Testosterone and prolactin regulation of metabolic genes and citrate metabolism of prostate epithelial cells

Study of Association of Serum Prolactin Levels with Insulin Resistance in Type 2 Diabetes Mellitus Patients

Objective

Prolactin (PRL) regulates glucose metabolism and insulin sensitivity. The study aimed to evaluate the role of PRL in glucose homeostasis and its association with insulin resistance in patients with diabetes mellitus (DM).

Methods and Materials

This cross-sectional, observational study included 100 patients (25-60 years) with T2DM. Primary information including demographics, anthropometric measurements, and biochemical measures (complete blood count, glucose parameters, liver and kidney function test, lipid profile, thyroid function test, serum fasting insulin levels, serum PRL levels) was collected.

Results

A total of 100 patients, 50 men and 50 women (25 premenopausal and 25 postmenopausal), were enrolled in this study. The correlation between serum cholesterol and PRL was found to be statistically non-significant (P = 0.129) in men and significant (P = 0.041) in women. There was an inverse relationship between fasting plasma glucose and serum PRL levels in both men (r = -0.88; P < 0.0001) and women patients (r = -0.768; P < 0.0001). Negative correlation between postprandial plasma glucose and PRL was found to be statistically significant (r = -0.398; P = 0.048) in postmenopausal women. The comparison in both men and women indicated an inverse correlation between serum PRL and glycated haemoglobin levels. There was a significant negative correlation between homeostasis model assessment-estimated insulin resistance (HOMA-IR) and PRL levels in both men (r = -0.362; P = 0.039) and women patients (r = -0.362; P = 0.003). Homeostasis model assessment of β cell function (HOMA-β), which directly correlates with residual pancreatic beta cell function, was positively correlated with prolactin levels, irrespective of gender and menopausal status of female subjects.

Conclusion

Serum PRL levels correlate with improved glycaemic control.

Impacts of endocrine-disrupting chemicals on prostate function and cancer

Because of their historical mode of action, endocrine-disrupting chemicals (EDCs) are associated with sex-steroid receptors, namely the two estrogen receptors (ERα and ERβ) and the androgen receptor (AR). Broadly, EDCs can modulate sex-steroid receptor functions. They can also indirectly impact the androgen and estrogen pathways by influencing steroidogenesis, expression of AR or ERs, and their respective activity as transcription factors. Additionally, many of these chemicals have multiple cellular targets other than sex-steroid receptors, which results in a myriad of potential effects in humans. The current article reviews the association between prostate cancer and the endocrine-disrupting functions of four prominent EDC families: bisphenols, phthalates, phytoestrogens, and mycoestrogens. Results from both in vitro and in vivo models are included and discussed to better assess the molecular mechanisms by which EDCs can modify prostate biology. To overcome the heterogeneity of results published, we established common guidelines to properly study EDCs in the context of endocrine diseases. Firstly, the expression of sex-steroid receptors in the models used must be determined before testing. Then, in parallel to EDCs, pharmacological compounds acting as positive (agonists) and negative controls (antagonists) have to be employed. Finally, EDCs need to be used in a precise range of concentrations to modulate sex-steroid receptors and avoid off-target effects. By adequately integrating molecular endocrinology aspects in EDC studies and identifying their underlying molecular mechanisms, we will truly understand their impact on prostate cancer and distinguish those that favor the progression of the disease from those that slow down tumor development.

Rapid Androgen-Responsive Proteome Is Involved in Prostate Cancer Progression

Androgen exerts its functions by binding with an androgen receptor (AR). It can activate many signaling pathways that are important to the progression of castration-resistant prostate cancer (CRPC). Here, we characterized the rapid proteomic changes seen at 5, 15, 30, and 60 min after the androgen treatment of VCaP cells via the tandem mass tag (TMT) labeling strategy. A total of 5529 proteins were successfully identified and quantified. Dynamic time profiling of protein expression patterns allowed us to identify five protein clusters involved in various stages of androgen-initiated signal transmission and processing. More details of protein functions and localization patterns, and our elucidation of an AR-interacting protein network, were obtained. Finally, we validated the expression level of AR-regulated proteins known to be significantly regulated in CRPC patients using the mouse xenograft model and patient samples. Our work offers a systematic analysis of the rapid proteomic changes induced by androgen and provides a global view of the molecular mechanisms underlying CRPC progression.

CMBD: a manually curated cancer metabolic biomarker knowledge database

The pathogenesis of cancer is influenced by interactions among genes, proteins, metabolites and other small molecules. Understanding cancer progression at the metabolic level is propitious to the visual decoding of changes in living organisms. To date, a large number of metabolic biomarkers in cancer have been measured and reported, which provide an alternative method for cancer precision diagnosis, treatment and prognosis. To systematically understand the heterogeneity of cancers, we developed the database CMBD to integrate the cancer metabolic biomarkers scattered over literatures in PubMed. At present, CMBD contains 438 manually curated relationships between 282 biomarkers and 76 cancer subtypes of 18 tissues reported in 248 literatures. Users can access the comprehensive metabolic biomarker information about cancers, references, clinical samples and their relationships from our online database. As case studies, pathway analysis was performed on the metabolic biomarkers of breast and prostate cancers, respectively. 'Phenylalanine, tyrosine and tryptophan biosynthesis', 'phenylalanine metabolism' and 'primary bile acid biosynthesis' were identified as playing key roles in breast cancer. 'Glyoxylate and dicarboxylate metabolism', 'citrate cycle (TCA cycle)', and 'alanine, aspartate and glutamate metabolism' have important functions in prostate cancer. These findings provide us with an understanding of the metabolic pathway of cancer initiation and progression. Database URL: http://www.sysbio.org.cn/CMBD/.

Testosterone activates glucose metabolism through AMPK and androgen signaling in cardiomyocyte hypertrophy

Background

Testosterone regulates nutrient and energy balance to maintain protein synthesis and metabolism in cardiomyocytes, but supraphysiological concentrations induce cardiac hypertrophy. Previously, we determined that testosterone increased glucose uptake—via AMP-activated protein kinase (AMPK)—after acute treatment in cardiomyocytes. However, whether elevated glucose uptake is involved in long-term changes of glucose metabolism or is required during cardiomyocyte growth remained unknown. In this study, we hypothesized that glucose uptake and glycolysis increase in testosterone-treated cardiomyocytes through AMPK and androgen receptor (AR).

Methods

Cultured cardiomyocytes were stimulated with 100 nM testosterone for 24 h, and hypertrophy was verified by increased cell size and mRNA levels of β-myosin heavy chain (β-mhc). Glucose uptake was assessed by 2-NBDG. Glycolysis and glycolytic capacity were determined by measuring extracellular acidification rate (ECAR).

Results

Testosterone induced cardiomyocyte hypertrophy that was accompanied by increased glucose uptake, glycolysis enhancement and upregulated mRNA expression of hexokinase 2. In addition, testosterone increased AMPK phosphorylation (Thr172), while inhibition of both AMPK and AR blocked glycolysis and cardiomyocyte hypertrophy induced by testosterone. Moreover, testosterone supplementation in adult male rats by 5 weeks induced cardiac hypertrophy and upregulated β-mhc, Hk2 and Pfk2 mRNA levels.

Conclusion

These results indicate that testosterone stimulates glucose metabolism by activation of AMPK and AR signaling which are critical to induce cardiomyocyte hypertrophy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40659-021-00328-4.

Bisphenols Threaten Male Reproductive Health via Testicular Cells

Male reproductive function and health are largely dependent on the testes, which are strictly regulated by their major cell components, i. e., Sertoli, Leydig, and germ cells. Sertoli cells perform a crucial phagocytic function in addition to supporting the development of germ cells. Leydig cells produce hormones essential for male reproductive function, and germ cell quality is a key parameter for male fertility assessment. However, these cells have been identified as primary targets of endocrine disruptors, including bisphenols. Bisphenols are a category of man-made organic chemicals used to manufacture plastics, epoxy resins, and personal care products such as lipsticks, face makeup, and nail lacquers. Despite long-term uncertainty regarding their safety, bisphenols are still being used worldwide, especially bisphenol A. While considerable attention has been paid to the effects of bisphenols on health, current bisphenol-related reproductive health cases indicate that greater attention should be given to these chemicals. Bisphenols, especially bisphenol A, F, and S, have been reported to elicit various effects on testicular cells, including apoptosis, DNA damage, disruption of intercommunication among cells, mitochondrial damage, disruption of tight junctions, and arrest of proliferation, which threaten male reproductive health. In addition, bisphenols are xenoestrogens, which alter organs and cells functions via agonistic or antagonistic interplay with hormone receptors. In this review, we provide in utero, in vivo, and in vitro evidence that currently available brands of bisphenols impair male reproductive health through their action on testicular cells.

Krebs Cycle Reborn in Macrophage Immunometabolism

A striking change has happened in the field of immunology whereby specific metabolic processes have been shown to be a critical determinant of immune cell activation. Multiple immune receptor types rewire metabolic pathways as a key part of how they promote effector functions. Perhaps surprisingly for immunologists, the Krebs cycle has emerged as the central immunometabolic hub of the macrophage. During proinflammatory macrophage activation, there is an accumulation of the Krebs cycle intermediates succinate and citrate, and the Krebs cycle–derived metabolite itaconate. These metabolites have distinct nonmetabolic signaling roles that influence inflammatory gene expression. A key bioenergetic target for the Krebs cycle, the electron transport chain, also becomes altered, generating reactive oxygen species from Complexes I and III. Similarly, alternatively activated macrophages require α-ketoglutarate-dependent epigenetic reprogramming to elicit anti-inflammatory gene expression. In this review, we discuss these advances and speculate on the possibility of targeting these events therapeutically for inflammatory diseases.

The Suppression of Prolactin is required for the Treatment of Advanced Prostate Cancer

Androgen-independent advanced prostate cancer is a terminal malignancy that generally results in death within five years. Its cause has been unknown, and a treatment did not exist. Prevailing views have mistakenly implicated impaired androgen receptor activity in the development of androgen-independent malignancy; which has deterred the existence of an effective treatment. Instead, recent reports have provided evidence that prolactin promotes the development and progression of androgen-independent malignancy; which follows androgen ablation treatment for androgen-dependent prostate cancer. That relationship dictates that a treatment for advanced prostate cancer should suppress the concentration plasma prolactin. This has been achieved with cabergoline (dopamine agonist; Dostinex) treatment of a patient that resulted in 88% decreased plasma prolactin, and terminated the malignancy. That likely represents the first effective treatment for advanced prostate cancer. It remains to establish if this treatment will be successful for other patients with advanced prostate cancer.

Mechanism Investigation of Tagetes patula L. against Chronic Nonbacterial Prostatitis by Metabolomics and Network Pharmacology

The major objective of this study was to investigate the anti-chronic nonbacterial prostatitis (CNP) mechanism of T. patula by metabolomics and network pharmacology. The study demonstrated that the flavonoids and polysaccharides of T. patula could alleviate prostatitis by improving the level of DHT, reducing the secretion of PSA and TNF-α. Besides, both could enhance Na⁺/K⁺-ATPase activity, decrease the O₂ consumption, CO₂ production, heat production, energy expenditure of rats and promote respiratory exchange ratio of rats. Up to 28 potential biomarkers and 8 key metabolic pathways related to the treatment of CNP were elucidated by the metabolomics analysis, including phenylalanine metabolism, taurine and hypotaurine metabolism, tryptophan metabolism etc. Network pharmacology prediction also reflected the potential mechanism was associated with tryptophan metabolism and energy pathway. Generally, the potential anti-CNP mechanism of flavonoids and polysaccharides of T. patula might be through reducing the expression of inflammation factors, adjusting the level of hormone and regulating the amino acid metabolism, energy metabolism and glucose and lipid metabolism.

A Novel Patient Case Report to Show the Successful Termination of Untreatable Androgen-independent Prostate Cancer: Treatment with Cabergoline (Dopamine agonist)

INTRODUCTION

Testosterone promotes the initial development of androgen-dependent prostate cancer. This is the basis for androgen ablation treatment, which attenuates, but does not terminate, the malignancy. Instead, it leads to prolactin-dependent malignancy; in which patient death generally occurs within 5 years. This report describes the novel treatment of a patient; which terminated androgen-independent prostate cancer.

RESULTS

Patient "XY" was diagnosed with prostate malignancy and metastases. He received hormonal androgen ablation treatment, chemotherapy, and radiation treatment. He developed androgen-independent prostate cancer; with expected death in 2-3 years. He was treated with cabergoline (dopamine agonist) treatment, which decreased the plasma prolactin 88%; by inhibiting the pituitary production of prolactin. The subsequent PET scan (positron emission tomography) revealed the absence of malignancy; and the CTC (circulating tumor cells) decreased from count=5.4 to count=0.

DISCUSSION

The cause of androgen-independent malignancy has been unknown, and an effective chemotherapy did not exist. The activities of normal and malignant prostate cells are regulated primarily by testosterone. When testosterone availability diminishes; prolactin regulation is manifested. This is represented when androgen ablation results in the development of prolactin-dependent malignancy. An effective chemotherapy would be targeted to eliminate the plasma prolactin-manifestation of the androgen-independent malignancy.

CONCLUSIONS

This report of a novel chemotherapy for androgen-independent malignancy corroborates our understanding of the implications of prolactin in its development and treatment. There are about 165,000 cases/year with 25,000 deaths/year in the U.S.; and 1.0 million cases/year with 260,000 deaths/year worldwide. Those patients with androgen-independent prostate cancer can now employ this cabergoline treatment to prevent or terminate this deadly type of prostate cancer.

A Proposed Efficacious Treatment with Clioquinol (Zinc Ionophore) and Cabergoline (Prolactin Dopamine Agonist) for the Treatment of Terminal Androgen-independent Prostate Cancer. Why and How?

All cases of prostate cancer exhibit the hallmark condition of marked decrease in zinc in malignancy compared to the high zinc levels in the normal and benign prostate. There exists no reported corroborated case of prostate cancer in which malignancy exhibits the high zinc levels that exist in the normal prostate acinar epithelium. The decrease in zinc is achieved by the downregulation of ZIP1 zinc transporter, which prevents the uptake and accumulation of cytotoxic zinc levels. Thus, prostate cancer is a "ZIP1-deficient" malignancy. Testosterone and prolactin are the major hormones that similarly regulate the growth, proliferation, metabolism, and functional activities of the acinar epithelial cells in the peripheral zone (the site of development and progression of malignancy). Testosterone regulation provides the basis for androgen ablation treatment of advanced prostate cancer, which leads to the development of terminal androgen-independent malignancy. Androgen-independent malignancy progresses under the influence of prolactin. These relationships provide the basis for the prevention and treatment of advanced prostate cancer. Clioquinol (zinc ionophore; 5-chloro-7-iodoquinolin-8-ol) is employed to facilitate zinc transport and accumulation in the ZIP1-deficient malignant cells and induce cytotoxic effects. Cabergoline (dopamine agonist) is employed to decrease prolactin production and its role in the progression of androgen-independent malignancy. We propose a clioquinol/cabergoline treatment regimen that will be efficacious for aborting terminal advanced prostate cancer. FDA policies permit this treatment regimen to be employed for these patients.

Testosterone, prolactin, and oncogenic regulation of the prostate gland. A new concept: Testosterone-independent malignancy is the development of prolactin-dependent malignancy!

Hormone-independent malignancy is a major issue of morbidity and deaths that confronts prostate cancer. Despite decades of research, the oncogenic and hormonal implications in the development and progression of prostate malignancy remain mostly speculative. This is largely due to the absence and/or lack of consideration by contemporary clinicians and biomedical investigators regarding the established implications of the co-regulation of testosterone and prolactin in the development, maintenance, metabolism and functions of the prostate gland. Especially relevant is the major metabolic function of production of high levels of citrate by the peripheral zone acinar epithelial cells. Citrate production, along with growth and proliferation by these cells, is regulated by co-existing testosterone and prolactin signaling pathways; and by the oncogenic down-regulation of ZIP1 transporter/zinc/citrate in the development of malignancy. These relationships had not been considered in the issues of hormonedependent malignancy. This review provides the relevant background that has established the dual role of testosterone and prolactin regulation of the prostate gland; which is essential to address the implications in the oncogenic development and progression of hormone-dependent malignancy. The oncogenic factor along with testosterone-dependent and prolactin-dependent relationships leads to the plausible concept that androgen ablation for the treatment of testosteronedependent malignancy results in the development of prolactindependent malignancy; which is testosterone-independent malignancy. Consequently, both testosterone ablation and prolactin ablation are required to prevent and/or abort terminal hormonedependent prostate cancer.

Differential Gene Expression in Prostate Tissue According to Ejaculation Frequency

In a prospective study of 31 925 men with 18 yr of follow-up, higher ejaculation frequency (EF) throughout adulthood was associated with lower rates of prostate cancer. To further explore this association, we evaluated whole transcriptome gene expression in the prostate tissue from study participants who developed prostate cancer between 1992 and 2004 (n=157 tumor tissue, n=85 adjacent normal). We tested for trends in gene expression according to the level of EF as self-reported in 1992 for ages 20-29 yr, 40-49 yr, and the year prior to the questionnaire, 1991. There were no associations between EF and gene expression in areas of tumor after accounting for multiple testing. In contrast, in the adjacent normal tissue, 409 genes and six pathways were differentially expressed at a false discovery rate ≤0.2 across categories of EF in 1991. These results suggest that ejaculation affects the expression of genes in the normal prostate tissue. The identified genes and pathways provide potential biological links between EF and prostate tumorigenesis.

PATIENT SUMMARY

To explore previous findings that men who ejaculate more frequently have lower risk of prostate cancer, we evaluated molecular alterations in the prostate tissue according to each man's frequency of ejaculation prior to diagnosis. We identified biological processes that could link ejaculation frequency and prostate cancer.

A comprehensive review of the role of zinc in normal prostate function and metabolism; and its implications in prostate cancer

The human prostate gland contains extremely high zinc levels; which is due to the specialized zinc-accumulating acinar epithelial of the peripheral zone. These cells evolved for their unique capability to produce and secrete extremely levels of citrate, which is achieved by the high cellular zinc level effects on the cell metabolism. This review highlights the specific functional and metabolic alterations that result from the accumulation of the high zinc levels, especially its effects on mitochondrial citrate metabolism and terminal oxidation. The implications of zinc in the development and progression of prostate cancer are described, which is the most consistent hallmark characteristic of prostate cancer. The requirement for decreased zinc resulting from down regulation of ZIP1 to prevent zinc cytotoxicity in the malignant cells is described as an essential early event in prostate oncogenesis. This provides the basis for the concept that an agent (such as the zinc ionophore, clioquinol) that facilitates zinc uptake and accumulation in ZIP1-deficient prostate tumors cells will markedly inhibit tumor growth. In the current absence of an efficacious chemotherapy for advanced prostate cancer, and for prevention of early development of malignancy; a zinc treatment regimen is a plausible approach that should be pursued.

Effect of hyperprolactinemia on PRL-receptor expression and activation of Stat and Mapk cell signaling in the prostate of long-term sexually-active rats

The abnormal elevation of serum PRL, referred to as hyperprolactinemia (HyperPRL), produces alterations in several reproductive parameters of male rats such as penile erection or decreased tendency to reach ejaculation. Additionally, this situation produces a significant modification of prostate histology, as observed in the epithelial structure and alveolar area, which could reach a level of hyperplasia in the long-term. In this tissue, HyperPRL produces an increase in expression of PRL receptors and activation of the Stat3 signaling pathway that is correlated with the evolution of prostate pathologies. However, the impact of HyperPRL in long-term sexually active male rats is unknown. In this work, using constantly copulating Wistar male rats with induced HyperPRL, we analyzed the level of serum PRL, the effect on prostate PRL receptors, and activation of pStat3, pStat5 and Mapk signaling pathways. Two procedures to induce HyperPRL were employed, comprising daily IP administration or adenohypophysis transplant, and although neither affected the execution of sexual behavior, the serum PRL profile following successive ejaculations was affected. Messenger RNA expression of the short and long isoforms of the PRL receptor at the ventral prostate was affected in different ways depending on the procedure to induce HyperPRL. The ventral prostate did not show any modification in terms of activation of the pStat5 signaling pathway in subjects with daily administration of PRL, although this was significantly increased in ADH transplanted subjects in the second and fourth consecutive ejaculation. A similar profile was found for the pStat3 pathway which additionally showed a significant increase in the third and fourth ejaculation of daily-injected subjects. The Mapk signaling pathway did not show any modifications in subjects with daily administration of PRL, but showed a significant increase in the second and third ejaculations of subjects with ADH transplants. Thus, although sexual behavior was not modified, HyperPRL modified the expression of PRL receptors and the activation of signal pathways in the prostate tissue. Hence, it is probable that prostatic alterations precede the sexual behavioral deficits observed in subjects with HyperPRL.

Maintaining and reprogramming genomic androgen receptor activity in prostate cancer

Prostate cancer treatment is dominated by strategies to control androgen receptor (AR) activity. AR has an impact on prostate cancer development through the regulation of not only transcription networks but also genomic stability and DNA repair, as manifest in the emergence of gene fusions. Whole-genome maps of AR binding sites and transcript profiling have shown changes in the recruitment and regulatory effect of AR on transcription as prostate cancer progresses. Defining other factors that are involved in this reprogramming of AR function gives various opportunities for cancer detection and therapeutic intervention.

Heterogeneity of tumor-induced gene expression changes in the human metabolic network

Reprogramming of cellular metabolism is an emerging hallmark of neoplastic transformation. However, it is not known how metabolic gene expression in tumors differs from that in normal tissues, or whether different tumor types exhibit similar metabolic changes. Here we compare expression patterns of metabolic genes across 22 diverse types of human tumors. Overall, the metabolic gene expression program in tumors is similar to that in the corresponding normal tissues. Although expression changes of some metabolic pathways (e.g., up-regulation of nucleotide biosynthesis and glycolysis) are frequently observed across tumors, expression changes of other pathways (e.g., oxidative phosphorylation and the tricarboxylic acid (TCA) cycle) are very heterogeneous. Our analysis also suggests that the expression changes of major metabolic processes across tumors can be rationalized in terms of several principal components. On the level of individual biochemical reactions, many hundreds of metabolic isoenzymes show significant and tumor-specific expression changes. These isoenzymes are potential targets for anticancer therapy.

The Important Role of Osteoblasts and Citrate Production in Bone Formation: "Osteoblast Citration" as a New Concept for an Old Relationship

It has been known for about seventy years that bone, in all vertebrates, contains uniquely high citrate levels. However, the role of citrate, its source, its regulation, and its implication in normal bone formation and in bone disorders have remained largely unknown. For the past thirty-five years, the relationship of citrate in bone has been a neglected area of attention and research. It has recently been discovered that citrate is critical for the structure of the apatite nanocrystal, and is required to impart the important properties of bone such as its stability, strength, and resistance to fracture. This brings to focus the need for a renewed interest and research into the relationships of citrate in bone formation. A most fundamental question that must be resolved is "What is the source of citrate in bone?". This presentation provides a historical review of the early research to the present status of citrate implications in bone. This leads to a new concept of the role of osteoblasts as specialized citrate producing cells that provide the source of citrate in bone formation; i.e. the "osteoblast citration" process. This also brings into focus a new insight into the role of zinc in bone in relation to osteoblast citrate production. The genetic/hormonal/metabolic relationships of "net citrate production" are described. The intent of this presentation is to provide the background for a new perspective of the important implications of osteoblasts and citrate in bone formation; which, hopefully, will stimulate a renewed interest and essential research.

Integration of molecular genetics and proteomics with cell metabolism: how to proceed; how not to proceed!

There now exists a resurgence of interest in the role of intermediary metabolism in medicine; especially in relation to medical disorders. Coupled with this is the contemporary focus on molecular biology, genetics and proteomics and their integration into studies of regulation and alterations in cellular metabolism in health and disease. This is a marriage that has vast potential for elucidation of the factors and conditions that are involved in cellular metabolic and functional changes, which heretofore could not be addressed by the earlier generations of biochemists who established the major pathways of intermediary metabolism. The achievement of this present potential requires the appropriate application and interpretation of genetic and proteomic studies relating to cell metabolism and cell function. This requires knowledge and understanding of the principles, relationships, and methodology, such as biochemistry and enzymology, which are involved in the elucidation of cellular regulatory enzymes and metabolic pathways. Unfortunately, many and possibly most contemporary molecular biologists are not adequately trained and knowledgeable in these areas of cell metabolism. This has resulted in much too common inappropriate application and misinformation from genetic/proteomic studies of cell metabolism and function. This presentation describes important relationships of cellular intermediary metabolism, and provides examples of the appropriate and inappropriate application of genetics and proteomics. It calls for the inclusion of biochemistry, enzymology, cell metabolism and cell physiology in the graduate and postgraduate training of molecular biology and other biomedical researchers.

Prolactin inhibits activity of pyruvate kinase M2 to stimulate cell proliferation

Mitogenic and prosurvival effects underlie the tumorigenic roles of prolactin (PRL) in the pathogenesis of breast cancer. PRL signaling is mediated through its receptor (PRLr). A proteomics screen identified the pyruvate kinase M2 (PKM2), a glycolytic enzyme known to play an important role in tumorigenesis, as a protein that constitutively interacts with PRLr. Treatment of cells with PRL inhibited pyruvate kinase activity and increased the lactate content in human cells in a manner that was dependent on the abundance of PRLr, activation of Janus kinase 2, and tyrosine phosphorylation of the intracellular domain of PRLr. Knockdown of PKM2 attenuated PRL-stimulated cell proliferation. The extent of this proliferation was rescued by the knock-in of the wild-type PKM2 but not of its mutant insensitive to PRL-mediated inhibition. We discuss a hypothesis that the inhibition of PKM2 by PRL contributes to the PRL-stimulated cell proliferation.

Molecular origin of plasma membrane citrate transporter in human prostate epithelial cells

The main function of the prostate gland is to produce and release large amounts of citrate into the prostatic fluid in order to sustain sperm motility and vitality. Mycielska and colleagues have now cloned the citrate transporter responsible for citrate release from prostatic cells. Interestingly, they find that it is an isoform of the transporter that is expressed in the mitochondrial membrane.

The prostate is a highly specialized mammalian organ that produces and releases large amounts of citrate. However, the citrate release mechanism is not known. Here, we present the results of molecular cloning of a citrate transporter from human normal prostate epithelial PNT2-C2 cells shown previously to express such a mechanism. By using rapid amplification of cDNA ends PCR, we determined that the prostatic carrier is an isoform of the mitochondrial transporter SLC25A1 with a different first exon. We confirmed the functionality of the clone by expressing it in human embryonic kidney cells and performing radiotracer experiments and whole-cell patch-clamp recordings. By using short interfering RNAs targeting different parts of the sequence, we confirmed that the cloned protein is the main prostatic transporter responsible for citrate release. We also produced a specific antibody and localized the cloned transporter protein to the plasma membrane of the cells. By using the same antibody, we have shown that the cloned transporter is expressed in non-malignant human tissues.

Dexras1 interacts with FE65 to regulate FE65-amyloid precursor protein-dependent transcription

FE65 is an adaptor protein that binds to and forms a transcriptionally active complex with the gamma-secretase-derived amyloid precursor protein (APP) intracellular domain. The regulatory mechanisms of FE65-APP-mediated transcription are still not clear. In this report, we demonstrate that Dexras1, a Ras family small G protein, binds to FE65 PTB2 domain and potently suppresses the FE65-APP-mediated transcription. The suppression is not via competition for binding of FE65 between Dexras1 and APP because the two proteins can simultaneously bind to the FE65 PTB2 domain. Phosphorylation of FE65 tyrosine 547 within the PTB2 domain has been shown to enhance FE65-APP-mediated transcription but not to influence binding to APP. Here we find that this phosphorylation event reduces the binding between Dexras1 and FE65. We also demonstrate that Dexras1 inhibits the FE65-APP-mediated transcription of glycogen synthase kinase 3beta (GSK3 beta). Moreover, small interfering RNA knockdown of Dexras1 enhances GSK3 beta expression and increases phosphorylation of Tau, a GSK3 beta substrate. Thus, Dexras1 functions as a suppressor of FE65-APP-mediated transcription, and FE65 tyrosine 547 phosphorylation enhances FE65-APP-mediated transcription, at least in part, by modulating the interaction between FE65 and Dexras1. These findings reveal a novel regulatory mechanism for FE65-APP-mediated signaling.

Hyperprolactinemia and immunohistochemical expression of intracellular prolactin and prolactin receptor in primary central nervous system tumors and their relationship with cellular replication

The role of prolactin (PRL) in the CNS remains uncertain. We evaluated the presence of hyperprolactinemia, intracellular prolactin (ICP), and prolactin receptor (PRL-R) in primary CNS tumors, and their relationship with cellular replication with a prospective cross-sectional study of 82 consecutive patients with primary CNS tumors admitted for neurosurgical resection between October 2003 and September 2005. Patients submitted to a questionnaire, and venous blood samples were obtained for measurement of serum PRL and TSH. Immunohistochemical analyses were performed to evaluate the presence of ICP, PRL-R, and Ki-67. Serum PRL levels ranged from 2 to 70 ng/ml, and hyperprolactinemia was detected in 25 cases (30.5%). ICP was detected in 18 patients (21.9%), in whom PRL ranged from 2 to 32 ng/ml. A positive correlation was found between PRL levels and the presence of ICP (Student's t test, P = 0.022). The PRL-R was observed immunohistochemically in 32 cases (39%). The frequencies of hyperprolactinemia, ICP, and PRL-R were similar across the several histological types of CNS tumors. Ki-67 index was similar in all groups. Hyperprolactinemia and intracellular presence of PRL and PRL-R were common findings in this population, suggesting a role for PRL in CNS tumor genesis.

The Prostate has Secretory Dysfunction for Category IIIA and IIIB Prostatitis

PURPOSE

We investigated whether the prostate has secretory dysfunction for category IIIA and IIIB prostatitis.

MATERIALS AND METHODS

Normal human prostatic secretions are remarkably rich in citrate, which is considered the most useful marker for determining prostate secretory function. It is certain that the prostate has secretory dysfunction for category I and II prostatitis, while it is not clear for category IIIA and IIIB prostatitis. To clarify this question expressed prostatic secretion citrate and pH were determined in 21, 25 and 25 outpatients with category II, IIIA and IIIB prostatitis, respectively, and in 21 normal controls without any prostatic disease. Outpatients with category II disease served as positive controls, while normal controls served as negative controls. No outpatients with category IIIA and IIIB prostatitis underwent treatment.

RESULTS

Mean +/- SD expressed prostatic secretion citrate was 3.32 +/- 0.79, 3.41 +/- 0.88, 4.37 +/- 0.77 and 8.55 +/- 1.20 mg/ml in groups II, IIIA, IIIB and normal controls, respectively. Compared to normal controls expressed prostatic secretion citrate was significantly decreased in category II, IIIA and IIIB cases. Furthermore, there was no overlap of expressed prostatic secretion citrate values between category IIIA and IIIB cases, and the normal control group.

CONCLUSIONS

The prostate has secretory dysfunction for category IIIA and IIIB prostatitis, which suggests that the prostate may be involved in category IIIA and IIIB prostatitis.

Metabolic regulation of citrate and iron by aconitases: role of iron–sulfur cluster biogenesis

Iron and citrate are essential for the metabolism of most organisms, and regulation of iron and citrate biology at both the cellular and systemic levels is critical for normal physiology and survival. Mitochondrial and cytosolic aconitases catalyze the interconversion of citrate and isocitrate, and aconitase activities are affected by iron levels, oxidative stress and by the status of the Fe-S cluster biogenesis apparatus. Assembly and disassembly of Fe-S clusters is a key process not only in regulating the enzymatic activity of mitochondrial aconitase in the citric acid cycle, but also in controlling the iron sensing and RNA binding activities of cytosolic aconitase (also known as iron regulatory protein IRP1). This review discusses the central role of aconitases in intermediary metabolism and explores how iron homeostasis and Fe-S cluster biogenesis regulate the Fe-S cluster switch and modulate intracellular citrate flux.

The prolactin-deficient mouse has an unaltered metabolic phenotype

Prolactin (PRL), best recognized for its lactogenic activity, is also involved in the regulation of metabolic homeostasis in both mammalian and nonmammalian species. Although several mouse models have been used to study the metabolic functions of PRL, a clear-cut consensus has not emerged given the limited and often conflicting data. To clarify the role of PRL in metabolic homeostasis in males and nonlactating females, we used the PRL-deficient mouse. Our objectives were to compare: 1) weight gain, 2) body composition, 3) serum lipid profile, 4) circulating leptin and adiponectin levels, and 5) glucose tolerance in PRL knockout, heterozygous, and wild-type mice maintained on standard chow, high-fat, or low-fat diets. In addition, we compared the lipolytic actions of PRL using adipose tissue explants from mice, rats, and humans. We are reporting that PRL deficiency does not affect the rate of weight gain, body composition, serum lipids, or adiponectin levels in either sex on any diet. Glucose tolerance was slightly impaired in very young PRL knockout male pups but not in adults or in females at any age. Leptin was elevated in male, but not female, PRL knockout mice maintained on a low-fat diet. PRL did not affect lipolysis in adipose tissue explants from mice but significantly inhibited glycerol release from both rat and human adipose explants in a dose-dependent manner. We conclude that PRL deficiency has negligible gross metabolic effects in mice.

Distribution of the glutamate transporters GLT-1 (SLC1A2) and GLAST (SLC1A3) in peripheral organs

The glutamate transporters GLT-1 and GLAST are widely expressed in astrocytes in the brain where they fulfill important functions during glutamatergic neurotransmission. The present study examines their distribution in peripheral organs using in situ hybridization (ISH) and immunocytochemistry. GLAST was found to be more widely distributed than GLT-1. GLAST was expressed primarily in epithelial cells, cells of the macrophage-lineage, lymphocytes, fat cells, interstitial cells, and salivary gland acini. GLT-1 was primarily expressed in glandular tissue, including mammary gland, lacrimal gland, and ducts and acini in salivary glands, but also by perivenous hepatocytes and follicular dendritic cells in spleen and lymph nodes. The findings demonstrate that, although expressed by the same cells in the brain, these two glutamate transporters have different distribution patterns in peripheral tissues and that they fulfill glutamate transport functions apart from glutamatergic neurotransmission in these areas.

Prostate response to prolactin in sexually active male rats

BACKGROUND

The prostate is a key gland in the sexual physiology of male mammals. Its sensitivity to steroid hormones is widely known, but its response to prolactin is still poorly known. Previous studies have shown a correlation between sexual behaviour, prolactin release and prostate physiology. Thus, here we used the sexual behaviour of male rats as a model for studying this correlation. Hence, we developed experimental paradigms to determine the influence of prolactin on sexual behaviour and prostate organization of male rats.

METHODS

In addition to sexual behaviour recordings, we developed the ELISA procedure to quantify the serum level of prolactin, and the hematoxilin-eosin technique for analysis of the histological organization of the prostate. Also, different experimental manipulations were carried out; they included pituitary grafts, and haloperidol and ovine prolactin treatments. Data were analyzed with a One way ANOVA followed by post hoc Dunnet test if required.

RESULTS

Data showed that male prolactin has a basal level with two peaks at the light-dark-light transitions. Consecutive ejaculations increased serum prolactin after the first ejaculation, which reached the highest level after the second, and started to decrease after the third ejaculation. These normal levels of prolactin did not induce any change at the prostate tissue. However, treatments for constant elevations of serum prolactin decreased sexual potency and increased the weight of the gland, the alveoli area and the epithelial cell height. Treatments for transient elevation of serum prolactin did not affect the sexual behaviour of males, but triggered these significant effects mainly at the ventral prostate.

CONCLUSION

The prostate is a sexual gland that responds to prolactin. Mating-induced prolactin release is required during sexual encounters to activate the epithelial cells in the gland. Here we saw a precise mechanism controlling the release of prolactin during ejaculations that avoid the detrimental effects produced by constant levels. However, we showed that minor elevations of prolactin which do not affect the sexual behaviour of males, produced significant changes at the prostate epithelium that could account for triggering the development of hyperplasia or cancer. Thus, it is suggested that minute elevations of serum prolactin in healthy subjects are at the etiology of prostate abnormal growth.

Mitochondrial aconitase and citrate metabolism in malignant and nonmalignant human prostate tissues

Background

In prostate cancer, normal citrate-producing glandular secretory epithelial cells undergo a metabolic transformation to malignant citrate-oxidizing cells. m-Aconitase is the critical step involved in this altered citrate metabolism that is essential to prostate malignancy. The limiting m-aconitase activity in prostate epithelial cells could be the result of a decreased level of m-aconitase enzyme and/or the inhibition of existing m-aconitase. Earlier studies identified zinc as an inhibitor of m-aconitase activity in prostate cells; and that the depletion of zinc in malignant cells is an important factor in this metabolic transformation. However, a possibility remains that an altered expression and level of m-aconitase enzyme might also be involved in this metabolic transformation. To address this issue, the in situ level of m-aconitase enzyme was determined by immunohistochemical analysis of prostate cancer tissue sections and malignant prostate cell lines.

Results

The immunocytochemical procedure successfully identified the presence of m-aconitase localized in the mitochondrial compartment in PC-3, LNCaP, and DU-145 malignant prostate cell lines. The examination of prostate tissue sections from prostate cancer subjects demonstrated that m-aconitase enzyme is present in the glandular epithelium of normal glands, hyperplastic glands, adenocrcinomatous glands, and prostatic intraepithelial neoplastic foci. Quantitative analysis of the relative level of m-aconitase in the glandular epithelium of citrate-producing adenomatous glands versus the citrate-oxidizing adenocarcinomatous glands revealed no significant difference in m-aconitase enzyme levels. This is in contrast to the down-regulation of ZIP1 zinc transporter in the malignant glands versus hyperplastic glands that exists in the same tissue samples.

Conclusion

The results demonstrate the existence of m-aconitase enzyme in the citrate-producing glandular epithelial cells; so that deficient m-aconitase enzyme is not associated with the limiting m-aconitase activity that prevents citrate oxidation in these cells. The level of m-aconitase is maintained in the malignant cells; so that an altered enzyme level is not associated with the increased m-aconitase activity. Consequently, the elevated zinc level that inhibits m-aconitase enzyme is responsible for the impaired citrate oxidation in normal and hyperplastic prostate glandular epithelial cells. Moreover, the down-regulation of ZIP1 zinc transporter and corresponding depletion of zinc results in the increase in the activity of the existing m-aconitase activity in the malignant prostate cells. The studies now define the mechanism for the metabolic transformation that characterizes the essential transition of normal citrate-producing epithelial cells to malignant citrate-oxidizing cells.

Focus on prolactin as a metabolic hormone

New information about the effects of prolactin (PRL) on metabolic processes warrants re-evaluation of the overall metabolic actions of PRL. PRL affects metabolic homeostasis by regulating key enzymes and transporters that are associated with glucose and lipid metabolism in several target organs. In the lactating mammary gland, PRL increases the production of milk proteins, lactose and lipids. In adipose tissue, PRL generally suppresses lipid storage and adipokine release. PRL supports the growth of pancreatic islets, stimulates insulin secretion and increases citrate production in the prostate. A specific case is made for PRL in the human breast and adipose tissue, where it acts as a circulating hormone and an autocrine or paracrine factor. Although the overall effects of PRL on body composition are modest and species specific, PRL might be involved in the manifestation of insulin resistance.

Benign prostatic hyperplasia: an insight into current investigational medical therapies

Benign prostatic hyperplasia (BPH) is a leading disorder of the elderly male population that is characterised by a progressive enlargement of prostatic tissue, resulting in obstruction of the proximal urethra and causing urinary flow disturbances. The pathophysiology of BPH associated with lower urinary tract symptoms is characterised by increased adrenergic tone (dynamic component) leading to smooth muscle contraction and prostatic overgrowth due to androgenic stimulation (static component); therefore, the therapeutic armamentarium of BPH can be broadly divided into antiadrenergic and antiandrogenic approaches. alpha1-Adrenoceptor antagonists and 5alpha-reductase inhibitors are well-established representatives of the two categories, respectively. Other antiandrogenic approaches involve gonadotropin-releasing hormone agonists and antagonists for the treatment of prostate hyperplasia. Apart from these approaches, new approaches with novel targets are emerging. The advent of new therapies is, however, more oriented towards the static component. These involve metabolic factors (hexokinase inhibitor), growth factors (vitamin D3 analogues), oxytocin antagonists and gonadotropin-releasing hormone Gi agonist-based therapies. Gene therapy and photodynamic therapies are other emerging therapies for relieving symptoms in BPH patients. With the initial success of upcoming targets, the unmet need to develop an efficacious and relatively safe therapeutic modality is discussed. Nevertheless, their long-term safety and efficacy needs to be evaluated in large-scale clinical trials. The future also belongs to combination therapies to combat both dynamic and static disease components and for extended indications such as micturition disorder and non-bacterial prostatitis.

EAAC1 is expressed in rat and human prostate epithelial cells; functions as a high-affinity L-aspartate transporter; and is regulated by prolactin and testosterone

Background

Prostate epithelial cells accumulate a high level of aspartate that is utilized as a substrate for their unique function of production and secretion of enormously high levels of citrate. In most mammalian cells aspartate is synthesized; and, therefore is a non-essential amino acid. In contrast, in citrate-producing prostate cells, aspartate is an essential amino acid that must be derived from circulation. The prostate intracellular/extracellular conditions present a 40:1 concentration gradient. Therefore, these cells must possess a plasma membrane-associated aspartate uptake transport process to achieve their functional activity. In earlier kinetic studies we identified the existence of a unique Na+-dependent high-affinity L-aspartate transport process in rat prostate secretory epithelial cells. The present report is concerned with the identification of this putative L-aspartate transporter in rat and human prostate cells.

Results

The studies show for the first time that EAAC1 is expressed in normal rat prostate epithelial cells, in normal and hyperplastic human prostate glands, and in human malignant prostate cell lines. EAAC1 expression and high-affinity L-aspartate transport are correspondingly down-regulated by EAAC1 siRNA knock down. Exposure of prostate cells to physiological levels of prolactin or testosterone results in an up-regulation of EAAC1 expression and a corresponding increase in the high-affinity transport of L-aspartate into the cells.

Conclusion

This study shows that EAAC1 functions as the high-affinity L-aspartate transporter that is responsible for the uptake and accumulation of aspartate in prostate cells. In other cells (predominantly excitable tissue cells), EAAC1 has been reported to function as a glutamate transporter rather than as an aspartate transporter. The regulation of EAAC1 expression and L-aspartate transport by testosterone and prolactin is consistent with their regulation of citrate production in prostate cells. The identification of EAAC1 as the high-affinity L-aspartate transporter now permits studies to elucidate the mechanism of hormonal regulation of EAAC1 gene expression, and to investigate the mechanism by which the cellular environment effects the functioning of EAAC1 as an aspartate transporter or as a glutamate transporter.

Zinc and prostate cancer: a critical scientific, medical, and public interest issue (United States)

The role of zinc in the development and progression of prostate malignancy and its potential application in the prevention and treatment of prostate cancer (PCa) are contemporary critical issues for the medical/scientific community and the public-at-large. The overwhelming clinical and experimental evidence provides a compelling rational basis for the expectation and concept that prostate zinc accumulation is an important factor in the development and progression of prostate malignancy; and that zinc could be efficacious in the prevention and treatment of PCa. In contrast, various epidemiologic studies have produced divergent and conflicting results regarding the efficacy of dietary and supplemental zinc against PCa. Before reaching any definitive conclusions regarding this complex issue, one should have a complete understanding of the clinical and experimental evidence associated with the involvement of zinc in the normal and malignant prostate. Also, an understanding of interacting effects of confounding factors on the absorption, assimilation, and bioavailability of supplemental dietary zinc is important. The purpose of this review is to present the current state of the clinical and experimental information regarding zinc relationships in the normal prostate and in the pathogenesis PCa. The evidence in support of a potential beneficial effect of zinc supplement versus potential harmful effects on PCa is assessed. A discussion of the divergent results of the epidemiologic studies is presented along with a description of important factors and conditions that impact or mask the effects of dietary zinc on PCa development and progression. We also hope to bring more attention to the medical and research community of the critical need for concerted clinical and basic research regarding zinc and PCa, for the development of appropriate human prostate models to investigate these relationships, for further appropriately designed epidemiologic studies, and for future well-controlled clinical trials.

Mitochondrial function, zinc, and intermediary metabolism relationships in normal prostate and prostate cancer

Human prostate secretory epithelial cells have the uniquely specialized function of accumulating and secreting extremely high levels of citrate. This is achieved by their ability to accumulate high cellular levels of zinc that inhibit citrate oxidation. This process of net citrate production requires unique metabolic/bioenergetic mitochondrial relationships. In prostate cancer, the malignant cells undergo a metabolic transformation from zinc-accumulating citrate-producing sane cells to citrate-oxidizing malignant cells that lost the ability to accumulate zinc. This review describes the metabolic/bioenergetic, zinc and mitochondrial relationships involved in normal and malignant prostate. Hopefully, this report will generate much needed interest and research in this neglected, but critically important, area of investigation.

In vivo magnetic resonance spectroscopy in cancer

Magnetic resonance spectroscopy (MRS) has been used for more than two decades to interrogate metabolite distributions in living cells and tissues. Techniques have been developed that allow multiple spectra to be obtained simultaneously with individual volume elements as small as 1 uL of tissue (i.e., 1 x 1 x 1 mm(3)). The most common modern applications of in vivo MRS use endogenous signals from (1)H, (31)P, or (23)Na. Important contributions have also been made using exogenous compounds containing (19)F, (13)C, or (17)O. MRS has been used to investigate cardiac and skeletal muscle energetics, neurobiology, and cancer. This review focuses on the latter applications, with specific reference to the measurement of tissue choline, which has proven to be a tumor biomarker that is significantly affected by anticancer therapies.

Zinc and zinc transporters in normal prostate and the pathogenesis of prostate cancer

Zinc is an essential metal for all cells. It plays a role in a wide variety of physiological and biochemical processes. In the prostate epithelial cell the accumulation of high cellular zinc is a specialized function that is necessary for these cells to carry out the major physiological functions of production and secretion of citrate. The production of citrate and its secretion into prostatic fluid is a differentiated function of the prostate epithelial cells that is apparently important for reproduction. The loss of citrate and zinc accumulation is the most consistent and persistent characteristic of prostate malignancy. This characteristic of prostate cancer indicates that the lost ability of the malignant cells to accumulate zinc and citrate is an important factor in the development and progression of malignancy. The lost ability of the epithelial cells to accumulate zinc and thus to also accumulate citrate is the result of decreased expression of specific zinc uptake transporters. The purpose of this presentation is to review the current understanding of zinc and zinc homeostasis in the prostate and the role of zinc and zinc transporters in the normal function of the prostate and the pathogenesis of prostate cancer.

Aging-associated changes in gene expression in the ACI rat prostate: Implications for carcinogenesis

BACKGROUND

Prostate cancer is the most frequently diagnosed neoplasm and the second leading cause of cancer-related mortality in men. Although the incidence of prostate cancer increases with age, the link between aging and prostate cancer is poorly understood.

METHODS

Affymetrix oligonucleotide microarrays were used to analyze the mRNA expression levels in the dorsolateral prostates from 6- and 18-month-old ACI rats. Real-time RT-PCR and immunohistochemistry was performed to validate microarray data in a select set of genes.

RESULTS

Microarray analysis revealed changes in gene expression associated with inflammation, oxidative stress, tissue remodeling, and energy metabolism. Most of these changes have been related to increased proliferative status of the prostate, anti-apoptosis, activated stroma, and alteration of the energy metabolism.

CONCLUSIONS

Age-associated alterations in the gene expression profile may put the aging prostate in risk for the initiation, promotion, and progression of neoplastic transformation in both our animal model and humans.

Proteasome-mediated degradation of RNase L in response to phorbol-12-myristate-13-acetate (PMA) treatment of mouse L929 cells

2'-5' Oligoadenylate (2-5A)-dependent RNase L is one of the key enzymes involved in the molecular mechanisms of interferon (IFN) function. Although the regulation of RNase L by 2-5A has been studied extensively, relatively little is known about how RNase L is controlled by posttranslational processes. Here, we report that phorbol-12-myristate-13-acetate (PMA) treatment of mouse L929 fibroblasts caused rapid degradation of RNase L in a dose-dependent and time-dependent manner. RNase L levels were decreased to 40% of control levels after only 5 min exposure of cells to PMA, suggesting the involvement of protein kinase C (PKC). After PMA treatment for 1 h, RNase L levels decreased to 18% of the pretreatment levels. Decay of RNase L was measured by 2-5A binding assay, ribonuclease activity, and protein levels in Western blots probed with antibody to murine RNase L. PMA treatment caused decreases in the levels of RNase L in both cytoplasm and nucleus. To explore the mechanism of RNase L degradation, we treated cells with the selective proteasome inhibitors, ALLN, MG132, and PSI, prior to PMA treatment. These inhibitors completely blocked the degradation of RNase L caused by PMA. Our results show a novel regulatory pathway for RNase L that could have an impact on its antitumor and antiviral functions.

The T Cell Receptor γ Chain Alternate Reading Frame Protein (TARP), a Prostate-specific Protein Localized in Mitochondria

We previously showed that mRNA encoding TARP (T cell receptor gamma chain alternate reading frame protein) is exclusively expressed in the prostate in males and is up-regulated by androgen in LNCaP cells, an androgen-sensitive prostate cancer cell line. We have now developed an anti-TARP monoclonal antibody named TP1, and show that TARP protein is up-regulated by androgen in both LNCaP and MDA-PCa-2b cells. We used TP1 to determine the subcellular localization of TARP by Western blotting following subcellular fractionation and immunocytochemistry. Both methods showed that TARP is localized in the mitochondria of LNCaP cells, MDA-PCa-2b cells, and PC-3 cells transfected with a TARP-expressing plasmid. We also transfected a plasmid encoding TARP fused to green fluorescent protein into LNCaP, MDA-Pca-2b, and PC-3 cells and confirmed its specific mitochondrial localization in living cells. Fractionation of mitochondria shows that TARP is located in the outer mitochondrial membrane. Immunohistochemistry using a human prostate cancer sample showed that TP1 reacted in a dot-like cytoplasmic pattern consistent with the presence of TARP in mitochondria. These data demonstrate that TARP is the first prostate-specific protein localizing in mitochondria and indicate that TARP, an androgen-regulated protein, may act on mitochondria to carry out its biological functions.

Proton high-resolution magic angle spinning NMR analysis of fresh and previously frozen tissue of human prostate

The previously observed improvement in spectral resolution of tissue proton NMR with high-resolution magic angle spinning (HRMAS) was speculated to be due largely to freeze-thawing artifacts resulting from tissue storage. In this study, 12 human prostate samples were analyzed on a 14.1T spectrometer at 3 degrees C, with HRMAS rates of 600 and 700 Hz. These samples were measured fresh and after they were frozen for 12-16 hr prior to thawing. The spectral linewidths measured from fresh and previously frozen samples were identical for all metabolites except citrate and acetate. The metabolite intensities of fresh and freeze-thawed samples depend on the quantification procedures used; however, in this experiment the differences of means were <30%. As expected, it was found that tissue storage impacts tissue quality for pathological analysis, and HRMAS conditions alone are not sufficiently destructive to impair pathological evaluation. Furthermore, although storage conditions affect absolute metabolite concentrations in NMR analysis, relative metabolite concentrations are less affected.

Identification of genetic pathways activated by the androgen receptor during the induction of proliferation in the ventral prostate gland

The androgen receptor (AR), when complexed with 5alpha-dihydrotestosterone (DHT), supports the survival and proliferation of prostate cells, a process critical for normal development, benign prostatic hypertrophy, and tumorigenesis. However, the androgen-responsive genetic pathways that control prostate cell division and differentiation are largely unknown. To identify such pathways, we examined gene expression in the ventral prostate 6 and 24 h after DHT administration to androgen-depleted rats. 234 transcripts were expressed significantly differently from controls (p < 0.05) at both time points and were subjected to extensive data mining. Functional clustering of the data reveals that the majority of these genes can be classified as participating in induction of secretory activity, metabolic activation, and intracellular signaling/signal transduction, indicating that AR rapidly modulates the expression of genes involved in proliferation and differentiation in the prostate. Notably AR represses the expression of several key cell cycle inhibitors, while modulating members of the wnt and notch signaling pathways, multiple growth factors, and peptide hormone signaling systems, and genes involved in MAP kinase and calcium signaling. Analysis of these data also suggested that p53 activity is negatively regulated by AR activation even though p53 RNA was unchanged. Experiments in LNCaP prostate cancer cells reveal that AR inhibits p53 protein accumulation in the nucleus, providing a post-transcriptional mechanism by which androgens control prostate cell growth and survival. In summary these data provide a comprehensive view of the earliest events in AR-mediated prostate cell proliferation in vivo, and suggest that nuclear exclusion of p53 is a critical step in prostate growth.