Androgen Receptor Protein Expression Research Articles

Tadalafil improves lean mass and endothelial function in nonobese men with mild ED/LUTS: in vivo and in vitro characterization.

Phosphodiesterase type-5 inhibitor administration in diabetic men with erectile dysfunction (ED) is associated with reduced waist circumference. We evaluated potential effects of daily tadalafil administration on body composition and investigated its possible mechanism(s) of action in C2C12 skeletal muscle cells in vitro. Forty-three men on stable caloric intake (mean age 48.5 ± 7; BMI 25.5 ± 0.9 kg/m2) complaining mild ED and/or low urinary tract symptoms (LUTS)were randomly assigned to receive tadalafil (TAD) 5 mg/daily (once-a-day=OAD-TAD; n = 23) or 20 mg on-demand (on-demand=OD-TAD; n = 20) for 2 months. Primary outcomes were variations of body composition measured by Dual-energy X-ray absorptiometry; secondary outcomes were ED/LUTS questionnaire scores along with hormone (testosterone, estradiol, insulin) and endothelial function (Endopat2000) variations. OAD-TAD increased abdominal lean mass (p < 0.01) that returned to baseline after 2 months withdrawal. LUTS scores improved (p<0.01) in OD-TAD while ED scoresimproved (p < 0.01) in both groups. We found significant improvements in endothelial function (p < 0.05) that directly correlated with serum insulin (p < 0.01; r = 0.3641) and inversely correlated with estradiol levels (p < 0.01; r = 0.3655) even when corrected for potential confounders. Exposure of C2C12 cells upon increasing tadalafil concentrations (10-7 to 10-6 M) increased total androgen receptor mRNA and protein expression as well as myogenin protein expression after 24 and 72 h (2.8 ± 0.4-fold and 1.4 ± 0.02-fold vs. control, respectively, p < 0.05). Daily tadalafil improved lean mass content in non-obese men probably via enhanced insulin secretion, estradiol reduction, and improvement of endothelial function in vivo. The in vitro increased myogenin and androgen receptor protein expression in skeletal muscle cells suggests a translational action of phosphodiesterase type-5 on this receptor.

Androgen Receptor Gene Copy Number and Protein Expression in Treatment-Naïve Prostate Cancer

Objectives: To evaluate the androgen receptor (AR) gene copy number in androgen deprivation therapy (ADT) treatment-naïve prostate cancer (PCa) patients and to evaluate the corresponding AR protein expression and assess the association between these features and prognostic factors. Materials and Methods: Chromosome X and AR gene copy number, using fluorescence-in-situ-hybridization, and epithelial-stromal AR expression, using AR immunohistochemistry, were analyzed in 62 ADT treatment-naïve PCa patients and 8 castration-refractory patients. Results: In ADT treatment-naïve PCa patients, the AR expression was higher in tumor epithelial cells versus surrounding stromal cells (p < 0.001) and versus normal epithelium in the same patient (p = 0.043). The difference between tumoral AR expression and expression in normal epithelium was higher in patients with ≥15% of tumor cells with increased AR copy number (p = 0.019). Peritumoral stroma had lower AR expression in patients with lymph-node or distant metastases compared to those without metastases (p = 0.038). Conclusions: This research evaluates the link between AR gene status, expression profile, and possible prognostic factors. Furthermore, it highlights the importance of the peritumoral environment in PCa. Additional research is needed to further clarify the role of stromal AR in PCa dissemination and identify possible therapeutic strategies to target this mechanism.

Exploitation of Castration-Resistant Prostate Cancer Transcription Factor Dependencies by the Novel BET Inhibitor ABBV-075.

The ability of BET family inhibitor ABBV-075 to inhibit transcription activation downstream of the initiating events of transcription factors like AR and TMPRSS2:ETS fusion proteins provides a promising therapeutic option for CRPC patients who have developed resistance to second-generation antiandrogens. Mol Cancer Res; 15(1); 35-44. ©2016 AACR.

Reproductive Hormones and Their Receptors May Affect Lung Cancer

Background/Aims: In contrast to men, women have experienced a rapid increase in lung cancer mortality. Numerous studies have found that the sex differences in lung cancer are due to reproductive hormones. Experiments in female mice with and without ovariectomy were performed to explore the possible mechanism by which sex hormones (and their receptors) influence lung cancer. Methods: Twenty-four female C57BL/6 mice aged 56-62 days were randomly divided into the ovariectomized group and the control group. In the ovariectomized group, the bilateral ovaries were removed via the dorsal approach, while the control group underwent a sham operation with bilateral ovarian fat resection at the same sites. After 3 weeks of recovery, Lewis lung cancer cells were transplanted into these mice by subcutaneous inoculation of a tumour cell suspension to establish the ovariectomized lung cancer model. Beginning on the 6^th day after subcutaneous inoculation, mouse weight and transplanted tumour volume were measured every 3 days. After 3 weeks, all the mice were killed by cervical dislocation, and we measured the tumour weight. Mouse serum and tumour tissues were removed. Then, the serum levels of E₂ (oestradiol) and T (testosterone) were detected by ELISA; the protein expression levels of AR (androgen receptor), ERα (oestrogen receptor α) and ERβ (oestrogen receptor β) were detected by Western Blot and IHC (immunohistochemistry); and the mRNA expression levels of AR, ERα and ERβ were detected by qRT-PCR (quantitative real-time polymerase chain reaction) in the ovariectomized and control groups. Results: Compared with the control group, both mouse weight and transplanted tumour volume increased rapidly in the ovariectomized group, and the transplanted tumour weight was significantly heavier in the ovariectomized group (1.83±0.40 and 3.13±0.43, P<0.05). E2 and T serum levels decreased exponentially in the ovariectomized group, while the E₂/T ratio increased compared with the control group (E₂: 55.88±11.45 and 78.21±9.37; T: 0.82±0.14 and 1.46±0.16; ratio: 69.62±14.43±29.81 and 52.22±5.42; all P<0.05). The Western blot and IHC results indicated that AR, ERα and ERβ protein expression levels were obviously higher in transplanted tumour and lung tissues from the ovariectomized group, with particular increases in ERβ in transplanted tumour tissue and in ERα in lung tissue. The PCR results also showed markedly higher mRNA expression levels of AR, ERα and ERβ in the ovariectomized group, and in particular, ERβ in transplanted tumour tissue and ERα in lung tissue were significantly increased in the ovariectomized group. Conclusion: Ovariectomy decreased E₂ and T serum levels and increased the E₂/T ratio in mice, and this imbalance in the internal environment promoted the growth of transplanted tumours. Sex hormone disorder not only promoted transplanted tumour growth but also significantly reduced the protein and mRNA expression levels of sex hormone receptors. The metabolism of E₂ and T may affect the growth, proliferation and metabolism of lung cancer cells, and the mechanism by which sex hormones and their receptors influence lung cancer is worthy of further research.

Correlation between ERG Fusion Protein and Androgen Receptor Expression by Immunohistochemistry in Prostate, Possible Role in Diagnosis and Therapy.

Background: Recent discovery of gene rearrangements have brought a new look to the molecular pathogenesis of cancer. Gene fusions occur in nearly 60% of prostate adenocarcinoma, being the TMPRSS2-ERG one of the most common. Evidence supports the role of ERG fusion in tumorigenesis, progression and invasion via effecting pathways such as WNT, MYC, uPA, PI3K/AKT/PTEN, RAS/RAF/MAPF, NKX3.1, GST-pi and androgen receptor (AR) mediated signaling. Most of the ERG fusions involve 5'-partners androgen responsive. Therefore, we aimed to evaluate AR and ERG fusion protein expression on prostate tissue to find clinicopathological applications and possible role in therapy.Methods: One hundred three samples, including prostate core biopsies and radical prostatectomy specimens, were evaluated for ERG and AR expression by immunohistochemistry (IHC). ERG rearrangement was done by fluorescence in situ hybridization (FISH) on 11 randomly selected cases and correlated with IHC results.Results: From the total of 103 samples, eight (8/103) were benign, fourteen (14/103) had atypical glands, two (2/103) had prostatic intraepithelial neoplasia (PIN), and seventy nine (79/103) showed prostate adenocarcinoma. Forty four (44/79) tumor cases were Gleason score (GS) 6-7 (lower GS), and thirty five (35/79) were GS of 8-10 (higher GS). ERG immunoreaction was observed in 27.8% (22/79) of the tumor cases, showing higher expression in those with lower GS (68.2%, 15/22) compared to higher GS (31.8%, 7/22). Neither benign glands nor PIN stained with ERG. AR expression was observed in 75% of benign samples, 78.5% of atypical glands, 100% of PIN, and in 87.3% of tumor cases with no significant difference based on GS. Co-expression of ERG and AR was evaluated on all the tumor samples. ERG+/AR+ was seen in 77.3% (17/22) of the ERG+ tumor cases, with higher frequency in lower GS (64.7%, 11/17) compared to those with higher GS (35.3%, 6/17). All but five corresponding ERG+ tumor samples were negative for AR. Only 5 samples were ERG-/AR- corresponding to adenocarcinoma GS of 6. Presence or absence of ERG rearrangement was confirmed by FISH and correlated with IHC results.Conclusions: Characterization of ERG status by IHC in prostate tissue has an excellent correlation with FISH. It may also assist in diagnosis since none of the benign glands stained with ERG. Co-expression of ERG+/AR+ in prostate tumor by IHC may suggest gene fusion between ERG and a 5'-partner driven by androgen signaling such as TMPRSS2, which it could represent an important ancillary test for clinical management and development of new therapeutic targets.

Enzalutamide inhibits proliferation of gemcitabine-resistant bladder cancer cells with increased androgen receptor expression.

Advanced bladder cancer is treated mainly with gemcitabine and cisplatin, but most patients eventually become resistance. Androgen receptor (AR) signaling has been implicated in bladder cancer as well as other types of cancer including prostate cancer. In this study, we investigated the expression and role of AR in gemcitabine-resistant bladder cancer cells and also the potential of enzalutamide, an AR inhibitor, as a therapeutic for the chemoresistance. First of all, we established gemcitabine-resistant T24 cells (T24GR) from T24 bladder cancer cells and performed gene expression profiling. Microarray analysis revealed upregulation of AR expression in T24GR cells compared with T24cells. AR mRNA and protein expression was confirmed to be increased in T24GR cells, respectively, by quantitative RT-PCR and western blot analysis, which was associated with more potent AR transcriptional activity as measured by luciferase reporter assay. The copy number of AR gene in T24GR cells determined by PCR was twice as many as that of T24 cells. AR silencing by siRNA transfection resulted in inhibition of proliferation of T24GR cells. Cell culture in charcoal-stripped serum and treatment with enzalutamide inhibited growth of T24GR cells, which was accompanied by cell cycle arrest. AR transcriptional activity was found to be reduced in T24GR cells by enzalutamide treatment. Lastly, enzalutamide also inhibited cell proliferation of HTB5 bladder cancer cells that express AR and possess intrinsic resistance to gemcitabine. Our results suggest that enzalutamide may have the potential to treat patients with advanced gemcitabine-resistant bladder cancer with increased AR expression.

Additive inhibitory effects of simvastatin and enzalutamide on androgen-sensitive LNCaP and VCaP prostate cancer cells

We evaluated the effects of simvastatin and antiandrogen enzalutamide on growth and androgen signaling in androgen-sensitive LNCaP and VCaP prostate cancer cells. Simvastatin alone abolished androgen-induced growth in both cell lines but decreased androgen receptor (AR) and prostate-specific antigen protein expression only in LNCaP, indicating that statin-induced growth inhibition is beyond AR transcriptional activity in VCaP. Combination of simvastatin and enzalutamide exerted additive growth inhibition in both cell lines accompanied with strong induction of autophagy in LNCaP. The data provide new insight into statins' effects on androgen signaling and their proposed role in enhancing androgen deprivation therapy in prostate cancer.

Expression and clinicopathologic significance of androgen recepto in breast cancer

Objective To investigate the meaning of androgen receptor(AR) expression estrogen receptor negative(ER-) and positive(ER+ ) breast cancer and the correlation between AR and clinicopathologic factors. Methods Ninety-four cases with ER+ and 74 cases with ER- patients were randomly allocated into two groups from patients with invasive ductal carcinoma(IDC). The protein expression of AR, ER, PR, Her-2 and Ki-67 were assayed by immunohistochemistry.The expression of AR in breast cancer and breast cancer molecular subtypes in different ER states and the correlation with clinicopathologic characteristics were analyzed. Results The positive rate of AR in IDC was 70.2%(118/168), in the ER+ group and ER- group were 84.0%(79/94) and 52.7%(39/74), respectively.The expression in different molecular subtypes were 80%(8/10), 84.5%(71/84), 77.1%(27/35), 30.8%(12/39) in Luminal A, Luminal B, Her-2 over expression and triple negative breast cancer, respectively.The AR epression in the ER+ tumors was related with age(P=0.008); The AR expression in the ER- tumors was related with age(P=0.019), menstruate status(P=0.010), axillary node status(P=0.040), Her-2 over-expression(χ2=15.914, P<0.001). Conclusion AR is widely expressed in breast cancer, and is associated with good clinicopathologic parameters in ER negative breast cancer.AR is a good clinicopathologic factor and it plays a potential role in the clinical management of patients in ER- breast cancer.AR can be considered as a target for endocrine therapy in ER negative breast cancer, and predict the prognosis. Key words: Breast cancer; Androgen receptor; Estrogen receptor; Immunohistochemistry; Clinicopathologic characteristics

Lactational exposure of polychlorinated biphenyls downregulates critical genes in Leydig cells of F1 male progeny (PND21).

Polychlorinated biphenyls (PCBs) are environmental contaminants. The present study was aimed to test the effect of lactational exposure of PCBs on Leydig cellular mRNA and protein expressions of 5α-reductase, aromatase and androgen receptor (AR) in F1 male offspring. Lactating dams were orally gavaged with different doses of PCBs (Aroclor 1254) 0, 1, 2 and 5mgkg b.wt-1 day-1 , respectively, from PND1 to PND21. Male offsprings were sacrificed at PND21. Testes were used to isolate Leydig cells. Blood was collected. Serum testosterone (T) and oestradiol (E2 ) were measured. Anogenital distance was measured. Dams' milk lipid and serum lipids of male pups were estimated. PCB (Aroclor 1254) concentration of dams' milk and serum of male pups were analysed by GC-ECD. Leydig cellular mRNA and protein expressions of 5α-reductase, aromatase and AR were significantly decreased. Our data suggest that lactational exposure of PCBs downregulates selected genes in Leydig cells of F1 generation on post-natal day 21.

Critical Role of Androgen Receptor Level in Prostate Cancer Cell Resistance to New Generation Antiandrogen Enzalutamide

Enzalutamide is an androgen receptor (AR) inhibitor approved for therapy of metastatic castration resistant prostate cancer. However, clinical application revealed that 30 to 40% of patients acquire resistance after a short period of treatment. Currently, the molecular mechanisms underlying such resistances are not completely understood, partly due to a lack of model systems. In the present study we established three different cellular models of enzalutamide resistance including a cell line with wild type AR (LAPC4), DuCaP cells which overexpress wild-type AR, as well as a cell which has been adapted to long term androgen ablation (LNCaP Abl) and harbors the AR T878A mutation. After 10 months of cultivation, sustained growth in the presence of enzalutamide was achieved. When compared to controls, resistant cells exhibit significantly decreased sensitivity to enzalutamide as measured with 3[H]thymidine incorporation and WST assay. Moreover, these cell models exhibit partly re-activated AR signaling despite presence of enzalutamide. In addition, we show that enzalutamide resistant cells are insensitive to bicalutamide but retain considerable sensitivity to abiraterone. Mechanistically, enzalutamide resistance was accompanied by increased AR and AR-V7 mRNA and protein expression as well as AR gene amplification, while no additional AR mutations have been identified.

Androgen Receptor Expression in Thai Breast Cancer Patients

The aim of this study was to investigate prevalence and related factors of androgen receptor (AR) expression in Thai breast cancer patients. A descriptive study was done in 95 patients, who were admitted to Charoenkrung Pracharak Hospital, Bangkok (2011–2013). Statistical relationships were examined between AR protein expression, tumor status, and patient characteristics. Compared with those from Western countries, ethnic Thai patients were younger at age of diagnosis and had a higher proliferative index (high Ki-67 expression), which indicates unfavorable prognosis. In addition, 91% of the Thai breast tumors that were positive for any of the following receptors, estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) also expressed the AR protein, while in triple negative breast tumors only 33% were AR positive. ER and PR expression was positively related with AR expression, while AR expression was inversely correlated to Ki-67 expression. AR status was strongly correlated with ER and PR status in Thai patients. There is an inverse relationship between Ki-67 and AR, which suggests that AR may be a prognostic factor for breast cancer.

Lactational exposure effect of polychlorinated biphenyl on rat Sertoli cell markers and functional regulators in prepuberal and puberal F1 offspring.

Polychlorinated biphenyls (PCBs) are persistent and bioaccumulative environmental toxicants acting as endocrine disruptors. Many researches evidenced that PCBs affect the male reproductive system in adult rats and it can transfer from mother to offspring through milk. We investigated whether the lactational exposure to PCBs affects the Sertoli cell function in F1 offspring. Dams were orally treated with different doses of PCB-Aroclor 1254 (1, 2 and 5mg/kgbw/day, respectively) from postpartum day 1-20. Male offspring rats were killed on PND 21 and PND 60. Testes were used both for histological study and to isolate Sertoli cell. Serum and testicular interstitial fluid (TIF) levels of testosterone, ABP and estradiol were analyzed by ELISA method. The mRNA and protein expressions of follicle-stimulating hormone (FSHR), androgen-binding protein (ABP), Inhibinβ, androgen receptor (AR) and estrogen receptor (ERβ) were studied using real-time PCR and immunoblotting, respectively. The testicular architecture was altered in PCB-treated groups of both prepuberal and puberal rats. Testosterone, estradiol and androgen-binding protein levels were altered in both serum and TIF in PCB treated groups. The gene expression level of FSHR, ABP, ERβ and AR was decreased in a dose-dependent manner, whereas Inhibinβ gene expression level was increased in PCB-treated groups. Lactational exposure to PCB affects both the histoarchitecture of testis, Sertoli cell maker and functional regulators in both prepuberal and puberal F1 male progeny.

Critical role of androgen receptor level in prostate cancer cell resistance to new generation antiandrogen enzalutamide.

Enzalutamide is an androgen receptor (AR) inhibitor approved for therapy of metastatic castration resistant prostate cancer. However, clinical application revealed that 30 to 40% of patients acquire resistance after a short period of treatment. Currently, the molecular mechanisms underlying such resistances are not completely understood, partly due to a lack of model systems. In the present study we established three different cellular models of enzalutamide resistance including a cell line with wild type AR (LAPC4), DuCaP cells which overexpress wild-type AR, as well as a cell which has been adapted to long term androgen ablation (LNCaP Abl) and harbors the AR T878A mutation. After 10 months of cultivation, sustained growth in the presence of enzalutamide was achieved. When compared to controls, resistant cells exhibit significantly decreased sensitivity to enzalutamide as measured with 3[H]thymidine incorporation and WST assay. Moreover, these cell models exhibit partly re-activated AR signaling despite presence of enzalutamide. In addition, we show that enzalutamide resistant cells are insensitive to bicalutamide but retain considerable sensitivity to abiraterone. Mechanistically, enzalutamide resistance was accompanied by increased AR and AR-V7 mRNA and protein expression as well as AR gene amplification, while no additional AR mutations have been identified.

Abstract LB-258: Upregulation of androgen receptor in breast cancer is associated with more aggressive disease when PI3K signaling is active

Abstract Endocrine treatment has been the therapeutic mainstay for hormone receptor positive breast cancer; however, as with all drugs, the development of resistance in some cases will be inevitable. In response to these challenges there has been a great deal of interest in the clinical potential of combined endocrine therapy and PI3K inhibition as a treatment for advanced breast cancers. As PI3K signalling has previously been associated with androgen receptor (AR) protein expression in a luminal A subtype, we wished to explore this further in the context of elevated AR protein expression. The role of the AR, in both triple-negative and hormone receptor positive breast cancer, has recently been reappraised with evidence suggesting that it may facilitate tumorigenesis. This current study explores the relationship between these two signalling pathways in endocrine receptor positive disease. A tissue microarray (n = 488) of breast tumor specimens was stained for AR (Novocastra) and p-AKT (Cell Signalling). All patients provided written consent and are currently enrolled on a clinical trial (ICORG - 09-07). The median follow-up period for the cohort was 60 months. In vitro cell line models used in the study included endocrine sensitive, MCF7 (AR low, p-AKT low), ZR75.1 (AR high, p-AKT moderate) and endocrine resistant, LetR (AR high, p-AKT high). Cell line evaluation of sensitivity to PI3K treatment (BEZ235) showed MCF7 cells to be most sensitive (IC50: 0.01M); whereas the AR high cell lines, ZR75.1 and the endocrine resistant, LetR, had reduced responsiveness to the drug (IC50: 0.0011M and 0.0018M respectively). In line with the findings of other studies we found elevated levels of AR protein to be associated with good disease free survival in the total population, however, the positive influence was diminished in AI treated patients. Furthermore when this dataset is stratified (as per Cochrane et al., 2014) to determine survival based on an elevated AR: ER ratio there is a significant association with poor outcome (p = 0.03). Analysis of clinical associations between p-AKT protein levels and elevated AR protein was performed (Stata10). Kaplan Meier analysis show that AR is indeed associated with good outcome in p-AKT negative patients but that this is lost when evaluated in the context of elevated p-AKT. In order to ascertain whether AR and PI3K mutational status may have an impact on clinical attributes, the breast invasive carcinoma TCGA dataset (n = 963) was investigated. Patients with upregulated AR mRNA and wildtype PI3K exhibited more invasive disease compared with those harboring a PI3K mutation (p = 0.02). In summary, breast cancers in which AR is upregulated associate with more aggressive disease when co-occurring with active PI3K signalling. Anti-AR therapies are currently undergoing clinical evaluation as treatment for advanced breast cancer and elucidation of the associated tumor subtypes warrants further investigation. Citation Format: Azlena Ali, Laura Creevey, Arnold Hill, Leonie Young, Marie McIlroy. Upregulation of androgen receptor in breast cancer is associated with more aggressive disease when PI3K signaling is active. [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 LB-258.

Abstract 4966: High-definition single cell analysis (HD-SCA) reveals enrichment in androgen receptor (AR) expression in tumor cell clusters in bone marrow and blood of metastatic castration-resistant prostate cancer (mCRPC) patients

Abstract Introduction. The analysis of tumor cells in the circulation (CTC) provides an opportunity for non-invasive characterization of mCRPC and monitoring of therapy response, but it is the bone where prostate cancer cells almost consistently migrate to, expand and adapt to therapy. We adapted the HD-CTC assay to bone marrow aspirates (BMA) to discern features most significant to the tumorigenicity and the dynamics of metastatic progression in this disease, and to allow for serial comparison of tumor cells in the circulatory and bone compartments. Since available experimental data suggests that tumor cells organized in clusters are more important contributors to metastasis than single CTC, we evaluated their presence and characteristics in the 2 compartments. Methods. Peripheral blood and BMA obtained through the posterior iliac crest were synchronously collected from individual mCRPC patients (n = 89) while progressing on therapy, and tumor cells in them were detected and characterized using the HD-SCA high-content platform. This flexible non-enrichment-based approach allows for quantification of cell morphometric and protein expression parameters and provides easy access to individual cells and cell clusters for single cell genomics and proteomics analysis. Candidate tumor cells based on cell size and morphology were presented and manually classified as DAPI and cytokeratin-positive and CD45-negative. Clusters were defined as two or more tumor cells in direct contact. AR protein expression and sub-cellular localization were also examined for each tumor cell and tumor cell cluster. Results. Metastatic tumor cells were detected in 24/61 (39%) available BMAs. A greater number of tumor cells were organized in clusters, and clusters were generally larger, in BMAs than in blood (50% vs. 33%, and 20% vs. 5% with 6 or more cells, respectively). In 14 patient-matched and synchronously collected blood and BMA specimens with at least 1 tumor cell, we found 10 (71%) with clusters in the BMA (13-357 clusters/case, with the exception of 1 case that had 1 cluster), while only 3 (21%) had CTC clusters (2-4 clusters/case) (p = 0.02). The 4 cases that had no clusters in the marrow did not have any clusters in the blood. Patients with larger cluster size did significantly worse both in terms of progression-free (p = 0.002) and overall survival (p = 0.02). AR expression in individual cells was significantly higher in those forming part of cell clusters than in single cells, and was positively correlated with cluster size, both in blood and BMAs. Conclusions. Tumor cell clusters are frequent in the circulation and especially in the bone marrow of mCRPC patients whose disease has progressed to therapy. In this setting, the increasing AR expression observed in tumor cell clusters is of probable biological relevance. Citation Format: Amado J. Zurita, Anders Carlsson, Patricia Troncoso, James Hicks, Christopher J. Logothetis, Peter Kuhn. High-definition single cell analysis (HD-SCA) reveals enrichment in androgen receptor (AR) expression in tumor cell clusters in bone marrow and blood of metastatic castration-resistant prostate cancer (mCRPC) patients. [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 4966.

Abstract 4694: ABBV-075, a novel BET family inhibitor, disrupts critical transcription programs that drive prostate cancer growth to induce potent anti-tumor activity in vitro and in vivo

Abstract The novel bromodomain inhibitor, ABBV-075, is being tested in a Phase I study for the treatment of solid tumors. Here, we show that potent inhibition of the BET (bromodomain and extra-terminal) family with ABBV-075 is a highly efficacious therapy in pre-clinical models of prostate cancer. The single-digit to low nanomolar anti-proliferative IC50s and potent in vivo tumor growth inhibition of ABBV-075 is mediated in part via inhibition of androgen receptor (AR)-dependent transcription. Prostate tumor incidence and CRPC clinical progression are driven by aberrant activation of the AR transcription program. Gene expression profiling and qPCR results indicate that ABBV-075 inhibited DHT-stimulated transcription of AR target genes without significant effect on AR protein expression. Further, ABBV-075 disrupted DHT-stimulated recruitment of the BET family member BRD4 to gene regulatory regions co-occupied by AR, including the well-established PSA and TMPRSS2 enhancers. Persistent BET inhibition led to the disassembly of AR occupied enhancers as measured by a reduction in AR and H3K27Ac ChIP signal and additionally downregulated enhancer RNA (eRNA) transcription. ABBV-075 displayed potent anti-proliferative activity in multiple models of resistance to the second generation anti-androgen Enzalutamide, including the F876L, L702H AR ligand binding domain mutations and the AR-V7 splicing variant. In addition to blocking the transcription activation downstream of AR, ABBV-075 is also a potent inhibitor of MYC and the TMPRSS2-ETS fusion proteins. Thus, we propose that ABBV-075 may provide a promising therapeutic option for CRPC patients who have developed resistance to second-generation anti-androgens. Citation Format: Emily J. Faivre, Denise M. Wilcox, Paul Hessler, Tamar Uziel, Paul Tapang, Terry Magoc, Daniel H. Albert, Guowei Fang, Saul Rosenberg, Keith McDaniel, Keith McDaniel, Warren Kati, Yu Shen. ABBV-075, a novel BET family inhibitor, disrupts critical transcription programs that drive prostate cancer growth to induce potent anti-tumor activity in vitro and in vivo. [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 4694.

Abstract 2060: Polymer mediated RNAi-based combination therapy for treating prostate cancer

Abstract Purpose. To determine whether RNAi-based combination therapy targeting androgen receptor (AR) and XIAP signaling pathways using polymeric micelles can treat prostate cancer. Methods. Potency of siRNAs targeting AR and XIAP genes was assessed using real time RT-PCR, Western Blot and ELISA. Cell viability was determined by MTT assay. A library of polymers designed to degrade via hydrolysis and enhance siRNA delivery was synthesized by conjugating hexylamine, pentaethylenehexamine and 3-morpholinopropylamine to poly(ethylene glycol)-block-poly(5-methyl-5-carboxyl-propylene carbonate) backbone using EDC/HOBT coupling chemistry. Polymer structure and molecular weight were verified with proton NMR and Gel Permeation Chromatography, respectively. Results. Three siRNA sequences targeting different regions of the AR and XIAP genes were designed, blasted against the human genome database to eliminate cross-silencing of nontarget genes and their potency screened in LNCaP and C4-2 cells following transfection. All siRNAs targeting AR (start site: 1172, 1648 and 1768) used in this study silenced AR mRNA and protein expression in both cell lines. Furthermore, 1172 was identified as the most potent sequence resulting in approximately 75% knockdown regardless of cell type. Also, the three siRNAs targeting XIAP (start site: 264, 297 and 458) down-regulated XIAP mRNA and protein levels in both cells and were generally more potent in C4-2 cells compared to LNCaP cells. C4-2 cells transfected with siRNA targeting AR (start site: 1172) and XIAP (start site: 264) alone or in combination and assayed after 96 hours revealed XIAP and AR down-regulation resulted in approximately 20% and 50% growth inhibition in C4-2 cells, respectively, compared to control. However, combined silencing of XIAP and AR genes decreased cell growth by 62% and was more potent in inhibiting cell proliferation compared to monotherapy. Additionally, combination of siRNA targeting AR (start site: 1172) and XIAP (start site: 264) significantly increased percentage of cells undergoing apoptosis (85%) compared to control or monotherapy. Poly(ethylene glycol)-block-poly(5-methyl-5-carboxyl-propylene carbonate) copolymer was synthesized by ring opening polymerization and conjugated with various ratios of hexylamine, pentaethylenehexamine and 3-morpholinopropylamine moieties. The resulting copolymer (PEG-b-P(CC-g-PHEXYL-g-PMORPH-g-PPHEA) were non-toxic even at concentration of 1500 μg/mL and successfully condensed siRNA at N/P of 25 with average hydrodynamic diameter of approximately 175 nm. Conclusions. Combination based therapy using siRNA targeting AR and XIAP can potentially treat prostate cancer. Citation Format: Michael Danquah. Polymer mediated RNAi-based combination therapy for treating prostate cancer. [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 2060.

The miR-367-3p Increases Sorafenib Chemotherapy Efficacy to Suppress Hepatocellular Carcinoma Metastasis through Altering the Androgen Receptor Signals

The androgen receptor (AR) was found to suppress hepatocellular carcinoma (HCC) metastasis at late stages. Due to this discovery, we searched for some AR enhancers to increase the efficacy of Sorafenib chemotherapy, and identified the microRNA (miR)-367-3p, whose expression is positively correlated with AR expression in advanced HCC, as an HCC metastasis suppressor. Combining miR-367-3p with Sorafenib showed better efficacy to suppress HCC cell invasion in vitro and in vivo. Mechanism dissection revealed that miR-367-3p could increase AR expression via directly targeting the 3′UTR of MDM2 to decrease MDM2 protein expression. The resultant increase of AR expression might then promote the expression of FKBP5 and PHLPP, thus dephosphorylating and inactivating AKT and ERK, to suppress the HCC cell invasion. Interestingly, the suppression of pAKT by miR-367-3p could subsequently attenuate the phosphorylation of AR and MDM2, giving rise to additional enhancement of AR protein expression, effectively forming a positive feedback loop. Together, these results suggest that miR-367-3p may function as an AR enhancer to increase Sorafenib chemotherapy efficacy via altering the MDM2/AR/FKBP5/PHLPP/(pAKT and pERK) signals to better suppress HCC metastasis. Successful development of this newly combined chemotherapy in the future may help us to better suppress the HCC metastasis at late stages.

Seasonal changes of androgen receptor, estrogen receptors and aromatase expression in the medial preoptic area of the wild male ground squirrels (Citellus dauricus Brandt).

The wild ground squirrel is a typical seasonal breeder. In this study, using RT-PCR, western blot and immunohistochemistry, we investigated the mRNA and protein expressions of androgen receptor (AR), estrogen receptors a and β (ERα and ERβ) and aromatase cytochrome P450 (P450arom) in the medial preoptic area (MPOA) of hypothalamus of the wild male ground squirrel during the breeding season (April), the non-breeding season (June) and pre-hibernation (September). AR, ERα, ERβ and P450arom protein/mRNA were present in the MPOA of all seasons detected. The immunostaining of AR and ERα showed no significant changes in different periods, whereas ERβ and P450arom had higher immunoreactivities during the breeding season and pre-hibernation when compared to those of the non-breeding season. Consistently, both the protein and mRNA levels of P450arom and ERβ were higher in the MPOA of pre-hibernation and the breeding season than in the non-breeding season, whereas no significant difference amongst the three periods was observed for AR and ERα levels. These findings suggested that the MPOA of hypothalamus may be a direct target of androgen and estrogen. Androgen may play important regulatory roles through its receptor and/or the aromatized estrogen in the MPOA of hypothalamus of the wild male ground squirrels.

Cholesterol biosynthesis inhibitor RO 48-8071 suppresses growth of hormone-dependent and castration-resistant prostate cancer cells.

Standard treatment for primary prostate cancer includes systemic exposure to chemotherapeutic drugs that target androgen receptor or antihormone therapy (chemical castration); however, drug-resistant cancer cells generally emerge during treatment, limiting the continued use of systemic chemotherapy. Patients are then treated with more toxic standard therapies. Therefore, there is an urgent need for novel and more effective treatments for prostate cancer. The cholesterol biosynthetic pathway is an attractive therapeutic target for treating endocrine-dependent cancers because cholesterol is an essential structural and functional component of cell membranes as well as the metabolic precursor of endogenous steroid hormones. In this study, we have examined the effects of RO 48-8071 (4′-[6-(allylmethylamino)hexyloxy]-4-bromo-2′-fluorobenzophenone fumarate; Roche Pharmaceuticals internal reference: RO0488071) (RO), which is an inhibitor of 2, 3-oxidosqualene cyclase (a key enzyme in the cholesterol biosynthetic pathway), on prostate cancer cells. Exposure of both hormone-dependent and castration-resistant human prostate cancer cells to RO reduced prostate cancer cell viability and induced apoptosis in vitro. RO treatment reduced androgen receptor protein expression in hormone-dependent prostate cancer cells and increased estrogen receptor β (ERβ) protein expression in both hormone-dependent and castration-resistant prostate cancer cell lines. Combining RO with an ERβ agonist increased its ability to reduce castration-resistant prostate cancer cell viability. In addition, RO effectively suppressed the growth of aggressive castration-resistant human prostate cancer cell xenografts in vivo without any signs of toxicity to experimental animals. Importantly, RO did not reduce the viability of normal prostate cells in vitro. Our study is the first to demonstrate that the cholesterol biosynthesis inhibitor RO effectively suppresses growth of human prostate cancer cells. Our findings suggest that cholesterol biosynthesis inhibitors such as RO, when used in combination with commonly used chemotherapeutic drugs or ERβ specific ligands, could represent a novel therapeutic approach to prevent the growth of prostate cancer tumors.