Prostate Secretory Epithelial Cells Research Articles

Morphometrical and Histological Analyses of the Epithelial Lining of Male Reproductive System in Wistar Rats Following Administration of Neem Leaves Extract

Background: Neem leaves (Azadirachta indica L.) have been used for many therapeutic purposes and medicinal applications. The extract of this plant has been used in both male and female genders as a traditional agent to prevent early pregnancy. In this study, the effect of this extract was investigated histologically and morphometrically on the germinal epithelia of the seminiferous tubules, epididymis and secretory epithelia of rats’ prostate glands. Methods: Twenty male albino rats were divided into four groups of five each and administered the extract at a concentration of zero, 100, 200 or 400 mg/kg of the body weight for 50 consecutive days. These rats were sacrificed and the male reproductive organs were removed, weighed and processed for routine histological examinations. The micrographs were analyzed and the structural changes in the epithelial lining and morphometric analyses were recorded, which included measuring the epithelial thickness in the seminiferous tubules, epididymis and secretory prostatic epithelia. Results: The extract was found to reduce the rats’ weight; decreased both the weight and dimension of the testes; reduced the number of germinal epithelial lining cells in the seminiferous tubules of the testes, the epididymal and prostatic secretory epithelial cells. Conclusion: The histological alterations were most significant in response to the treatment with the extract at 200 mg/kg of the rats with the greatest damages observed in the epithelial lining. The deleterious effects of the extract were found to be dose-dependent and this corroborates the use of this extract as a contraceptive in animal models, and potentially in humans.

Covid-19 pathogenesis in prostatic cancer and TMPRSS2-ERG regulatory genetic pathway.

Members of Coronaviridae family have been the source of respiratory illnesses. The outbreak of SARS-CoV-2 that produced a severe lung disease in afflicted patients in China and other countries was the reason for the incredible attention paid toward this viral infection. It is known that SARS-CoV-2 is dependent on TMPRSS2 activity for entrance and subsequent infection of the host cells and TMPRSS2 is a host cell molecule that is important for the spread of viruses such as coronaviruses.Different factors can increase the risk of prostate cancer, including older age, a family history of the disease. Androgen receptor (AR) initiates a transcriptional cascade which plays a serious role in both normal and malignant prostate tissues. TMPRSS2 protein is highly expressed in prostate secretory epithelial cells, and its expression is dependent on androgen signals. One of the molecular signs of prostate cancer is TMPRSS2-ERG gene fusion. In TMPRSS2-ERG-positive prostate cancers different patterns of changed gene expression can be detected. The possible molecular relation between fusion positive prostate cancer patients and the increased risk of lethal respiratory viral infections especially SARS-CoV-2 can candidate TMPRSS2 as an attractive drug target. The studies show that some molecules such as nicotinamide, PARP1, ETS and IL-1R can be studied deeper in order to control SARS-CoV-2 infection especially in prostate cancer patients.This review attempts to investigate the possible relation between the gene expression pattern that is produced through TMPRSS2-ERG fusion positive prostate cancer and the possible influence of these fluctuations on the pathogenesis and development of viral infections such as SARS-CoV-2.

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

BackgroundProstate 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.ResultsThe 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.ConclusionThis 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.

Evidence for specific TRPM8 expression in human prostate secretory epithelial cells: functional androgen receptor requirement

TRPM8 (melastatine-related transient receptor potential member 8), a member of the transient receptor potential (TRP) superfamily of cation channels, has been shown to be a calcium-channel protein. TRPM8 mRNA has also been shown to be overexpressed in prostate cancer and is considered to play an important role in prostate physiology. This study was designed to determine the androgen-regulation mechanisms for TRPM8 mRNA expression and to identify the phenotype of TRPM8-expressing cells in the human prostate. Our findings show that trpm8 gene expression requires a functional androgen receptor. Furthermore, this article argues strongly in favour of the fact that the trpm8 gene is a primary androgen-responsive gene. Single-cell reverse transcriptase PCR and immunohistochemical experiments also showed that the trpm8 gene was mainly expressed in the apical secretory epithelial cells of the human prostate and trpm8 down-regulation occurred during the loss of the apical differentiated phenotype of the primary cultured human prostate epithelial cells. The androgen-regulated trpm8 expression mechanisms are important in understanding the progression of prostate cancer to androgen-independence. These findings may contribute to design a strategy to predict prostate cancer status from the TRPM8 mRNA level. Furthermore, as the TRPM8 channel is localized in human prostate cells, it will be interesting to understand its physiological function in the normal prostate and its potential role in prostate cancer development.

Ca2+-activated Cl- channel currents in rat ventral prostate epithelial cells.

In many epithelial tissues, the Cl(-) efflux via Ca(2+)-activated Cl(-) channels (Cl(Ca)) play a key role for the fluid secretion. To elucidate the mechanism of prostatic fluid secretion, the properties of whole-cell chloride conductance were investigated. Rat prostate secretory epithelial cells (RPSECs) were isolated by collagenase treatment, and were used for the whole-cell voltage clamp. Both extra- and intracellular monovalent cations were replaced by N-methyl-D-glucamate to record the Cl(-) current selectively. A bath application of Ca(2+)-ionophore, ionomycin (0.2 micro M), increased the membrane conductance with outwardly rectifying voltage-dependence. On step-like depolarization from -60 to +80 mV (500 msec), the ionomycin-induced current showed slowly activating kinetics, a known property of Cl(Ca) current (I(Cl(Ca))) of other tissues. The relative permeability of Cl(Ca) to various anions was calculated from the reversal potentials measured under a total replacement of extracellular Cl(-) with various anions, and the relative order of permeability was SCN(-)>I(-)>Br(-)>Cl(-)>>gluconate. The amplitude of I(Cl(Ca)) was decreased by various anion channel blockers: niflumic acid (100 micro M), DPC (100 micro M), DIDS (1 mM), and NPPB (200 micro M). RPSECs have Cl(Ca) that may provide Cl(-) efflux pathways for the exocrine secretions of the prostate.

ErbB-2 signaling is involved in regulating PSA secretion in androgen-independent human prostate cancer LNCaP C-81 cells.

The expression and secretion of prostate-specific antigen (PSA) are regulated by androgens in normal prostate secretory epithelial cells. In prostate cancer patients, the serum PSA level is usually elevated and cancer cells are initially responsive to androgens. However, those cancer cells become androgen-independent after androgen ablation therapy. In hormone-refractory cancer patients, even in an androgen-deprived environment, the circulation level of PSA rebounds and is constitutively elevated through a yet unknown mechanism. Tyrosine phosphorylation of ErbB-2 is involved in regulating the androgen-responsive phenotype of prostate cancer cells, and it is at least partly regulated by the cellular form of prostatic acid phosphatase (PAcP), a prostate-unique protein tyrosine phosphatase. We investigated the ErbB-2 signal pathway in androgen-independent PSA secretion. LNCaP C-81 cells, which are androgen-independent LNCaP cells lacking endogenous PAcP expression with a hypertyrosine phosphorylated ErbB-2, secreted a higher level of PSA in conditioned media than did androgen-sensitive LNCaP C-33 parental cells. A restored expression of cellular PAcP in C-81 cells was concurrent with a decrease in tyrophosphorylation of ErbB-2 and reduction of PSA secretion. Moreover, transient transfection of C-33 cells with the wild-type ErbB-2 or a constitutively active mutant of MEK1 cDNA resulted in an increased level of secreted PSA. The elevation of secreted PSA level by the forced expression of ErbB-2 was inhibited by an MEK inhibitor, PD98059. In C-81 cells, the expression of a dominant negative mutant of ErbB-2 reduced the secreted level of PSA. The inhibition of ErbB-2 or mitogen-activated protein (MAP) kinases by specific inhibitors AG879, AG825, or PD98059 led to a decrease in PSA secretion. Taken together, our data clearly indicate that the ErbB-2 signal pathway via MAP kinases (ERK1/2) is involved in regulating the secretion of PSA by androgen-independent human prostate cancer LNCaP C-81 cells in an androgen-depleted environment.

K+ channel currents in rat ventral prostate epithelial cells.

Electrophysiological function of the normal prostate has not been extensively studied. In particular, ion channel currents and their regulation have not been studied in freshly-isolated prostate cells. Rat prostate secretory epithelial (RPSE) cells were isolated by collagenase treatment. Columnar epithelial cells were used for nystatin-perforated, whole-cell voltage clamp, and the intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured using fura-2. Step-like depolarizing pulses (900 msec) starting from - 90 mV induced outwardly rectifying K(+) currents without inactivation. ACh (10 microM) or ATP (100 microM) increased the outward current and hyperpolarized the cell membrane potential. Ionomycin (0.1 microM), a Ca(2+) ionophore, induced a similar increase in the outward current. TEA (5 mM), charybdotoxin (50 nM), and iberiotoxin (30 nM) inhibited the effect of ACh (or ATP) on the outward current, whereas apamin (100 nM) had no effect. The [Ca(2+)](i) of RPSE cells was increased by ACh, ATP, and UTP. RPSE cells have iberiotoxin-sensitive Ca(2+)-activated K(+) channels that may play an important role in the exocrine secretions of the prostate.

Caspase 3 expression in benign prostatic hyperplasia and prostate carcinoma.

Apoptotic resistance to androgen ablation represents a significant problem in the treatment of prostate cancer. Over expression of antiapoptotic proteins such as Bcl-2 and mutations in p53 contribute to this resistance. The caspase family of proteases are central executioners of the cell death pathway. They are expressed in normal prostate secretory epithelial cells. Altered expression may represent an additional component leading to cell resistance. The aim of this study was to determine by immunohistochemistry caspase 3 expression in benign prostatic hyperplasia and prostate cancers. Twenty-two patients with histologically determined prostate cancer and benign prostatic hyperplasia (BPH) were investigated. All specimens were obtained from patients undergoing surgical resection of the prostate. Immunohistochemical analysis was performed on formalin fixed paraffin embedded sections to assess caspase 3 expression. Caspase 3 was expressed in 18/22 (81.1%) samples, with high expression in BPH which demonstrated staining in both basal and secretory epithelial cells. Increasing grades of prostatic cancer showed a significant loss of expression in secretory epithelial layers and little staining in epithelial cells in high-grade prostatic carcinoma. Altered caspase 3 expression may represent an additional mechanism of apoptotic resistance to androgen ablation. Prostate 47:183-188, 2001.

Mitochondrial aconitase gene expression is regulated by testosterone and prolactin in prostate epithelial cells .

m-aconitase catalyzes the first step leading to the oxidation of citrate via the Krebs cycle. It is a constituitive enzyme in virtually all mammalian cells, found in excess, and is considered to be a regulatory or regulated enzyme. In contrast to these general relationships, prostate secretory epithelial cells possess a uniquely limiting mitochondrial (m-) aconitase which minimizes the oxidation of citrate. This permits the unique prostate function of accumulating and secreting extraordinarily high levels of citrate. Previous animal studies demonstrated that testosterone and prolactin regulate the level of m-aconitase specifically in citrate-producing prostate cells. The present studies were conducted to determine if testosterone and prolactin regulated the expression of the m-aconitase gene in prostate cells, and to determine the effect of the hormones on human prostate cells. The studies were conducted with freshly prepared rat ventral, rat lateral, and pig prostate epithelial cells, and with the human malignant cell lines LNCaP and PC-3. The effects of 1 nM testosterone and 3 nM prolactin on the level of m-aconitase mRNA and on the transcription rate of m-aconitase were determined. The studies revealed that both prolactin and testosterone increase the levels of m-aconitase mRNA and the transcription rates of m-aconitase in rat ventral prostate cells, pig prostate cells, and human malignant prostate cells (LNCaP and PC-3). In contrast, both hormones decreased the level of m-aconitase mRNA and repressed m-aconitase gene transcription in rat lateral prostate cells. The hormonal regulation of m-aconitase corresponded with the levels of m-aconitase enzyme, m-aconitase activity, and citrate oxidation. In addition to the constitutive expression of m-aconitase, the m-aconitase gene is testosterone- and prolactin-regulated in specifically targeted prostate cells. The hormonal regulation of m-aconitase gene expression and biosynthesis of m-aconitase provide a regulatory mechanism for the oxidation of citrate, and consequently, the level of net citrate production by prostate. The hormonally increased expression and biosynthesis of m-aconitase in human malignant cells might be involved in the increased citrate oxidation associated with the development of true malignant cells in prostate cancer.

Zinc causes a shift toward citrate at equilibrium of the m-aconitase reaction of prostate mitochondria

Prostate secretory epithelial cells have the unique function and capability of accumulating and secreting extraordinarily high levels of citrate. To achieve this, these cells possess a uniquely limiting mitochondrial (m)-aconitase activity that minimizes the oxidation of citrate via the Krebs cycle. The steady-state citrate/isocitrate ratio of mammalian tissues is generally maintained at about 10–11/1, independent of the concentration of citrate, which is the result of the chemical equilibrium reached in the presence of m-aconitase. In contrast, the citrate/isocitrate ratio of prostate tissue is about 30–40/1. Zinc, which is also accumulated in prostate cells at much higher levels than in other cells, inhibits m-aconitase activity thereby minimizing citrate oxidation. This current report is concerned with an effect of zinc on the equilibrium of the reaction catalyzed by m-aconitase. Studies were conducted with mitochondrial extract preparations from rat ventral prostate epithelial cells. With citrate as the initial substrate, the addition of zinc (7–10 μM) to the prostate mitochondrial preparation resulted in a change in the citrate/isocitrate ratio at equilibrium from an average of 10.5/1 to 13.5/1. In contrast, the identical treatment of kidney mitochondrial preparations resulted in no zinc-induced change in the citrate/isocitrate ratio. When either cis-aconitate or isocitrate was employed as the initial substrate, the addition of zinc did not alter the citrate/isocitrate ratio of prostate or kidney preparations. Partial purification of the prostate preparation revealed that the prostate mitochondrial extract contained a putative protein (which we have designated as ‘citrate factor protein’) that is required for the zinc-induced increase in the citrate/isocitrate ratio. This novel effect of zinc provides another mechanism by which it is assured that the accumulation of citrate is maximized in citrate-producing prostate epithelial cells.

The Pyruvate Dehydrogenase E1 Alpha Gene Is Testosterone And Prolactin Regulated In Prostate Epithelial Cells

The prostate gland of humans and other animals has the unique function of accumulating and secreting extraordinarily high levels of citrate. The prostate secretory epithelial cells synthesize citrate which, due to a limiting mitochondrial (m-) aconitase, accumulates rather than being oxidized. Thus citrate is essentially an end product of metabolism in prostate. For continued net citrate production, a continual source of oxaloacetate (OAA) and acetyl CoA is required. Glucose via pyruvate oxidation provides the source of Acetyl CoA. In prostate cells, citrate production is regulated by testosterone and/or by prolactin. Both hormones selectively regulate the level and activity of pyruvate dehydrogenase E1 alpha (E1 a) in animal prostate cells; thereby regulating the availability of acetyl CoA for citrate synthesis. Studies were conducted to determine if testosterone and prolactin might regulate the expression of the E1a gene in prostate epithelial cells. Prolactin treatment of rat ventral and lateral prostate cells and human PC3 cells increased the levels of E1a mRNA and the rates of transcription of the E1a gene. Testosterone also increased the mRNA level and transcription of E1a in rat ventral prostate cells, and in PC3 cells transfected with androgen receptor. However, testosterone treatment resulted in a repression of E1a gene expression in lateral prostate cells. Evidence is presented which supports the view that prolactin regulation of E1a is mediated via PKC. The rapidity of the effects of both hormones is representative of an immediate-early gene response. To our knowledge this represents the first report in any mammalian cells that, in addition to its constitutive expression in all mammalian cells, the E1a gene is a hormonally-regulated gene in specifically targeted prostate epithelial cells.

Mitogenic activation of human prostate-derived fibromuscular stromal cells by bradykinin.

Biologically active kinin peptides are released from precursor kininogens by kallikreins. Kinins act on kinin receptors to mediate diverse biological functions including smooth muscle contraction, inflammation, pain and mitogenicity. All components of the kallikrein-kinin system exist in human male genital secretions suggesting that these molecules participate in physiological and pathophysiological genitourinary function. The objective of this study was to assess the consequences of kinin action on prostate cells. Primary cultures of prostate secretory epithelial (PE) and prostate fibromuscular stromal (PS) cells were established from human prostate tissue. Transcripts encoding both the human B1 and B2 bradykinin receptor subtypes were detected in human prostate transition-zone tissue and in cultured cells by RT-PCR. In receptor binding assays, the B1 subtype predominated on PE cell membranes and the B2 subtype predominated on PS cell membranes. In PS cells, but not in PE cells, BK induced significant inositol phosphate accumulation and [3H]-thymidine uptake. These responses were mediated through the B2 receptor subtype. The use of signal transduction inhibitors indicated that mitogenic activation by BK occurred through both protein kinase C (PKC) and protein tyrosine kinase dependent mechanisms. PMA (phorbol 12-myristate 13-acetate) produced maximal [3H]-thymidine uptake by PS cells, resulted in cell elongation and caused the alpha-actin fibres present in PS smooth muscle cells to became organized into parallel arrays along the length of the elongated cells. In summary, the prostate contains a functional kallikrein-kinin system, which could be significant in physiological and pathophysiological prostate function.

Endothelin-1 production and agonist activities in cultured prostate-derived cells: implications for regulation of endothelin bioactivity and bioavailability in prostatic hyperplasia.

Endothelin-1 (ET-1) interacts with specific G-protein-coupled receptors to initiate short-term (contraction) and long-term (mitogenesis) events in target cells. ET-1 is an abundant prostate secretory protein that, in its biologically active form, elicits prostatic smooth muscle contraction. The present study was designed to determine the effects of ET-1 on prostate cell growth and to examine the regulation of endogenous ET-1 activity and bioavailability. Primary cultures of prostate secretory epithelial (PE) and prostate fibromuscular stromal (PS) cells were established from benign human prostate tissue. In culture, PE cells secrete immunoreactive ET-1 (38.5 +/- 1.6 pg/ml/10(6) cells/24 hr) into the conditioned medium. Levels of immunoreactive ET-1 produced by PS cells were more than 10-fold lower. Endothelin-converting enzyme-1 (ECE-1) mRNA was detected in PE cells and not in PS cells; however, big ET-1 was the predominant immunoreactive ET-1 secretory product of PE cells. The ET(B) endothelin receptor was the predominant subtype in both PE and PS cells. In PS cells, but not PE cells, ET-1 induced significant inositol phosphate accumulation and [3H]-thymidine uptake. Agonist activity was inhibited by the ET(B) receptor selective antagonist, BQ 788. Intact PE cell monolayers secrete ET-1 through the apical surface, consistent with secretion of ET-1 into the glandular lumen in vivo. On the basis of these findings, regulation of ET-1 activity and bioavailability appears to be tightly regulated. Such findings have important implications in the pathophysiology of prostate disease.

Testosterone and prolactin stimulation ofmitochondrial aconitase in pig prostate epithelial cells

Objectives. The function of the prostate gland in many animals, including humans, is to accumulate andsecrete large quantities of citrate. This function derives from the metabolic characteristics of the prostate secretory epithelial cells. These cells possess a uniquely limiting mitochondrial aconitase (m-aconitase) that minimizes citrate oxidation and thus permits citrate to accumulate. Unfortunately, the characteristics of prostate m-aconitase and its manner of regulation have not been established. The hormones testosterone and prolactin, however, are significantly involved in regulating prostate citrate production. Thus it is reasonable to hypothesize that these hormones may be involved in the regulation of both m-aconitase and citrate oxidation. Methods. Using freshly prepared pig prostate epithelial cells, we attempted to determine the effects oftestosterone and prolactin treatment on the level of m-aconitase enzyme, on the level of m-aconitase activity, and on citrate utilization. The epithelial cells were incubated for 3 hours with either testosterone (10 −9 M), prolactin (1 μg/mL), or vehicle (control). Results. Both hormone applications caused a marked increase in the level of m-aconitase. In contrast, neitherhormone had any effect on the m-aconitase level of pig seminal vesicle cells, which are also citrate-producing cells. Moreover, neither hormone had any effect on pyruvate dehydrogenase E1a. These findings suggest that testosterone and prolactin regulation of prostate m-aconitase is a highly specific effect. Along with the increase in the level of m-aconitase enzyme, both hormones also increased m-aconitase activity and prostate-cell utilization of citrate. Conclusions. These studies demonstrate that testosterone and prolactin can regulate m-aconitase and subsequent citrate oxidation of specific prostate epithelial cells. This unique aconitase relationship is not observed in other mammalian cells.

Prolactin specifically regulates citrate oxidation and m-aconitase of rat prostate epithelial cells

The prostate gland of many animals, including humans, produces and secretes extremely high levels of citrate. To achieve this function, prostate secretory epithelial cells possess unique metabolic properties that permit accumulation and ultimate secretion (net citrate production) of citrate. Mounting evidence continues to support the concept that prostate epithelial cells possess a limiting mitochondrial (m)-aconitase activity that minimizes citrate oxidation and results in the accumulation of citrate synthesized by the cells. Recent studies have revealed that prolactin (PRL) stimulates net citrate production of rat lateral prostate (RLP). The mechanism of this PRL effect has not been established. The current studies were concerned with the possibility that PRL might be involved in the regulation of citrate oxidation and m-aconitase of prostate cells. Studies were conducted with RLP, RVP (rat ventral prostate), RDP (rat dorsal prostate), and kidney cells. The results showed that PRL in vitro and in vivo decreased citrate utilization and the level of m-aconitase in RLP cells, and conversely increased citrate utilization and m-aconitase in RVP cells. Furthermore, PRL had no effect on either RDP or kidney cells. The effects of PRL on both citrate utilization and m-aconitase of RLP and RVP were abolished by cycloheximide and actinomycin. Mitochondrial studies revealed that PRL decreased citrate oxidation of RLP and increased citrate oxidation of RVP, but had no effect on isocitrate oxidation. In conclusion, these studies establish that PRL has a physiological role in the regulation of citrate oxidation in prostate, and that this action is associated with PRL regulation of the biosynthesis of m-aconitase. Furthermore, the effects of PRL are cell-specific and targeted at m-aconitase.

Tumor suppression and apoptosis of human prostate carcinoma mediated by a genetic locus within human chromosome 10pter-q11.

Prostate cancer is the second leading cause of male cancer deaths in the United States. Yet, despite a large international effort, little is known about the molecular mechanisms that underlie this devastating disease. Prostate secretory epithelial cells and androgen-dependent prostate carcinomas undergo apoptosis in response to androgen deprivation and, furthermore, most prostate carcinomas become androgen independent and refractory to further therapeutic manipulations during disease progression. Definition of the genetic events that trigger apoptosis in the prostate could provide important insights into critical pathways in normal development as well as elucidate the perturbations of those key pathways in neoplastic transformation. We report the functional definition of a novel genetic locus within human chromosome 10pter-q11 that mediates both in vivo tumor suppression and in vitro apoptosis of prostatic adenocarcinoma cells. A defined fragment of human chromosome 10 was transferred via microcell fusion into a prostate adenocarcinoma cell line. Microcell hybrids containing only the region 10pter-q11 were suppressed for tumorigenicity following injection of microcell hybrids into nude mice. Furthermore, the complemented hybrids undergo programmed cell death in vitro via a mechanism that does not require nuclear localization of p53. These data functionally define a novel genetic locus, designated PAC1, for prostate adenocarcinoma 1, involved in tumor suppression of human prostate carcinoma and furthermore strongly suggest that the cell death pathway can be functionally restored in prostatic adenocarcinoma.

Androgen receptor immunostaining and its tissue distribution in formalin-fixed, paraffin-embedded sections after microwave treatment.

We used microwave (MW) oven heat treatment to unmask human androgen receptor (AR) immunostaining in formalin-fixed, paraffin-embedded tissue. Prostate tissue was used as an AR-positive control. Tissue sections were boiled in citrate buffer in a conventional MW oven for 30 min, followed by immunostaining with a validated murine monoclonal antibody (MAb), F39.4.1, raised against a peptide included in the N-terminal domain of the 100 KD human AR. AR immunostaining was localized to the nuclei of prostate secretory epithelial cells but was weak or absent in basal cells and of variable intensity in the stromal cells. Slides exposed to less than 10 min of MW heat treatment or none at all manifested no AR immunoreactivity. Tissue morphology was well preserved. Immunohistochemical determination of AR status in a wide variety of human tissues was consistent with that previously reported by others using frozen sections. MW heat treatment of tissue samples in an excellent method of localizing AR antigenicity, enabling immunohistochemical evaluation of AR status in formalin-fixed, paraffin-embedded material.

Testosterone Regulates Pyruvate Dehydrogenase Activity of Prostate Mitochondria

A major and unique function of the prostate is the production of extremely high levels of citrate. Testosterone is an important regulator of this function. This regulation is achieved by hormonal stimulation of citrate synthesis by prostate secretory epithelial cells. Previous studies have established that testosterone stimulates the mitochondrial transamination of aspartate to OAA for citrate synthesis. However, increased citrate synthesis would also require an increased availability of AcCoA which is derived from pyruvate. The present studies were concerned with the in vivo effect of testosterone on pyruvate dehydrogenase (PDH) activity of prostate mitochondria isolated from rat ventral prostate (VP). The results demonstrated that testosterone administration to castrated rats stimulates PDH activity and citrate production from pyruvate in the presence of OAA. Therefore testosterone increases both OAA and acetyl CoA production which results in increased citrate synthesis. The mechanism of testosterone regulation of PDH can now be investigated.

High‐affinity L‐aspartate transporter in prostate epithelial cells that is regulated by testosterone

The prostate gland produces and secretes extraordinarily high levels of citrate. Studies with rat ventral prostate (VP) have demonstrated that aspartate can serve as a four-carbon source of oxalacetate in the synthesis of citrate. To achieve this, prostate secretory epithelial cells must contain a transport system for the active uptake of aspartate from circulation. The present studies with VP epithelial cells confirm the existence of a Na(+)-dependent high-affinity L-aspartate transporter. The transporter has an optimal pH approximately 7.5 and is temperature dependent. It appears to be an anionic amino acid transporter capable of transporting L-glutamate but not basic or neutral amino acids. The transporter is inhibited by ATPase inhibitors, thereby indicating its dependency on a Na+ gradient. The characteristics of the high-affinity L-aspartate transporter are consistent with its operation at the basilar membrane for the transport of circulating aspartate into the cell. Castration (24 hr) resulted in a significant decrease in the ability of VP epithelial cells to transport L-aspartate. The administration of testosterone to castrated rats completely restored L-aspartate transport. In addition, in vitro testosterone addition (10(-8) M for 30 min) to isolated prostate epithelial cells markedly increased L-aspartate transport. Both cycloheximide and actinomycin inhibited the testosterone effect. The studies reveal that testosterone is a regulator of this Na(+)-dependent high-affinity L-aspartate transporter. The mechanism of this testosterone effect appears to involve both RNA and protein synthesis. We now have a model system to elucidate this novel effect of testosterone.

Concepts of citrate production and secretion by prostate: 2. Hormonal relationships in normal and neoplastic prostate

A unique and major function of prostate secretory epithelial cells is to synthesize, accumulate, and secrete extraordinarily high levels of citrate. This function is regulated by testosterone and by prolactin. Concepts of the mechanisms of hormonal regulation are presented. The relationship of testosterone and prolactin to the origin and homologies of different prostate cell lines is described. The metabolic differentiation of citrate and non-citrate producing prostate secretory epithelial cells is discussed. Concepts of the pathogenesis of prostatic neoplasms are presented based on hormonal, metabolic, and homologous relationships associated with citrate production. Characterization of normal and neoplastic secretory epithelial cells by their citrate function is emphasized. The urgency and necessity for research relating to all aspects of prostate citrate production in normal and pathological prostate are emphasized.