Prostate-specific Antigen Promoter Research Articles

Inhibition of orthotopic castration-resistant prostate cancer growth and metastasis in mice by JC VLPs carrying a suicide gene driven by the PSA promoter.

Metastatic castration-resistant prostate cancer (mCRPC) is challenging to treat. Virus-like particles (VLPs), originating from JC polyomavirus (JCPyV) and carrying a suicide gene driven by the PSA promoter (PSAtk-VLPs), can inhibit tumor growth in animal models of human prostate cancer. However, the efficacy of suppression of orthotopic PCa growth and metastasis by PSAtk-VLPs remains undetermined. Here, we established an iRFP stable expression CRPC cell line suitable for deep-tissue observation using fluorescence molecular tomography (FMT). These cells were implanted into murine prostate tissue, and PSAtk-VLPs were systemically administered via the tail vein along with the prodrug ganciclovir (GCV), allowing for the real-time observation of orthotopic prostate tumor growth and CRPC tumor metastasis. Our findings demonstrated that systemic PSAtk-VLPs administration with GCV and subsequent FMT scanning facilitated real-time observation of the suppressed growth in mouse iRFP CRPC orthotopic tumors, which further revealed a notable metastasis rate reduction. Systemic PSAtk-VLPs and GCV administration effectively inhibited orthotopic prostate cancer growth and metastasis. These findings suggest the potential of JCPyV VLPs as a promising vector for mCRPC gene therapy. Conclusively, systemically administered JCPyV VLPs carrying a tissue-specific promoter, JCPyV VLPs can protect genes within the bloodstream to be specifically expressed in specific organs.

Newly developed preclinical models reveal broad-spectrum CDK inhibitors as potent drugs for CRPC exhibiting primary resistance to enzalutamide.

Androgen-deprivation therapy is a standard treatment for advanced prostate cancer. However, most patients eventually acquire resistance and progress to castration-resistant prostate cancer (CRPC). In this study, we established new CRPC cell lines, AILNCaP14 and AILNCaP15, from LNCaP cells under androgen-deprived conditions. Unlike most pre-existing CRPC cell lines, both cell lines expressed higher levels of androgen receptor (AR) and prostate-specific antigen (PSA) than parental LNCaP cells. Moreover, these cells exhibited primary resistance to enzalutamide. Since AR signaling plays a significant role in the development of CRPC, PSA promoter sequences fused with GFP were introduced into AILNCaP14 cells to conduct GFP fluorescence-based chemical screening. We identified flavopiridol, a broad-spectrum CDK inhibitor, as a candidate drug that could repress AR transactivation of CRPC cells, presumably through the inhibition of phosphorylation of AR on the serine 81 residue (pARSer81 ). Importantly, this broad-spectrum CDK inhibitor inhibited the proliferation of AILNCaP14 cells both in vitro and in vivo. Moreover, a newly developed liver metastatic model using AILNCaP15 cells revealed that the compound attenuated tumor growth of CRPC harboring highly metastatic properties. Finally, we developed a patient-derived xenograft (PDX) model of CRPC and DCaP CR from a patient presenting therapeutic resistance to enzalutamide, abiraterone, and docetaxel. Flavopiridol successfully suppressed the tumor growth of CRPC in this PDX model. Since ARSer81 was found to be phosphorylated in clinical CRPC samples, our data suggested that broad-spectrum CDK inhibitors might be a potent candidate drug for the treatment of CRPC, including those exhibiting primary resistance to enzalutamide.

Dynamic plasticity of prostate cancer intermediate cells during androgen receptor-targeted therapy.

Treatment-emergent small cell neuroendocrine prostate cancer (t-SCNC) is associated with an epithelial lineage switch from an androgen receptor (AR)-positive to neuroendocrine (NE)-marker-positive status. Understanding the potential for reversibility of this aggressive disease state has been hampered by the paucity of models suitable for studying rate-limiting, transitional, or intermediate tumor cell subpopulations. We define a dual reporter model that measures acute transcriptional changes in response to castration or AR targeting agents. We identify steady-state transcriptional heterogeneity in AR and NE biomarkers, including intermediate subpopulations that are coordinately high for prostate-specific antigen (PSA) and neuron-specific enoclase (NSE) promoter activity. In the presence of castration or AR inhibitors, intermediate cells were necessary and sufficient for therapy-induced conversion of human PC cells to an NSE-high transcriptional status. Using hormone add-back studies, treatment-induced PSA-NSE transcriptional plasticity was reversible in PTEN-deficient PC cells but not in the presence of secondary genetic driver genes, including MYCN.

Kaempferol inhibits benign prostatic hyperplasia by resisting the action of androgen

Kaempferol is a natural compound that inhibits tumor development in androgenic related prostate cancer. However, it is still not clear about its phyto-androgenic activity and whether it suppresses testosterone-induced benign prostatic hyperplasia (BPH) development.In this study, molecular docking, cellular immunofluorescence staining, chromatin immunoprecipitation and dual luciferase reporter assay were performed to investigate the androgenic activity of kaempferol. Dihydrotestosterone-induced gene expression and cell proliferation were further analyzed upon treatment with kaempferol. Testosterone-induced BPH was established in rats and the effect and mechanism of action of kaempferol on BPH development was then assessed.Docking data showed that kaempferol could bind to ASN705 and THR877 residues of androgen receptor which were also the binding sites of dihydrotestosterone. The nuclear translocation of androgen receptor was promoted directly by kaempferol in androgen-dependent prostate cancer LNCaP cells. In addition, the in vivo interaction of androgen receptor with PSA promoter region and the transcriptional activity of androgen receptor were both significantly enhanced after kaempferol stimulation. However, kaempferol pretreatment suppressed dihydrotestosterone-induced effects including the transcriptional activity of androgen receptor, the expressions of PSA and AR genes and cell proliferation of LNCaP, BPH-1 and WPMY-1 cells. Consistently, kaempferol declined the prostate index and improved the pathological properties in BPH rats, and the up-regulated T level in serum from BPH rats was highly decreased after kaempferol administration.Kaempferol exhibited its androgenic-like activity and served as a selective androgen receptor modulator that contributes to androgen-related BPH development.

Phosphorylation of the androgen receptor at Ser81 is co-sustained by CDK1 and CDK9 and leads to AR-mediated transactivation in prostate cancer.

Androgen receptor (AR) is the principal molecule in prostate cancer (PCa) etiology and therapy. AR re‐activation still remains a major challenge during treatment of castration‐resistant prostate cancer (CRPC) tumors that relapse after castration therapies. Recent reports have indicated the enrichment of Ser81‐phosphorylated AR (pS81) in the nucleus of CRPC cells, and CDK1 and CDK9 as the kinases phosphorylating AR at S81. In the current study we showed that pS81 is preferentially localized in the nucleus in both rapid biopsy metastatic CRPC samples and PCa xenografts, and nuclear pS81 localization is correlated with AR transactivation in tumor xenografts. Chromatin immunoprecipitation (ChIP) analysis demonstrated an alignment of S81 phosphorylation and AR‐mediated transactivation with the chromatin locus openness. Moreover, pS81‐specific ChIP‐Seq showed a disproportional occupancy of pS81 on AR‐activated promoters, while 3C‐ChIP assays further indicated an enrichment of pS81 at the PSA enhancer‐promoter loop, a known AR activating hub. In the latter, CDK9 was shown to modulate the transactivation of the AR and RNA Pol II. Indeed, ChIP and re‐ChIP assays also confirmed that AR‐dependent activation of the PSA enhancer and promoter mediated by pS81 was coupled with activation of Pol II and the pTEFb complex. Mechanistically, we determined that CDK1 and CDK9 sustained the pS81 AR modification in the soluble and chromatin‐bound fractions of PCa cells, respectively. Finally, we demonstrated that CDK1 activity was maintained throughout the cell cycle, and that CDK1 inhibitors restored androgen sensitivity in CRPC tumor cells. Based on these findings, CDK1 and CDK9 could be targeted as pS81 kinases in patients with CRPC, either alone or in conjunction with direct AR antagonists.

Anticancer Imidazoacridinone C-1311 is Effective in Androgen-Dependent and Androgen-Independent Prostate Cancer Cells.

The androgen receptor (AR) plays a critical role in prostate cancer (PCa) development and metastasis. Thus, blocking AR activity and its downstream signaling constitutes a major strategy for PCa treatment. Here, we report on the potent anti-PCa activity of a small-molecule imidazoacridinone, C-1311. In AR-positive PCa cells, C-1311 was found to inhibit the transcriptional activity of AR, uncovering a novel mechanism that may be relevant for its anticancer effect. Mechanistically, C-1311 decreased the AR binding to the prostate-specific antigen (PSA) promoter, reduced the PSA protein level, and, as shown by transcriptome sequencing, downregulated numerous AR target genes. Importantly, AR-negative PCa cells were also sensitive to C-1311, suggesting a promising efficacy in the androgen-independent PCa sub-type. Irrespective of AR status, C-1311 induced DNA damage, arrested cell cycle progression, and induced apoptosis. RNA sequencing indicated significant differences in the transcriptional response to C-1311 between the PCa cells. Gene ontology analysis showed that in AR-dependent PCa cells, C-1311 mainly affected the DNA damage response pathways. In contrast, in AR-independent PCa cells, C-1311 targeted the cellular metabolism and inhibited the genes regulating glycolysis and gluconeogenesis. Together, these results indicate that C-1311 warrants further development for the treatment of PCa.

Extragonadal Steroids Contribute Significantly to Androgen Receptor Activity and Development of Castration Resistance in Recurrent Prostate Cancer after Primary Therapy.

Beyond testosterone, several steroids contribute to the activation of the androgen receptor pathway, but their relative contributions to the activation of the androgen receptor signaling axis in patients with castrated prostate cancer remain unknown. Serum levels of 9 steroids were measured by mass spectrometry from continuously castrated patients of the PR.7 study (219) and from the PCA24 cohort (116). For each steroid standard curves for dose dependent prostate specific antigen promoter activation were built in castration sensitive (LAPC4) and resistant (VCaP) prostate cancer models. Standard curves were used to determine the androgen receptor activation potency for each steroid measurement from patients in these trials. In LAPC4 and VCaP cells testosterone, dihydrotestosterone and androstenedione induced androgen receptor transcriptional activity, while dehydroepiandrosterone, 5alpha-androstan-3beta,17beta-diol, androstenediol and androsterone stimulated androgen receptor only in VCaP cells. Extragonadal steroids were responsible for 34% (LAPC4) and 88% (VCaP) of the serum total androgen receptor transcriptional activity found in castrated cases. The total androgen receptor transcriptional activity secondary to testosterone, dihydrotestosterone and androstenedione was associated with time to castration resistance in patients from the PR.7 study (HR 2.17, 95% CI 1.12-4.23, p=0.02) in multivariate analysis using the castration sensitive model (LAPC4). Androgen receptor transcriptional activity of extragonadal androstenedione was the only steroid statistically associated with time to castration resistance in univariate analysis (HR 1.89, 95% CI 1.04-3.44, p=0.036). Extragonadal steroids contribute significantly to the androgen receptor axis activation at castration levels of testosterone in recurrent nonmetastatic prostate cancer and these sustain the development of castration resistance after primary local treatment.

Contribution of extragonadal steroids to the androgen receptor activity and to the castration-resistance development in recurrent prostate cancers after primary therapy.

148 Background: Beyond testosterone, several steroids contribute to the activation of the androgen receptor (AR) pathway, but their relative contributions in castrated prostate cancer (PCa) patients remain unknown. Methods: Serum levels of nine steroids were measured by mass spectrometry from continuously castrated patients of the PR.7 study (n=219) and from the PCA24 cohort (n=116). For each steroid, standard curves for dose-dependent prostate-specific antigen promoter activation were built in castration-sensitive (LAPC4) and resistant (VCaP) PCa models. Standard curves were used to determine the AR activation potency for each steroid measurement from patients. Results: In LAPC4 and VCaP cells, testosterone, dihydrotestosterone and androstenedione induced AR transcriptional activity, while dehydroepiandrosterone, 5alpha-androstan-3beta,17beta-diol, androstenediol, androsterone stimulated AR only in VCaP cells. Extragonadal steroids were responsible for 34% (LAPC4) and 88% (VCaP) of the serum total AR transcriptional activity found in castrated patients. The total AR transcriptional activity secondary to testosterone, dihydrotestosterone and androstenedione was associated with time to castration resistance in patients from the PR.7 study (HR=2.17; 95% CI: 1.12-4.23; p=0.02) in multivariate analysis using the castration-sensitive model (LAPC4). AR transcriptional activity of extragonadal androstenedione was the only steroid statistically associated with time to castration resistance in univariate analysis (HR=1.89; 95% CI: 1.04-3.44; p=0.036). Conclusions: Extragonadal steroids contribute significantly to the AR axis activation at testosterone castration levels in recurrent non-metastatic PCa and these sustain the development of castration resistance after primary local treatment.

Inhibition of enhancer of zeste homolog 2 (EZH2) overcomes enzalutamide resistance in castration-resistant prostate cancer

Enzalutamide, approved by the United States Food and Drug Administration in 2018 for the management of metastatic castration-resistant prostate cancer (CRPC), is an androgen receptor (AR) inhibitor. It blocks androgen binding to the AR, AR nuclear translocation, and AR-mediated DNA binding. Unfortunately, a considerable proportion of tumors eventually develop resistance during the treatment. The molecular mechanisms underlying enzalutamide resistance are not completely understood. Enhancer of zeste homolog 2 (EZH2), the catalytic subunit of polycomb repressor complex 2, has been proposed as a prognostic marker for prostate cancer (PCa). With the goal to test whether EZH2 also plays a critical role in acquisition of enzalutamide resistance in CRPC, here we examined whether EZH2 inhibition/depletion enhances the efficacy of enzalutamide in enzalutamide-resistant PCa cells. We show that combining the EZH2 inhibitor GSK126 with enzalutamide synergistically inhibits cell proliferation and colony formation and promotes apoptosis in enzalutamide-resistant PCa cells. EZH2 depletion also overcomes enzalutamide resistance in both cultured cells and xenograft tumors. Mechanistically, we found that EZH2 directly binds to the promoter of prostate-specific antigen and inhibits its expression in enzalutamide-resistant PCa cells. In agreement, bioinformatics analysis of clinical RNA sequencing data involving GSEA indicated a strong correlation between AR and EZH2 gene expression during PCa progression. Our study provides critical insights into the mechanisms underlying enzalutamide resistance, which may offer new approaches to enhance the efficacy of enzalutamide in CRPC.

SUN-026 Selective Androgen Receptor Modulator S42 Has Anabolic and Anti-Catabolic Effects on Cultured Myotubes

Introduction: In an effort to develop a selective androgen receptor modulator (SARM) with beneficial activity in energy homeostasis, we previously screened 119 steroid analogs for the ability to induce uncoupling protein-1 (UCP-1) mRNA without increasing prostate-specific antigen promoter activity in human prostate cancer cell line, LNCap. As a result, we identified a novel SARM, S42, which is structural analog of testosterone. S42 dose not stimulate prostate growth but has a beneficial effect on lipid metabolism and also increased muscle weight of lavator ani in orchiectomized Sprague-Dawley rats. These findings prompted us to investigate whether S42 has a direct effect on cultured C2C12 myotubes. Method: Mouse myoblast C2C12 were seeded into 6well-plates at 2×105cells/well and maintained in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum (FBS). When the cultured cells became 80-90% confluent, the medium was changed to DMEM supplemented with 2% horse serum (HS) and cells were further cultured for 4 days to induce differentiation into myotubes. Next, the medium was changed to DMEM containing 2% dextran-coated-stripped HS from one day before treatment with various drugs: S42, 5α-dihydrotestosterone (DHT), insulin and rapamycin were tested. Protein and mRNA expression levels were detected by Western blotting and Real time RT-PCR, respectively. Results: Muscle atrophy is mainly controlled by two specific genes encoding muscle ubiquitin ligase, atrogin1 and Muscle RING-Finger Protein1 (MuRF1). S42 significantly lowered expression levels of atrogin1 and MuRF1 in C2C12 myotubes, as determined by Real time RT-PCR. Phosphorylation of p70 S6 kinase (p70S6K), an essential factor for promoting protein synthesis in skeletal muscle, was significantly increased by S42 to almost the same extent as by insulin, but this was prevented by treatment with rapamycin, an inhibitor of mechanistic target of rapamycin complex 1 (mTORC1). However, phosphorylation of Akt upstream regulator mTORC1, was not changed by S42. S42 did not increase insulin-like growth factor 1 (IGF1) mRNA levels in C2C12 myotubes. Conclusion: These results suggest that S42 may have an anabolic effect through activation of mTORC1-p70S6K signaling, independent of IGF1-Akt signaling and may exert an anti-catabolic effect through inhibition of the degradation pathway in cultured C2C12 myotubes.

1001 - Investigation of gene therapy for prostate cancer by the JC virus-like particles delivering a PSA promoter driven-suicide gene

1001 - Investigation of gene therapy for prostate cancer by the JC virus-like particles delivering a PSA promoter driven-suicide gene

Gene therapy for castration-resistant prostate cancer cells using JC polyomavirus-like particles packaged with a PSA promoter driven-suicide gene.

Prostate cancer is the second most common cancer in men globally. Prostate cancer patients at advanced stages are usually treated with androgen deprivation therapy (ADT). However, with disease progression, it often becomes the incurable castration-resistant prostate cancer (CRPC). JC polyomavirus (JCPyV) is a human DNA virus. Its virus-like particles (VLPs) exhibit similar tropism to native virions and they are capable of delivering exogenous genes to the target cells for expression. JCPyV has been detected in prostate cells; therefore, prostate cancer cells may be susceptible to JCPyV infection and JCPyV VLPs may be used as a vector for gene therapy against prostate cancer. Here we constructed a plasmid (pPSAtk) that allows expression of the thymidine kinase suicide gene only in androgen receptor (AR) positive prostate cancer cells using the prostate-specific antigen (PSA) promoter, and used JCPyV VLPs as a vector to carry pPSAtk (PSAtk-VLPs) for transcriptional targeting in prostate cancer cells. In this study, we found that PSAtk-VLPs could only kill AR-positive CRPC 22Rv1 cells in vitro and inhibit the growth of tumor nodules in the xenograft mouse model. Our results reveal that PSAtk-VLPs could potentially be used as a new option for treating CRPC patients in the future.

Abstract 254: Chemopreventive effects of angiotensin II receptor type 2 agonist on prostate carcinogenesis by the downregulation of the androgen receptor

Abstract [Background] We previously reported that angiotensin II receptor blockers (ARB), anti-hypertensive drug, have chemopreventive and chemotherapeutic potential against prostate cancer via the reduction of androgen receptor (AR) expression. It is generally known that angiotensin II binds to two kinds of receptors, AT1R and AT2R, and the biological function of AT2R signaling has the opposite effect to that of AT1R signaling in many aspects. We therefore hypothesized that AT2R agonism might attenuate the proliferative activity in prostate cancer cells. In this study, we investigated the effects of the AT2R agonist Compound 21 (C21) designed by Vicore Pharma (Sweden), which is expected to play similar roles to an ARB, on prostate carcinogenesis using the transgenic rat for adenocarcinoma of prostate (TRAP) model previously established in our laboratory. [Materials and Methods] In vitro analyses of the cell growth, Western blotting and PSA-reporter gene assays were performed using LNCaP and 22RV1 cells. TRAP rats at 6 weeks of age were randomly divided into 3 groups of 12 animals each and treated with C21 at 1 or 2 mg/kg/day in drinking water for 12 weeks. They were pathologically examined the classification as prostatic intraepithelial neoplasia and non-invasive adenocarcinoma. The proteins extracted from TRAP prostate glands were examined for Western blotting. [Results] C21 reduced the proliferation activity of prostate cancer cells and down-regulated the PSA promoter activity, medium PSA levels and the AR protein expression. We discovered that C21 inhibited the progression of prostate carcinogenesis in TRAP rats and decreased the incidence of adenocarcinoma in the lateral prostate. A significant increase in the apoptotic index with activation of caspase 3 and 7 were observed by immunohistochemistry and Western blotting analyses. C21 also down-regulated the expression of AR significantly in TRAP rat prostate. C21 decreased the expression of AR and AR-relevant genes reduced the proliferation activity effectively in prostate cancer cells and TRAP rat prostate. [Conclusion] The present study demonstrated that the epoch-making AT2R agonist C21 down-regulated the proliferation activity and the expression of AR both in vitro and in vivo. C21 is a promising drug not only for hypertension but also for human prostate cancer chemoprevention. Citation Format: Hiroji Uemura, Yusuke Ito, Aya Naiki-Ito, Hiroyuki Kato, Shugo Suzuki, Toshiya Kuno, Satoru Takahashi. Chemopreventive effects of angiotensin II receptor type 2 agonist on prostate carcinogenesis by the downregulation of the androgen receptor [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 254.

Crosstalk Between Androgen-sensitive and Androgen-insensitive Prostate Cancer Cells.

To investigate how androgen-sensitive LNCaP cells crosstalk with androgen-insensitive DU145 or PC-3 cells. The numbers of LNCaP cells were counted when co-cultured with DU145 or PC-3 cells and vise versa. Androgen receptor (AR) activity in LNCaP cells was examined by luciferase reporter assay after transfection with a luciferase reporter driven by PSA promoter in the presence of DU145 or PC-3 cells. Concentration of androgens in the medium was measured by liquid chromatography-mass spectrometry (LC-MS/MS). The ability of migration and invasion of PC-3 and DU145 cells was investigated using a 2-layer chamber, in the presence of LNCaP cells. Co-culture of LNCaP cells with DU145 cells resulted in the conversion of dehydroepiandrosterone (DHEA) to dihydrotestosterone (DHT), which stimulated cell proliferation and PSA promoter activity in LNCaP cells. The increased cell proliferation rate and AR activity, induced in LNCaP cells after DHT treatment, was further enhanced by co-culture with DU145 cells. LNCaP cells also stimulated the proliferation of DU145 and PC-3 cells, via secreting soluble factors. Finally, LNCaP cells promoted migration and invasion of PC-3 cells, in a co-culture system; however inhibited migration and invasion of DU145 cells. Crosstalk between androgen-sensitive PCa cells and androgen-insensitive PCa cells might develop the progression of PCa.

Chemopreventive effects of angiotensin II receptor type 2 agonist on prostate carcinogenesis by the down-regulation of the androgen receptor.

We recently reported that angiotensin II receptor blockers (ARBs) have chemopreventive and chemotherapeutic potential against prostate cancer via the reduction of androgen receptor (AR) expression. In this study, we investigated the effects of the angiotensin II receptor type 2 (AT2R) agonist Compound 21 (C21), which is expected to play similar roles to an ARB, on prostate carcinogenesis using the transgenic rat for adenocarcinoma of prostate (TRAP) model previously established in our laboratory. In vitro analyses of the cell growth, Western blotting and reporter gene assays were performed using LNCaP cells. TRAP rats at 6 weeks of age were randomly divided into 3 groups of 12 animals each and treated with C21 at 1 or 2 mg/kg/day in drinking water for 12 weeks. C21 reduced the proliferation activity of prostate cancer cells and down-regulated the PSA promoter activity and the AR protein expression. We discovered that C21 inhibited the progression of prostate carcinogenesis in TRAP rats and decreased the incidence of adenocarcinoma in the lateral prostate. A significant increase in the apoptotic index with activation of caspase 3 and 7 were observed by immunohistochemistry and Western blotting analyses. C21 also down-regulated the expression of AR significantly in TRAP rat prostate. C21 decreased the expression of AR and reduced the proliferation activity effectively in prostate cancer cells and TRAP rat prostate. These findings suggest that AT2R agonist may be a candidate novel chemopreventive agent against human prostate cancer.

The effects of specific expression of apoptin under the control of PSES and PSA promoter on cell death and apoptosis of LNCaP cells.

Objective(s):Apoptotic effect of apoptin has been demonstrated in numerous studies. However, its tumor specificity has been questioned by some reports. The aim of this study was to confine the expression of apoptin in the prostate tumor cells by inducing its gene expression under the control of a chimeric enhancer composing of prostate-specific membrane antigen (PSMA) and prostate-specific antigen (PSA) regulatory elements (PSES). Furthermore, we investigated the effects of apoptin expression on LNCaP prostate carcinoma cell survival and apoptosis using MTT assay and annexin V/7-AAD flow cytometry assay.Materials and Methods:Recombinant plasmids containing apoptin gene under the control of PSES/PSA promoter or Cytomegalovirus (CMV) promoter were constructed. Tumor cell lines including LNCaP cells and HeLa cells, and LX-2 cells (as a normal control) were transfected with the plasmids and the expression of apoptin was evaluated by real time-PCR and western blot analyses. The effects of apoptin expression on cell survival and apoptosis were then investigated using MTT and annexinV/7-AAD flow cytometry assay, respectively.Results:Western blot and real time PCR analyses confirmed the specific expression of apoptin under the control of PSES/PSA regulatory element in the LNCaP cells, while CMV promoter caused apoptin expression in both tumor and normal cell lines. Apoptin expression significantly increased cell death and apoptosis in tumor cells when compared with the normal cells (P<0.001).Conclusion:These results suggest that PSES/PSA regulatory element may be considered as an efficient approach for specific expression of apoptin gene in prostate tumor cells and treatment of prostate cancer.

Capillarisin blocks prostate-specific antigen expression on activation of androgen receptor in prostate carcinoma cells.

Capillarisin (Cap), an active ingredient of Artemisia capillaris extracts, has known for its anti-inflammatory, antioxidant, and anticancer properties. Functions of Cap in prostate cancer are not clear. We investigate effects of Cap on downregulation of prostate specific antigen (PSA) via modulation of androgen receptor (AR) in prostate carcinoma cells. Cell proliferation was measured by water-soluble tetrazolium-1 (WST-1) cell proliferation assays. The PSA and AR expressions were assessed by immunoblotting and RT-qPCR assays. Effects of Cap on PSA expressions were determined by ELISA, immunoblotting, and reporter assays. Co-immunoprecipitation and immunoblotting assays were used to define the effects of Cap on dissociation of AR-heat shock protein 90 (Hsp90) interaction. Cap inhibited LNCaP cell growth in a dose- and/or time-dependent way without inducing poly ADP-Ribose Polymerase (PARP) cleavage. Cap not only effectively suppressed AR and PSA protein expressions, but also attenuated activations of synthetic androgen (R1881) on PSA promoter activity dose- and time-dependently. The Cap pretreatment abrogated effects of R1881 on AR activity by reducing AR translocation to the nucleus. Immunoblotting assays indicated that Cap promoted a degradation of AR proteins dose-dependently in either cycloheximide pretreated-LNCaP cells or AR-ectopic expressed PC-3 cells. Pretreatment of MG132, a proteasome inhibitor, attenuated effect of Cap on AR degradation. Cap lessened AR stability by dissociation of AR-Hsp90 interaction. Our results indicated that Cap inhibited growth of LNCaP cells. Cap effectively suppressed androgen activation on AR-mediated transactivation, which is AR-dependent through AR degradation and dissociation of AR-Hsp90 in prostate carcinoma cells.

Niclosamide and Bicalutamide Combination Treatment Overcomes Enzalutamide- and Bicalutamide-Resistant Prostate Cancer.

Activation of the androgen receptor (AR) and its splice variants is linked to advanced prostate cancer and drives resistance to antiandrogens. The roles of AR and AR variants in the development of resistance to androgen deprivation therapy (ADT) and bicalutamide treatment, however, are still incompletely understood. To determine whether AR variants play a role in bicalutamide resistance, we developed bicalutamide-resistant LNCaP cells (LNCaP-BicR) and found that these resistant cells express significantly increased levels of AR variants, particularly AR-V7, both at the mRNA and protein levels. Exogenous expression of AR-V7 in bicalutamide-sensitive LNCaP cells confers resistance to bicalutamide treatment. Knockdown of AR-V7 in bicalutamide- and enzalutamide-resistant CWR22Rv1, enzalutamide-resistant C4-2B (C4-2B MDVR), and LNCaP-BicR cells reversed bicalutamide resistance. Niclosamide, a potent inhibitor of AR variants, significantly enhanced bicalutamide treatment. Niclosamide and bicalutamide combination treatment not only suppressed AR and AR variants expression and inhibited their recruitment to the PSA promoter, but also significantly induced apoptosis in bicalutamide- and enzalutamide-resistant CWR22Rv1 and C4-2B MDVR cells. In addition, combination of niclosamide with bicalutamide inhibited the growth of enzalutamide-resistant tumors. In summary, our results demonstrate that AR variants, particularly AR-V7, drive bicalutamide resistance and that targeting AR-V7 with niclosamide can resensitize bicalutamide-resistant cells to bicalutamide treatment. Furthermore, combination of niclosamide with bicalutamide inhibits enzalutamide resistant tumor growth, suggesting that the combination of niclosamide and bicalutamide could be a potential cost-effective strategy to treat advanced prostate cancer in patients, including those who fail to respond to enzalutamide therapy. Mol Cancer Ther; 16(8); 1521-30. ©2017 AACR.

Lgr4 promotes prostate tumorigenesis through the Jmjd2a/AR signaling pathway

Lgr4 (leucine-rich repeat domain containing G protein-coupled receptor 4) is implicated in the transcriptional regulation of multiple histone demethylases in the progression of diverse cancers, but there are few reports concerning the molecular mechanism by which Lgr4 regulates histone demethylase activation in prostate cancer (PCa) progression. As Jmjd2a is a histone demethylase, in the current study, we investigated the relationship between interaction Lgr4 with Jmjd 2a and Jmjd2a/androgen receptor (AR) signaling pathway in PCa progression. Firstly, Lgr4 was overexpressed by transfecting pcDNA3.1(+)/Lgr4 plasmids into PCa (LNCaP and PC-3) cell lines. Next, we found that Lgr4 overexpression promoted Jmjd2a mRNA expression, reduced cell apoptosis and arrested cell cycle in the S phase, these effects were reversed by Jmjd2a silencing. Moreover, Lgr4 overexpression markedly elevated AR levels and its interaction with Jmjd2a, which was tested by co-immunoprecipitation and luciferase reporter assays. Furthermore, interaction AR with PSA promoter (containing an AR response element) was obviously improved by Lgr4 overexpression, and PSA silencing reduced Lgr4-induced cell apoptosis and cell cycle arrest in PCa cells. Taken together, Lgr4 may be a novel tumor marker providing new mechanistic insights into PCa progression. Lgr4 activates Jmjd2a/AR signaling pathway to promote interaction AR with PSA promoter, causing reduction of PCa apoptosis and cell cycle arrest.

Abstract 4764: Development of a multigenic bioluminescence imaging system to detect prostate cancer cells and assess their response to therapy

Abstract BACKGROUND Currently, liquid biposies for imaging single cancer cell to provide personalised medicine is gaining importance. In the last years, molecular imaging techniques using transcriptional amplification systems have been developed but a system enabling both PCa cell detection and treatment response assessment is lacking. PCA3 RNA is a unique PCa biomarker that has been widely studied for PCa screening and detection while the PSA gene is another biomarker of high clinical significance as it gives an account of response to androgen deprivation treatments (ADT). In this study, we have developed and studied an imaging system based on the combined transcriptional activities of the PCA3 and PSA gene promoters for single PCa cell detection and ADT response assessment from patients body fluids. METHODS Adenoviruses (Ad) were constructed utilizing the ability of site-specific recombination of the Cre-Lox system. The PCA3 and PSA promoters were integrated into a single Ad backbone with one promoter driving the expression of CRE recombinase and the other driving the Two Step Transcriptional Amplification system and the Firefly luciferase gene (fl) to generate a new system that we named the Multigenic Integrative Transcriptional Amplification System (MP-ITSTA). PCa cells specificity and ADT response was tested by transient infection. To detect cells in body fluid, 22Rv1-GFP cells were spiked in urine or blood of healthy control, infected with MP-ITSTA after purification and single cell imaging was done using the LV200 bioluminescence microscope. RESULTS We show that the PCA3-TSTA driven fl expression is specific to PCa cells (22Rv1, LAPC4, PC3, DU145) giving 8.5-108.4 fold higher expression when compared to SW780 bladder cancer cells. Contrary to PCA3-TSTA, the PSA-TSTA activity is regulated by androgen treatment but is not prostate cancer-specific as it is active in AR responsive breast cancer cells (CAMA-1 and ZR-75). We show that MP-ITSTA reporter expression is dependent on the combined activation of two promoters (PCA3 and PSA promoter) in a DHT dependent manner. MP-ITSTA could therefore also give an account of responsiveness to bicalutamide or enzalutamide treatments PCa cells. The signal obtained by MP-ITSTA system is 2.3 and 1.6 times higher than PCA3-TSTA in 22Rv1 and LAPC4, respectively proving that MP-ITSTA has the ability to enhance the reporter gene expression from a weak but PCa specific PCA3 promoter. Finally, MP-ITSTA could specifically target spiked 22Rv1-mcherry cells isolated from urine while no signal was found in non-spiked samples. CONCLUSIONS MP-ITSTA therefore represents a prostate cancer specific and non-invasive tool to target with high accuracy PCa cells and to detect their response to ADT cell per cell from body fluids. Citation Format: Pallavi Jain, Bertrand Neveu, Yves Fradet, Frédéric Pouliot. Development of a multigenic bioluminescence imaging system to detect prostate cancer cells and assess their response to therapy. [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 4764.