Regulation Of Androgen Receptor Signaling Research Articles

Cinnamomum cassia and Rosa laevigata Mixture Improves Benign Prostatic Hyperplasia in Rats by Regulating Androgen Receptor Signaling and Apoptosis.

Benign prostatic hyperplasia (BPH) is the most common condition in elderly men that is characterized by an increase in the size of the prostate gland. Cinnamomum cassia and Rosa laevigata have been reported to treat the symptoms associated with BPH. The aim of this study was to evaluate the effects of HT080, an herbal extract of C. cassia and R. laevigata, on a testosterone propionate (TP)-induced BPH rat model. The rats received a daily subcutaneous injection of TP (3 mg/kg) for 4 weeks to induce BPH. Rats were divided into four groups: group 1 (sham), group 2 (BPH, TP alone), group 3 (Fina, TP + finasteride 1 mg/kg/day), and group 4 (HT080, TP + HT080 200 mg/kg/day). At the end of the experiment, all rats were sacrificed, and their prostate glands were removed, weighed, and subjected to histopathological examination and western blot analyses. Serum testosterone and dihydrotestosterone (DHT) levels were determined. In addition, serum alanine and aspartate aminotransferase levels were measured to evaluate the toxicity in the liver. The Hershberger bioassay was also conducted to investigate the effects of HT080 on androgenic and antiandrogenic activities. In the BPH model, the prostate weight, prostate index, prostate epithelial thickness, and serum testosterone and DHT levels in the HT080 group were significantly reduced compared to the BPH group. Histological studies showed that HT080 reduced prostatic hyperplasia. The protein expression of androgen receptor from the HT080 group was significantly reduced in comparison with the BPH group (p < 0.05). HT080 also induced apoptosis by regulating Bcl-2 and Bax expression. In addition, HT080 showed no toxicity in the liver and did not exhibit androgenic and antiandrogenic activities. Our finding revealed that HT080 can be a potential candidate for the treatment of BPH by regulating androgen receptor signaling and apoptosis.

A distinct M2 macrophage infiltrate and transcriptomic profile decisively influence adipocyte differentiation in lipedema.

Lipedema is a chronic and progressive adipose tissue disorder, characterized by the painful and disproportionate increase of the subcutaneous fat in the lower and/or upper extremities. While distinct immune cell infiltration is a known hallmark of the disease, its role in the onset and development of lipedema remains unclear. To analyze the macrophage composition and involved signaling pathways, anatomically matched lipedema and control tissue samples were collected intra-operatively from gender- and BMI-matched patients, and the Stromal Vascular Fraction (SVF) was used for Cytometry by Time-of-Flight (CyTOF) and RNA sequencing. The phenotypic characterization of the immune component of lipedema versus control SVF using CyTOF revealed significantly increased numbers of CD163 macrophages. To gain further insight into this macrophage composition and molecular pathways, RNA sequencing of isolated CD11b+ cells was performed. The analysis suggested a significant modification of distinct gene ontology clusters in lipedema, including cytokine-mediated signaling activity, interleukin-1 receptor activity, extracellular matrix organization, and regulation of androgen receptor signaling. As distinct macrophage populations are known to affect adipose tissue differentiation and metabolism, we evaluated the effect of M2 to M1 macrophage polarization in lipedema using the selective PI3Kγ inhibitor IPI-549. Surprisingly, the differentiation of adipose tissue-derived stem cells with conditioned medium from IPI-549 treated SVF resulted in a significant decreased accumulation of lipids in lipedema versus control SVF. In conclusion, our results indicate that CD163+ macrophages are a critical component in lipedema and re-polarization of lipedema macrophages can normalize the differentiation of adipose-derived stem cells in vitro evaluated by the cellular lipid accumulation. These data open a new chapter in understanding lipedema pathophysiology and may indicate potential treatment options.

A genome-scale CRISPR screen reveals PRMT1 as a critical regulator of androgen receptor signaling in prostate cancer.

Androgen receptor (AR) signaling is the central driver of prostate cancer across disease states. While androgen deprivation therapy (ADT) is effective in the initial treatment of prostate cancer, resistance to ADT or to next-generation androgen pathway inhibitors invariably arises, most commonly through the re-activation of the AR axis. Thus, orthogonal approaches to inhibit AR signaling in advanced prostate cancer are essential. Here, via genome-scale CRISPR-Cas9 screening, we identify protein arginine methyltransferase 1 (PRMT1) as a critical mediator of AR expression and signaling. PRMT1 regulates the recruitment of AR to genomic target sites and the inhibition of PRMT1 impairs AR binding at lineage-specific enhancers, leading to decreased expression of key oncogenes, including AR itself. In addition, AR-driven prostate cancer cells are uniquely susceptible to combined AR and PRMT1 inhibition. Our findings implicate PRMT1 as a key regulator of AR output and provide a preclinical framework for co-targeting of AR and PRMT1 in advanced prostate cancer.

BRD9 Is a Critical Regulator of Androgen Receptor Signaling and Prostate Cancer Progression.

Switch/sucrose-nonfermentable (SWI/SNF) chromatin-remodeling complexes are critical regulators of chromatin dynamics during transcription, DNA replication, and DNA repair. A recently identified SWI/SNF subcomplex termed GLTSCR1/1L-BAF (GBAF; or "noncanonical BAF", ncBAF) uniquely contains bromodomain-containing protein BRD9 and glioma tumor suppressor candidate region 1 (GLTSCR1) or its paralog GLTSCR1-like (GLTSCR1L). Recent studies have identified a unique dependency on GBAF (ncBAF) complexes in synovial sarcoma and malignant rhabdoid tumors, both of which possess aberrations in canonical BAF (cBAF) and Polybromo-BAF (PBAF) complexes. Dependencies on GBAF in malignancies without SWI/SNF aberrations, however, are less defined. Here, we show that GBAF, particularly its BRD9 subunit, is required for the viability of prostate cancer cell lines in vitro and for optimal xenograft tumor growth in vivo. BRD9 interacts with androgen receptor (AR) and CCCTC-binding factor (CTCF), and modulates AR-dependent gene expression. The GBAF complex exhibits overlapping genome localization and transcriptional targets as bromodomain and extraterminal domain-containing (BET) proteins, which are established AR coregulators. Our results demonstrate that GBAF is critical for coordinating SWI/SNF-BET cooperation and uncover a new druggable target for AR-positive prostate cancers, including those resistant to androgen deprivation or antiandrogen therapies. SIGNIFICANCE: Advanced prostate cancers resistant to androgen receptor antagonists are still susceptible to nontoxic BRD9 inhibitors, making them a promising alternative for halting AR signaling in progressed disease.

Long non-coding RNA regulating androgen receptor signaling in breast and prostate cancer.

The human genome transcribe an array of RNAs that do not encode proteins and may act as mediators in the regulation of gene expression. Long non-coding RNAs (lncRNAs) are a group of non-coding RNAs consisting of more than 200 nucleotides of RNA transcripts that play important role in tumor development. Numerous lncRNAs have been characterized as functional transcripts associated with several biological processes and pathologic stages. Although the biological function and molecular mechanisms of lncRNAs remains to be explored, recent studies demonstrate aberrant expression of several lncRNAs linked with various human cancers. The present review summarizes the current knowledge of lncRNA expression patterns and mechanisms that contribute to carcinogenesis. In particular, we focus on lncRNAs regulating androgen receptor signaling pathways in prostate and breast cancer subtype having prognostic and therapeutic implications.

Abstract 1311A: CYP3A5 regulation of androgen receptor signaling: Relevance in African American prostate cancer patients and its development as novel target

Abstract Background: Previously we demonstrated that CYP3A5 positively regulates androgen receptor (AR) signaling and growth of prostate cancer (PC) cells. CYP3A5 inhibition decreases nuclear AR localization and downregulates AR downstream signaling (e.g. PSA and TMPRSS2), resulting in decreased PC cell growth both with and without dihydrotestosterone (DHT) induction. Our current work focusses on the effect of CYP3A5 modulation on AR signaling and therapeutic resistance, mostly in African Americans (AA) widely carrying (73%) wild type CYP3A5 (*1/*1). AAs and have higher incidence of PC and double the mortality rate compared to Non-Hispanic White Americans (NHWA) carrying mutated CY3A5 gene (*3/3, 95%) and expressing truncated non-functional CYP3A5 protein. Methods: Immunoprecipitation was used to identify binding partners of AR. q-RT-PCR based profiler assays was used to detect changes in AR downstream signaling and effect on genes responsible for therapeutic resistance after CYP3A5 inhibition. Effect of CYP3A5 on AR nuclear translocation and induction of synthetic lethality in combination with PARP inhibitors were evaluated using cell fractionation and immunocytochemistry studies. Results: Co-immunoprecipitation of flag-tagged CYP3A5 transfected LNCaP cell extracts showed that CYP3A5 was in a complex with HSP90, AR, HSP70 and HSP40, also confirmed with reverse immunoprecipitation using AR/ HSP90 antibodies and agarose A/G beads. AR regulated genes (SCL45A3, FKBP5, MYC, ELL2, and MT2A) were downregulated with CYP3A5 siRNA treatment in MDA PCa 2b cells (*1/*3, AA origin) in a qPCR-based profiler assay with high fold difference and a P value of ≤0.005. PC patients are often prescribed medications for comorbidities, many of which are CYP3A modulators. Our results indicate that CYP inhibitors (amiodarone, ritonavir, fluoxetine etc.) decrease AR nuclear translocation and inducers (phenytoin, rifampicin, pioglitazone and hyperforin) increase AR nuclear translocation and activation. CYP3A5 siRNA treatment downregulates genes involved in cancer drug therapeutic resistance (TOP2A, BRCA1/2, CCNE1, CDK2/4, DHFR, MVP, MYC, RARB and HPRT1, P ≤ 0.005 ). Loss of TOP2A, BRCA2 and BRCA1is known to impair homologous recombination (HR). In combination with topoisomerase inhibitor etoposide, CYP3A5 siRNA in PC cells increases number of gamma-H2AX foci indicating synthetic lethality. Conclusion: A-Developing CYP3A5-AR-HSP90 interface as a target may provide a novel strategy to block PC growth. B-CYP3A5 modulation of AR signaling can affect the efficacy of androgen deprivation therapy specifically AA patients carrying wild type CYP3A5. C-Since CYP3A5 inhibition, downregulates DNA damage repair genes and impairs HR, CYP3A5 inhibition in combination with PARP inhibitors can be a novel strategy to induce synthetic lethality in PC patients. Citation Format: Priyatham Gorjala, Oscar B. Goodman, Ranjana Mitra. CYP3A5 regulation of androgen receptor signaling: Relevance in African American prostate cancer patients and its development as novel target [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1311A.

Transcribed ultraconserved region Uc.63+ promotes resistance to cisplatin through regulation of androgen receptor signaling in bladder cancer

Cisplatin (CDDP)‑based combination chemotherapy is the standard for muscle‑invasive bladder cancer (MIBC). However, nearly all patients undergoing CDDP chemotherapy become refractory due to the development of CDDP resistance. Therefore, clarification of the mechanisms of CDDP resistance is urgently needed. The transcribed ultraconserved regions (T‑UCRs) are a novel class of non‑coding RNAs that are highly conserved across species and are associated with carcinogenesis and cancer progression. In addition, emerging evidence has shown the involvement of androgen receptor (AR) signals in urothelial carcinoma (UC) progression. The aim of the present study was to investigate the expression of transcribed ultraconserved region Uc.63+, and to analyze the effects of Uc.63+ on AR expression and CDDP resistance in UC. Quantitative reverse transcription‑polymerase chain reaction (qRT‑PCR) revealed that the expression of Uc.63+ was higher in UC tissues than that in non‑neoplastic bladder tissues and 15types of normal tissue. An MTT assay revealed that Uc.63+ was involved in cell proliferation. Western blotting demonstrated that the expression of AR was disrupted by the overexpression or knockdown of Uc.63+ in AR‑positive UMUC3cells. Furthermore, knockdown of Uc.63+ increased sensitivity to CDDP in UMUC3cells. Conversely, overexpression of Uc.63+ had no effect on CDDP sensitivity in AR‑negative RT112cells. Additionally, we observed that the expression of Uc.63+ was increased in CDDP‑resistant UMUC3cells (UMUC3‑CR) in comparison with that in parental UMUC3cells. Knockdown of Uc.63+ re‑sensitized the UMUC3‑CR cells to CDDP. These results indicated that Uc.63+ may be a promising therapeutic target to overcome CDDP resistance in UC.

Tumor-Suppressive Function of miR-30d-5p in Prostate Cancer Cell Proliferation and Migration by Targeting NT5E.

MiR-30d-5p, a member of the microRNA family, was recently reported to regulate androgen receptor signaling in prostate cancer (PCa). Ecto-5'-nucleotidase (NT5E/CD73) is a pivotal regulator of tumor migration and has angiogenetic properties. However, the undiscovered function of miR-30d-5p and whether it targeted NT5E in PCa remain uncertain. In this study, the authors observed miR-30d-5p was significantly downregulated in PCa tissues and cell lines compared with the adjacent normal tissues and normal prostate cells, respectively. The lower expression of miR-30d-5p was found to be inversely correlated with the NT5E expression in PCa tissues. Subsequently, the biological function of miR-30d-5p was evaluated in PCa in vitro. The results indicated that miR-30d-5p overexpression inhibited PCa cell growth and invasion by MTT, Transwell assays, respectively, as well as induced cell cycle G0/G1 phase arrest and apoptosis using flow cytometry analysis. In addition, miR-30d-5p directly bound to the 3'UTR (3' untranslated region) of NT5E in DU-145 and PC-3 cells by luciferase reporter assay. Furthermore, enforced NT5E expression alleviated miR-30d-5p inhibition of PCa cell growth and invasion in DU145 cells. Taken together, these data indicated that miR-30d-5p may be a potential therapeutic target for the treatment of PCa by serving as a tumor suppressor, by negatively regulating NT5E.

Transcribed ultraconserved region Uc.63+ promotes resistance to docetaxel through regulation of androgen receptor signaling in prostate cancer.

Docetaxel is the standard chemotherapy for metastatic castration-resistant prostate cancer (CRPC). However, nearly all patients ultimately become refractory due to the development of docetaxel resistance. The transcribed ultraconserved regions (T-UCRs) are a novel class of non-coding RNAs that are absolutely conserved across species and are involved in carcinogenesis including prostate cancer (PC). In this study, we investigated the transcriptional levels of 26 representative T-UCRs and determined the regions that were differentially expressed in PC. Quantitative real-time polymerase chain reaction analysis revealed that the expression of T-UCR Uc.63+ was increased in PC tissues. MTT assay and wound healing assay revealed that Uc.63+ was involved in cell growth and cell migration. miR-130b was predicted to have binding sites within the Uc.63+ sequence. The expression of miR-130b was significantly disturbed by the overexpression or knockdown of Uc.63+. We also showed that Uc.63+ regulated the expression of MMP2 via miR-130b regulation. Furthermore, overexpression of Uc.63+ increased the expression of AR and its downstream molecule PSA and promoted resistance to docetaxel through AR regulation. In patients treated with docetaxel, the expression of serum Uc.63+ in the docetaxel-resistant patients was higher than that in the docetaxel-sensitive patients (P = 0.011). Moreover, Kaplan-Meier analysis showed that the high expression of serum Uc.63+ correlated with a worse prognosis (P = 0.020). These results substantially support the important role that Uc.63+ plays in PC progression by interacting with miR-130b and indicate that Uc.63+ could potentially be a promising serum marker for deciding the best treatment for patients with CRPC.

Regulation of androgen receptor signaling by ubiquitination during folliculogenesis and its possible dysregulation in polycystic ovarian syndrome

Although chronic hyperandrogenism suppresses antral follicular development, a phenomenon often observed in polycystic ovarian syndrome (PCOS), whether and how deregulation of androgen receptor (AR) signaling is involved, is not well understood. In the present study, we examined the role of ring finger protein 6 (RNF6) in AR ubiquitination and the possible dysregulation in the expression and actions of growth differentiation factor 9 (GDF9) and kit-ligand (Kitlg) in a chronic androgenized PCOS rat model. 5α-dihydrotestosterone (DHT) treatment in vivo inhibited antral follicle growth, a response mediated through increased RNF6 content, suppressed K63- but increased K48-linked AR ubiquitination as well as the mRNA expression and content of soluble KIT-L (sKitlg) and content of GDF9. These androgenic responses were attenuated by gonadotropin treatment in vivo. Growth of antral follicles from DHT-treated rats in vitro was significantly slower when compared to those of control but was significantly enhanced by exogenous GDF9, suggesting the DHT-induced antral follicular growth arrest is in part the results of GDF9 suppression. Our findings indicate how hyperandrogenism modulates RNF6 content and subsequently AR ubiquitination, resulting in antral follicle growth arrest in a chronically androgenized PCOS rat model.

Abstract 3130: CYP3A5 positively regulates androgen receptor signaling in prostate cancer cells: Potential for therapeutic targeting

Abstract Purpose: Prostate cancer is the most common malignancy and second leading cause of cancer-specific mortality in US men. The androgen receptor (AR) plays a major role in promoting growth and progression of prostate cancer and thus has been successfully targeted therapeutically. Therapeutic resistance to androgen deprivation therapy (ADT) accounts for much of the morbidity and mortality attributable to prostate cancer. Therapeutic resistance is typically accompanied by insufficient blockade of AR activation, whose initial step involves translocation of AR to the nucleus. Previously we demonstrated that CYP3A5 facilitates the nuclear translocation of AR, promoting prostate cancer growth. Targeting CYP3A5 and blocking AR nuclear translocation may override therapeutic resistance to ADT, representing a novel approach for treating men with advanced prostate cancer. This work focuses on understanding the role of CYP3A5 in regulating AR nuclear translocation process and its subsequent promotion of prostate cancer growth. Methods: AR nuclear translocation is tightly regulated through a process involving several chaperones, multiple cofactors, and kinases, including HSP90, HSP70, HSP40 and HSP27. Complexed HSP90 maintains the AR as an inactive receptor in the cytoplasm. Upon androgen binding and activation, AR associates with HSP27, then translocates to the nucleus where it activates transcription of AR regulated genes responsible for prostate cancer growth. To decipher the role of CYP3A5 in this AR translocation process we performed a series of co-immunoprecipitation experiments with CYP3A5 and components of HSP90-AR complex, at different stages of AR translocation process. We used extracts of LNCaP transfected with a CYP3A5-Flag-tagged construct with either Flag-agarose or HSP90 and AR antibodies with A/G beads for immunoprecipitation. Results: Our co-immunoprecipitation experiments using CYP3A5-Flag transfected LNCaP extracts demonstrate that CYP3A5 associates with the HSP90-AR complex that helps to maintain AR in a form that can be readily activated by androgen. Using Flag-agarose in co-immunoprecipitation experiments, we demonstrated that CYP3A5 is a component of the HSP90-AR complex, associating with AR, HSP90, HSP70 and HSP40 each which are chaperones regulating AR nuclear translocation. We further confirmed the presence of CYP3A5 in the HSP90-AR complex by co-immunoprecipitation using HSP90 and AR antibodies in combination with A/G beads instead of flag-agarose. Conclusion: Our current finding supports the notion that CYP3A5 is a part of the HSP90-AR complex and positively regulates AR nuclear translocation. Therefore, targeting CYP3A5 to block AR nuclear translocation may be a therapeutic adjunctive approach in advanced prostate cancer. Citation Format: Ranjana Mitra, Priyatham Gorjala, Oscar B. Goodman. CYP3A5 positively regulates androgen receptor signaling in prostate cancer cells: Potential for therapeutic targeting [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3130. doi:10.1158/1538-7445.AM2017-3130

Estrogen receptor β, a regulator of androgen receptor signaling in the mouse ventral prostate.

As estrogen receptor β-/- (ERβ-/-) mice age, the ventral prostate (VP) develops increased numbers of hyperplastic, fibroplastic lesions and inflammatory cells. To identify genes involved in these changes, we used RNA sequencing and immunohistochemistry to compare gene expression profiles in the VP of young (2-mo-old) and aging (18-mo-old) ERβ-/- mice and their WT littermates. We also treated young and old WT mice with an ERβ-selective agonist and evaluated protein expression. The most significant findings were that ERβ down-regulates androgen receptor (AR) signaling and up-regulates the tumor suppressor phosphatase and tensin homolog (PTEN). ERβ agonist increased expression of the AR corepressor dachshund family (DACH1/2), T-cadherin, stromal caveolin-1, and nuclear PTEN and decreased expression of RAR-related orphan receptor c, Bcl2, inducible nitric oxide synthase, and IL-6. In the ERβ-/- mouse VP, RNA sequencing revealed that the following genes were up-regulated more than fivefold: Bcl2, clusterin, the cytokines CXCL16 and -17, and a marker of basal/intermediate cells (prostate stem cell antigen) and cytokeratins 4, 5, and 17. The most down-regulated genes were the following: the antioxidant gene glutathione peroxidase 3; protease inhibitors WAP four-disulfide core domain 3 (WFDC3); the tumor-suppressive genes T-cadherin and caveolin-1; the regulator of transforming growth factor β signaling SMAD7; and the PTEN ubiquitin ligase NEDD4. The role of ERβ in opposing AR signaling, proliferation, and inflammation suggests that ERβ-selective agonists may be used to prevent progression of prostate cancer, prevent fibrosis and development of benign prostatic hyperplasia, and treat prostatitis.

Epigenomic Regulation of Androgen Receptor Signaling: Potential Role in Prostate Cancer Therapy.

Androgen receptor (AR) signaling remains the major oncogenic pathway in prostate cancer (PCa). Androgen-deprivation therapy (ADT) is the principle treatment for locally advanced and metastatic disease. However, a significant number of patients acquire treatment resistance leading to castration resistant prostate cancer (CRPC). Epigenetics, the study of heritable and reversible changes in gene expression without alterations in DNA sequences, is a crucial regulatory step in AR signaling. We and others, recently described the technological advance Chem-seq, a method to identify the interaction between a drug and the genome. This has permitted better understanding of the underlying regulatory mechanisms of AR during carcinogenesis and revealed the importance of epigenetic modifiers. In screening for new epigenomic modifiying drugs, we identified SD-70, and found that this demethylase inhibitor is effective in CRPC cells in combination with current therapies. The aim of this review is to explore the role of epigenetic modifications as biomarkers for detection, prognosis, and risk evaluation of PCa. Furthermore, we also provide an update of the recent findings on the epigenetic key processes (DNA methylation, chromatin modifications and alterations in noncoding RNA profiles) involved in AR expression and their possible role as therapeutic targets.

Galectin-3 Is Implicated in Tumor Progression and Resistance to Anti-androgen Drug Through Regulation of Androgen Receptor Signaling in Prostate Cancer.

Castration-resistant prostate cancer (CRPC)-related deaths are increasing worldwide. Therefore, clarification of the mechanisms of hormone-related tumor progression and resistance to anti-androgen drugs is useful in order to develop strategies for appropriate treatment of CRPC. Galectin-3 has been shown to be correlated with tumor progression in a variety of cancer types through the regulation of tumor proliferation, angiogenesis, and apoptosis. We examined tumor cell invasion and migration using the xCELLigence system. Control LNCaP and galectin-3-expressing LNCaP (LNCaP-Gal-3) cells were cultured with androgen-depleted medium with 5% charcoal-stripped serum. Cells were treated for 24 h with or without dihydrotestosterone alone or combined with MDV3100 and bicalutamide; gene profile was then analyzed by microarray analysis and mRNA expression was confirmed by quantitative real-time polymerase chain reaction (qRT-PCR). We evaluated tumor growth using spheroids and xenograft tumor growth in a mouse model. In vitro, LNCaP-Gal-3 cells promoted both cell migration and invasion in an androgen-independent manner compared to control LNCaP cells. Galectin-3 also enhanced anchorage-independent growth and xenograft tumor growth even after castration. Importantly, galectin-3 greatly enhanced transcriptional activity of the androgen receptor (AR), especially on treatment with dihydrotestosterone. In microarray and qRT-PCR analyses, galectin-3 increased the expression of several AR-target genes, such as kallikrein-related peptidase 3 (KLK3), and transmembrane protease, serine 2 (TMPRSS2). These AR-target genes were not fully suppressed by anti-androgen drugs such as bicalutamide or MDV3100. Galectin-3 significantly inhibited the effect induced by anti-androgen drugs MDV3100 and bicalutamide, suggesting that galectin-3 may be involved in resistance to anti-androgen drug through enhancement of transcriptional activity of AR and expression of AR-related genes. These results suggest that galectin-3 is a potential target molecule for future treatment of anti-androgen drug-resistant prostate cancer.

Abstract 1805: CYP3A4 regulation of androgen receptor signaling in ER+ breast cancer

Abstract Purpose: Eighty percent of breast cancers that are estrogen receptor-positive (ER+) express AR. According to American Cancer Society, every two out of three women are ER+ and initially respond to estrogen-receptor targeted therapies but later almost 50% of breast cancers, despite the presence of ER, fail to respond. Acquired resistance to these therapies is common and portends a poor prognosis, frequently requiring the use of cytotoxic therapies. Our preliminary results indicate that endocrine-resistant tumors express higher levels of AR and may depend on AR for their growth. Hence AR targeted therapies may be appropriate for these resistant tumors. As we have recently demonstrated that CYP3A regulates androgen receptor signaling, we wish to ascertain the role of CYP3A in regulating AR in endocrine-resistant breast cancer. Methods: The ER+ cell lines MCF7 and T47D were used to study the role of AR in breast cancer. To study endocrine resistance in breast cancer, tamoxifen resistant MCF7 and T47D lines were generated with recurrent treatment of IC90 dosage of tamoxifen over 6 months’ time period. Cell fractionation, western blotting and q-RTPCR techniques were used to study the role of AR. siRNA inhibition of CYP3A4, the isoform expressed in breast, was used to study its role in regulating AR in breast cancer. Results: Our results indicate that both MCF7 and T47D express active AR, inducible by DHT and R1881. Similar to prostate cancer we also observe that AR in these lines is regulated by CYP3A4. Cell fractionation studies indicate that inhibition of CYP3A4 by siRNA results in reduced AR migration to the nucleus inhibiting its role as a transcription factor. Our results also indicate that tamoxifen resistant cell lines express increased levels of AR. Tamoxifen resistant cell lines respond to bicalutamide/enzalutamide with a lower IC50 value than the native cell lines, reflecting their AR dependence. The resistant cell lines also show increased AR nuclear migration with R1881 induction as compared to native breast cell lines. Conclusions: Endocrine-resistant breast cancer is sensitive to antiandrogen therapy. CYP3A4 may play an important role in endocrine-resistant breast cancer by negatively regulating AR activity. Citation Format: Priyatham Gorjala, Oscar Goodman Jr, Ranjana Mitra. CYP3A4 regulation of androgen receptor signaling in ER+ breast 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 1805.

A novel crosstalk between the tumor suppressors ING1 and ING2 regulates androgen receptor signaling.

• The tumor suppressors ING1 and 2 are dysregulated in human prostate cancer. • ING1 deficiency reduces AR-mediated gene expression in vitro and in vivo. • ING2, like ING1, inhibits AR-mediated transactivation and prostate cancer cell growth. • ING1 regulates ING2. • ING1 and ING2 crosstalk with each other to inhibit AR signaling in prostate cancer.

Non-Coding RNAs in Castration-Resistant Prostate Cancer: Regulation of Androgen Receptor Signaling and Cancer Metabolism.

Hormone-refractory prostate cancer frequently relapses from therapy and inevitably progresses to a bone-metastatic status with no cure. Understanding of the molecular mechanisms conferring resistance to androgen deprivation therapy has the potential to lead to the discovery of novel therapeutic targets for type of prostate cancer with poor prognosis. Progression to castration-resistant prostate cancer (CRPC) is characterized by aberrant androgen receptor (AR) expression and persistent AR signaling activity. Alterations in metabolic activity regulated by oncogenic pathways, such as c-Myc, were found to promote prostate cancer growth during the development of CRPC. Non-coding RNAs represent a diverse family of regulatory transcripts that drive tumorigenesis of prostate cancer and various other cancers by their hyperactivity or diminished function. A number of studies have examined differentially expressed non-coding RNAs in each stage of prostate cancer. Herein, we highlight the emerging impacts of microRNAs and long non-coding RNAs linked to reactivation of the AR signaling axis and reprogramming of the cellular metabolism in prostate cancer. The translational implications of non-coding RNA research for developing new biomarkers and therapeutic strategies for CRPC are also discussed.

Regulation of Human UGT2B15 and UGT2B17 by miR-376c in Prostate Cancer Cell Lines.

Given the prime importance of UDP-glucuronosyltransferase (UGT) 2B15 and UGT2B17 in inactivating testosterone and dihydrotestosterone, control of their expression and activity in the prostate is essential for androgen signaling homeostasis in this organ. Although several studies provide evidence of transcriptional control of UGT2B15 and UGT2B17 by various endogenous and exogenous compounds, potential post-transcriptional regulation of UGT2B15 and UGT2B17 by microRNAs (miRs) in prostate cancer cells has not been examined. The present study identified a putative miR-376c target site in the 3'-untranslated regions (UTRs) of both UGT2B15 and UGT2B17 mRNAs. In accordance with the possibility that this miRNA negatively regulates UGT2B15 and UGT2B17 expression, there is an inverse correlation in the levels of miR-376c and UGT2B15/UGT2B17 mRNAs in prostate cancer cell lines versus normal prostate tissue. In LNCaP cells, transfection of miR-376c mimics inhibited the glucuronidations of testosterone, 4-methylumbelliferone (a substrate of UGT2B15), and androsterone (a substrate of UGT2B17). miR-376c reduced both UGT2B15 and UGT2B17 mRNA and protein levels and the activity of luciferase reporters containing UGT2B15 or UGT2B17 3'-UTRs. This microRNA-mediated repression was significantly abrogated by mutating the miR-376c binding site in the 3'-UTRs of both UGTs. Collectively, these data indicate that the expression of UGT2B15 and UGT2B17 is negatively regulated by the binding of miR-376c to the 3'-UTRs of UGT2B15 and UGT2B17 in prostate cancer cells. This represents the first evidence for post-transcriptional regulation of UGT2B15 and UGT2B17 by miRNAs in prostate cancer cells and may have importance in regulating androgen receptor signaling.

Identification of novel genes that regulate androgen receptor signaling and growth of androgen-deprived prostate cancer cells.

Prostate cancer progression to castration refractory disease is associated with anomalous transcriptional activity of the androgen receptor (AR) in an androgen-depleted milieu. To identify novel gene products whose downregulation transactivates AR in prostate cancer cells, we performed a screen of enzymatically-generated shRNA lenti-libraries selecting for transduced LNCaP cells with elevated expression of a fluorescent reporter gene under the control of an AR-responsive promoter. The shRNAs present in selected populations were analyzed using high-throughput sequencing to identify target genes. Highly enriched gene targets were then validated with siRNAs against selected genes, testing first for increased expression of luciferase from an AR-responsive promoter and then for altered expression of endogenous androgen-regulated genes in LNCaP cells. We identified 20 human genes whose silencing affected the expression of exogenous and endogenous androgen-responsive genes in prostate cancer cells grown in androgen-depleted medium. Knockdown of four of these genes upregulated the expression of endogenous AR targets and siRNAs targeting two of these genes (IGSF8 and RTN1) enabled androgen-independent proliferation of androgen-dependent cells. The effects of IGSF8 appear to be mediated through its interaction with a tetraspanin protein, CD9, previously implicated in prostate cancer progression. Remarkably, homozygous deletions of IGSF8 are found almost exclusively in prostate cancers but not in other cancer types. Our study shows that androgen independence can be achieved through the inhibition of specific genes and reveals a novel set of genes that regulate AR signaling in prostate cancers.

Hydrogen Sulfide Represses Androgen Receptor Transactivation by Targeting at the Second Zinc Finger Module

Androgen receptor (AR) signaling is indispensable for the development of prostate cancer from the initial androgen-dependent state to a later aggressive androgen-resistant state. This study examined the role of hydrogen sulfide (H(2)S), a novel gasotransmitter, in the regulation of AR signaling as well as its mediation in androgen-independent cell growth in prostate cancer cells. Here we found that H(2)S inhibits cell proliferation of both androgen-dependent (LNCaP) and antiandrogen-resistant prostate cancer cells (LNCaP-B), with more significance on the latter, which was established by long term treatment of parental LNCaP cells with bicalutamide. The expression of cystathionine γ-lyase (CSE), a major H(2)S producing enzyme in prostate tissue, was reduced in both human prostate cancer tissues and LNCaP-B cells. LNCaP-B cells were resistant to bicalutamide-induced cell growth inhibition, and CSE overexpression could rebuild the sensitivity of LNCaP-B cells to bicalutamide. H(2)S significantly repressed the expression of prostate-specific antigen (PSA) and TMPRSS2, two AR-targeted genes. In addition, H(2)S inhibited AR binding with PSA promoter and androgen-responsive element (ARE) luciferase activity. We further found that AR is post-translationally modified by H(2)S through S-sulfhydration. Mutation of cysteine 611 and cysteine 614 in the second zinc finger module of AR-DNA binding domain diminished the effects of H(2)S on AR S-sulfhydration and AR dimerization. These data suggest that reduced CSE/H2S signaling contributes to antiandrogen-resistant status, and sufficient level of H(2)S is able to inhibit AR transactivation and treat castration-resistant prostate cancer.