Gene expression profiling of androgen deficiency predicts a pathway of prostate apoptosis that involves genes related to oxidative stress

Identification of a targetable JAK-STAT enriched androgen receptor and androgen receptor splice variant positive triple-negative breast cancer subtype

Triple-negative breast cancer (TNBC) is an aggressive subtype with no targeted therapeutics. The luminal androgen receptor (LAR) subtype constitutes 15% of TNBC and is enriched for androgen receptor (AR) and AR target genes. Here, we show that a cohort of TNBC not only expresses AR at a much higher rate (∼80%) but also expresses AR splice variants (AR-SVs) (∼20%), further subclassifying LAR-TNBC. Higher AR and AR-SV expression and corresponding aggressive phenotypes are observed predominantly in specimens obtained from African American women. LAR TNBC specimens are enriched for interferon, Janus kinase (JAK)-signal activator and transducer (STAT), and androgen signaling pathways, which are exclusive to AR-expressing epithelial cancer cells. AR- and AR-SV-expressing TNBC cell proliferation and xenograft and patient-tumor explant growth are inhibited by AR N-terminal domain-binding selective AR degrader or by a JAK inhibitor. Biochemical analysis suggests that STAT1 is an AR coactivator. Collectively, our work identifies pharmacologically targetable TNBC subtypes and identifies growth-promoting interaction between AR and JAK-STAT signaling.

Social status influences relationships between hormones and oxidative stress in a cichlid fish

An individual's social environment can have widespread effects on their physiology, including effects on oxidative stress and hormone levels. Many studies have suggested that variation in oxidative stress experienced by individuals of different social statuses might be due to endocrine differences, however, few studies have evaluated this hypothesis. Here, we assessed whether a suite of markers associated with oxidative stress in different tissues (blood/plasma, liver, and gonads) had social status-specific relationships with circulating testosterone or cortisol levels in males of a cichlid fish, Astatotilapia burtoni. Across all fish, blood DNA damage (a global marker of oxidative stress) and gonadal synthesis of reactive oxygen species [as indicated by NADPH-oxidase (NOX) activity] were lower when testosterone was high. However, high DNA damage in both the blood and gonads was associated with high cortisol in subordinates, but low cortisol in dominants. Additionally, high cortisol was associated with greater production of reactive oxygen species (greater NOX activity) in both the gonads (dominants only) and liver (dominants and subordinates). In general, high testosterone was associated with lower oxidative stress across both social statuses, whereas high cortisol was associated with lower oxidative stress in dominants and higher oxidative stress in subordinates. Taken together, our results show that differences in the social environment can lead to contrasting relationships between hormones and oxidative stress.

Testosterone enhances taurine synthesis by upregulating androgen receptor and cysteine sulfinic acid decarboxylase expressions in male mouse liver

Taurine is an end-product of cysteine metabolism, whereas cysteine dioxygenase (CDO) and cysteine sulfinate decarboxylase (CSAD) are key enzymes regulating taurine synthesis. Sex steroids, including estrogens and androgens, are associated with liver physiopathological processes; however, we still do not know whether taurine and sex steroids interact in regulating liver physiology and hepatic diseases, and whether there are sex differences, although our recent study shows that the estrogen is involved in regulating taurine synthesis in mouse liver. The present study was thus proposed to identify whether 17-β-estradiol and testosterone (T) play their roles by regulating CDO and CSAD expression and taurine synthesis in male mouse liver. Our results demonstrated that testosterone did not have a significant influence on CDO expression but significantly enhanced CSAD, androgen receptor (AR) expressions, and taurine levels in mouse liver, cultured hepatocytes, and HepG2 cells, whereas these effects were abrogated by AR antagonist flutamide. Furthermore, our results showed that testosterone increased CSAD-promoter-luciferase activity through the direct interaction of the AR DNA binding domain with the CSAD promoter. These findings first demonstrate that testosterone acts as an important factor to regulate sulfur amino acid metabolism and taurine synthesis through AR/CSAD signaling pathway. In addition, the in vivo and in vitro experiments showed that 17-β-estradiol has no significant effects on liver CSAD expression and taurine synthesis in male mice and suggest that the effects of sex steroids on the taurine synthesis in mouse liver have sex differences. These results are crucial for understanding the physiological functions of taurine/androgen and their interacting mechanisms in the liver.NEW & NOTEWORTHY This study demonstrates that testosterone functions to enhance taurine synthesis by interacting with androgen receptor and binding to cysteine sulfinate decarboxylase (CSAD) promoter zone. Whereas estrogen has no significant effects either on liver CSAD expression or taurine synthesis in male mice and suggests that the effects of sex steroids on taurine synthesis in the liver have gender differences. These new findings are the potential for establishing effective protective and therapeutic strategies for liver diseases.

Receptor-Mediated Redox Imbalance: An Emerging Clinical Avenue against Aggressive Cancers

Cancer cells are more vulnerable to abnormal redox fluctuations due to their imbalanced antioxidant system, where cell surface receptors sense stress and trigger intracellular signal relay. As canonical targets of many targeted therapies, cell receptors sensitize the cells to specific drugs. On the other hand, cell target mutations are commonly associated with drug resistance. Thus, exploring effective therapeutics targeting diverse cell receptors may open new clinical avenues against aggressive cancers. This paper uses focused case studies to reveal the intrinsic relationship between the cell receptors of different categories and the primary cancer hallmarks that are associated with the responses to external or internal redox perturbations. Cold atmospheric plasma (CAP) is examined as a promising redox modulation medium and highly selective anti-cancer therapeutic modality featuring dynamically varying receptor targets and minimized drug resistance against aggressive cancers.

Ezrin gone rogue in cancer progression and metastasis: An enticing therapeutic target

Cancer metastasis is the primary cause of morbidity and mortality in cancer as it remains the most complicated, devastating, and enigmatic aspect of cancer. Several decades of extensive research have identified several key players closely associated with metastasis. Among these players, cytoskeletal linker Ezrin (the founding member of the ERM (Ezrin-Radixin-Moesin) family) was identified as a critical promoter of metastasis in pediatric cancers in the early 21st century. Ezrin was discovered 40 years ago as a aminor component of intestinal epithelial microvillus core protein, which is enriched in actin-containing cell surface structures. It controls gastric acid secretion and plays diverse physiological roles including maintaining cell polarity, regulating cell adhesion, cell motility and morphogenesis. Extensive research for more than two decades evinces that Ezrin is frequently dysregulated in several human cancers. Overexpression, altered subcellular localization and/or aberrant activation of Ezrin are closely associated with higher metastatic incidence and patient mortality, thereby justifying Ezrin as a valuable prognostic biomarker in cancer. Ezrin plays multifaceted role in multiple aspects of cancer, with its significant contribution in the complex metastatic cascade, through reorganizing the cytoskeleton and deregulating various cellular signaling pathways. Current preclinical studies using genetic and/or pharmacological approaches reveal that inactivation of Ezrin results in significant inhibition of Ezrin-mediated tumor growth and metastasis as well as increase in the sensitivity of cancer cells to various chemotherapeutic drugs. In this review, we discuss the recent advances illuminating the molecular mechanisms responsible for Ezrin dysregulation in cancer and its pleiotropic role in cancer progression and metastasis. We also highlight its potential as a prognostic biomarker and therapeutic target in various cancers. More importantly, we put forward some potential questions, which we strongly believe, will stimulate both basic and translational research to better understand Ezrin-mediated malignancy, ultimately leading to the development of Ezrin-targeted cancer therapy for the betterment of human life.

PPFIA4 promotes castration-resistant prostate cancer by enhancing mitochondrial metabolism through MTHFD2

Background

The development of castration-resistant prostate cancer (CRPC) remains a major obstacle in the treatment of prostate cancer (PCa). Dysregulated mitochondrial function has been linked to the initiation and progression of diverse human cancers. Deciphering the novel molecular mechanisms underlying mitochondrial function may provide important insights for developing novel therapeutics for CRPC.

Methods

We investigate the expression of the protein tyrosine phosphatase receptor type F polypeptide interacting protein alpha 4 (PPFIA4) using public datasets and tumor specimens from PCa cases by immunohistochemistry. Gain- and loss-of-function studies are performed in PCa cell lines and mouse models of subcutaneous xenograft to characterize the role of PPFIA4 in CRPC. Gene expression regulation is evaluated by a series of molecular and biochemical experiments in PCa cell lines. The therapeutic effects of methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) inhibitor combined enzalutamide are assessed using in vitro functional assays and in vivo mouse models.

Results

We show that the increase of PPFIA4 exacerbates aggressive phenotype resembling CRPC. A fraction of PPFIA4 localizes to mitochondria and interacts with MTHFD2, a key enzyme for one-carbon metabolism. Androgen deprivation increases the translocation of PPFIA4 into mitochondria and increases the interaction between PPFIA4 and MTHFD2, which result in the elevation of tyrosine phosphorylated MTHFD2. Consequently, the levels of NADPH synthesis increase, resulting in protection against androgen deprivation-induced mitochondrial dysfunction, as well as promotion of tumor growth. Clinically, PPFIA4 expression is significantly increased in CRPC tissues compared with localized PCa ones. Importantly, an MTHFD2 inhibitor, DS18561882, combined with enzalutamide can significantly inhibit CRPC cell proliferation in vitro and tumor growth in vivo.

Conclusion

Overall, our findings reveal a PPFIA4-MTHFD2 complex in mitochondria that links androgen deprivation to mitochondrial metabolism and mitochondrial dysfunction, which suggest a potential strategy to inhibit CRPC progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02331-3.

Curcumin ameliorates atrophy of seminal vesicle via reduction of oxidative stress in castrated mice

Background

The growth and function of seminal vesicle are dependent on androgen. This study was conducted to investigate the role of oxidative stress in castration-induced seminal vesicle atrophy and to explore the effects of curcumin, an antioxidant extracted from rhizome of turmeric, on seminal vesicle of castrated mice.

Methods

C57BL/6J mice were randomly divided into three groups: control, castration, and castration with curcumin (n = 10 for each group). After surgical castration, mice in the curcumin treatment group received intragastric administration of curcumin at 100 mg/kg body weight for 4 weeks, whereas mice in the other two groups were treated with olive oil. After that, the body weight, seminal vesicle weight and serum testosterone of mice were measured. Apoptosis and oxidative stress levels in seminal vesicle were also determined.

Results

After castration, both the weight and size of seminal vesicle decreased dramatically. The expression of three NADPH oxidase (NOX) subtypes: NOX1, NOX2 and NOX4, increased in seminal vesicle of castrated mice, resulting in high level oxidative stress. The ratio of Bax to Bcl-2 was also elevated after castration, accompanied by enhanced caspase3 activity. Additionally, castration increased the number of apoptotic cells in seminal vesicle. Curcumin treatment could inhibit the expression of NOX1, NOX2 and NOX4, decreasing oxidative stress and apoptosis. The atrophy of seminal vesicle caused by castration was ameliorated by curcumin.

Conclusion

Castration could cause atrophy of seminal vesicle probably via inducing oxidative stress. Curcumin treatment could reduce the oxidative stress in seminal vesicle by decreasing the expression of NOX1, NOX2 and NOX4, thereby ameliorating apoptosis and atrophy of seminal vesicle. Oxidative stress might play a role in castration-induced seminal vesicle atrophy.

Iodine prevents the increase of testosterone-induced oxidative stress in a model of rat prostatic hyperplasia

Oxidative stress and inflammation are involved in the development and/or progression of benign prostatic hyperplasia (BPH). Molecular iodine (I₂) induces antiproliferative and apoptotic effects in prostate cancer cells, but it is unknown if I₂ regulates oxidative stress in the normal and/or tumoral prostate. The purpose of this study was to analyze the effects of I₂ and celecoxib (Cxb) on oxidative stress and inflammation in a model of prostatic hyperplasia. Cxb was used as positive control of cyclooxygenase-2 (COX-2) inhibition. Prostatic hyperplasia was induced in male Wistar rats (170g) with testosterone (5mg/kg/week, for three weeks). One week before hyperplasia induction, I₂ (25mg/day/rat) or Cxb (1.25mg/day/rat) was supplied for four weeks in the drinking water. Prostatic hyperplasia was evaluated by histological analysis, DNA content, and/or proliferating cell nuclear antigen (PCNA) expression. Lipoperoxidation (malondialdehyde) and nitrite (NO2^-) levels were analyzed by colorimetric methods, while nitric oxide synthase (NOS), COX, and myeloperoxidase (MPO) enzymes were analyzed using RT-PCR, immunoblotting, and/or enzymatic assays. Levels of 15-F2t-isoprostanes, prostaglandins (PGE₂), leukotrienes (LTB₄), and tumor necrosis factor alpha (TNFα) were measured by ELISA. Control testosterone-treated animals exhibited hyperplasia in the dorsolateral prostate, as well as increments in almost all oxidative parameters except for COX-1, TNFα, or MPO. I₂ and Cxb prevented epithelial hyperplasia (DNA content) and oxidative stress induction generated by testosterone in almost the same intensity, and the minimum I₂ dose required was 2.5mg/rat. The antioxidant capacity of I₂ was also analyzed in a cell-free system, showing that this element inhibited the conversion of nitrate (NO₃^-) to NO₂^-. I₂ did not modify the prostatic oxidative state in testosterone untreated rats. In summary, our data showed that antiproliferative and antioxidant effects of I₂ involve the inhibition of NOS and the COX-2 pathway. Further studies are necessary to analyze the therapeutic and/or adjuvant effects of I₂ with first-line medications used to treat BPH.

Androgen receptor mitigates postoperative disease progression of hepatocellular carcinoma by suppressing CD90+ populations and cell migration and by promoting anoikis in circulating tumor cells

Purpose

Although hepatectomy and liver transplantation surgery for hepatocellular carcinoma (HCC) are effective treatment modalities, the risk of recurrence remains high, particularly in patients with a high number of circulating tumor cells (CTCs) expressing cancer stem/progenitor cell markers. Androgen receptor (AR) signaling has been shown to suppress HCC metastasis in rodent models of HCC. In this study, we investigated whether AR is associated with postoperative HCC recurrence.

Experimental Design

CTCs were obtained from patients with HCC who had undergone hepatectomy to investigate whether they are associated with disease outcome. AR knockout was introduced in two mouse models of spontaneous HCC (carcinogen- and hepatitis B virus-related HCC) to delineate the role that AR plays in HCC recurrence. Biological systems analysis was used to investigate the cellular and molecular mechanisms.

Results

We found that the expression of AR in CTCs was negatively associated with HCC recurrence/progression after hepatectomy. Our results suggest that AR-mediated suppression of HCC recurrence/progression is governed by a three-pronged mechanism. First, AR suppresses the expression of CD90 in CTCs by upregulating Histone 3H2A. Second, AR suppresses cell migration at the transcriptome level. Third, AR promotes anoikis of CTCs via dysregulation of cytoskeletal adsorption.

Conclusions

The results indicate that AR expression may be the gatekeeper of postoperative HCC recurrence. Therefore, targeting AR in presurgical down-staging procedures may serve as a secondary prevention measure against HCC recurrence in the future.

Thioredoxin-1 protects against androgen receptor-induced redox vulnerability in castration-resistant prostate cancer

Androgen deprivation (AD) therapy failure leads to terminal and incurable castration-resistant prostate cancer (CRPC). We show that the redox-protective protein thioredoxin-1 (TRX1) increases with prostate cancer progression and in androgen-deprived CRPC cells, suggesting that CRPC possesses an enhanced dependency on TRX1. TRX1 inhibition via shRNA or a phase I-approved inhibitor, PX-12 (untested in prostate cancer), impedes the growth of CRPC cells to a greater extent than their androgen-dependent counterparts. TRX1 inhibition elevates reactive oxygen species (ROS), p53 levels and cell death in androgen-deprived CRPC cells. Unexpectedly, TRX1 inhibition also elevates androgen receptor (AR) levels under AD, and AR depletion mitigates both TRX1 inhibition-mediated ROS production and cell death, suggesting that AD-resistant AR expression in CRPC induces redox vulnerability. In vivo TRX1 inhibition via shRNA or PX-12 reverses the castration-resistant phenotype of CRPC cells, significantly inhibiting tumor formation under systemic AD. Thus, TRX1 is an actionable CRPC therapeutic target through its protection against AR-induced redox stress.

Stimulation of cellular senescent processes, including secretory phenotypes and anti-oxidant responses, after androgen deprivation therapy in human prostate cancer

Endocrine resistance is a major problem in prostate cancer. Recent studies suggest that cellular plasticity plays a key role in therapy resistance. Yet little is known about the cellular changes of human prostate cancer after androgen deprivation therapy (ADT). In this study, we investigated cellular senescence, senescence-associated secretory phenotypes (SASPs), and anti-oxidant responses. Hormone ablation upregulated senescence-associated (SA)-β-Gal activity in prostate glands, as well as the expressions of p27^KIP1 and p53, in a mouse castration model. In line with this, the expressions of p21^CIP1 and p27^KIP1 were significantly more upregulated in human non-pathological prostatic glands after ADT than in untreated specimens. In a study of SASP markers, the expressions of IL6 and IL8 were also more upregulated in human non-pathological prostatic glands after ADT than in untreated specimens. IL6, IL8, and MMP2 were expressed more strongly in human prostate cancer specimens resected after ADT than in untreated tumors. Of note, treatment with the anti-oxidant reagent NAC significantly suppressed SA-β-Gal activity in androgen-sensitive human prostate cancer LNCaP cells. In immunohistochemical analyses on anti-oxidant response genes, NRF2 and NQO1 were more upregulated after hormone ablation in human prostate gland and carcinoma specimens after ADT than in untreated specimens or in murine prostate glands after castration. Taken together, these findings suggest that ADT induces cellular senescence processes accompanied by secretory phenotypes and anti-oxidant responses in prostate. These cellular changes may be attractive targets for preventing endocrine resistance in prostate cancer.

Low-Activity Haplotype of the Microsomal Epoxide Hydrolase Gene Is Protective Against Placental Abruption

OBJECTIVE

We wanted to determine whether genetic variability in the gene encoding microsomal epoxide hydrolase (EPHX) contributes to individual differences in susceptibility to the occurrence of placental abruption.

METHODS

The study involved 117 women with placental abruption and 115 healthy control pregnant women who were genotyped for two single nucleotide polymorphisms (SNPs), T-->C (Tyr113His) in exon 3 and A-->G (His139Arg) in exon 4, in the EPHX gene. Chi-square analysis was used to assess genotype and allele frequency differences between the women with placental abruption and the control group. In addition, single-point analysis was expanded to pair of loci haplotype analysis to examine the estimated haplotype frequencies of the two SNPs, of unknown phase, among the women with placental abruption and the control group. Estimated haplotype frequencies were assessed using the maximum-likelihood method, employing an expectation-maximization algorithm.

RESULTS

Single-point allele and genotype distributions in exons 3 and 4 of the EPHX gene were not statistically different between the groups. However, in the haplotype estimation analysis we observed a significantly decreased frequency of haplotype C-A (His113-His139) among the placental abruption group compared with the control group (P = .007). The odds ratio for placental abruption associated with the low-activity haplotype C-A (His113-His139) was 0.552 (95% confidence interval, 0.358 to 0.851).

CONCLUSIONS

The use of two intragenic SNPs jointly in haplotype analysis of association demonstrated that the genetically determined low-activity haplotype C-A (His113-His139) was significantly less frequent in women with placental abruption.

Genome-wide gene expression profiling of ischemia-reperfusion injury in rat kidney, intestine and skeletal muscle implicate a common involvement of MAPK signaling pathway

The mechanisms of ischemia‑reperfusion (I/R) injury have not been fully elucidated to date. In order to determine the genetic involvement across different organs during I/R injury, a DNA microarray approach was used to analyze the gene expression profiles of the kidney, intestine, and skeletal muscle in a rat model of I/R injury. Fifteen male Lewis rats were divided randomly into three different organ groups; a sham operation (control group), 60‑min‑ischemia (Is group) only, and 60‑min‑ischemia plus 60‑min‑reperfusion (I/R group), respectively. The target genes were identified by DNA microarray and studied by quantitative polymerase chain reaction (qPCR). By comparing the I/R group with the control group, a 2‑fold upregulation of 467, 172, and 3932 and a 2‑fold downregulation of 437, 416, and 4203 genes were identified in the kidney, small intestine, and skeletal muscle, respectively. Several commonly upregulated genes associated with mitogen‑activated protein kinase (MAPK) pathways, including Jun, Atf3, junB, Fos, Adm and Dusp 1, were differentially expressed in the I/R group. The mRNA expression levels of the target genes were confirmed by qPCR. The present study hypothesized that the MAPK pathway may function in a common pathway of I/R injury and regulate the pathogenesis through activator protein 1. The findings of the present study contributed to the understanding of the molecular pathways associated with I/R injury.

Testosterone level in men with type 2 diabetes mellitus and related metabolic effects: A review of current evidence

A significant proportion of patients with type 2 diabetes mellitus have a low testosterone level relative to reference ranges based on healthy young men. Only a small number of these patients suffer from classical hypogonadism as a result of recognizable hypothalamic-pituitary-gonadal axis pathology. The cut-off value of the serum testosterone level in men without obvious hypothalamic-pituitary-gonadal axis pathology is controversial. It is unclear to what extent a low serum testosterone level causally leads to type 2 diabetes and/or the metabolic syndrome. From a theoretical standpoint, there can be complex interactions among the hypothalamic-pituitary-gonadal axis, body composition and insulin resistance, which can be further influenced by intrinsic and extrinsic factors to give rise to metabolic syndrome, glucose intolerance, and low-grade inflammation to increase the risk of cardiovascular disease. Although a low serum testosterone level frequently coexists with cardiometabolic risk factors and might serve as a biomarker, more studies are required to clarify the causal, mediating or modifying roles of low serum testosterone level in the development of adverse clinical outcomes. Currently, there are insufficient randomized clinical trial data to evaluate the effects of testosterone replacement therapy on meaningful clinical outcomes. The risk-to-benefit ratio of testosterone therapy in high-risk subjects, such as those with type 2 diabetes, also requires elucidation. The present article aims to review the current evidence on low serum testosterone levels in patients with type 2 diabetes, and its implications on cardiovascular risk factors, metabolic syndrome and adverse clinical outcomes.

Transcription factors involved in prostate gland adaptation to androgen deprivation

Androgens regulate prostate physiology, and exert their effects through the androgen receptor. We hypothesized that androgen deprivation needs additional transcription factors to orchestrate the changes taking place in the gland after castration and for the adaptation of the epithelial cells to the androgen-deprived environment, ultimately contributing to the origin of castration-resistant prostate cancer. This study was undertaken to identify transcription factors that regulate gene expression after androgen deprivation by castration (Cas). For the sake of comparison, we extended the analysis to the effects of administration of a high dose of 17β-estradiol (E2) and a combination of both (Cas+E2). We approached this by (i) identifying gene expression profiles and enrichment terms, and by searching for transcription factors in the derived regulatory pathways; and (ii) by determining the density of putative transcription factor binding sites in the proximal promoter of the 10 most up- or down-regulated genes in each experimental group in comparison to the controls Gapdh and Tbp7. Filtering and validation confirmed the expression and localized EVI1 (Mecom), NFY, ELK1, GATA2, MYBL1, MYBL2, and NFkB family members (NFkB1, NFkB2, REL, RELA and RELB) in the epithelial and/or stromal cells. These transcription factors represent major regulators of epithelial cell survival and immaturity as well as an adaptation of the gland as an immune barrier in the absence of functional stimulation by androgens. Elk1 was expressed in smooth muscle cells and was up-regulated after day 4. Evi1 and Nfy genes are expressed in both epithelium and stroma, but were apparently not affected by androgen deprivation.

Oxidative actions of hydrogen peroxide in human gingival and oral periosteal fibroblasts: responses to glutathione and nicotine, relevant to healing in a redox environment

Background

This study aims to validate pro-oxidant actions of nicotine (N), using hydrogen peroxide (H₂O₂) and the antioxidant glutathione (G) in an in vitro model of human gingival fibroblasts (HGF) and human oral periosteal fibroblasts (HPF); radiolabelled androgens are used as biomarkers of redox status. Oxidative stress is an important mediator of inflammatory repair. The androgen metabolite 5α-dihydrotestosterone (DHT) is an effective biomarker of oxidative stress and healing.

Methods

6 Cell-lines of HGF and HPF established in confluent monolayer culture were incubated in Eagle's MEM using 14C-testosterone and 14C-4-androstendione as substrate; in conjunction with effective concentrations of N, G and H₂O₂ established at N250, G3 μg/ml and 3%H₂O₂ w/w, 0.5 μl/ml. Combinations of H₂O₂G and H₂O₂GN were used in order to compare the oxidative effects of N/H₂O₂ and their responses to glutathione. At 24 h, the medium was solvent extracted, evaporated to dryness and subjected to TLC in a benzene/acetone solvent system 4:1 v/v for the separation of metabolites. The separated metabolites were quantified using a radioisotope scanner.

Results

The mean trends of 6 cell-lines for both substrates and each cell type demonstrated that the yield of the main metabolite DHT was significantly reduced by N and H₂O₂ alone (2-fold, n=6; p<0.01). The inhibition caused by H₂O₂ was overcome by the antioxidant glutathione in the combination H₂O₂G, to values similar to those of controls (n=6; p<0.01). It is relevant that when N was added to this neutralized combination, the decrease in yields of DHT triggered by N were comparable to those induced by H₂O₂; and retaining the positive effect of G.

Conclusion

Oxidative stress mediated by H₂O₂ was overcome by glutathione and recurred when nicotine was added, suggestive of a pro- oxidant role for nicotine. Androgen biomarkers are a sensitive index of oxidative stress which affects wound healing.

•

DHT is an effective redox marker in HGF and oral periosteal fibroblasts in vitro.

•

Both nicotine and H₂O₂ reduced yields of DHT, indicative of induced oxidative stress.

•

Nicotine has oxidative effects that are comparable to those of H₂O₂ mediated by AR.

•

Effects of nicotine and H₂O₂ were reduced by glutathione in HGF and HPF cultures.

•

Redox status is relevant to androgen receptor-mediated inflammatory wound healing.

Aberrant expression of the PRAC gene in prostate cancer

Identification of aberrant expression patterns of genes in prostate cancer (PCa) is a key step towards the development of effective therapies. Prostate-specific antigen (PSA) levels are commonly measured for the early detection of PCa, but which itself is still not an ideal biomarker. We analysed the expression patterns of prostate cancer susceptibility candidate (PRAC) in prostate cancer. The PRAC gene is known to be commonly expressed in prostate tissue, rectum and colon. To provide clear insights into the expression patterns of PRAC in PCa, we examined the gene expression by quantitative real-time PCR (qRT-PCR), western blot analysis and immunohistochemistry (IHC). The results showed that PRAC expression levels in androgen‑insensitive cells (DU145 and PC3) are lower than those in androgen-sensitive cell lines (LNCaP, LNCaP-R and CW22R). However, treatment of the LNCaP cell line with androgen and anti-androgen demonstrated that PRAC is expressed in an androgen-independent manner. Further, PRAC expression was restored upon treatment of DU145 and PC3 cells with the methyltransferase inhibitor, 5-aza-2'-deoxycytidine (5-aza-CdR), which indicates the effect of methylation in the control of PRAC expression. In addition, IHC analysis revealed a significantly decreased immunoreactivity of PRAC protein in PCa tissues compared to benign prostatic hyperplasia (BPH) (p<0.0001). Thus, our findings suggest that the pathogenesis of PCa may be due to the expression levels of PRAC protein, and this protein can serve as a potential biomarker for the management of PCa.

The Role of Tricho-Rhino-Phalangeal Syndrome (TRPS) 1 in Apoptosis during Embryonic Development and Tumor Progression

TRPS1 is a GATA-type transcription factor that is closely related to human tricho-rhino-phalangeal syndrome (TRPS) types I and III, variants of an autosomal dominant skeletal disorder. During embryonic development, Trps1 represses Sox9 expression and regulates Wnt signaling pathways that determine the number of hair follicles and their normal morphogenesis. In the growth plate, Trps1 regulates chondrocytes condensation, proliferation, and maturation and phalangeal joint formation by functioning downstream of Gdf5 signaling and by targeting at Pthrp, Stat3 and Runx2. Also, Trps1 protein directly interacts with an activated form of Gli3. In embryonic kidneys, Trps1 functions downstream of BMP7 promoting the mesenchymal-to-epithelial transition, and facilitating tubule morphogenesis and ureteric bud branching. Moreover, Trps1 has been found to be closely related to tumorigenesis, invasion, and metastasis in prostate and breast cancers. It is interesting to note that during the development of hair follicles, bones, and kidneys, mutations in Trps1 cause, either directly or through crosstalk with other regulators, a notable change in cell proliferation and cell death. In this review, we will summarize the most recent studies on Trps1 and seek to elucidate the role for Trps1 in apoptotic regulation.

cDNA microarray profiling of rat cholangiocarcinoma induced by thioacetamide

Cholangiocarcinoma (CCA) is a malignant neoplasm affecting thousands of individuals worldwide. CCA develops through a multistep process. In the current study, an oral thioacetamide (TAA)‑induced model of rat CCA was established which generates the histological progression of human CCA, particularly the mass‑forming type. Seven male Sprague‑Dawley rats were treated with TAA for 24 weeks to induce CCA. Following the generation of the rat CCA model, whole rat genomic oligo microarray was performed to examine gene expression profiles in CCA and non‑cancerous liver samples. In brief, 10,427 genes were found to be differentially expressed (8,318 upregulated and 3,489 downregulated) in CCA compared with non‑tumor liver tissue. The top 50 genes (upregulated or downregulated) were selected and their functional involvement in various pathways associated with cancer progression was analyzed, including cell proliferation, apoptosis, metabolism and the cell cycle. In addition, increased expression of CLCA3, COL1A2, DCN, GLIPr2 and NID1, and decreased expression of CYP2C7 and SLC10A1 were validated by quantitative real‑time PCR. Immunohistochemical analysis was performed to determine the protein expression levels of GLIPr2 and SLC10A1. The gene expression profiling performed in this study provides a unique opportunity for understanding the carcinogenesis of TAA‑induced CAA. In addition, expression profiling of a number of specific genes is likely to provide important novel biomarkers for the diagnosis of CCA and the development of novel therapeutic strategies for CCA.

Androgen modulates cardiac fibrosis contributing to gender differences on heart failure

Chronic heart failure (HF) is a major health problem throughout the world. Gender has significant effects on the pathophysiology of HF. Low levels of free testosterone are independently associated with increased chronic HF symptoms and mortality. Cardiac fibrosis plays a pivotal role in structural remodeling in HF. Transforming growth factor (TGF)-β, angiotensin II and oxidative stress contribute to the activity/extent of cardiac fibrosis. Androgen deficiency can up-regulate TGF-β expression under angiotensin II stimulation in vivo. In this review, we summarized the potential mechanisms accounting for the effects of androgen on cardiac fibrosis through regulating fibrocytes activity under TGF, which can explain wound healing and cardiac fibrosis in male with acute myocardial injury and chronic HF.

Pro-survival and anti-apoptotic properties of androgen receptor signaling by oxidative stress promote treatment resistance in prostate cancer

Oxidative stress caused by an increase in reactive oxygen species levels or a decrease in cellular antioxidant capacity can evoke the modulation of various cellular events including androgen receptor (AR) signaling via direct or indirect interactions. In this review, we summarize the mechanisms of AR activation by oxidative stress including: i) AR overexpression; ii) AR activation by AR co-regulators or intracellular signal transduction pathways; iii) generation of AR mutations or splice variants; and iv) de novo androgen synthesis. AR signaling augmented by oxidative stress appears to contribute to pro-survival and anti-apoptotic effects in prostate cancer cells in response to androgen deprivation therapy. In addition, AR signaling suppresses anti-survival and pro-apoptotic effects in prostate cancer cells in response to various cytotoxic and tumor-suppressive interventions including taxanes and radiation through the modulation of βIII-tubulin and ataxia telangiectasia-mutated kinase expression respectively. Taken together, AR signaling appears to render prostate cancer cells refractory to various therapeutic interventions including castration, taxanes, and radiation, indicating that AR signaling is a comprehensive resistant factor and crucial target for prostate cancer treatment.

Glycoprotein transmembrane nmb: an androgen-downregulated gene attenuates cell invasion and tumorigenesis in prostate carcinoma cells

BACKGROUND

Glycoprotein transmembrane nmb (GPNMB) gene was originally identified in osteoblasts and belongs to the pmel-17/nmb family. The function or regulation of GPNMB in the human prostate remains unknown.

METHODS

The expression of GPNMB in prostate carcinoma cells were determined by real-time reverse transcription-polymerase chain reaction (RT-qPCR) and immunoblot assays. Effects of ectopic GPNMB overexpression on cell proliferation, invasion, and tumorigenesis were determined by (3) H-thymidine incorporation, matrigel invasion, soft agar cloning assays, and murine xenograft study. Effects of GPNMB, p53, and androgen on target gene were assessed using RT-PCR, immunoblotting, and transient gene expression assays.

RESULTS

In vitro analysis using several prostate cell lines suggested that expression of GPNMB may be relevant to the extent of neoplasia. Ectopic overexpression of GPNMB significantly attenuated cell proliferation and invasion and exerted antitumorigenic activity on PC-3 cells in vitro and in vivo. GPNMB overexpression induced the gene expressions of N-myc downstream regulated gene 1 (Ndrg1) and maspin in PC-3 cells. Doxorubicin treatment or transient overexpression of p53 increased GPNMB expression. Androgen (R1881) treatment has a divergent effect on gene expression of prostate-specific antigen (PSA) and GPNMB in LNCaP cells. Androgen treatment enhanced cell proliferation but downregulated GPNMB protein expression in stably overexpressed androgen receptor (AR) CA-HPV-10 cells.

CONCLUSIONS

Together these results suggest that GPNMB gene is a p53- and androgen-dysregulated gene and should be regarded as an anti-tumor gene for prostate cancer. The enhancement of Ndrg1 and maspin gene expressions may account for the anti-proliferative and anti-invasive function of GPNMB in PC-3 cells.

Mechanisms for redox actions of nicotine and glutathione in cell culture, relevant to periodontitis

The oxidative effect of nicotine was investigated using androgen biomarkers of redox status and wound healing in fibroblasts; using the antioxidant glutathione for confirmation of responses. Cultures of human gingival (HGF) and periosteal fibroblasts (HPF) were incubated with substrates 14C-testosterone/14C-4-androstenedione in the presence or absence of serial concentrations of nicotine (N_100-500), glutathione (G_1–5) and their combinations, in medium. At 24 h the medium was solvent extracted for metabolites, separated by TLC and quantified using radioisotope scanning. Nicotine caused significant inhibition in yields of the physiologically active metabolite 5α-dihydrotestosterone (DHT) in HGF and HPF, overcome to varying degrees by the anti-oxidant glutathione (n = 6; p<0.01, one way ANOVA); this is suggestive of moderation of an oxidative mechanism induced by nicotine. Down-regulation of 5α-reductase activity by nicotine resulting in reduced yields of DHT was overcome by glutathione. Overcoming oxidative stress in a redox environment is applicable to treatment outcome.

Hepatic protein expression networks associated with masculinization in the female fathead minnow (Pimephales promelas)

Endocrine disruptors that act via the androgen receptor (AR) are less well studied than environmental estrogens, and there is evidence that treatment with AR agonists can result in masculinization of female fish. In this study, female fathead minnows (FHM) were exposed to the model nonaromatizable androgen 5-alpha dihydrotestosterone (DHT) (100 μg/L), the ureic-based herbicide linuron (LIN) (100 μg/L), and a mixture of DHT and LIN (100 μg/L each) to better characterize androgen action in females. LIN was used because of reports that this chemical has an antiandrogenic mode of action in fish. After 21d, DHT and LIN treatments resulted in a significant depression of plasma vitellogenin (Vtg) and DHT and DHT+LIN increased the prevalence of nuptial tubercles in female FHMs indicating masculinization. Using iTRAQ and an LTQ Orbitrap Velos, ∼2000 proteins were identified in the FHM liver and the number of proteins quantified after exposures was >1200. Proteins that significantly and consistently changed in abundance across biological replicates included prostaglandin E synthase 3, programmed cell death 4a, glutathione S transferases, canopy, selenoprotein U, and ribosomal proteins. Subnetwork enrichment analysis identified that interferon and epidermal growth factor signaling were regulated by DHT and LIN, suggesting that these signaling pathways are correlated to depressed plasma vitellogenin. These data provide novel insight into hepatic protein networks that are associated with the process of masculinization in teleosts.

Anabolic Actions of the Regenerative Agent Enamel Matrix Derivative (EMD) in Oral Periosteal Fibroblasts and MG 63 Osteoblasts, Modulation by Nicotine and Glutathione in a Redox Environment

Our study seeks to explore anabolic effects of a periodontal regenerative agent enamel matrix derivative (EMD). Its modulation by nicotine and the anti-oxidant glutathione (GSH) are investigated in human periosteal fibroblasts (HPF) and MG63 osteoblasts. Androgen biomarkers of oxidative stress and healing, resulting from radiolabeled androgen substrates are assayed. This in vitro model simulates a redox environment relevant to the periodontal lesion. It aims to confirm the hypothesis that EMD is an effective regenerative agent in a typically redox environment of the periodontal lesion. Monolayer cultures of MG63 osteoblasts and HPF established in culture medium are incubated with androgen substrates, and optimal concentrations of EMD, nicotine and GSH, alone and in combination. EMD significantly enhances yields of 5α-dihydrotestosterone (DHT) an effective bioactive metabolite, alone and in combination with GSH, to overcome oxidative effects of nicotine across cultures. The ‘in vitro’ findings of this study could be extrapolated to “in vivo” applications of EMD as an adjunctive regenerative therapeutic agent in an environment of chronic inflammation and oxidative stress. Increased yields of DHT implicated in matrix synthesis and direct antioxidant capacity, confirm the potential applications for enamel matrix derivative in periodontal regenerative procedures.

Antioxidants for prostate cancer chemoprevention: challenges and opportunities

Extensive research has led to the firm conclusion that antioxidants protect cells from damage caused by oxidative stress and its associated pathological conditions including inflammation. It has also been established that inflammation is a precursor in neoplastic transformation of the prostate. Although, a vast body of experimental and clinical evidence shows efficacy of antioxidants as preventive strategies for prostate cancer, there is a lack of consistent agreement in outcomes especially from recent large-scale randomized clinical trials. Despite these concerns, our understanding of the preventive mechanisms as well as clinical efficacy and safety data indicate that novel antioxidant therapeutics still hold great promise for prostate cancer chemoprevention. We propose that for effective use of antioxidants for prostate cancer prevention, further high impact translational research is needed with special attention on selecting those patients who will benefit from such intervention. Therefore, it is important to validate predictive biomarkers from successful trials and combine this with knowledge of preclinical characterization of antioxidants (and combinations) that will eventually facilitate the development of 'personalized prostate cancer chemoprevention'. In this review, we briefly describe some common and emerging antioxidants that have shown benefits in preclinical and clinical settings. Above all, we focus on summarizing the progress we made thus far in prostate cancer chemoprevention using antioxidants, the heightened interest and challenges in the future.

Advanced prostate cancer: reinforcing the strings between inflammation and the metastatic behavior

It is currently estimated that inflammatory responses are linked to 15-20% of all deaths from cancer worldwide. Although many studies point to an important role of inflammation in prostate growth, the contribution of inflammation to castration-resistant prostate cancer is not completely understood. The presence of inflammatory mediators in tumor microenvironment raises the question whether genetic events that participate in cancer development and progression are responsible for the inflammatory milieu inside and surrounding tumors. Activated oncogenes, cytokines, chemokines and their receptors, sustained oxidative stress and antioxidant imbalance share the capacity to orchestrate these pro-inflammatory programs; however, the diversity of the inflammatory cell components will determine the final response in the prostate tissue. These observations give rise to the concept that early genetic events generate an inflammatory microenvironment promoting prostate cancer progression and creating a continuous loop that stimulates a more aggressive stage. It is imperative to dissect the molecular pathologic mechanism of inflammation involved in the generation of the castration-resistant phenotype in prostate cancer. Here, we present a hypothesis where molecular signaling triggered by inflammatory mediators may evolve in prostate cancer progression. Thus, treatment of chronic inflammation may represent an important therapeutic target in advanced prostate cancer.

Oxidative stress and androgen receptor signaling in the development and progression of castration-resistant prostate cancer

Aberrant androgen receptor (AR) signaling plays a critical role in androgen-dependent prostate cancer (PCa), as well as in castration-resistant PCa (CRPC). Oxidative stress seems to contribute to the tumorigenesis and progression of PCa, as well as the development of CRPC, via activation of AR signaling. This notion is supported by the fact that there is an aberrant or improper regulation of the redox status in these disorders. Additionally, androgen-deprivation-induced oxidative stress seems to be involved in the pathogenesis of several disorders caused by androgen-deprivation therapy (ADT), including osteoporosis, neurodegenerative disease, and cardiovascular disease. Oxidative stress can be suppressed with antioxidants or via a reduction in reactive oxygen species production. Thus, developing new therapeutic agents that reduce oxidative stress might be useful in preventing the conversion of androgen-dependent PCa into CRPC, as well as reducing the adverse effects associated with ADT. The objective of this review is to provide an overview regarding the relationship between oxidative stress and AR signaling in the context of PCa and especially CRPC. Additionally, we discuss the potential use of antioxidant therapies in the treatment of PCa.

Peroxiredoxin 5: structure, mechanism, and function of the mammalian atypical 2-Cys peroxiredoxin

Peroxiredoxin 5 (PRDX5) was the last member to be identified among the six mammalian peroxiredoxins. It is also the unique atypical 2-Cys peroxiredoxin in mammals. Like the other five members, PRDX5 is widely expressed in tissues but differs by its surprisingly large subcellular distribution. In human cells, it has been shown that PRDX5 can be addressed to mitochondria, peroxisomes, the cytosol, and the nucleus. PRDX5 is a peroxidase that can use cytosolic or mitochondrial thioredoxins to reduce alkyl hydroperoxides or peroxynitrite with high rate constants in the 10(6) to 10(7) M(-1)s(-1) range, whereas its reaction with hydrogen peroxide is more modest, in the 10(5) M(-1)s(-1) range. PRDX5 crystal structures confirmed the proposed enzymatic mechanisms based on biochemical data but revealed also some specific unexpected structural features. So far, PRDX5 has been viewed mainly as a cytoprotective antioxidant enzyme acting against endogenous or exogenous peroxide attacks rather than as a redox sensor. Accordingly, overexpression of the enzyme in different subcellular compartments protects cells against death caused by nitro-oxidative stresses, whereas gene silencing makes them more vulnerable. Thus, more than 10 years after its molecular cloning, mammalian PRDX5 appears to be a unique peroxiredoxin exhibiting specific functional and structural features.

Selenium, but not lycopene or vitamin E, decreases growth of transplantable dunning R3327-H rat prostate tumors

Background

Lycopene, selenium, and vitamin E are three micronutrients commonly consumed and supplemented by men diagnosed with prostate cancer. However, it is not clear whether consumption of these compounds, alone or in combination, results in improved outcomes.

Methodology/Principal Findings

We evaluated the effects of dietary lycopene (250 mg/kg diet), selenium (methylselenocysteine, 1 mg/kg diet), and vitamin E (γ-tocopherol, 200 mg/kg diet) alone and in combination on the growth of androgen-dependent Dunning R3327-H rat prostate adenocarcinomas in male, Copenhagen rats. AIN-93G diets containing these micronutrients were prefed for 4 to 6 weeks prior to tumor implantation by subcutaneous injection. Tumors were allowed to grow for ∼18 weeks. Across diet groups, methylselenocysteine consumption decreased final tumor area (P = 0.003), tumor weight (P = 0.003), and the tumor weight/body weight ratio (P = 0.003), but lycopene and γ-tocopherol consumption intake did not alter any of these measures. There were no significant interactions among nutrient combinations on tumor growth. Methylselenocysteine consumption also led to small, but significant decreases in body weight (P = 0.007), food intake (P = 0.012), and body weight gain/food intake ratio (P = 0.022). However, neither body weight nor gain/food intake ratio was correlated with tumor weight. Methylselenocysteine, lycopene, and γ-tocopherol consumed alone and in combination did not alter serum testosterone or dihydrotestosterone concentrations; tumor proliferation or apoptosis rates. In addition, the diets also did not alter tumor or prostate androgen receptor, probasin, selenoprotein 15, selenoprotein P, or selenium binding protein 2 mRNA expression. However, using castration and finasteride-treated tissues from a previous study, we found that androgen ablation altered expression of these selenium-associated proteins.

Conclusions

Of the three micronutrients tested, only methylselenocysteine consumption reduced growth of transplantable Dunning R3327-H prostate tumors, albeit through an unresolved mechanism.

The evolutionary impact of androgen levels on prostate cancer in a multi-scale mathematical model

Background

Androgens bind to the androgen receptor (AR) in prostate cells and are essential survival factors for healthy prostate epithelium. Most untreated prostate cancers retain some dependence upon the AR and respond, at least transiently, to androgen ablation therapy. However, the relationship between endogenous androgen levels and cancer etiology is unclear. High levels of androgens have traditionally been viewed as driving abnormal proliferation leading to cancer, but it has also been suggested that low levels of androgen could induce selective pressure for abnormal cells. We formulate a mathematical model of androgen regulated prostate growth to study the effects of abnormal androgen levels on selection for pre-malignant phenotypes in early prostate cancer development.

Results

We find that cell turnover rate increases with decreasing androgen levels, which may increase the rate of mutation and malignant evolution. We model the evolution of a heterogeneous prostate cell population using a continuous state-transition model. Using this model we study selection for AR expression under different androgen levels and find that low androgen environments, caused either by low serum testosterone or by reduced 5α-reductase activity, select more strongly for elevated AR expression than do normal environments. High androgen actually slightly reduces selective pressure for AR upregulation. Moreover, our results suggest that an aberrant androgen environment may delay progression to a malignant phenotype, but result in a more dangerous cancer should one arise.

Conclusions

The model represents a useful initial framework for understanding the role of androgens in prostate cancer etiology, and it suggests that low androgen levels can increase selection for phenotypes resistant to hormonal therapy that may also be more aggressive. Moreover, clinical treatment with 5α-reductase inhibitors such as finasteride may increase the incidence of therapy resistant cancers.

Reviewers

This article was reviewed by Ariosto S. Silva (nominated by Marek Kimmel) and Marek Kimmel.

The protective effect of testosterone on streptozotocin-induced apoptosis in beta cells is sex specific

OBJECTIVES

To investigate the protective role of steroid hormones on streptozotocin (STZ)-induced apoptosis in rat pancreatic beta cells.

METHODS

Two sets of experiments were performed. In the first, male rats were orchidectomized and substituted 72 hours later with testosterone, estradiol, or progesterone, and 24 hours later, administered with STZ. Subjects were killed 6 hours later, and apoptosis was determined in sections of the pancreas. In the second experiment, male or female rats were gonadectomized, were further substituted with testosterone, and then administered STZ. Six hours later, the animals were killed, and apoptosis, as well as immunoreactive expression of insulin, catalase, or Cu/Zn superoxide dismutase, was determined in sections of the pancreas. In addition, gonadectomized male or female subjects were substituted with testosterone and administered STZ, and 24 hours later, serum glucose and insulin were measured.

RESULTS

It was found that the cytoprotective effect was only shown in testosterone-treated male rats but not progesterone- or estradiol-treated male rats. In addition, the effect was seen in male rats but not in female rats, and there was an inverse correlation between apoptotic index and antioxidant enzyme immunoreactivity.

CONCLUSIONS

The cytoprotective effect of testosterone is sex specific and is related to the induction of antioxidant enzyme activities in pancreatic beta cells.

Ezrin mediates c-Myc actions in prostate cancer cell invasion

The forced overexpression of c-Myc in mouse prostate and in normal human prostate epithelial cells results in tumor transformation with an invasive phenotype. How c-Myc regulates cell invasion is poorly understood. In this study, we have investigated the interplay of c-Myc and androgens in the regulation of prostate cancer cell invasion. We found that c-Myc induces cell invasion and anchorage-independent growth by regulating ezrin protein expression in the presence of androgens. The activity of the ezrin promoter is controlled by androgens through c-Myc, which binds to a phylogenetically conserved E-Box located in the proximal promoter region. Besides, we also show that ezrin is an important regulator of c-Myc protein levels. These effects are achieved through androgen-induced changes in ezrin phosphorylation, which results in the regulation of downstream signals. These downstream signals involve the modulation of Akt and GSK-3beta activity resulting in increased c-Myc protein synthesis and inhibition of its degradation. In summary, we have shown a key role for ezrin as a mediator of c-Myc-induced tumorigenesis in prostate cancer cells.

Castration resistance of prostate cancer cells caused by castration-induced oxidative stress through Twist1 and androgen receptor overexpression

There are few successful therapies for castration-resistant prostate cancer (CRPC). Recently, CRPC has been thought to result from augmented androgen/androgen receptor (AR) signaling pathway, for most of which AR overexpression has been observed. In this study, Twist1, a member of basic helix-loop-helix transcription factors as well as AR was upregulated in response to hydrogen peroxide, and the response to which was abolished by an addition of N-acetyl-L-cysteine and Twist1 knockdown. In addition, castration-resistant LNCaP derivatives and hydrogen peroxide-resistant LNCaP derivatives exhibited a similar phenotype to each other. Then, both castration and AR knockdown increased intracellular reactive oxygen species level. Moreover, Twist1 was shown to regulate AR expression through binding to E-boxes in AR promoter region. Silencing of Twist1 suppressed cell growth of AR-expressing LNCaP cells as well as castration-resistant LNCaP derivatives by inducing cell-cycle arrest at G1 phase and cellular apoptosis. These findings indicated that castration-induced oxidative stress may promote AR overexpression through Twist1 overexpression, which could result in a gain of castration resistance. Modulation of castration-induced oxidative stress or Twist1/AR signaling might be a useful strategy for developing a novel therapeutics in prostate cancer, even in CRPC, which remains dependent on AR signaling by overexpressing AR.

Impaired autoimmune T helper 17 cell responses following DNA vaccination against rat experimental autoimmune encephalomyelitis

Background

We have previously shown that vaccination with DNA encoding the encephalitogenic peptide myelin oligodendrocyte glycoprotein (MOG)_91–108 (pMOG) suppresses MOG_91–108-induced rat Experimental Autoimmune Encephalomyelitis (EAE), a model for human Multiple Sclerosis (MS). The suppressive effect of pMOG is dependent on inclusion of CpG DNA in the plasmid backbone and is associated with early induction of Interferon (IFN)-β.

Principal Findings

In this study we examined the mechanisms underlying pMOG-induced protection. We found that in the DNA vaccinated cohort proinflammatory Interleukin (IL)-17 and IL-21 responses were dramatically reduced compared to in the control group, but that the expression of Foxp3 and Tumor Growth Factor (TGF)-β1, which are associated with regulatory T cells, was not enhanced. Moreover, genes associated with Type I IFNs were upregulated. To delineate the role of IFN-β in the protective mechanism we employed short interfering RNA (siRNA) to IFN-β in the DNA vaccine. SiRNA to IFN-β completely abrogated the protective effects of the vaccine, demonstrating that a local early elaboration of IFN-β is important for EAE protection. IL-17 responses comparable to those in control rats developed in rats injected with the IFN-β-silencing DNA vaccine.

Conclusions

We herein demonstrate that DNA vaccination protects from proinflammatory Th17 cell responses during induction of EAE. The mechanism involves IFN-β as IL-17 responses are rescued by silencing of IFN-β during DNA vaccination.

Transcriptional profiling of inductive mesenchyme to identify molecules involved in prostate development and disease

Comparison of SAGE libraries for prostatic inductive mesenchyme and the complete prostatic rudiment revealed 219 transcripts that were enriched in, or specific to, inductive mesenchyme. Further analysis suggested that Scube1 is a novel stromal molecule involved in prostate development and tumorigenesis.

Background

The mesenchymal compartment plays a key role in organogenesis, and cells within the mesenchyme/stroma are a source of potent molecules that control epithelia during development and tumorigenesis. We used serial analysis of gene expression (SAGE) to profile a key subset of prostatic mesenchyme that regulates prostate development and is enriched for growth-regulatory molecules.

Results

SAGE libraries were constructed from prostatic inductive mesenchyme and from the complete prostatic rudiment (including inductive mesenchyme, epithelium, and smooth muscle). By comparing these two SAGE libraries, we generated a list of 219 transcripts that were enriched or specific to inductive mesenchyme and that may act as mesenchymal regulators of organogenesis and tumorigenesis. We identified Scube1 as enriched in inductive mesenchyme from the list of 219 transcripts; also, quantitative RT-PCR and whole-mount in situ hybridization revealed Scube1 to exhibit a highly restricted expression pattern. The expression of Scube1 in a subset of mesenchymal cells suggests a role in prostatic induction and branching morphogenesis. Additionally, Scube1 transcripts were expressed in prostate cancer stromal cells, and were less abundant in cancer associated fibroblasts relative to matched normal prostate fibroblasts.

Conclusion

The use of a precisely defined subset of cells and a back-comparison approach allowed us to identify rare mRNAs that could be overlooked using other approaches. We propose that Scube1 encodes a novel stromal molecule that is involved in prostate development and tumorigenesis.

Proteomic analysis of proteins regulated by TRPS1 transcription factor in DU145 prostate cancer cells

The aim of the present study was to identify proteins differentially regulated by TRPS1 in human prostate cancer cells in order to better understand the role of TRPS1 in prostate cancer development. The proteomes of androgen-independent DU145 prostate cancer cells, that do not express TRPS1 and of genetically engineered DU145 cells that stable and inducible express recombinant TRPS1 protein, were compared. Using two-dimensional electrophoresis followed by mass spectrometric analysis, 13 proteins that were differentially expressed between these two cell lines were identified. These proteins represent a dominant reduction of expression of antioxidant proteins, including superoxide dismutase, protein disulfide isomerase A3 precursor, endoplasmin precursor and annexin A2. Furthermore, regulation was observed for mitochondrion-associated proteins, glycolytic enzymes, a cytoskeleton-associated protein, a nuclear protein and proteins involved in apoptosis. Our data indicate that overexpression of TRPS1 protein is correlated with reduced protein expression of certain antioxidants. This suggests a possible involvement of TRPS1 in oxidative stress, and possibly in apoptosis in androgen-independent DU145 prostate cancer cells.

Evaluation of anin vitro model of androgen ablation and identification of the androgen responsive proteome in LNCaP cells

Proteins responsive to androgen and anti-androgen may be involved in the development and progression of prostate cancer and the ultimate failure of androgen-ablation therapy. These proteins represent potential diagnostic and therapeutic targets for improved management of prostate cancer. We have investigated the effect of androgen (R1881) and anti-androgen (bicalutamide) on the androgen-responsive prostate cancer LNCaP cell line using a quantitative gel-based proteomic approach. Prior to analysis, the in vitro system was evaluated for reproducibility and validated by appropriate molecular responses to treatment. Six replicate samples were independently generated and analysed by 2-D DIGE. According to strict statistical criteria, 197 spots were differentially expressed, of which we have successfully identified 165 spots corresponding to 125 distinct proteins. Following androgen supplementation, 108 spots (68 proteins) were increased and 57 spots (39 proteins) were decreased. Essentially no difference was observed between control and anti-androgen-treated samples, confirming the absence of "off-target" effects of bicalutamide. Identified proteins were involved in diverse processes including the stress response and intracellular signalling. The potential contribution to disease of these processes and identified constituent proteins are discussed. This rigorous, statistically supported study of androgen responses has provided a number of potential candidates for development as diagnostic/prognostic markers and drug targets.

Serum selenium and risk of prostate cancer-a nested case-control study

BACKGROUND

Selenium is a potential chemopreventive agent against prostate cancer, whose chemoprotective effects are possibly mediated through the antioxidative properties of selenoenzymes. Interrelations with other antioxidative agents and oxidative stressors, such as smoking, are poorly understood.

OBJECTIVES

The aims were to investigate the association between serum selenium and prostate cancer risk and to examine interactions with other antioxidants and tobacco use.

DESIGN

A nested case-control study was performed within the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Serum selenium in prospectively collected samples was compared between 724 incident prostate cancer case subjects and 879 control subjects, frequency-matched for age, time since initial screen, and year of blood draw. The men were followed for up to 8 y.

RESULTS

Overall, serum selenium was not associated with prostate cancer risk (P for trend = 0.70); however, higher serum selenium was associated with lower risks in men reporting a high (more than the median: 28.0 IU/d) vitamin E intake [odds ratio (OR) for the highest compared with the lowest quartile of selenium: 0.58; 95% CI: 0.37, 0.91; P for trend = 0.05; P for interaction = 0.01] and in multivitamin users (OR for highest compared with the lowest quartile of selenium: 0.61; 95% CI: 0.36, 1.04; P for trend = 0.06; P for interaction = 0.05). Furthermore, among smokers, high serum selenium concentrations were related to reduced prostate cancer risk (OR for the highest compared with the lowest quartile of selenium: 0.65; 95% CI: 0.44, 0.97; P for trend = 0.09; P for interaction = 0.007).

CONCLUSION

Greater prediagnostic serum selenium concentrations were not associated with prostate cancer risk in this large cohort, although greater concentrations were associated with reduced prostate cancer risks in men who reported a high intake of vitamin E, in multivitamin users, and in smokers.

Identification of genes potentially involved in the acquisition of androgen-independent and metastatic tumor growth in an autochthonous genetically engineered mouse prostate cancer model

BACKGROUND

A major focus of prostate cancer research has been to identify genes that are deregulated during tumor progression, potentially providing diagnostic markers and therapeutic targets.

METHODS

We have employed serial analysis of gene expression (SAGE) and microarray hybridization to identify alterations that occur during malignant transformation in the Transgenic Adenocarcinoma of the Mouse Prostate (TRAMP) model. Many of these alterations were validated by real-time PCR (rtPCR).

RESULTS

We identified several hundred mRNAs that were deregulated. Cluster analysis of microarray profiles with samples from various stages of the disease demonstrated that androgen-independent (AI) primary tumors are similar to metastases; 180 transcripts have expression patterns suggesting an involvement in the genesis of late-stage tumors, and our data support a role for phospholipase A2 group IIA in the acquisition of their highly aggressive characteristics.

CONCLUSIONS

Our analyses identified well-characterized genes that were previously known to be involved in prostate cancer, validating our study, and also uncovered transcripts that had not previously been implicated in prostate cancer progression.

Expression profiling of the mouse prostate after castration and hormone replacement: implication of H-cadherin in prostate tumorigenesis

Mice have been used extensively for studying normal prostate development and for generation of transgenic or knock-out prostate cancer animal models. To understand systematically and thoroughly the androgen responsive program in the mouse prostate, we carried out microarray analysis to profile gene expression changes during prostate involution and re-growth triggered by castration and subsequent hormone replacement. Genes with significant changes in these two processes were identified and gene ontology analyses revealed that they were mainly involved in response mechanisms, cell adhesion, metabolism, protein metabolism, and cell-cycle progression. The changes observed during prostate involution were largely reversed during re-growth. Sixty-four genes, including Nkx3.1 and probasin, and 65 other genes, including insulin-like growth factor binding protein 3 and H-cadherin (H-Cad), were further identified respectively as androgen-responsive genes and genes inversely correlated with androgen, based on their down- or up-regulation following castration and up- or down-regulation following androgen replacement. Potential androgen-responsive elements were found in the 5' upstream promoter region of 47 of those 65 genes, suggesting a potential suppression mechanism by androgen receptor. Of these, the role of H-Cad in tumorigenesis was further evaluated. Reduction of H-Cad transcript level was found in the majority of human prostate cancer cell lines and prostatic adenocarcinoma samples examined. Furthermore, induced H-Cad expression in DU145 cells, and knock-down of H-Cad expression in BPH1 cells inhibited and facilitated tumorigenicity, respectively. Taken together, our study provides a molecular understanding of the mouse prostate involution and re-growth processes and identifies a set of genes that are inversely correlated with androgen and may be potentially suppressive for tumorigenesis.

Oxidant/antioxidant interactions of nicotine, Coenzyme Q10, Pycnogenol and phytoestrogens in oral periosteal fibroblasts and MG63 osteoblasts

BACKGROUND

There is a growing awareness that oxidative stress may play a role in periodontal disease. The aim of this investigation was to evaluate potential oxidant/antioxidant interactions of nicotine with antioxidants (Coenzyme Q10 (CoQ), Pycnogenol and phytoestrogens in a cell culture model.

METHODS

Duplicate incubations of human periosteal fibroblasts and osteoblasts were performed with 14C-testosterone as substrate, in the presence or absence of CoQ (20 microg/ml), Pycnogenol (150 microg/ml), and phytoestrogens (10 and 40 microg/ml), alone and in combination with nicotine (250 microg/ml). At the end of a 24-h incubation period, the medium was solvent extracted and testosterone metabolites were separated by thin-layer chromatography and quantified using a radioisotope scanner.

RESULTS

The incubations of osteoblasts and periosteal fibroblasts with CoQ, Pycnogenol or phytoestrogens stimulated the synthesis of the physiologically active androgen DHT, while the yields of DHT were significantly reduced in response to nicotine compared to control values (p<0.001 for phytoestrogens). The combination of nicotine with CoQ, Pycnogenol or phytoestrogens increased the yields of DHT compared with incubation with nicotine alone in both cell types.

CONCLUSION

This investigation suggests that the catabolic effects of nicotine could be reversed by the addition of antioxidants such as CoQ or Pycnogenol and phytoestrogens.

Polymorphisms in polycyclic aromatic hydrocarbon metabolism and conjugation genes, interactions with smoking and prostate cancer risk

The relationship between cigarette smoking and prostate cancer remains unclear. Any potential association may depend on the individuals' ability to metabolize and detoxify cigarette carcinogens--such as polycyclic aromatic hydrocarbons. To investigate this, we studied the association between prostate cancer and smoking, as well as the main and modifying effects of functional polymorphisms in genes that metabolize polycyclic aromatic hydrocarbons (CYP1A1 Ile(462)Val, microsomal epoxide hydrolase His(139)Arg) and detoxify reactive derivatives (GSTM1 null deletion, GSTT1 null deletion, GSTP1 Ile(105)Val and Ala(114)Val) using a family-based case-control design (439 prostate cancer cases and 479 brother controls). Within the entire study population, there were no main effects for smoking or any of the polymorphisms. However, the nondeleted GSTM1 allele was inversely associated with prostate cancer [odds ratio (OR), 0.50; 95% confidence interval (95% CI), 0.26-0.94] among men with less aggressive disease (Gleason score < 7 and clinical tumor stage < T2c) and positively associated (OR, 1.68; 95% CI, 1.01-2.79) with prostate cancer in men with more aggressive disease (Gleason score > or = 7 or clinical tumor stage > or = T2c). We also found a statistically significant negative multiplicative interaction between the GSTM1 nondeleted allele and heavy smoking (> 20 pack-years) in the total study population (P = 0.01) and in Caucasians (P = 0.01). Among Caucasians, heavy smoking increased prostate cancer risk nearly 2-fold in those with the GSTM1 null genotype (OR, 1.73; 95% CI, 0.99-3.05) but this increased risk was not observed in heavy smokers who carried the GSTM1 nondeleted allele (OR, 0.95; 95% CI, 0.53-1.71). Our results highlight the importance of considering genetic modifiers of carcinogens when evaluating smoking in prostate cancer.

Increased expression of the metastasis-associated gene Ehm2 in prostate cancer

BACKGROUND

Alterations of fibroblast growth factors and their receptors contribute to prostate cancer progression by enhancing cell survival, motility, and proliferation. The expression of the FGFR-4 Arg(388) variant is correlated with the occurrence of pelvic lymph node metastasis and biochemical (PSA) recurrence in men undergoing radical prostatectomy. Ehm2 is an androgen-regulated gene that has been associated with metastasis in other systems, so we sought to determine if it is expressed in prostate cancer and if the FGFR-4 Arg(388) variant can increase its expression.

METHODS

Expression of Ehm2 was examined by quantitative RT-PCR and Western blotting in prostate cell lines and by quantitative RT-PCR, in situ hybridization, and immunohistochemistry in prostate tissues. The effect of Ehm2 expression on collagen IV adhesion was tested by transient overexpression and RNA interference.

RESULTS

Ehm2 expression is upregulated in prostate cancer cell lines and prostate cancer tissues. Expression of the FGFR-4 Arg(388) variant results in increased expression of Ehm2. Increased expression of Ehm2 leads to decreased adhesion to collagen IV, which has been associated with metastasis in cancers. Analysis of tissue microarrays revealed that increased Ehm2 expression is associated with biochemical recurrence after radical prostatectomy, which is indicative of more aggressive disease.

CONCLUSIONS

Ehm2 is overexpressed in prostate cancer and may enhance disease progression and metastasis.

Protein Profiling of Rat Ventral Prostate following Chronic Finasteride Administration

To better understand the effects of antiandrogens on the prostate, we investigated the changes in the proteome of rat ventral prostate (VP) following treatment with a well characterized 5alpha-reductase inhibitor, finasteride. Sprague-Dawley rats were treated daily by gavage with finasteride at 0, 1, 5, 25, and 125 mg/kg/day. Changes in plasma hormone levels as well as the weight and histology of sex accessory tissues were determined after 28 days of treatment and showed a dose-related decrease of VP weights together with a marked atrophy of the tissue visible at the macroscopic and microscopic levels. In addition, significant reductions in seminal vesicle and epididymis weights were noted. VP proteins were analyzed by two-dimensional gel electrophoresis: 37 proteins, mainly involved in protein synthesis, processing, and cellular trafficking and in metabolism, detoxification, and oxidative stress, were identified as modulated by finasteride. The prominent feature of this study is the demonstration of finasteride dose-dependent up-regulation of a protein similar to l-amino-acid oxidase 1 (Lao1). An up-regulation of this protein was also observed with the antiandrogen flutamide. Lao1 expression occurred as early as 48 h after antiandrogen administration and persisted throughout the treatment duration. Immunohistochemistry showed that this protein was only detectable in epithelial cells and secretory vesicles. Altogether these data point to a potential use of Lao1 to reveal antiandrogen-induced prostate injury.

Androgen Induction of Prostate Cancer Cell Invasion Is Mediated by Ezrin

Ezrin is a key signaling molecule that regulates cell survival, adhesion migration, and invasion. We have previously shown that ezrin is regulated by androgen in rat prostate and that its expression is increased in prostate cancer and in prostate intraepithelial neoplasia. We have used the androgen-sensitive cell line LNCaP-FGC to investigate the role of ezrin in androgen-induced cell invasion. We found that androgen treatment of LNCaP-FGC cells induces ezrin expression, an effect that is inhibited by the androgen receptor antagonist, bicalutamide. In addition, androgen treatment induces the phosphorylation of ezrin in Thr-567 and Tyr-353 in a sequential manner. This is mediated through protein kinase C alpha and Src tyrosine kinase, respectively. Androgen treatment induces the translocation of both protein kinase C alpha and ezrin to the cell membrane and their association. Inhibition of ezrin function using short interference RNA or the overexpression of T567A and Y353F-ezrin mutants significantly reduces androgen-induced Matrigel invasion but does not affect cell proliferation or cell adhesion. Matrigel invasion of the androgen-insensitive prostate cancer cell lines PC-3 and LNCaP-R is also dependent on ezrin. In summary, we have shown that androgens regulate ezrin at transcriptional and posttranscriptional levels. Hormonal regulation of ezrin phosphorylation is required for androgen-induced cell invasion.

Cytogenetic and expression profiles associated with transformation to androgen-resistant prostate cancer

BACKGROUND

The mechanisms underlying the progression of prostate cancer to androgen-resistant cancer are still not fully understood. Here, we studied the genetic events associated with this transformation.

METHODS

The androgen sensitive prostate cancer cells line LNCaP-FGC and its androgen resistant subline LNCaP-r were investigated using SKY, CGH, and cDNA microarray.

RESULTS

Karyotypically, several additional chromosomal aberrations were seen in LNCaP-r as compared to the parental line. CGH also revealed unique net chromosomal alterations in LNCaP-r compared to LNCaP-FGC, including gain of 2p13-23, 2q21-32, and 13q and loss of 6p22-pter. cDNA microarray analysis identified several genes involved in DNA methylation, such as DNMT2, DNMT3a, and methyl-CpG binding domain protein 2 and 4 that were higher expressed in LNCaP-r. Interestingly, androgen responsiveness of LNCaP-r was restored after treated with DNA methyltransferase inhibitor.

CONCLUSIONS

Our findings may serve as a basis for molecular dissection of the mechanisms involved in development of androgen resistant prostate cancer.

Differential attenuation of oxidative/nitrosative injuries in early prostatic neoplastic lesions in TRAMP mice by dietary antioxidants

BACKGROUND

Dietary antioxidants with yet unproven efficacies in averting prostate cancer (PCa) are widely used in the United States as preventives. Experimental evidence establishing a causal relationship between oxidative and nitrosative stress (OS/NS) and PCa development and showing its modulation by dietary antioxidants would help justify their usage.

METHODS

The TRAMP (Transgenic Adenocarcinoma of the Mouse Prostate) mouse model was used to demonstrate the OS/NS-associated damage, as evident by 8-hydroxy-2'-deoxyguanosine (8-OHdG), 4-hydroxynonenal (4-HNE)-protein-adducts and nitrotyrosine (Ntyr), in prostatic premalignant lesions, and to evaluate the antioxidant efficacy of various dietary supplements [natural antioxidant (NAO) from spinach extracts, (-) epigallocatechin-3-gallate (EGCG), or N-acetylcystein (NAC)] during the early PCa development.

RESULT

We show, for the first time, that oxidative/nitrosative damages of genomic DNA and cellular proteins were discretely localized in premalignant lesions, but not in adjacent morphologically normal epithelia, of TRAMP prostates; these injuries were absent in age-matched nontransgenic littermates. The extent of OS/NS-related injuries correlated well with the tempo of development and prevalence of premalignant lesions in various prostatic lobes and exhibited a clear trend of increase from 12 to 20 weeks of age. Treatment of TRAMP mice with various antioxidants as dietary supplements resulted in differential alleviation of OS/NS-related prostatic injuries. The antioxidant potencies of the dietary supplements did not fully correlate with their documented antiPCa actions, suggest that they may exert additional "nonantioxidant," antitumor effects in this model.

CONCLUSIONS

Our data indicate that in TRAMP mice, OS/NS injuries are likely involved in early prostatic tumorigenesis and can be modulated by various antioxidants.

Androgens regulate the immune/inflammatory response and cell survival pathways in rat ventral prostate epithelial cells

A major hurdle in understanding the role of androgens is the heterogeneity of androgen receptor (AR) expression in the prostate. Because the majority of prostate cancer arises from the AR-positive secretory luminal epithelial cells, identifying the androgen-mediated pathways in the prostate epithelium is of great significance to understanding their role in prostate pathogenesis. To meet this objective, the current study was designed to identify immediate-early genes expressed in response to the synthetic androgen R1881 in cultured rat ventral prostate epithelial cells. Rat ventral prostate epithelial cells, purified from 20-d-old rats, were cultured, and the presence of AR and the response to androgen were established. The cells were then treated with R1881 for 2 and 12 h to capture immediate-early genes in an Affymetrix-based gene chip platform. A total of 66 nonredundant genes were identified that were responsive to R1881. The functional androgen response elements were identified in the proximal promoter to determine possible molecular mechanism. Cluster analysis identified five distinct signatures of R1881-induced genes. Pathway analysis suggested that R1881 primarily influences cell proliferation/differentiation and inflammatory/immune response pathways. Androgens appear to regulate cell renewal by regulating differentiation, cell proliferation, and apoptosis. Two mutually exclusive inflammatory response pathways were observed. The interferon pathway was up-regulated, and the ILs were down-regulated. The data identified novel androgen-regulated genes (e.g. Id1, Id3, IL-6, IGF-binding protein-2 and -3, and JunB). The loss of androgen regulation of these genes can have important consequences for cellular transformation and transition to androgen-independent growth and survival.