using siRNA system. Changes to cell number, migration and invasion were assessed after knocking down CAV2. Our results showed that down-regulating CAV2 resulted in reduced cell numbers, migration and invasion in PC3 cells. This preliminary study suggests that CAV2 may act to promote malignant behavior in an androgen independent prostate cancer cell line. Further studies are required to fully elucidate the role of CAV2 in androgen independent prostate cancer.

Identification of Mutations, Expression Alterations and Fusion Transcripts by Next Generation RNAseq in Castration-Resistant Prostate Cancer Cell lines with Possible Clinical Relevance

Androgen Deprivation Therapy (ADT) would benefit prostate cancer patients initially but cancer cells can eventually develop castration resistance. In this study, we compared androgen-dependent and androgenindependent cell lines to find potential genes associated with acquired resistance to ADT. Using RNAseq, we found 4397 mutations distributed in 2579 genes, out of which, 1574 mutated genes could also be found in prostate cancer tumor samples collected in Cosmic database (http://cancer.sanger.ac.uk/cosmic). We also discovered 157 and 549 genes which were down and up-regulated respectively in both PC3 and DU145 compared to LNCaP. Network analysis resulted in 3 dominant connection notes: GCR/MCR (NR3C1) and PKA-cat kinase (PRKACB) and PKC family (PRKD1). By ChimeraScan analysis, 48, 117 and 60 chimeric transcripts were discovered in DU145, LNCaP and PC3 respectively. Among them, six predicted fusions expressed specifically in androgen-independent cell lines (DU145 and PC3). Some of these gene mutations and transcription alterations have been reported in tumor samples from prostate cancer patients and may have certain associations with acquired resistance to anti-hormone therapy in prostate cancer. A proportion of mutations are enriched in genes involved in immune response pathways, suggesting new targets to develop effective treatments to overcome castration resistance.

SH003 induces apoptosis of DU145 prostate cancer cells by inhibiting ERK-involved pathway.

BackgroundHerbal medicines have been used in cancer treatment, with many exhibiting favorable side effect and toxicity profiles compared with conventional chemotherapeutic agents. SH003 is a novel extract from Astragalus membranaceus, Angelica gigas, and Trichosanthes Kirilowii Maximowicz combined at a 1:1:1 ratio that impairs the growth of breast cancer cells. This study investigates anti-cancer effects of SH003 in prostate cancer cells.MethodsSH003 extract in 30% ethanol was used to treat the prostate cancer cell lines DU145, LNCaP, and PC-3. Cell viability was determined by MTT and BrdU incorporation assays. Next, apoptotic cell death was determined by Annexin V and 7-AAD double staining methods. Western blotting was conducted to measure protein expression levels of components of cell death and signaling pathways. Intracellular reactive oxygen species (ROS) levels were measured using H2DCF-DA. Plasmid-mediated ERK2 overexpression in DU145 cells was used to examine the effect of rescuing ERK2 function. Results were analyzed using the Student’s t-test and P-values < 0.05 were considered to indicate statistically-significant differences.ResultsOur data demonstrate that SH003 induced apoptosis in DU145 prostate cancer cells by inhibiting ERK signaling. SH003 induced apoptosis of prostate cancer cells in dose-dependent manner, which was independent of androgen dependency. SH003 also increased intracellular ROS levels but this is not associated with its pro-apoptotic effects. SH003 inhibited phosphorylation of Ras/Raf1/MEK/ERK/p90RSK in androgen-independent DU145 cells, but not androgen-dependent LNCaP and PC-3 cells. Moreover, ERK2 overexpression rescued SH003-induced apoptosis in DU145 cells.ConclusionsSH003 induces apoptotic cell death of DU145 prostate cancer cells by inhibiting ERK2-mediated signaling.Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-016-1490-5) contains supplementary material, which is available to authorized users.

Lithocholic acid induces endoplasmic reticulum stress, autophagy and mitochondrial dysfunction in human prostate cancer cells.

Lithocholic acid (LCA) is a secondary bile acid that is selectively toxic to human neuroblastoma, breast and prostate cancer cells, whilst sparing normal cells. We previously reported that LCA inhibited cell viability and proliferation and induced apoptosis and necrosis of androgen-dependent LNCaP and androgen-independent PC-3 human prostate cancer cells. In the present study, we investigated the roles of endoplasmic reticulum (ER) stress, autophagy and mitochondrial dysfunction in the toxicity of LCA in PC-3 and autophagy deficient, androgen-independent DU-145 cells. LCA induced ER stress-related proteins, such as CCAAT-enhancer-binding protein homologous protein (CHOP), and the phosphorylation of eukaryotic initiation factor 2-alpha (p-eIF2α) and c-Jun N-terminal kinases (p-JNK) in both cancer cell-types. The p53 upregulated modulator of apoptosis (PUMA) and B cell lymphoma-like protein 11 (BIM) levels were decreased at overtly toxic LCA concentrations, although PUMA levels increased at lower LCA concentrations in both cell lines. LCA induced autophagy-related conversion of microtubule-associated proteins 1A/1B light chain 3B (LC3BI–LC3BII), and autophagy-related protein ATG5 in PC-3 cells, but not in autophagy-deficient DU-145 cells. LCA (>10 µM) increased levels of reactive oxygen species (ROS) concentration-dependently in PC-3 cells, whereas ROS levels were not affected in DU-145 cells. Salubrinal, an inhibitor of eIF2α dephosphorylation and ER stress, reduced LCA-induced CHOP levels slightly in PC-3, but not DU-145 cells. Salubrinal pre-treatment increased the cytotoxicity of LCA in PC-3 and DU-145 cells and resulted in a statistically significant loss of cell viability at normally non-toxic concentrations of LCA. The late-stage autophagy inhibitor bafilomycin A1 exacerbated LCA toxicity at subtoxic LCA concentrations in PC-3 cells. The antioxidant α-tocotrienol strongly inhibited the toxicity of LCA in PC-3 cells, but not in DU-145 cells. Collectively, although LCA induces autophagy and ER stress in PC-3 cells, these processes appear to be initially of protective nature and subsequently consequential to, but not critical for the ROS-mediated mitochondrial dysfunction and cytotoxicity of LCA. The full mechanism of LCA-induced mitochondrial dysfunction and cytotoxicity in the similarly sensitive DU-145 cells remains to be elucidated.

Roles of aldo-keto reductases 1B10 and 1C3 and ATP-binding cassette transporter in docetaxel tolerance

Docetaxel (DTX) is widely used for treatment of inveterate lung and prostate cancers, but its continuous administration elicits the hyposensitivity. Here, we established the DTX-resistant variants of human lung cancer A549 and androgen-independent prostate cancer Du145 cells and found that the resistance development provoked aberrant up-regulations of aldo-keto reductase (AKR) 1B10 and AKR1C3 in A549 and Du145 cells, respectively. In addition, the sensitivity to the DTX toxicity was significantly decreased and increased by overexpression and knockdown of the two AKR isoforms, respectively. Furthermore, the resistant cells exhibited a decreased level of reactive 4-hydroxy-2-nonenal formed during DTX treatment, and the decrease was alleviated by adding the AKR inhibitors, inferring that the two AKRs confer the chemoresistance through elevating the antioxidant properties. The development of DTX resistance was also associated with enhanced expression of an ATP-binding cassette (ABC) transporter ABCB1 among the ABC transporter isoforms. The combined treatment with inhibitors of the two AKRs and ABCB1 additively sensitized the resistant cells to DTX. Intriguingly, the AKR1B10 inhibitor also suppressed the lung cancer cross-resistance against cisplatin. The results suggest that combined treatment with AKRs (1B10 and 1C3) and ABCB1 inhibitors exerts overcoming effect against the cancer resistance to DTX and cisplatin, and can be used as the adjuvant therapy.

High-Content Screening Identifies Src Family Kinases as Potential Regulators of AR-V7 Expression and Androgen-Independent Cell Growth.

AR-V7 is an androgen receptor (AR) splice variant that lacks the ligand-binding domain and is isolated from prostate cancer cell lines. Increased expression of AR-V7 is associated with the transition from hormone-sensitive prostate cancer to more advanced castration-resistant prostate cancer (CRPC). Due to the loss of the ligand-binding domain, AR-V7 is not responsive to traditional AR-targeted therapies, and the mechanisms that regulate AR-V7 are still incompletely understood. Therefore, we aimed to explore existing classes of small molecules that may regulate AR-V7 expression and intracellular localization and their potential therapeutic role in CRPC. We used AR high-content analysis (AR-HCA) to characterize the effects of a focused library of well-characterized clinical compounds on AR-V7 expression at the single-cell level in PC3 prostate cancer cells stably expressing green fluorescent protein (GFP)-AR-V7 (GFP-AR-V7:PC3). In parallel, an orthogonal AR-HCA screen of a small interfering (si)RNA library targeting 635 protein kinases was performed in GFP-AR-V7:PC3. The effect of the Src-Abl inhibitor PD 180970 was further characterized using cell-proliferation assays, quantitative PCR, and western blot analysis in multiple hormone-sensitive and CRPC cell lines. Compounds that tended to target Akt, Abl, and Src family kinases (SFKs) decreased overall AR-V7 expression, nuclear translocation, absolute nuclear level, and/or altered nuclear distribution. We identified 20 protein kinases that, when knocked down, either decreased nuclear GFP-AR-V7 levels or altered AR-V7 nuclear distribution, a set that included the SFKs Src and Fyn. The Src-Abl dual kinase inhibitor PD180970 decreased expression of AR-V7 by greater than 46% and decreased ligand-independent transcription of AR target genes in the 22RV1 human prostate carcinoma cell line. Further, PD180970 inhibited androgen-independent cell proliferation in endogenous-AR-V7-expressing prostate cancer cell lines and also overcame bicalutamide resistance observed in the 22RV1 cell line. SFKs, especially Src and Fyn, may be important upstream regulators of AR-V7 expression and represent promising targets in a subset of CRPCs expressing high levels of AR-V7. Prostate 77:82-93, 2017. © 2016 Wiley Periodicals, Inc.

Phosphorylation and activation of androgen receptor by Aurora-A.

Aurora-A kinase is frequently overexpressed/activated in various types of human malignancy, including prostate cancer. In this study, we demonstrate elevated levels of Aurora-A in androgen-refractory LNCaP-RF but not androgen-sensitive LNCaP cells, which prompted us to examine whether Aurora-A regulates the androgen receptor (AR) and whether elevated Aurora-A is involved in androgen-independent cell growth. We show that ectopic expression of Aurora-A induces AR transactivation activity in the presence and absence of androgen. Aurora-A interacts with AR and phosphorylates AR at Thr282 and Ser293 in vitro and in vivo. Aurora-A induces AR transactivation activity in a phosphorylation-dependent manner. Ectopic expression of Aurora-A in LNCaP cells induces prostate-specific antigen expression and cell survival, whereas knockdown of Aurora-A sensitizes LNCaP-RF cells to apoptosis and cell growth arrest. These data indicate that AR is a substrate of Aurora-A and that elevated Aurora-A could contribute to androgen-independent cell growth by phosphorylation and activation of AR.

Identification of miR-30b-3p and miR-30d-5p as direct regulators of androgen receptor signaling in prostate cancer by complementary functional microRNA library screening.

The Androgen Receptor (AR) plays a key role in prostate biology and in the progression of prostate cancer (PCa) to castration resistance. The role of microRNAs (miRNAs) in aberrant AR signaling have not been fully characterized. Here we screened a library of 810 miRNA mimics to identify miRNAs that alter AR activity in complementary functional assays including protein lysate microarray (LMA) quantification of AR and PSA protein levels, AR transcriptional reporter activity, and AR-positive PCa cell viability. Candidate AR-regulating miRNAs were verified through AR transcriptional reporter and cell viability assays. MiRNA binding sites were found within the AR 3′-untranslated region (UTR) and within the AR and AR-V7 coding regions. MiRNA activity was characterized by western blotting, 3′-UTR reporter assay, and AR-GFP and AR-V7-GFP reporter assays. Results uncovered miR-30 family members as direct AR inhibitors. Inhibition of endogenous miR-30b-3p and miR-30d-5p enhanced AR expression and androgen-independent cell growth. Droplet digital RT-PCR quantification of miR-30c-5p and miR-30d-5p revealed significantly reduced levels in metastatic castration resistant PCa (CRPC), when compared to healthy prostate tissues. MiR-30d-5p levels were inversely correlated with AR activity, as measured by PSA mRNA, in metastatic CRPC. Collectively, these studies provide a comprehensive evaluation of AR-regulating miRNAs in PCa.

SMC1A promotes growth and migration of prostate cancer in vitro and in vivo.

Structural maintenance of chromosome 1 alpha (SMC1A) gene has been reported to be related to tumor development in some types of human cancers. However, the misregulation of SMC1A and its functions in castration-resistant prostate cancer (CRPC) have not been well understood. In the present study, we found that SMC1A was elevated in androgen-independent PCa cell lines PC-3 and DU-145 compared to androgen sensitive LNCap and 22RV1 cells by qPCR and western blot assay. Knockdown of SMC1A inhibited cell growth, colony formation and cell migration abilities of PC-3 and DU145 cells by MTT, colony formation and transwell assays, and affected cell cycle progression in PC-3 and DU145 cells by flow cytometry. Moreover, SMC1A knockdown significantly reduced tumor growth invivo in a nude mouse model. Additionally, we also found that the expression of SMC1A gene was higher in prostate cancer tissues than in the adjacent normal tissues by immunohistochemical staining, and was positively correlated to tumor metastasis and recurrence by Oncomine database mining. Taken together, the present study indicates that SMC1A may play an important role in malignant transformation of PCa under conditions of androgen deprivation and act as a new target for PCa diagnosis and treatment.

Epigenetic modulation of AR gene expression in prostate cancer DU145 cells with the combination of sodium butyrate and 5'-Aza-2'-deoxycytidine.

The androgen receptor (AR) plays an essential role in the development and progression of prostate cancer. Castration-resistant prostate cancer (CRPC) is a consequence of androgen deprivation therapy. Unchecked CRPC followed by metastasis is lethal. Some CRPCs show decreased AR gene expression due to epigenetic mechanisms such as DNA methylation and histone deacetylation. The aim of this study was to epigenetically modulate the methylated state of the AR gene leading to targeted demethylation and AR gene expression in androgen-independent human prostate cancer DU145 cell line, representing the CRPC model with very low or undetectable AR levels. The cell treatment was based on single and combined applications of two epigenetic inhibitors, sodium butyrate (NaB) as histone deacetylases inhibitor and 5'-Aza-2'-deoxycytidine (Aza-dC) as DNA methyltransferases inhibitor. We found that the Aza-dC in combination with NaB may help reduce the toxicity of higher NaB concentrations in cancer cells. In normal RWPE-1 cells and even stronger in cancer DU145 cells, the combined treatment induced both AR gene expression on the mRNA level and increased histone H4 acetylation in AR gene promoter. Also activation and maintenance of G2/M cell cycle arrest and better survival in normal RWPE-1 cells compared to cancer DU145 cells were observed after the treatments. These results imply the selective toxicity effect of both inhibitors used and their potentially more effective combined use in the epigenetic therapy of prostate cancer patients.

Sulforaphane increases the efficacy of anti-androgens by rapidly decreasing androgen receptor levels in prostate cancer cells.

Prostate cancer (PCa) cells utilize androgen for their growth. Hence, androgen deprivation therapy (ADT) using anti-androgens, e.g. bicalutamide (BIC) and enzalutamide (ENZ), is a mainstay of treatment. However, the outgrowth of castration resistant PCa (CRPC) cells remains a significant problem. These CRPC cells express androgen receptor (AR) and utilize the intratumoral androgen towards their continued growth and invasion. Sulforaphane (SFN), a naturally occurring isothiocyanate found in cruciferous vegetables, can decrease AR protein levels. In the present study, we tested the combined efficacy of anti-androgens and SFN in suppressing PCa cell growth, motility and clonogenic ability. Both androgen-dependent (LNCaP) and androgen-independent (C4-2B) cells were used to monitor the effects of BIC and ENZ, alone and in combination with SFN. Co-exposure to SFN significantly (p<0.005) enhanced the anti-proliferative effects of anti-androgens and downregulated expression of the AR-responsive gene, prostate specific antigen (PSA) (p<0.05). Exposure to SFN decreased AR protein levels in a time- and dose-dependent manner with almost no AR detected at 24h with 15µM SFN (p<0.005). This rapid and potent AR suppression by SFN occurred by both AR protein degradation, as suggested by cycloheximide (CHX) co-exposure studies, and by suppression of AR gene expression, as evident from quantitative RT-PCR experiments. Pre-exposure to SFN also reduced R1881-stimulated nuclear localization of AR, and combined treatment with SFN and anti-androgens abrogated the mitogenic effects of this AR-agonist (p<0.005). Wound-healing assays revealed that co-exposure to SFN and anti-androgens can significantly (p<0.005) reduce PCa cell migration. In addition, long-term exposures (14 days) to much lower concentrations of these agents, SFN (0.2µM), BIC (1µM) and/or ENZ (0.4µM) significantly (p<0.005) decreased the number of colony forming units (CFUs). These findings clearly suggest that SFN may be used as a promising adjunct agent to augment the efficacy of anti-androgens against aggressive PCa cells.

Growth Inhibition by Testosterone in an Androgen Receptor Splice Variant-Driven Prostate Cancer Model

Castration resistance creates a significant problem in the treatment of prostate cancer. Constitutively active splice variants of androgen receptor (AR) have emerged as drivers for resistance to androgen deprivation therapy, including the next-generation androgen-AR axis inhibitors abiraterone and enzalutamide. In this study, we describe the characteristics of a novel castration-resistant prostate cancer (CRPC) model, designated JDCaP-hr (hormone refractory). JDCaP-hr was established from an androgen-dependent JDCaP xenograft model after surgical castration. The expression of AR and its splice variants in JDCaP-hr was evaluated by immunoblotting and quantitative reverse transcription-polymerase chain reaction. The effects of AR antagonists and testosterone on JDCaP-hr were evaluated in vivo and in vitro. The roles of full-length AR (AR-FL) and AR-V7 in JDCaP-hr cell growth were evaluated using RNA interference. JDCaP-hr acquired a C-terminally truncated AR protein during progression from the parental JDCaP. The expression of AR-FL and AR-V7 mRNA was upregulated by 10-fold in JDCaP-hr compared with that in JDCaP, indicating that the JDCaP and JDCaP-hr models simulate castration resistance with some clinical features, such as overexpression of AR and its splice variants. The AR antagonist bicalutamide did not affect JDCaP-hr xenograft growth, and importantly, testosterone induced tumor regression. In vitro analysis demonstrated that androgen-independent prostate-specific antigen secretion and cell proliferation of JDCaP-hr were predominantly mediated by AR-V7. JDCaP-hr cell growth displayed a bell-shaped dependence on testosterone, and it was suppressed by physiological concentrations of testosterone. Testosterone induced rapid downregulation of both AR-FL and AR-V7 expression at physiological concentrations and suppressed expression of the AR target gene KLK3. Our findings support the clinical value of testosterone therapy, including bipolar androgen therapy, in the treatment of AR-overexpressed CRPC driven by AR splice variants that are not clinically actionable at present. Prostate 76:1536-1545, 2016. © 2016 Wiley Periodicals, Inc.