Activation of phosphatidylinositol 3-kinase/Akt pathway by androgen through interaction of p85alpha, androgen receptor, and Src

Network Pharmacology Reveals Curcuma aeruginosa Roxb. Regulates MAPK and HIF-1 Pathways to Treat Androgenetic Alopecia

Androgenetic alopecia (AGA) is the most prevalent hair loss disorder worldwide, driven by excessive sensitivity or response to androgen. Herbal extracts, such as Curcuma aeruginosa Roxb., have shown promise in AGA treatment due to their anti-androgenic activities and hair growth effects. However, the precise mechanism of action remains unclear. Hence, this study aims to elucidate the active compounds, putative targets, and underlying mechanisms of C. aeruginosa for the therapy of AGA using network pharmacology and molecular docking. This study identified 66 bioactive compounds from C. aeruginosa, targeting 59 proteins associated with AGA. Eight hub genes were identified from the protein-protein interaction network, namely, CASP3, AKT1, AR, IL6, PPARG, STAT3, HIF1A, and MAPK3. Topological analysis of components-targets network revealed trans-verbenol, myrtenal, carvone, alpha-atlantone, and isoaromandendrene epoxide as the core components with potential significance in AGA treatment. The molecular docking verified the binding affinity between the hub genes and core compounds. Moreover, the enrichment analyses showed that C. aeruginosa is involved in hormone response and participates in HIF-1 and MAPK pathways to treat AGA. Overall, this study contributes to understanding the potential anti-AGA mechanism of C. aeruginosa by highlighting its multi-component interactions with several targets involved in AGA pathogenesis.

A Dominant-Negative Mutant of ANXA7 Impairs Calcium Signaling and Enhances the Proliferation of Prostate Cancer Cells by Downregulating the IP3 Receptor and the PI3K/mTOR Pathway

Annexin A7/ANXA7 is a calcium-dependent membrane fusion protein with tumor suppressor gene (TSG) properties, which is located on chromosome 10q21 and is thought to function in the regulation of calcium homeostasis and tumorigenesis. However, whether the molecular mechanisms for tumor suppression are also involved in the calcium- and phospholipid-binding properties of ANXA7 remain to be elucidated. We hypothesized that the 4 C-terminal endonexin-fold repeats in ANXA7 (GX(X)GT), which are contained within each of the 4 annexin repeats with 70 amino acids, are responsible for both calcium- and GTP-dependent membrane fusion and the tumor suppressor function. Here, we identified a dominant-negative triple mutant (DNTM/DN-ANXA7J) that dramatically suppressed the ability of ANXA7 to fuse with artificial membranes while also inhibiting tumor cell proliferation and sensitizing cells to cell death. We also found that the [DNTM]ANA7 mutation altered the membrane fusion rate and the ability to bind calcium and phospholipids. In addition, in prostate cancer cells, our data revealed that variations in phosphatidylserine exposure, membrane permeabilization, and cellular apoptosis were associated with differential IP3 receptor expression and PI3K/AKT/mTOR modulation. In conclusion, we discovered a triple mutant of ANXA7, associated with calcium and phospholipid binding, which leads to the loss of several essential functions of ANXA7 pertinent to tumor protection and highlights the importance of the calcium signaling and membrane fusion functions of ANXA7 for preventing tumorigenesis.

Androgens Regulate Tau Phosphorylation Through Phosphatidylinositol 3-Kinase-Protein Kinase B-Glycogen Synthase Kinase 3β Signaling

Age-related testosterone depletion in men is a risk factor for Alzheimer's disease (AD). How testosterone modulates AD risk remains to be fully elucidated, although regulation of tau phosphorylation has been suggested as a contributing protective action. To investigate the relationship between testosterone and tau phosphorylation, we first evaluated the effect of androgen status on tau phosphorylation in 3xTg-AD mice. Depletion of endogenous androgens via gonadectomy resulted in increased tau phosphorylation that was prevented by acute testosterone treatment. Parallel alterations in the phosphorylation of both glycogen synthase kinase 3β (GSK3β) and protein kinase B (Akt) suggest possible components of the underlying signaling pathway. To further explore mechanism, primary cultured neurons were treated with a physiological concentration of testosterone or its active metabolite dihydrotestosterone (DHT). Results showed that testosterone and DHT induced significant decreases in phosphorylated tau and significant increases in phosphorylation of Akt and GSK3β. Pharmacological inhibition of phosphatidylinositol 3-kinase (PI3K) effectively inhibited androgen-induced increases in Akt and GSK3β phosphorylation, and decreases in tau phosphorylation. In addition, androgen receptor (AR) knock-down by small interfering RNA prevented androgen-induced changes in the phosphorylation of Akt, GSK3β and tau, suggesting an AR-dependent mechanism. Additional experiments demonstrated androgen-induced changes in Akt, GSK3β and tau phosphorylation in AR-expressing PC12 cells but not in AR-negative PC12 cells. Together, these results suggest an AR-dependent pathway involving PI3K-Akt-GSK3β signaling through which androgens can reduce tau phosphorylation. These findings identify an additional protective mechanism of androgens that can improve neural health and inhibit development of AD.

Testosterone Levels Are Decreased and Associated with Disease Duration in Male Spinocerebellar Ataxia Type 2 Patients

Spinocerebellar ataxia type 2 (SCA2) is a progressive neurodegenerative disorder due to an unstable expansion of a CAG repeat in the ATXN2 gene. Despite clinical and experimental evidence indicating the relevance of the gonadotropic axis to the prognosis and therapeutics for several late-onset neurodegenerative disorders, its functioning and association with disease severity have not been previously explored in SCA2. To assess serum levels of testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH), and their clinical relevance in SCA2 patients. A case-control study involving 94 Cuban SCA2 patients and 101 gender- and age-matched healthy controls was conducted. Testosterone, LH, and FSH serum levels were determined by radioimmunoassay or immunoradiometric assay systems. Clinical outcomes included age at onset, disease duration, Scale for the Assessment and Rating of Ataxia (SARA) score, and progression rate. Univariate general linear models were generated. Testosterone, LH, and FSH serum levels were significantly reduced in male SCA2 patients relative to control individuals. On average, there was a 35% reduction in testosterone levels in male patients versus male control individuals. Testosterone levels were associated with disease duration (r = 0.383; p = 0.025) and age at onset (r = 0.414; p = 0.011) in male SCA2 patients, but no association was observed between testosterone and CAG expansion size, SARA score, or progression rate. Testosterone levels might be a biomarker of disease progression in male SCA2 patients. Further studies are needed to explore the effects of low testosterone levels on non-motor symptoms, and to assess the potential of testosterone replacement therapy in male SCA2 patients.

Azithromycin: Immunomodulatory and antiviral properties for SARS-CoV-2 infection

Azithromycin, a member of the macrolide family of antibiotics, is commonly used to treat respiratory bacterial infections. Nevertheless, multiple pharmacological effects of the drug have been revealed in several investigations. Conceivably, the immunomodulatory properties of azithromycin are among its critical features, leading to its application in treating inflammatory diseases, such as asthma and chronic obstructive pulmonary disease (COPD). Additionally, azithromycin may directly inhibit viral load as well as its replication, or it could demonstrate indirect inhibitory impacts that might be associated with the expression of antiviral genes. Currently, coronavirus disease 2019 (COVID-19) is an extra urgent issue affecting the entire world, and it is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Acute respiratory distress syndrome (ARDS), which is associated with hyper inflammation due to cytokine release, is among the leading causes of death in COVID-19 patients with critical conditions. The present paper aims to review the immunomodulatory and antiviral properties of azithromycin as well as its potential clinical applications in the management of COVID-19 patients.

Lycium barbarum Polysaccharide Ameliorates Heat-Stress-Induced Impairment of Primary Sertoli Cells and the Blood-Testis Barrier in Rat via Androgen Receptor and Akt Phosphorylation

Male infertility induced by heat stress has been attracting more and more attention. Heat stress not only causes apoptosis of spermatocytes but also has adverse effects on Sertoli cells, further damaging spermatogenesis. Lycium barbarum polysaccharide (LBP) is the main bioactive component of Lycium barbarum, which has a protective effect on male reproduction, but its mechanism is still unclear. In this study, our results proved that LBP blocked the inhibitory effect on the proliferation activity of Sertoli cells after heat stress, reversed the dedifferentiation of Sertoli cells induced by heat stress, and ameliorated the structural integrity of the blood-testis barrier. In addition, it increased the expression of the androgen receptor and activated Akt signaling pathway to resist heat-stress-induced injury of Sertoli cells.

Novel Therapeutic Strategies for CDK4/6 Inhibitors in Metastatic Castrate-Resistant Prostate Cancer

The majority of patients with castrate-resistant prostate cancer will have metastatic disease at the time of diagnosis. Investigative efforts on new therapeutics for this patient population have improved with the development of androgen signaling inhibitors, such as abiraterone and enzalutamide, and PARP inhibitors, such as rucaparib and olaparib, to accompany the previously FDA-approved docetaxel, cabazitaxel, sipuleucel-T, and Radium 223. However, new therapeutic strategies are necessary to prolong survival as progression after these agents is inevitable. CDK4/6 inhibitors have advanced the field of estrogen receptor positive breast cancer treatment and are being investigated in prostate cancer given the role of androgen receptor signaling effects on the cell cycle. Response to CDK4/6 inhibitors may be predicted by the tumors' genomic profile and may provide insight into combinatory therapy with CDK4/6 inhibitors in order to delay resistance or provide synergistic effects. Here, we review the use of CDK4/6 inhibitors in prostate cancer and potential combinations based on known resistance mechanisms to CDK4/6 inhibitors, prostate cancer regulatory pathways, and prostate-cancer-specific genomic alterations.

Enhancement of androgen transcriptional activation assay based on genome edited glucocorticoid knock out human prostate cancer cell line

Endocrine-disrupting chemicals (EDCs) interfere with the biological activity of hormones. Among EDC's, (anti-)androgenic compounds potentially cause several androgen-related diseases. To improve the accuracy of an in vitro transactivation assay (TA) for detection of (anti-)androgenic compounds, We established the glucocorticoid receptor (GR) knockout 22Rv1/MMTV cell line by using an RNA-guided engineered nuclease (RGEN)-derived CRISPR/Cas system. The 22Rv1/MMTV GRKO cell line was characterized and validated by androgen receptor (AR)-mediated TA assay compared with the AR-TA assay using 22Rv1/MMTV. In conclusion, the AR-TA assay with the 22Rv1/MMTV GRKO cell line was more accurate, excluding the misleading signals derived from glucocorticoids or equivalent chemicals, and might be an effective method for screening potential (anti-)androgenic compounds.

Androgens Induce Invasiveness of Triple Negative Breast Cancer Cells Through AR/Src/PI3-K Complex Assembly

Breast cancer (BC) is still characterized by high morbidity and mortality. A specific BC subtype named triple negative BC (TNBC) lacks estrogen and progesterone receptors (ER and PR, respectively) and is characterized by the absence of overexpression/amplification of human epidermal growth factor receptor 2 (HER2). The androgen receptor (AR) is expressed in TNBC, although its function in these cancers is still debated. Moreover, few therapeutic options are currently available for the treatment of TNBC. In this study, we have used TNBC-derived MDA-MB231 and MDA-MB453 cells that, albeit at different extent, both express AR. Androgen challenging induces migration and invasiveness of these cells. Use of the anti-androgen bicalutamide or AR knockdown experiments show that these effects depend on AR. Furthermore, the small peptide, S1, which mimics the AR proline-rich motif responsible for the interaction of AR with SH3-Src, reverses the effects in both cell lines, suggesting that the assembly of a complex made up of AR and Src drives the androgen-induced motility and invasiveness. Co-immunoprecipitation experiments in androgen-treated MDA-MB231 and MDA-MB453 cells show that the AR/Src complex recruits p85α, the regulatory subunit of PI3-K. In such a way, the basic machinery leading to migration and invasiveness is turned-on. The S1 peptide inhibits motility and invasiveness of TNBC cells and disrupts the AR/Src/p85α complex assembly in MDA-MB231 cells. This study shows that the rapid androgen activation of Src/PI3-K signaling drives migration and invasiveness of TNBC cells and suggests that the S1 peptide is a promising therapeutic option for these cancers.

VEGFR1 promotes cell migration and proliferation through PLCγ and PI3K pathways

The ability to control vascular endothelial growth factor (VEGF) signaling offers promising therapeutic potential for vascular diseases and cancer. Despite this promise, VEGF-targeted therapies are not clinically effective for many pathologies, such as breast cancer. VEGFR1 has recently emerged as a predictive biomarker for anti-VEGF efficacy, implying a functional VEGFR1 role beyond its classically defined decoy receptor status. Here we introduce a computational approach that accurately predicts cellular responses elicited via VEGFR1 signaling. Aligned with our model prediction, we show empirically that VEGFR1 promotes macrophage migration through PLCγ and PI3K pathways and promotes macrophage proliferation through a PLCγ pathway. These results provide new insight into the basic function of VEGFR1 signaling while offering a computational platform to quantify signaling of any receptor.

Androgen receptor regulates SRC expression through microRNA-203

The SRC kinase has pivotal roles in multiple developmental processes and in tumor progression. An inverse relationship has been observed between androgen receptor (AR) activity and SRC signaling in advanced prostate cancer (PCa); however, the modulation of AR/SRC crosstalk that leads to metastatic PCa is unclear. Here, we showed that patients with high SRC levels displayed correspondingly low canonical AR gene signatures. Our results demonstrated that activated AR induced miR-203 and reduced SRC levels in PCa model systems. miR-203 directly binds to the 3′ UTR of SRC and regulates the stability of SRC mRNA upon AR activation. Moreover, we found that progressive PCa cell migration and growth were associated with a decrease in AR-regulated miR-203 and an increase in SRC. Relationships among AR, miR-203, and SRC were also confirmed in clinical datasets and specimens. We suggest that the induction of SRC results in increased PCa metastasis that is linked to the dysregulation of the AR signaling pathway through the inactivation of miR-203.

Androgens Regulate Ovarian Gene Expression Through Modulation of Ezh2 Expression and Activity

A substantial amount of evidence suggests that androgen signaling through classical androgen receptors is critical for both normal and pathologic ovarian physiology. Specifically, we and others have shown that, in mouse granulosa cells, androgen actions through both extranuclear and nuclear androgen receptor signaling are critical for normal follicle development and ovulation. Here, we show that androgens through the PI3K/Akt pathway rapidly (within minutes) phosphorylate and inhibit activity of the Polycomb group protein enhancer of zeste homolog 2 (Ezh2). Over the course of 24 to 48 hours, androgens then induce expression of the microRNA miR-101, which targets Ezh2 messenger RNA (mRNA), leading to a nearly complete loss of Ezh2 protein expression. This long-term androgen-induced loss of Ezh2 actions ultimately results in sustained reduction of the H3K27me3-repressive mark in the promoter region of the Runt-related transcription factor-1 (Runx1) gene, a luteinizing hormone (LH)-induced transcription factor essential for ovulation, leading to increased Runx1 mRNA expression. Accordingly, blocking androgen-induced inhibition of Ezh2 in vivo adversely affects LH-induced Runx1 mRNA expression and subsequent ovulation. Importantly, although estrogen treatment of granulosa cells similarly causes rapid activation of the PI3K/Akt pathway and short-term phosphorylation of Ezh2, it does not induce miR-101 expression and thereby does not reduce overall Ezh2 expression, demonstrating the androgen specificity of long-term Ezh2 suppression. Thus, this study provides insight regarding how androgen-induced extranuclear kinase signaling and intranuclear transcription through Ezh2 modifications may influence the expression pattern of genes, ultimately affecting various downstream physiological processes.

Iminoenamine based novel androgen receptor antagonist exhibited anti-prostate cancer activity in androgen independent prostate cancer cells through inhibition of AKT pathway

Treatment by androgen receptor (AR) antagonists is one of the regimens for prostate cancer. The prolonged treatment with AR antagonist leads to the expression of point mutation in the ligand binding domain of the AR. This point mutation causes resistance to AR antagonist by converting them into an agonist. The T887A mutated AR was frequently expressed in androgen independent prostate cancer (AIPC) patients. Through literature survey and molecular modelling, we have identified a novel AR antagonist having a bulky β-iminoenamine BF2 complex scaffold. The tested and standard ligands were screened in AR positive (LNCaP, MCF-7 and MDA-MB-453), AR negative (PC3), and non-cancerous (3T3) cell lines through anti-proliferation assay. The ligand, ARA3 was the most potent molecule among all the tested ligands and was 7.6 folds selective for AR positive cell lines. The mechanism of anti-prostate cancer activity of ARA3 was confirmed by western blot, qPCR, and apoptotic assays in LNCaP (T887A positive AR) cells. Structural activity relationship was derived by correlating the in-vitro and in-silico data. Consequently, we have identified the essential functional groups that could prevent the resistance concerning mutant AR. The ARA3 induces the apoptosis in AIPC cells by preventing the AR mediated activation of AKT pathway. The bicalutamide did not induce the apoptosis because it failed to prevent the AR mediated activation of AKT.

Modulation of nongenomic activation of PI3K signalling by tetramerization of N-terminally-cleaved RXRα

Retinoid X receptor-alpha (RXRα) binds to DNA either as homodimers or heterodimers, but it also forms homotetramers whose function is poorly defined. We previously discovered that an N-terminally-cleaved form of RXRα (tRXRα), produced in tumour cells, activates phosphoinositide 3-kinase (PI3K) signalling by binding to the p85α subunit of PI3K and that K-80003, an anti-cancer agent, inhibits this process. Here, we report through crystallographic and biochemical studies that K-80003 binds to and stabilizes tRXRα tetramers via a ‘three-pronged’ combination of canonical and non-canonical mechanisms. K-80003 binding has no effect on tetramerization of RXRα, owing to the head–tail interaction that is absent in tRXRα. We also identify an LxxLL motif in p85α, which binds to the coactivator-binding groove on tRXRα and dissociates from tRXRα upon tRXRα tetramerization. These results identify conformational selection as the mechanism for inhibiting the nongenomic action of tRXRα and provide molecular insights into the development of RXRα cancer therapeutics.

The transcription factor retinoid X receptor-alpha (RXRα) can also form homotetramers. Here the authors show that the anti-cancer agent K-80003 selectively inhibits the nongenomic action of N-terminally-cleaved RXRα in tumour cells by stabilizing its tetramerization but not that of full-length RXRα.

Role of free testosterone levels in patients with metastatic castration-resistant prostate cancer receiving second-line therapy

A range of new treatment options has recently become available for patients with advanced metastatic castration-resistant prostate cancer (mCRPC). Androgen deprivation therapy (ADT) with luteinizing hormone-releasing hormone is continued when performing chemotherapy or androgen deprivation with new second-generation therapeutic agents such as enzalutamide or abiraterone acetate. Despite the fact that free testosterone (FT) is the biologically active form, it is common practice that androgen suppression is monitored via total testosterone levels only. The aim of the present study was to evaluate the role of FT as a prognostic biomarker for cancer-specific survival (CSS) and its feasibility as an ADT monitoring biomarker in patients with mCRPC for the first time. The requirement for continued ADT in mCRPC patients is discussed within the basis of the current literature. A total of 34 patients with continuous measurements of FT levels and mCRPC status underwent therapy with docetaxel, abiraterone acetate, enzalutamide, cabozantinib, carboplatin or cabazitaxel. Data were obtained from the Departments of Urology and Urological Oncology, Hannover Medical School (Hannover, Germany) between March 2009 and April 2014. A cutoff point of 0.5 pg/ml was used to discriminate between patients according to FT levels. Statistical evaluation of CSS was performed by applying Kaplan Meier survival estimates, multivariate Cox regression analyses and log-rank tests. The median age of all 34 patients was 72 years (range, 51–86 years). The mean follow-up interval was 16.1 months (range, 0.7–55.6 months). Despite the fact that all patients were undergoing androgen deprivation, the mean serum FT levels for each patient varied; the mean FT concentration in the cohort was 0.328 pg/ml, ranging from 0.01–9.1 pg/ml. A notable difference with regard to CSS was observed for patients with regard to serum FT concentration; CSS was significantly longer for patients with a serum FT level below the cutoff level (43.6 vs. 17.3 months, respectively, P=0.0063). Upon multivariate Cox regression analysis, the mean FT concentration during treatment remained a significant prognostic factor for CSS (hazard ratio, 1.22; 95% confidence interval, 1.03–1.43; P=0.0182). In conclusion, in patients with mCRPC, the serum FT level is a strong predictor of CSS in patients under therapy with second-line anti-hormonal therapeutic medication and chemotherapy. It may be concluded that FT levels should be included into the routine control of androgen suppression while under treatment with ADT and second-generation hormonal therapy.

Androgen receptor (AR) signaling promotes RCC progression via increased endothelial cell proliferation and recruitment by modulating AKT → NF-κB → CXCL5 signaling

Androgen receptor (AR) signaling may promote renal cell carcinoma (RCC) progression via altered HIF-2α/VEGF signaling. However, it remains unclear whether AR signaling also promotes RCC progression by recruiting vascular endothelial cells (ECs), key players in the development of blood vessels. In our study, AR increased EC proliferation and recruitment to the tumor microenvironment and promoted RCC progression. Mechanistically, AR modulated cytokine CXCL5 expression by altering AKT → NF-κB signaling, and interruption of AKT → NF-κB → CXCL5 signaling using either specific inhibitors or siRNA suppressed AR-enhanced EC recruitment and AR-EC-promoted RCC progression. The results obtained using an in vivo mouse model and a human clinical sample survey confirmed the role of AR in promoting RCC progression through enhancement of EC proliferation and/or recruitment via altered AKT → NF-κB → CXCL5 signaling. Targeting this newly identified AR-induced AKT → NF-κB → CXCL5 pathway may facilitate the development of new therapies for slowing RCC progression.

Inhibition of AKT signaling by supercritical CO2 extract of mango ginger (Curcuma amada Roxb.) in human glioblastoma cells

BACKGROUND

Mango ginger (Curcuma amada Roxb.) is a less-investigated herb for anticancer properties than other related Curcuma species. AKT (a serine/threonine protein kinase B, originally identified as an oncogene in the transforming retrovirus AKT8) plays a central role in the development and promotion of cancer. In this investigation, we have analyzed the effect of supercritical CO2 extract of mango ginger (CA) on the genetic pathways associated with AKT signaling in human glioblastoma cells.

METHODS

The inhibitory effect of supercritical CO2 extract of mango ginger (Curcuma amada) on AKT signaling was investigated in U-87MG glioblastoma cells.

RESULTS

CA was highly cytotoxic to glioblastoma cell line (IC50=4.92±0.81 µg/mL) compared to mHypoE-N1 normal mouse hypothalamus cell line (IC50=40.57±0.06 µg/mL). CA inhibits AKT (protein Kinase B) and adenosine monophophate -activated protein kinase α (AMPKα) phosphorylation significantly in a dose-dependent manner. The cell migration which is necessary for invasion and metastasis was also inhibited by CA treatment, with about 43% reduction at 20 µg/mL concentration. Analysis of mRNA and protein expression of genes associated with apoptosis, cell proliferation and angiogenesis showed that CA modulates expression of genes associated with apoptosis (Bax, Bcl-2, Bcl-X, BNIP3, caspase-3, mutant p53 and p21), cell proliferation (Ki67) and angiogenesis vascular endothelial growth factor (VEGF). Additionally, heat shock protein 90 (HSP90) and AMPKα genes interacting with the AKT signaling pathway were also downregulated by CA treatment.

CONCLUSIONS

These results indicate the molecular targets and mechanisms underlying the anticancer effect of CA in human glioblastoma cells.

Post-translational regulation of the cleaved fragment of Par-4 in ovarian and endometrial cancer cells

We recently reported the caspase3-dependent cleavage of Par-4 resulting in the accumulation of a 25kDa cleaved-Par-4 (cl-Par-4) fragment and we investigated in the present study the mechanisms regulating this fragment using cl-Par-4-expressing stable clones derived from ovarian and endometrial cancer cell lines.Cl-Par-4 protein was weakly express in all stable clones despite constitutive expression. However, upon cisplatin treatment, cl-Par-4 levels increased up to 50-fold relative to baseline conditions. Treatment of stable clones with proteasome and translation inhibitors revealed that cisplatin exposure might in fact protect cl-Par-4 from proteasome-dependent degradation. PI3K and MAPK pathways were also implicated as evidenced by an increase of cl-Par-4 in the presence of PI3K inhibitors and a decrease using MAPK inhibitors. Finally using bioinformatics resources, we found diverse datasets showing similar results to those we observed with the proteasome and cl-Par-4 further supporting our data.These new findings add to the complex mechanisms regulating Par-4 expression and activity, and justify further studies addressing the biological significance of this phenomenon in gynaecological cancer cells.

Androgen-Sensitized Apoptosis of HPr-1AR Human Prostate Epithelial Cells

Androgen receptor (AR) signaling is crucial to the development and homeostasis of the prostate gland, and its dysregulation mediates common prostate pathologies. The mechanisms whereby AR regulates growth suppression and differentiation of luminal epithelial cells in the prostate gland and proliferation of malignant versions of these cells have been investigated in human and rodent adult prostate. However, the cellular stress response of human prostate epithelial cells is not well understood, though it is central to prostate health and pathology. Here, we report that androgen sensitizes HPr-1AR and RWPE-AR human prostate epithelial cells to cell stress agents and apoptotic cell death. Although 5α-dihydrotestosterone (DHT) treatment alone did not induce cell death, co-treatment of HPr-1AR cells with DHT and an apoptosis inducer, such as staurosporine (STS), TNFt, or hydrogen peroxide, synergistically increased cell death in comparison to treatment with each apoptosis inducer by itself. We found that the synergy between DHT and apoptosis inducer led to activation of the intrinsic/mitochondrial apoptotic pathway, which is supported by robust cleavage activation of caspase-9 and caspase-3. Further, the dramatic depolarization of the mitochondrial membrane potential that we observed upon co-treatment with DHT and STS is consistent with increased mitochondrial outer membrane permeabilization (MOMP) in the pro-apoptotic mechanism. Interestingly, the synergy between DHT and apoptosis inducer was abolished by AR antagonists and inhibitors of transcription and protein synthesis, suggesting that AR mediates pro-apoptotic synergy through transcriptional regulation of MOMP genes. Expression analysis revealed that pro-apoptotic genes (BCL2L11/BIM and AIFM2) were DHT-induced, whereas pro-survival genes (BCL2L1/BCL-XL and MCL1) were DHT-repressed. Hence, we propose that the net effect of these AR-mediated expression changes shifts the balance of BCL2-family proteins, such that androgen signaling sensitizes mitochondria to apoptotic signaling, thus rendering HPr-1AR more vulnerable to cell death signals. Our study offers insight into AR-mediated regulation of prostate epithelial cell death signaling.

The importance of non-nuclear AR signaling in prostate cancer progression and therapeutic resistance

The androgen receptor (AR) remains the major oncogenic driver of prostate cancer, as evidenced by the efficacy of androgen deprivation therapy (ADT) in naïve patients, and the continued effectiveness of second generation ADTs in castration resistant disease. However, current ADTs are limited to interfering with AR ligand binding, either through suppression of androgen production or the use of competitive antagonists. Recent studies demonstrate 1) the expression of constitutively active AR splice variants that no longer depend on androgen, and 2) the ability of AR to signal in the cytoplasm independently of its transcriptional activity (non-genomic); thus highlighting the need to consider other ways to target AR. Herein, we review canonical AR signaling, but focus on AR non-genomic signaling, some of its downstream targets and how these effectors contribute to prostate cancer cell behavior. The goals of this review are to 1) re-highlight the continued importance of AR in prostate cancer as the primary driver, 2) discuss the limitations in continuing to use ligand binding as the sole targeting mechanism, 3) discuss the implications of AR non-genomic signaling in cancer progression and therapeutic resistance, and 4) address the need to consider non-genomic AR signaling mechanisms and pathways as a viable targeting strategy in combination with current therapies.

A Functional Polymorphism (rs2494752) in the AKT1 Promoter Region and Gastric Adenocarcinoma Risk in an Eastern Chinese Population

AKT is an important signal transduction protein that plays a crucial role in cancer development. Therefore, we evaluated associations between single nucleotide polymorphisms (SNPs) in the AKT promoter region and gastric cancer (GCa) risk in a case-control study of 1,110 GCa patients and 1,114 matched cancer-free controls. We genotyped five SNPs (AKT1 rs2494750G >C, AKT1 rs2494752A >G, AKT1 rs10138227C >T, AKT2 rs7254617G>A and AKT2 rs2304186G >T) located in the 5' upstream regulatory, first intron or promoter regions. In the logistic regression analysis, a significantly elevated GCa risk was associated with the rs2494752 AG/GG variant genotypes (adjusted odds ratio [OR] = 1.20, 95% confidence interval [CI] = 1.02-1.42) under a dominant genetic model, and this risk was more evident in subgroups of ever drinkers. The luciferase reporter assay showed that the rs2494752 G allele significantly increased luciferase activity. Our results suggest that the potentially functional AKT1 rs2494752 SNP may affect GCa susceptibility, likely by modulating the AKT1 promoter transcriptional activity. Larger, independent studies are warranted to validate our findings.

Androgen receptor-mediated non-genomic regulation of prostate cancer cell proliferation

Androgen receptor (AR)-mediated signaling is necessary for prostate cancer cell proliferation and an important target for therapeutic drug development. Canonically, AR signals through a genomic or transcriptional pathway, involving the translocation of androgen-bound AR to the nucleus, its binding to cognate androgen response elements on promoter, with ensuing modulation of target gene expression, leading to cell proliferation. However, prostate cancer cells can show dose-dependent proliferation responses to androgen within minutes, without the need for genomic AR signaling. This proliferation response known as the non-genomic AR signaling is mediated by cytoplasmic AR, which facilitates the activation of kinase-signaling cascades, including the Ras-Raf-1, phosphatidyl-inositol 3-kinase (PI3K)/Akt and protein kinase C (PKC), which in turn converge on mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) activation, leading to cell proliferation. Further, since activated ERK may also phosphorylate AR and its coactivators, the non-genomic AR signaling may enhance AR genomic activity. Non-genomic AR signaling may occur in an ERK-independent manner, via activation of mammalian target of rapamycin (mTOR) pathway, or modulation of intracellular Ca²⁺ concentration through plasma membrane G protein-coupled receptors (GPCRs). These data suggest that therapeutic strategies aimed at preventing AR nuclear translocation and genomic AR signaling alone may not completely abrogate AR signaling. Thus, elucidation of mechanisms that underlie non-genomic AR signaling may identify potential mechanisms of resistance to current anti-androgens and help developing novel therapies that abolish all AR signaling in prostate cancer.

Androgen receptor non-nuclear regulation of prostate cancer cell invasion mediated by Src and matriptase

Castration-resistant prostate cancers still depend on nuclear androgen receptor (AR) function despite their lack of dependence on exogenous androgen. Second generation anti-androgen therapies are more efficient at blocking nuclear AR; however resistant tumors still develop. Recent studies indicate Src is highly active in these resistant tumors. By manipulating AR activity in several different prostate cancer cell lines through RNAi, drug treatment, and the use of a nuclear-deficient AR mutant, we demonstrate that androgen acting on cytoplasmic AR rapidly stimulates Src tyrosine kinase via a non-genomic mechanism. Cytoplasmic AR, acting through Src enhances laminin integrin-dependent invasion. Active Matriptase, which cleaves laminin, is elevated within minutes after androgen stimulation, and is subsequently shed into the medium. Matriptase activation and shedding induced by cytoplasmic AR is dependent on Src. Concomitantly, CDCP1/gp140, a Matriptase and Src substrate that controls integrin-based migration, is activated. However, only inhibition of Matriptase, but not CDCP1, suppresses the AR/Src-dependent increase in invasion. Matriptase, present in conditioned medium from AR-stimulated cells, is sufficient to enhance invasion in the absence of androgen. Thus, invasion is stimulated by a rapid but sustained increase in Src activity, mediated non-genomically by cytoplasmic AR, leading to rapid activation and shedding of the laminin protease Matriptase.

Targeting truncated RXRα for cancer therapy

Retinoid X receptor-alpha (RXRα), a unique member of the nuclear receptor superfamily, is a well-established drug target, representing one of the most important targets for pharmacologic interventions and therapeutic applications for cancer. However, how RXRα regulates cancer cell growth and how RXRα modulators suppress tumorigenesis are poorly understood. Altered expression and aberrant function of RXRα are implicated in the development of cancer. Previously, several studies had demonstrated the presence of N-terminally truncated RXRα (tRXRα) proteins resulted from limited proteolysis of RXRα in tumor cells. Recently, we discovered that overexpression of tRXRα can promote tumor growth by interacting with tumor necrosis factor-alpha-induced phosphoinositide 3-kinase and NF-κB signal transduction pathways. We also identified nonsteroidal anti-inflammatory drug Sulindac and analogs as effective inhibitors of tRXRα activities via a unique binding mechanism. This review discusses the emerging roles of tRXRα and modulators in the regulation of cancer cell survival and death as well as inflammation and our recent understanding of tRXRα regulation by targeting the alternate binding sites on its surface.

Sustained proliferation in cancer: Mechanisms and novel therapeutic targets

Proliferation is an important part of cancer development and progression. This is manifest by altered expression and/or activity of cell cycle related proteins. Constitutive activation of many signal transduction pathways also stimulates cell growth. Early steps in tumor development are associated with a fibrogenic response and the development of a hypoxic environment which favors the survival and proliferation of cancer stem cells. Part of the survival strategy of cancer stem cells may manifested by alterations in cell metabolism. Once tumors appear, growth and metastasis may be supported by overproduction of appropriate hormones (in hormonally dependent cancers), by promoting angiogenesis, by undergoing epithelial to mesenchymal transition, by triggering autophagy, and by taking cues from surrounding stromal cells. A number of natural compounds (e.g., curcumin, resveratrol, indole-3-carbinol, brassinin, sulforaphane, epigallocatechin-3-gallate, genistein, ellagitannins, lycopene and quercetin) have been found to inhibit one or more pathways that contribute to proliferation (e.g., hypoxia inducible factor 1, nuclear factor kappa B, phosphoinositide 3 kinase/Akt, insulin-like growth factor receptor 1, Wnt, cell cycle associated proteins, as well as androgen and estrogen receptor signaling). These data, in combination with bioinformatics analyses, will be very important for identifying signaling pathways and molecular targets that may provide early diagnostic markers and/or critical targets for the development of new drugs or drug combinations that block tumor formation and progression.

Identification of a Novel Coregulator, SH3YL1, That Interacts With the Androgen Receptor N-Terminus

Nuclear receptor (NR)-mediated transcriptional activity is a dynamic process that is regulated by the binding of ligands that induce distinct conformational changes in the NR. These structural alterations lead to the differential recruitment of coregulators (coactivators or corepressors) that control the expression of NR-regulated genes. Here, we show that a stretch of proline residues located within the N-terminus of androgen receptor (AR) is a bona fide coregulator binding surface, the disruption of which reduces the androgen-dependent proliferation and migration of prostate cancer (PCa) cells. Using T7 phage display, we identified a novel AR-interacting protein, Src homology 3 (SH3)-domain containing, Ysc84-like 1 (SH3YL1), whose interaction with the receptor is dependent upon this polyproline domain. As with mutations within the AR polyproline domain, knockdown of SH3YL1 attenuated androgen-mediated cell growth and migration. RNA expression analysis revealed that SH3YL1 was required for the induction of a subset of AR-modulated genes. Notable was the observation that ubinuclein 1 (UBN1), a key member of a histone H3.3 chaperone complex, was a transcriptional target of the AR/SH3YL1 complex, correlated with aggressive PCa in patients, and was necessary for the maximal androgen-mediated proliferation and migration of PCa cells. Collectively, these data highlight the importance of an amino-terminal activation domain, its associated coregulator, and downstream transcriptional targets in regulating cellular processes of pathological importance in PCa.

The AhR Ligand, TCDD, Regulates Androgen Receptor Activity Differently in Androgen-Sensitive versus Castration-Resistant Human Prostate Cancer Cells

The reported biological effects of TCDD include induction of drug metabolizing enzymes, wasting syndrome and tumor promotion. TCDD elicits most of its effects through binding the aryl hydrocarbon receptor (AhR). TCDD induced degradation of AhR has been widely reported and requires ubiquitination of the protein. The rapid depletion of AhR following TCDD activation serves as a mechanism to modulate AhR mediated gene induction. In addition to inducing AhR degradation, TCDD has been reported to induce degradation of hormone receptors. The studies reported here, evaluate the effect of TCDD exposure on androgen receptor (AR) expression and activity in androgen-sensitive LNCaP and castration-resistant C4-2 prostate cancer cells. Our results show that TCDD exposure does not induce AhR or AR degradation in C4-2 cells. However, both AhR and AR are degraded in LNCaP cells following TCDD exposure. In addition, TCDD enhances AR phosphorylation and induces expression of AR responsive genes in LNCaP cells. Our data reveals that TCDD effect on AR expression and activity differs in androgen-sensitive and castration-resistant prostate cancer cell models.

Axon diameter and axonal transport: In vivo and in vitro effects of androgens

Testosterone is a sex hormone involved in brain maturation via multiple molecular mechanisms. Previous human studies described age-related changes in the overall volume and structural properties of white matter during male puberty. Based on this work, we have proposed that testosterone may induce a radial growth of the axon and, possibly, modulate axonal transport. In order to determine whether this is the case we have used two different experimental approaches. With electron microscopy, we have evaluated sex differences in the structural properties of axons in the corpus callosum (splenium) of young rats, and tested consequences of castration carried out after weaning. Then we examined in vitro the effect of the non-aromatizable androgen Mibolerone on the structure and bidirectional transport of wheat-germ agglutinin vesicles in the axons of cultured sympathetic neurons. With electron microscopy, we found robust sex differences in axonal diameter (males>females) and g ratio (males>females). Removal of endogenous testosterone by castration was associated with lower axon diameter and lower g ratio in castrated (vs. intact) males. In vitro, Mibolerone influenced the axonal transport in a time- and dose-dependent manner, and increased the axon caliber as compared with vehicle-treated neurons. These findings are consistent with the role of testosterone in shaping the axon by regulating its radial growth, as predicted by the initial human studies.

Antiandrogenic therapy with finasteride attenuates cardiac hypertrophy and left ventricular dysfunction

BACKGROUND

In comparison with men, women have a better prognosis when experiencing aortic valve stenosis, hypertrophic cardiomyopathy, or heart failure. Recent data suggest that androgens like testosterone or the more potent dihydrotestosterone contribute to the development of cardiac hypertrophy and failure. Therefore, we analyzed whether antiandrogenic therapy with finasteride, which inhibits the generation of dihydrotestosterone by the enzyme 5-α-reductase, improves pathological ventricular remodeling and heart failure.

METHODS AND RESULTS

We found a strongly induced expression of all 3 isoforms of the 5-α-reductase (Srd5a1 to Srd5a3) in human and mouse hearts with pathological hypertrophy, which was associated with increased myocardial accumulation of dihydrotestosterone. Starting 1 week after the induction of pressure overload by transaortic constriction, mice were treated with finasteride for 2 weeks. Cardiac function, hypertrophy, dilation, and fibrosis were markedly improved in response to finasteride treatment in not only male, but also in female mice. In addition, finasteride also very effectively improved cardiac function and mortality after long-term pressure overload and prevented disease progression in cardiomyopathic mice with myocardial Gαq overexpression. Mechanistically, finasteride, by decreasing dihydrotestosterone, potently inhibited hypertrophy and Akt-dependent prohypertrophic signaling in isolated cardiac myocytes, whereas the introduction of constitutively active Akt blunted these effects of finasteride.

CONCLUSIONS

Finasteride, which is currently used in patients to treat prostate disease, potently reverses pathological cardiac hypertrophy and dysfunction in mice and might be a therapeutic option for heart failure.

Immunoelectron microscope localization of androgen receptors and proliferating cell nuclear antigen in the epithelial cells of albino rat ventral prostate

Androgen receptor (AR) and proliferating cell nuclear antigen (PCNA) play a crucial role in development and progression of various prostatic diseases including prostatic carcinoma that is a leading cause of death in males. Previous studies have evaluated the expression pattern of AR and PCNA in prostate epithelial cells using immunohistochemistry (IHC). However, this technique has limited ability to identify their precise subcellular localization. Therefore, the aim of this study was to localize, subcellularly, AR and PCNA in the secretory epithelial cells of rat ventral prostate using post embedding immunogold-electron microscopy. The ventral lobes were dissected from six adult male albino rats after being perfused with paraformaldehyde. Some specimens were immuno-labeled with AR or PCNA and others were processed for immuno-electron microscope of AR and PCNA using 15-nm gold conjugated secondary antibodies. The results showed that, by immunoperoxidase reaction, AR and PCNA were localized diffusely throughout the nuclei of the epithelial cells of prostatic acini without visible cytoplasmic expression. However, the higher resolution immuno-electron microscopy was able to detect AR and PCNA in the nucleus and some cytoplasmic organelles. In conclusion, this study emphasizes the importance of immuno-electron microscopy in precise localization of AR and PCNA at the subcelullar levels in the secretory epithelial cells of the rat prostatic acini. These findings will help to further understand the mechanism of action of these receptors under normal and pathological conditions that could have future clinical application after careful human investigation.

Antiproliferative activity of novel imidazopyridine derivatives on castration-resistant human prostate cancer cells

Metastatic prostate cancer (mPCa) relapses after a short period of androgen deprivation therapy and becomes the castration-resistant prostate cancer (CR PCa); to which the treatment is limited. Hence, it is imperative to identify novel therapeutic agents towards this patient population. In the present study, antiproliferative activities of novel imidazopyridines were compared. Among three derivatives, PHE, AMD and AMN, examined, AMD showed the highest inhibitory activity on LNCaP C-81 cell proliferation, following dose- and time-dependent manner. Additionally, AMD exhibited significant antiproliferative effect against a panel of PCa cells, but not normal prostate epithelial cells. Further, when compared to AMD, its derivative DME showed higher inhibitory activities on PCa cell proliferation, clonogenic potential and in vitro tumorigenicity. The inhibitory activity was apparently in part due to the induction of apoptosis. Mechanistic studies indicate that AMD and DME treatments inhibited both AR and PI3K/Akt signaling. The results suggest that better understanding of inhibitory mechanisms of AMD and DME could help design novel therapeutic agents for improving the treatment of CR PCa.

Aging impairs VEGF-mediated, androgen-dependent regulation of angiogenesis

There is a progressive impairment of vascular repair mechanisms with advancing age concomitant with a steady decline in circulating androgen levels in men. Emerging evidence indicates androgens regulate angiogenesis; however, little research has focused on the impact of age upon androgen-mediated regulation of angiogenic mechanisms. Human dermal fibroblasts from young (<30 years) and older (>65 years) men were incubated with DHT, with or without androgen receptor antagonist hydroxyflutamide, or phosphoinositide 3-kinase inhibitor. Fibroblast-conditioned medium was used to stimulate angiogenic functions in human umbilical vein endothelial cells. Nuclear fractionation and fluorescence microscopy were used to study androgen receptor (AR) distribution. Conditioned medium from fibroblasts of young men, but not old men, treated with DHT produced a 3-fold increase in human umbilical vein endothelial cell tubulogenesis and 2-fold increase in migration via increased vascular endothelial growth factor (VEGF) expression and secretion, predominantly of VEGF145. DHT-induced VEGF secretion from fibroblasts of young men was AR-dependent and increased AKT phosphorylation, which was abrogated by phosphoinositide 3-kinase inhibition. By contrast, fibroblasts from older men were unresponsive to DHT and lacked androgen-mediated enhancement in VEGF production. These findings were associated with reduced AR nuclear translocation in old fibroblasts. The failure of DHT-induced paracrine stimulation of angiogenesis in fibroblasts from older men is likely due to defective nuclear translocation of AR. This first demonstration of androgen resistance (or insensitivity) acquired by human fibroblasts with aging suggests that pharmacological testosterone therapy for old men may be less effective in enhancing angiogenesis and facilitating tissue regeneration mechanisms reliant on paracrine release of VEGF.

Steroid receptors and their ligands: effects on male gamete functions

In recent years a new picture of human sperm biology is emerging. It is now widely recognized that sperm contain nuclear encoded mRNA, mitochondrial encoded RNA and different transcription factors including steroid receptors, while in the past sperm were considered incapable of transcription and translation. One of the main targets of steroid hormones and their receptors is reproductive function. Expression studies on Progesterone Receptor, estrogen receptor, androgen receptor and their specific ligands, demonstrate the presence of these systems in mature spermatozoa as surface but also as nuclear conventional receptors, suggesting that both systemic and local steroid hormones, through sperm receptors, may influence male reproduction. However, the relationship between the signaling events modulated by steroid hormones and sperm fertilization potential as well as the possible involvement of the specific receptors are still controversial issues. The main line of this review highlights the current research in human sperm biology examining new molecular systems of response to the hormones as well as specific regulatory pathways controlling sperm cell fate and biological functions. Most significant studies regarding the identification of steroid receptors are reported and the mechanistic insights relative to signaling pathways, together with the change in sperm metabolism energy influenced by steroid hormones are discussed.The reviewed evidences suggest important effects of Progesterone, Estrogen and Testosterone and their receptors on spermatozoa and implicate the involvement of both systemic and local steroid action in the regulation of male fertility potential.

Gestational exposure to elevated testosterone levels induces hypertension via heightened vascular angiotensin II type 1 receptor signaling in rats

Pre-eclampsia is a life-threatening pregnancy disorder whose pathogenesis remains unclear. Plasma testosterone levels are elevated in pregnant women with pre-eclampsia and polycystic ovary syndrome, who often develop gestational hypertension. We tested the hypothesis that increased gestational testosterone levels induce hypertension via heightened angiotensin II signaling. Pregnant Sprague-Dawley rats were injected with vehicle or testosterone propionate from Gestational Day 15 to 19 to induce a 2-fold increase in plasma testosterone levels, similar to levels observed in clinical conditions like pre-eclampsia. A subset of rats in these two groups was given losartan, an angiotensin II type 1 receptor antagonist by gavage during the course of testosterone exposure. Blood pressure levels were assessed through a carotid arterial catheter and endothelium-independent vascular reactivity through wire myography. Angiotensin II levels in plasma and angiotensin II type 1 receptor expression in mesenteric arteries were also examined. Blood pressure levels were significantly higher on Gestational Day 20 in testosterone-treated dams than in controls. Treatment with losartan during the course of testosterone exposure significantly attenuated testosterone-induced hypertension. Plasma angiotensin II levels were not significantly different between control and testosterone-treated rats; however, elevated testosterone levels significantly increased angiotensin II type 1 receptor protein levels in the mesenteric arteries. In testosterone-treated rats, mesenteric artery contractile responses to angiotensin II were significantly greater, whereas contractile responses to K(+) depolarization and phenylephrine were unaffected. The results demonstrate that elevated testosterone during gestation induces hypertension in pregnant rats via heightened angiotensin II type 1 receptor-mediated signaling, providing a molecular mechanism linking elevated maternal testosterone levels with gestational hypertension.

Is there an anti-androgen withdrawal syndrome for enzalutamide?

BACKGROUND

The anti-androgen withdrawal syndrome (AAWS) can be seen in one-third of patients after discontinuation of first-generation non-steroidal anti-androgen therapy. With the introduction of new agents for anti-androgen therapy as well as alternate mechanisms of action, new therapeutic options before and after docetaxel chemotherapy have arisen (Ohlmann et al. in World J Urol 30(4):495-503, 2012). The question regarding the occurrence of an enzalutamide withdrawal syndrome (EWS) has not been evaluated yet. In this study, we assess prostate-specific antigen (PSA) response after discontinuation of enzalutamide.

METHODS

In total 31 patients with metastatic castration-resistant prostate cancer (mCRPC) underwent an enzalutamide withdrawal and were evaluated. Data were gathered from 6 centres in Germany. Patients with continuous oral administration of enzalutamide with rising serum PSA levels were evaluated, starting from enzalutamide withdrawal until subsequent therapy was initiated, follow-up ended or death of the patient occurred. Statistical evaluation was performed applying one-sided binomial testing using R-statistical software, version 3.0.1.

RESULTS

Mean withdrawal follow-up was 6.5 weeks (range 1-26.1 weeks). None of the 31 patients showed a PSA decline. Mean relative PSA rise over all patients was 73.9 % (range 0.5-440.7 %) with a median of 44.9 %.

CONCLUSIONS

If existent, an AAWS is at least very rare for enzalutamide in patients with mCRPC after taxane-based chemotherapy and does not play a clinical role in this setting. This may be attributed to the different pharmacodynamics of enzalutamide. Longer duration of therapy or a longer withdrawal interval may reveal a rare EWS in the future.

Epigenetic modification and inheritance in sexual reversal of fish

Environmental sex determination (ESD) occurs in divergent, phylogenetically unrelated taxa, and in some species, co-occurs with genetic sex determination (GSD) mechanisms. Although epigenetic regulation in response to environmental effects has long been proposed to be associated with ESD, a systemic analysis on epigenetic regulation of ESD is still lacking. Using half-smooth tongue sole (Cynoglossus semilaevis) as a model—a marine fish that has both ZW chromosomal GSD and temperature-dependent ESD—we investigated the role of DNA methylation in transition from GSD to ESD. Comparative analysis of the gonadal DNA methylomes of pseudomale, female, and normal male fish revealed that genes in the sex determination pathways are the major targets of substantial methylation modification during sexual reversal. Methylation modification in pseudomales is globally inherited in their ZW offspring, which can naturally develop into pseudomales without temperature incubation. Transcriptome analysis revealed that dosage compensation occurs in a restricted, methylated cytosine enriched Z chromosomal region in pseudomale testes, achieving equal expression level in normal male testes. In contrast, female-specific W chromosomal genes are suppressed in pseudomales by methylation regulation. We conclude that epigenetic regulation plays multiple crucial roles in sexual reversal of tongue sole fish. We also offer the first clues on the mechanisms behind gene dosage balancing in an organism that undergoes sexual reversal. Finally, we suggest a causal link between the bias sex chromosome assortment in the offspring of a pseudomale family and the transgenerational epigenetic inheritance of sexual reversal in tongue sole fish.

Androgen receptor (AR) positive vs negative roles in prostate cancer cell deaths including apoptosis, anoikis, entosis, necrosis and autophagic cell death

Androgen/androgen receptor (AR) signaling plays pivotal roles in the prostate development and homeostasis as well as in the progression of prostate cancer (PCa). Androgen deprivation therapy (ADT) with anti-androgens remains as the main treatment for later stage PCa, and it has been shown to effectively suppress PCa growth during the first 12-24 months. However, ADT eventually fails and tumors may re-grow and progress into the castration resistant stage. Recent reports revealed that AR might play complicated and even opposite roles in PCa progression that might depend on cell types and tumor stages. Importantly, AR may influence PCa progression via differential modulation of various cell deaths including apoptosis, anoikis, entosis, necrosis, and autophagic cell deaths. Targeting AR may induce PCa cell apoptosis, autophagic cell deaths and programmed necrosis, yet targeting AR may suppress cell deaths via anoikis and entosis that may potentially lead to increased metastasis. These differential functions of AR in various types of PCa cell death might challenge the current ADT with anti-androgens treatment. Further detailed dissection of molecular mechanisms by which AR modulates different PCa cell deaths will help us to develop a better therapy to battle PCa.

Androgen deprivation and androgen receptor competition by bicalutamide induce autophagy of hormone-resistant prostate cancer cells and confer resistance to apoptosis

BACKGROUND

Treatment of advanced prostate cancer (PCa) relies on pharmacological or surgical androgen deprivation. However, it is only temporarily efficient. After a few months or years, the tumor relapses despite the absence of androgenic stimulation: a state referred to as hormone-refractory prostate cancer (HRPCa). Although autophagy confers chemoresistance in some cancers, its role in the development of HRPCa remains unknown.

METHODS

Autophagic flux was assayed by GFP-LC3 clustering, by LC3-I to LC3-II conversion and transmission electron microscopy. Cell death was detected by sub-G1 quantification and concomitant measurement of transmembrane mitochondrial potential and plasma membrane permeabilization. Inhibition of autophagy was achieved by siRNAs and pharmacological inhibitors.

RESULTS

Androgen deprivation or treatment with the anti-androgen bicalutamide promoted autophagy in HRPCa-derived LNCaP cells. This effect was dramatically reduced after depletion of Atg5 and Beclin-1, two canonical autophagy genes, and was associated with an inhibition of the androgen-induced mTOR pathway. The depletion of Atg5 and Beclin-1 significantly increased the level of cell death induced by androgen deprivation or bicalutamide. Finally, the safe anti-malarial drug chloroquine, an inhibitor of autophagy, dramatically increased cell death after androgen deprivation or bicalutamide treatment.

CONCLUSION

Taken together, our data suggest that autophagy is a protective mechanism against androgen deprivation in HRPCa cells and that chloroquine could restore hormone dependence. This set of data could lead to the development of new therapeutic strategy against HRPCa.

Androgen receptor promotes sex-independent angiogenesis in response to ischemia and is required for activation of vascular endothelial growth factor receptor signaling

BACKGROUND

Hypoandrogenemia is associated with an increased risk of ischemic diseases. Because actions of androgens are exerted through androgen receptor (AR) activation, we studied hind-limb ischemia in AR knockout mice to elucidate the role of AR in response to ischemia.

METHODS AND RESULTS

Both male and female AR knockout mice exhibited impaired blood flow recovery, more cellular apoptosis, and a higher incidence of autoamputation after ischemia. In ex vivo and in vivo angiogenesis studies, AR-deficient vascular endothelial cells showed reduced angiogenic capability. In ischemic limbs of AR knockout mice, reductions in the phosphorylation of the Akt protein kinase and endothelial nitric oxide synthase were observed despite a robust increase in hypoxia-inducible factor 1α and vascular endothelial cell growth factor (VEGF) gene expression. In in vitro studies, siRNA-mediated ablation of AR in vascular endothelial cells blunted VEGF-stimulated phosphorylation of Akt and endothelial nitric oxide synthase. Immunoprecipitation experiments documented an association between AR and kinase insert domain protein receptor that promoted the recruitment of downstream signaling components.

CONCLUSIONS

These results document a physiological role of AR in sex-independent angiogenic potency and provide evidence of novel cross-talk between the androgen/AR signaling and VEGF/kinase insert domain protein receptor signaling pathways.

Juglone, isolated from Juglans mandshurica Maxim, induces apoptosis via down-regulation of AR expression in human prostate cancer LNCaP cells

Juglone is a natural compound which has been isolated from Juglans mandshurica Maxim. Recent studies have shown that juglone had various pharmacological effects such as anti-viral, anti-bacterial and anti-cancer. However, its anti-cancer activity on human prostate cancer LNCaP cell has not been examined. Thus, the current study was designed to elucidate the molecular mechanism of apoptosis induced by juglone in androgen-sensitive prostate cancer LNCaP cells. MTT assay was performed to examine the anti-proliferative effect of juglone. Occurrence of apoptosis was detected by Hoechst 33342 staining and flow cytometry in LNCaP cells treated with juglone for 24h. The result shown that juglone inhibited the growth of LNCaP cells in a dose-dependent manner. Morphological changes of apoptotic body formation after juglone treatment were observed by Hoechst 33342 staining. This apoptotic induction was associated with loss of mitochondrial membrane potential, and caspase-3, -9 activation. Moreover, we found that juglone significantly inhibited the expression levels of androgen receptor (AR) and prostate-specific antigen (PSA) in a dose-dependent manner, as well as abrogated up-regulation of AR and PSA genes with and/or without dihydrotestosterone (DHT). Take together, our results demonstrated that juglone might induce the apoptosis in LNCaP cell via down-regulation of AR expression. Therefore, our results indicated that juglone may be a potential candidate of drug for androgen-sensitive prostate cancer.

Molecular pathways: environmental estrogens activate nongenomic signaling to developmentally reprogram the epigenome

Exposure to environmental xenoestrogens is a major health concern because of the ability of these compounds to perturb estrogen receptor (ER) signaling and act as endocrine disrupting compounds (EDC). Inappropriate exposure to EDCs during development, even at low doses, can predispose individuals to an increased lifetime risk of disease, including cancer. Recent data indicate that perinatal exposure to EDCs increases cancer risk by (re)programming the epigenome via alterations in DNA and histone methylation. We and others have begun to dissect the mechanisms by which xenoestrogens disrupt the epigenetic machinery to reprogram the epigenome and induce developmental reprogramming. Our studies revealed that xenoestrogens induce nongenomic ER signaling to activate PI3K/AKT, resulting in AKT phosphorylation and inactivation of the histone methyltransferase EZH2, thus providing a direct link to disruption of the epigenome. Other epigenetic "readers, writers, and erasers" may also be targeted by nongenomic signaling, suggesting this is a central mechanism by which xenoestrogens and other EDCs disrupt the epigenome to induce developmental reprogramming. Elucidating mechanisms of developmental reprogramming of the epigenome is important for understanding how environmental exposures increase cancer risk, and provides a rationale for developing epigenetic interventions that can reverse the effects of environmental exposures to reduce cancer risk.

With a little help from my friends: androgens tap BDNF signaling pathways to alter neural circuits

Gonadal androgens are critical for the development and maintenance of sexually dimorphic regions of the male nervous system, which is critical for male-specific behavior and physiological functioning. In rodents, the motoneurons of the spinal nucleus of the bulbocavernosus (SNB) provide a useful example of a neural system dependent on androgen. Unless rescued by perinatal androgens, the SNB motoneurons will undergo apoptotic cell death. In adulthood, SNB motoneurons remain dependent on androgen, as castration leads to somal atrophy and dendritic retraction. In a second vertebrate model, the zebra finch, androgens are critical for the development of several brain nuclei involved in song production in males. Androgen deprivation during a critical period during postnatal development disrupts song acquisition and dimorphic size-associated nuclei. Mechanisms by which androgens exert masculinizing effects in each model system remain elusive. Recent studies suggest that brain-derived neurotrophic factor (BDNF) may play a role in androgen-dependent masculinization and maintenance of both SNB motoneurons and song nuclei of birds. This review aims to summarize studies demonstrating that BDNF signaling via its tyrosine receptor kinase (TrkB) receptor may work cooperatively with androgens to maintain somal and dendritic morphology of SNB motoneurons. We further describe studies that suggest the cellular origin of BDNF is of particular importance in androgen-dependent regulation of SNB motoneurons. We review evidence that androgens and BDNF may synergistically influence song development and plasticity in bird species. Finally, we provide hypothetical models of mechanisms that may underlie androgen- and BDNF-dependent signaling pathways.

Dihydrotestosterone regulating apolipoprotein M expression mediates via protein kinase C in HepG2 cells

Background

Administration of androgens decreases plasma concentrations of high-density lipid cholesterol (HDL-C). However, the mechanisms by which androgens mediate lipid metabolism remain unknown. This present study used HepG2 cell cultures and ovariectomized C57BL/6 J mice to determine whether apolipoprotein M (ApoM), a constituent of HDL, was affected by dihydrotestosterone (DHT).

Methods

HepG2 cells were cultured in the presence of either DHT, agonist of protein kinase C (PKC), phorbol-12-myristate-13-acetate (PMA), blocker of androgen receptor flutamide together with different concentrations of DHT, or DHT together with staurosporine at different concentrations for 24 hrs. Ovariectomized C57BL/6 J mice were treated with DHT or vehicle for 7d or 14d and the levels of plasma ApoM and livers ApoM mRNA were measured. The mRNA levels of ApoM, ApoAI were determined by real-time RT-PCR. ApoM and ApoAI were determined by western blotting analysis.

Results

Addition of DHT to cell culture medium selectively down-regulated ApoM mRNA expression and ApoM secretion in a dose-dependent manner. At 10 nM DHT, the ApoM mRNA levels were about 20% lower than in untreated cells and about 40% lower at 1000 nM DHT than in the control cells. The secretion of ApoM into the medium was reduced to a similar extent. The inhibitory effect of DHT on ApoM secretion was not blocked by the classical androgen receptor blocker flutamide but by an antagonist of PKC, Staurosporine. Agonist of PKC, PMA, also reduced ApoM. At 0.5 μM PMA, the ApoM mRNA levels and the secretion of ApoM into the medium were about 30% lower than in the control cells. The mRNA expression levels and secretion of another HDL-associated apolipoprotein AI (ApoAI) were not affected by DHT. The levels of plasma ApoM and liver ApoM mRNA of DHT-treated C57BL/6 J mice were lower than those of vehicle-treated mice.

Conclusions

DHT directly and selectively down-regulated the level of ApoM mRNA and the secretion of ApoM by protein kinase C but independently of the classical androgen receptor.

Evidence of mTOR Activation by an AKT-Independent Mechanism Provides Support for the Combined Treatment of PTEN-Deficient Prostate Tumors with mTOR and AKT Inhibitors

Activation of the phosphoinositide 3-kinase pathway is commonly observed in human prostate cancer. Loss of function of phosphatase and tensin homolog (PTEN) is associated with the activation of AKT and mammalian target of rapamycin (mTOR) in many cancer cell lines as well as in other model systems. However, activation of mTOR is also dependent of kinases other than AKT. Here, we show that activation of mTOR is not dependent on AKT in a prostate-specific PTEN-deficient mouse model of prostate cancer. Pathway bifurcation of AKT and mTOR was noted in both mouse and human prostate tumors. We demonstrated for the first time that cotargeting mTOR and AKT with ridaforolimus/MK-8669 and M1K-2206, respectively, delivers additive antitumor effects in vivo when compared to single agents. Our preclinical data suggest that the combination of AKT and mTOR inhibitors might be more effective in treating prostate cancer patients than current treatment regimens or either treatment alone.

Characterisation of AmphiAmR4, an amphioxus (Branchiostoma floridae) α₂-adrenergic-like G-protein-coupled receptor

Little is known about the evolutionary relationship between vertebrate adrenergic receptors and invertebrate octopamine and tyramine receptors. The complexity of the adrenergic signalling system is believed to be an innovation of the vertebrate lineage but the presence of noradrenaline has been reported in some invertebrate species. The cephalochordate, amphioxus (Branchiostoma floridae), is an ideal model organism for studying the evolution of vertebrate GPCRs, given its unique position at the base of the chordate lineage. Here, we describe the pharmacological characterisation and second messenger coupling abilities of AmphiAmR4, which clusters with α₂-adrenergic receptors in a phylogenetic tree but also shares a high sequence similarity to invertebrate octopamine/tyramine receptors in both BLAST and Hidden Markov Model analyses. Thus, it was of particular interest to determine if AmphiAmR4 displayed similar functional properties to the vertebrate α₂-adrenergic receptors or to invertebrate octopamine or tyramine receptors. When stably expressed in Chinese hamster ovary (CHO) cells, noradrenaline couples the receptor to both the activation of adenylyl cyclase and to the activation of the MAPKinase pathway. Pharmacological studies with a wide range of agonists and antagonists suggest that AmphiAmR4 functions as an α₂-adrenergic-like receptor when expressed in CHO cells.

Transcriptional and Non-Transcriptional Functions of PPARβ/δ in Non-Small Cell Lung Cancer

Peroxisome proliferator-activated receptor β/δ (PPARβ/δ) is a nuclear receptor involved in regulation of lipid and glucose metabolism, wound healing and inflammation. PPARβ/δ has been associated also with cancer. Here we investigated the expression of PPARβ/δ and components of the prostaglandin biosynthetic pathway in non-small cell lung cancer (NSCLC). We found increased expression of PPARβ/δ, Cox-2, cPLA₂, PGES and VEGF in human NSCLC compared to normal lung. In NSCLC cell lines PPARβ/δ activation increased proliferation and survival, while PPARβ/δ knock-down reduced viability and increased apoptosis. PPARβ/δ agonists induced Cox-2 and VEGF transcription, suggesting the existence of feed-forward loops promoting cell survival, inflammation and angiogenesis. These effects were seen only in high PPARβ/δ expressing cells, while low expressing cells were less or not affected. The effects were also abolished by PPARβ/δ knock-down or incubation with a PPARβ/δ antagonist. Induction of VEGF was due to both binding of PPARβ/δ to the VEGF promoter and PI3K activation through a non-genomic mechanism. We found that PPARβ/δ interacted with the PI3K regulatory subunit p85α leading to PI3K activation and Akt phosphorylation. Collectively, these data indicate that PPARβ/δ might be a central element in lung carcinogenesis controlling multiple pathways and representing a potential target for NSCLC treatment.