Androgen receptor regulates SRC expression through microRNA-203.
Ontology highlight
ABSTRACT:
SUBMITTER: Siu MK
PROVIDER: S-EPMC5041939 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Gene expression is potently regulated through the action of microRNAs (miRNAs). Here, we present evidence of a miRNA regulating Hakai protein. Hakai was discovered as an E3 ubiquitin-ligase that mediates the posttranslational downregulation of E-cadherin, a major component of adherens junctions in epithelial cells and a potent tumour suppressor. Recent data have provided evidence that Hakai affects cell proliferation in an E-cadherin-independent manner, thus revealing a role for Hakai in the early stages of tumour progression. Furthermore, Hakai is highly up-regulated in human colon adenocarcinomas compared to normal tissues. However, the molecular mechanisms that regulate Hakai abundance are unknown. We identified two putative sites of miR-203 interaction on the Hakai mRNA, in its 3'-untranslated region (UTR). In several human carcinoma cell lines tested, overexpression of a miR-203 precursor (Pre-miR-203) reduced Hakai abundance, while inhibiting miR-203 by using an antisense RNA (Anti-miR-203) elevated Hakai levels. The repressive influence of miR-203 on the Hakai 3'-UTR was confirmed using heterologous reporter constructs. In keeping with Hakai's proliferative influence, Anti-miR-203 significantly increased cell number and BrdU incorporation, while Pre-miR-203 reduced these parameters. Importantly, the growth-promoting effects of anti-miR-203 required the presence of Hakai, because downregulation of Hakai by siRNA suppressed its proliferative action. Finally, in situ hybridization showed that miR-203 expression is attenuated in colon tumour tissues compared to normal colon tissues, suggesting that miR-203 could be a potential new prognostic marker and therapeutic target to explore in colon cancer. In conclusion, our findings reveal, for the first time, a post-transcriptional regulator of Hakai expression. Furthermore, by lowering Hakai abundance, miR-203 also reduces Hakai-regulated-cell division.
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Project description:Androgen therapy is the mainstay of treatment for the hypogonadotropic hypogonadal micropenis because it obviously enhances penis growth in prepubescent microphallic patients. However, the molecular mechanisms of androgen treatment leading to penis growth are still largely unknown. To clarify this well-known phenomenon, we successfully generated a castrated male Sprague Dawley rat model at puberty followed by testosterone administration. Interestingly, compared with the control group, testosterone treatment stimulated a dose-dependent increase of penis weight, length, and width in castrated rats accompanied with a dramatic recovery of the pathological changes of the penis. Mechanistically, testosterone administration substantially increased the expression of androgen receptor (AR) protein. Increased AR protein in the penis could subsequently initiate transcription of its target genes, including keratin 33B (Krt33b). Importantly, we demonstrated that KRT33B is generally expressed in the rat penis and that most KRT33B expression is cytoplasmic. Furthermore, AR could directly modulate its expression by binding to a putative androgen response element sequence of the Krt33b promoter. Overall, this study reveals a novel mechanism facilitating penis growth after testosterone treatment in precastrated prepubescent animals, in which androgen enhances the expression of AR protein as well as its target genes, such as Krt33b.
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Project description:Aging and testosterone almost inexorably cause benign prostatic hyperplasia (BPH) in Human males. However, etiology of BPH is largely unknown. Serotonin (5-HT) is produced by neuroendocrine prostatic cells and presents in high concentration in normal prostatic transition zone, but its function in prostate physiology is unknown. Previous evidence demonstrated that neuroendocrine cells and 5-HT are decreased in BPH compared to normal prostate. Here, we show that 5-HT is a strong negative regulator of prostate growth. In vitro, 5-HT inhibits rat prostate branching through down-regulation of androgen receptor (AR). This 5-HT's inhibitory mechanism is also present in human cells of normal prostate and BPH, namely in cell lines expressing AR when treated with testosterone. In both models, 5-HT's inhibitory mechanism was replicated by specific agonists of 5-Htr1a and 5-Htr1b. Since peripheral 5-HT production is specifically regulated by tryptophan hydroxylase 1(Tph1), we showed that Tph1 knockout mice present higher prostate mass and up-regulation of AR when compared to wild-type, whereas 5-HT treatment restored the prostate weight and AR levels. As 5-HT is decreased in BPH, we present here evidence that links 5-HT depletion to BPH etiology through modulation of AR. Serotoninergic prostate pathway should be explored as a new therapeutic target for BPH.
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Project description:Bladder cancer is often associated with recurrence and progression to invasive metastatic disease that have palliative therapeutic options. The use of traditional chemotherapeutic agents for bladder cancer management often suffers from toxicity and resistance concerns. This emphasizes the need for development of safer, natural, nontoxic compounds as chemotherapeutic/chemopreventive agents. Curcumin (diferuloylmethane) is a natural compound that has been known to possess anticancer properties in various cancers, including bladder cancer. However, the biological targets of curcumin are not well defined. Recently, it has been proposed that curcumin may mediate epigenetic modulation of expression of microRNAs (miRNA). In this article, we define for the first time, that curcumin directly induces a tumor-suppressive miRNA, miR-203, in bladder cancer. miR-203 is frequently downregulated in bladder cancer due to DNA hypermethylation of its promoter. We studied the functional significance of miR-203 in bladder cancer cell lines and found that miR-203 has tumor suppressive properties. Also, we define Akt2 and Src as novel miR-203 targets in bladder cancer. Curcumin induces hypomethylation of the miR-203 promoter and subsequent upregulation of miR-203 expression. This leads to downregulation of miR-203 target genes Akt2 and Src that culminates in decreased proliferation and increased apoptosis of bladder cancer cells. This is the first report that shows a direct effect of curcumin on inducing epigenetic changes at a miRNA promoter with direct biological consequences. Our study suggests that curcumin may offer a therapeutic advantage in the clinical management of refractory bladder cancer over other standard treatment modalities.
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Project description:The androgen receptor (AR) is important in the development of both experimental and human bladder cancer. However, the role of AR in bladder cancer growth and progression is less clear, with literature indicating that more advanced stage and grade disease are associated with reduced AR expression. To determine the mechanisms underlying these relationships, we profiled AR-expressing human bladder cancer cells by AR chromatin immunoprecipitation sequencing and complementary transcriptomic approaches in response to in vitro stimulation by the synthetic androgen R1881. In vivo functional genomics consisting of pooled shRNA or pooled open reading frame libraries was employed to evaluate 97 genes that recapitulate the direction of expression associated with androgen stimulation. Interestingly, we identified CD44, the receptor for hyaluronic acid, a potent biomarker and driver of progressive disease in multiple tumor types, as significantly associated with androgen stimulation. CRISPR-based mutagenesis of androgen response elements associated with CD44 identified a novel silencer element leading to the direct transcriptional repression of CD44 expression. In human patients with bladder cancer, tumor AR and CD44 mRNA and protein expression were inversely correlated, suggesting a clinically relevant AR-CD44 axis. Collectively, our work describes a novel mechanism partly explaining the inverse relationship between AR and bladder cancer tumor progression and suggests that AR and CD44 expression may be useful for prognostication and therapeutic selection in primary bladder cancer. SIGNIFICANCE: This study describes novel AREs that suppress CD44 and an expected inverse correlation of AR-CD44 expression observed in human bladder tumors.
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Project description:Zinc finger E-box binding homeobox 1 (ZEB1) is a transcription factor that plays a central role in the epithelial to mesenchymal transition (EMT) of cancer cell lines. Studies on its regulation have mostly focused on the negative 3'UTR binding of miR200c. Interestingly, it has been previously reported that androgen receptor (AR) regulates ZEB1 expression in breast and prostate cancers. In order to validate this, various ZEB1 promoter deletions were cloned into a luciferase reporter system to elucidate the contribution of two putative androgen response elements (AREs). The in vivo contribution of AR was also assessed in cell lines after R1881 treatment using qPCR with prostate specific antigen (PSA) as the positive control. We discovered that AR upregulates the levels of expression of ZEB1 10-fold on a luciferase promoter that only contains the distal ARE. However, when the proximal ARE is included, no additional activation is apparent with AR or its hormone independent variant, AR-V7. Furthermore, we demonstrate here that a promoter construct containing both AREs activates transcription of ZEB1 even in the AR-null cell lines DU145 and PC3. Incubation of the AR-positive cell line, LNCaP with R1881, failed to substantially increase the expression levels of ZEB1. Despite the presence of AREs in the promoter region, it appears that ZEB1 expression can be induced even without AR. In addition, the region around the distal ARE is a potent repressor in AR-null cell lines.
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Project description:In Astatotilapia burtoni, dominant males have higher levels of sex steroid hormones than subordinate males. Because of the complex regulatory interactions between steroid hormones and receptors, we asked whether dominance is also associated with variation in sex steroid receptor gene expression. Using quantitative PCR, we compared the expression of specific subtypes of androgen (AR) and estrogen (ER) receptor genes between dominant and subordinated males in 3 divisions of the brain, the pituitary, and the testes. We measured mRNA levels of AR-alpha, AR-beta, ER-alpha, ER-betaa, and ER-betab, gonadotropin-releasing hormone 1 (GnRH1), and GnRH receptor 1 (GnRH-R1) relative to 18S rRNA. In the anterior part of the brain, we found that dominant males had higher mRNA expression of AR-alpha, AR-beta, ER-betaa, and ER-betab, but not ER-alpha, compared to subordinate males. This effect of dominance was reflected in a positive correlation between testes size and AR-alpha, AR-beta, ER-betaa, and ER-betab in the anterior brain. In addition, mRNA levels of all ARs and ERs in the anterior brain were positively correlated with mRNA level of GnRH1. In the middle and posterior portions of the brain, as well as the testes, steroid receptor mRNA levels were similar among dominants and subordinates. In the pituitary, ER-alpha mRNA level was positively correlated with testes size and AR-alpha mRNA was positively correlated with GnRH-R1 mRNA level. These data suggest that dominant male brains could be more sensitive to sex steroids, which may contribute to the increased complexity of the behavioral repertoires of dominant males.
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Project description:The androgen receptor (AR) is a nuclear receptor that is expressed in growing follicles and involved in folliculogenesis and follicle growth. The orphan nuclear receptor, Nur77, also has an important role in steroid signaling and follicle maturation. We hypothesized that AR levels and androgen signaling through AR are regulated by Nur77 in the ovary. In the ovaries of Nur77 knockout mice (n = 5), real-time PCR results showed that the mRNA levels of AR and an androgen signaling target gene, Kitl, were decreased by 35% and 24%, respectively, relative to wild-type mice (n = 5), which suggested transcriptional regulation of AR by Nur77 in vivo. In cultured mouse granulosa cells and a steroidogenic human ovarian granulosa-like tumor cell line, KGN, mRNA and protein expression levels of AR were increased by overexpressing Nur77 but decreased by knocking down endogenous Nur77. Consistent with increased AR expression, chromatin immunoprecipitation showed that Nur77 bound to the NGFI-B response element (NBRE) in the AR promoter sequence. AR promoter activity was stimulated by Nur77 in HEK293T cells and attenuated in Nur77 knockout mouse granulosa cells (luciferase assay). Overexpression of Nur77 enhanced the androgenic induction of Kitl (200 nM; 48h), while knockout of Nur77 attenuated this induction. These results demonstrate that AR is regulated by Nur77 in the ovaries, and they suggest that the participation of Nur77 in androgen signaling may be essential for normal follicular development.
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Project description:The involvement of testosterone in pain, inflammation, and analgesia has been reported, but the role of androgen receptor (AR), a steroid receptor for testosterone, is not well understood. We have previously shown that peripheral inflammation upregulates μ-opioid receptor (MOR) in rat trigeminal ganglia (TG) in a testosterone-dependent manner. In this study, we hypothesized that testosterone regulates MOR expression via transcriptional activities of AR in TG. We first examined whether AR is co-expressed with MOR in TG neurons. Our immunohistochemical experiment revealed that AR staining is detected in neurons of all sizes in TG and that a subset of AR is expressed in MOR as well as in TRPV1-positive neurons. We identified the promoter region of the rat MOR gene contains putative AR binding sites. Using chromatin immunoprecipitation assay, we demonstrated that AR directly binds to these sites in TG extracts. We confirmed with luciferase reporter assay that AR activated the MOR promoter in response to androgens in a human neuroblastoma cell line (5H-5YSY). These data demonstrated that AR functions as a transcriptional regulator of the MOR gene activity. Finally, we showed that flutamide, a specific AR antagonist, prevents complete Freund's adjuvant (CFA)-induced upregulation of MOR mRNA in TG, and that flutamide dose-dependently blocks the efficacy of DAMGO, a specific MOR agonist, on CFA-induced mechanical hypersensitivity. Our results expand the knowledge regarding the role of androgens and their receptor in pain and analgesia and have important clinical implications, particularly for inflammatory pain patients with low or compromised plasma testosterone levels.
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Project description:LIN28B is an RNA-binding protein necessary for maintaining pluripotency in stem cells and plays an important role in trophoblast cell differentiation. LIN28B action on target gene function often involves the Let-7 miRNA family. Previous work in cancer cells revealed that LIN28 through Let-7 miRNA regulates expression of androgen receptor (AR). Considering the similarities between cancer and trophoblast cells, we hypothesize that LIN28B also is necessary for the presence of AR in human trophoblast cells. The human first-trimester trophoblast cell line, ACH-3P was used to evaluate the regulation of AR by LIN28B, and a LIN28B knockdown cell line was constructed using lentiviral-based vectors. LIN28B knockdown in ACH-3P cells resulted in significantly decreased levels of AR and increased levels of Let-7 miRNAs. Moreover, treatment of ACH-3P cells with Let-7c mimic, but not Let-7e or Let-7f, resulted in a significant reduction in LIN28B and AR. Finally, forskolin-induced syncytialization and Let-7c treatment both resulted in increased expression of syncytiotrophoblast marker ERVW-1 and a significant decrease in AR in ACH-3P. These data reveal that LIN28B regulates AR levels in trophoblast cells likely through its inhibitory actions on let-7c, which may be necessary for trophoblast cell differentiation into the syncytiotrophoblast.
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