Search PubMed⌕ Search

Biomedical subjects

G Verhoeven

Publications and source records attributed to G Verhoeven.

At least 37 records · Page 2Linked to original sources
PubMed2000

Nandrolone decanoate does not enhance training effects but increases IGF-I mRNA in rat diaphragm.

To examine whether concomitant anabolic steroid treatment combined with training might enhance previously observed training effects (A. Bisschop, G. Gayan-Ramirez, H. Rollier, R. Gosselink, R. Dom, V. de Bock, and M. Decramer. Am. J. Respir. Crit. Care Med. 155: 1583-1589, 1997) and whether insulin-like growth factor I (IGF-I) was involved in these changes, male and female rats were submitted to inspiratory muscle training (IMT) for 8 wk (30 min/day, 5 times/wk) and were compared with untrained controls. During the last 5 wk of training, trained rats were divided to receive weekly either low-dose (LD; 1.5 mg/kg) or high-dose (HD; 7.5 mg/kg) nandrolone decanoate or saline for the IMT and control rats. In both sexes, diaphragm muscle mass and contractile properties were unchanged with treatment. In males, HD resulted in decreased diaphragm type I cross-sectional area (-15%; P < 0.05, HD vs. IMT), whereas no changes were observed in females. Finally, an increase in IGF-I mRNA levels was present in HD male (+73%; P < 0.05, HD vs. IMT) and female treated rats [LD (+58%) and HD (+96%) vs. IMT; P < 0.001]. We conclude that administration of nandrolone decanoate did not enhance the previously observed training effects in rat diaphragm, although it increased the IGF-I mRNA expression levels.

Anabolic Agents↗
PubMed2000

Peritubular cell-Sertoli cell interactions: factors involved in PmodS activity.

The widespread occurrence of peritubular myoid cells in mammalian and other species suggests that they form an integral and functional component of the testis. Peritubular cells contribute to the contractile activity of testicular tubules and maintain mesenchymal-epithelial interactions with Sertoli cells both by cooperation in the deposition of extracellular matrix elements and by secretion of paracrine agonists. One of the most intriguing of these paracrine agonists is known as PModS (Peritubular factor that Modulates Sertoli cell function). The demonstration that, at least under some conditions, PModS production may be stimulated by androgens has led to the hypothesis that PModS may mediate part or all of the effects of androgens on Sertoli cells. The identity of PModS, however, remains elusive. Here we summarize data showing: (1) that production of PModS (-like factors) may not be limited to peritubular cells; (2) that the role of androgens in the control of PModS production remains controversial; (3) that other known mediators including IGF-I, bFGF, cytokines and heregulins mimic some or all of the effects of PModS; (4) that combinations of such growth factors have potent effects. It is concluded that, until PModS has been identified unambiguously, the hypothesis that it acts as an essential andromedin in the testis should be regarded with caution.

Androgens↗
PubMed1999

Androgens down-regulate the expression of the human homologue of paternally expressed gene-3 in the prostatic adenocarcinoma cell line LNCaP.

mRNA differential display polymerase chain reaction analysis was used to screen systematically for novel androgen-regulated genes in the human prostatic adenocarcinoma cell line LNCaP. A 232 bp PCR fragment was found to be consistently down-regulated by the synthetic androgen R1881. Sequencing revealed complete identity with the human homologue of mouse Paternally expressed gene 3 (Peg3), an imprinted gene that plays an important role as a downstream mediator of the effects of tumor necrosis factor (TNF). The down-regulation of Peg3 mRNA by androgens was confirmed by Northern blot hybridization. The effect proved time and dose dependent with maximal repression (3.5-fold) after 24 h of treatment with 10(-8) M R1881. The steroid specificity of Peg3 mRNA regulation reflected the aberrant ligand specificity of the mutated androgen receptor in LNCaP cells, supporting the involvement of the androgen receptor in the repression process. Basal expression of Peg3 mRNA was almost completely abolished by the protein synthesis inhibitor cycloheximide. Experiments with Actinomycin D suggested that androgens act at a transcriptional level rather than by changing the stability of Peg3 mRNA. Comparison of the expression of Peg3 mRNA in 50 different human tissues revealed ubiquitous expression, but low levels in the prostate. The highest levels were observed in endocrine tissues such as ovary, placenta, adrenal and pituitary. High levels were also noted in various parts of the brain. No detectable levels of Peg3 mRNA were observed in two other androgen receptor-positive prostate tumor cell lines (MDA PCa-2a and -2b), and in the poorly differentiated and androgen receptor-negative prostate tumor lines PC-3 and DU-145. It is concluded that both androgens and loss of differentiation may affect the expression of Peg3, a mediator of the effects of TNF. Further experiments will be required to explore whether these changes affect the responsiveness of prostate tumor cells to TNF.

Adenocarcinoma↗
PubMed1999

Androgens decrease and retinoids increase the expression of insulin-like growth factor-binding protein-3 in LNcaP prostatic adenocarcinoma cells.

Changes in circulating levels of insulin-like growth factors (IGF) and IGF-binding proteins (IGFBP) have been related to prostate cancer, but the nature and the significance of this relationship remains elusive. Recent reports suggest that modulation of the production of IGFBP-3 by retinoids may affect growth of breast and prostate tumor cells. In the present study we explored whether androgens (R1881), retinoids (all-trans- and 9-cis-retinoic acid: atRA and 9cRA), deltanoids (1alpha,25-dihydroxycholecalciferol: VD3) and thyroid hormone (triiodothyronine: T3) influence the production of IGFBPs by LNCaP prostatic adenocarcinoma cells and whether the observed changes affect tumor cell growth. Northern blot experiments demonstrated that LNCaP cells express IGFBP-2, -3, -4 and (to a small extent) -5. IGFBP-4 and -5 were not measurably affected by the mentioned agonists. At a growth promoting concentration (10(-10) M), R1881 increased IGFBP-2 transcript levels two- to three-fold and this effect was neutralized by atRA and VD3. Similar effects could not be demonstrated, however, at the protein level using Western ligand blotting. R1881 decreased and atRA increased the mRNA levels of IGFBP-3 and these effects were confirmed by Western ligand blotting and by radioimmunoassay. The effects of atRA were mimicked by 9cRA and by a specific RAR agonist but not by a RXR agonist. VD3 and T3 had no significant effect on IGFBP-3 secretion but respectively enhanced or decreased the effect of 9cRA. The effects of retinoids required high concentrations (10(-6)-10(-5) M) that also induced growth inhibition. R1881, however, decreased IGFBP-3 at growth promoting (10(-10) M) as well as at growth inhibitory (10(-8) M) concentrations. Moreover, under serum-free conditions, we were unable to demonstrate any growth modulating effect of IGFBP-3. It is concluded that several agonists acting by nuclear receptors affect IGFBP-3 secretion by LNCaP cells but that the functional significance of these changes warrants further investigation.

Adenocarcinoma↗
PubMed1999

Differential DNA binding by the androgen and glucocorticoid receptors involves the second Zn-finger and a C-terminal extension of the DNA-binding domains.

The androgen and glucocorticoid hormones evoke specific in vivo responses by activating different sets of responsive genes. Although the consensus sequences of the glucocorticoid and androgen response elements are very similar, this in vivo specificity can in some cases be explained by differences in DNA recognition between both receptors. This has clearly been demonstrated for the androgen response element PB-ARE-2 described in the promoter of the rat probasin gene. Swapping of different fragments between the androgen- and glucocorticoid-receptor DNA-binding domains demonstrates that (i) the first Zn-finger module is not involved in this sequence selectivity and (ii) that residues in the second Zn-finger as well as a C-terminal extension of the DNA-binding domain from the androgen receptor are required. For specific and high-affinity binding to response elements, the DNA-binding domains of the androgen and glucocorticoid receptors need a different C-terminal extension. The glucocorticoid receptor requires 12 C-terminal amino acids for high affinity DNA binding, while the androgen receptor only involves four residues. However, for specific recognition of the PB-ARE-2, the androgen receptor also requires 12 C-terminal residues. Our data demonstrate that the mechanism by which the androgen receptor binds selectively to the PB-ARE-2 is different from that used by the glucocorticoid receptor to bind a consensus response element. We would like to suggest that the androgen receptor recognizes response elements as a direct repeat rather than the classical inverted repeat.

Amino Acid Sequence↗
PubMed1999

The differentiation-related gene 1, Drg1, is markedly upregulated by androgens in LNCaP prostatic adenocarcinoma cells.

A differential display technique was used to identify androgen-regulated genes in LNCaP prostatic adenocarcinoma cells. One of the genes markedly upregulated by androgens proved to be identical to differentiation-related gene 1 (Drg1; also described as RTP, Cap43 and rit42), a gene whose expression has recently been shown to be diminished in colon, breast and prostate tumors. We show that Drg1 is abundantly expressed in the (androgen-exposed) human prostate and that its expression is stimulated some 14-fold in androgen-treated LNCaP cells. The ligand specificity of the induction reflects the altered specificity of the mutated androgen receptor in LNCaP. In androgen receptor negative tumor lines basal expression is slightly higher than in LNCaP but inducibility is absent. These data suggest that Drg1 is a novel marker of androgen-induced differentiation in the human prostate.

Adenocarcinoma↗
PubMed1999

Indirect mechanisms and cascades of androgen action.

Androgens are the main hormones responsible for the induction of the male phenotype. This process involves a complex combination of reversible and irreversible effects. As for other steroid hormones, many of the effects of androgens are mediated by a specific intracellular receptor that interacts with cis-acting regulatory regions (AREs) in the affected genes. Apart from these direct effects, however, androgens may indirectly affect the expression of a variety of genes that do not necessarily contain AREs. Indirect effects may be related to androgen-induced changes in the concentration or activity of secondary transcription factors, autocrine and paracrine mediators, and circulating hormones. Such indirect effects may induce cascade-like actions and may play an important role in more complex effects of androgens involving coordinated responses of genes, cells and organs.

Androgens↗
PubMed1999

74As-arsenate metabolism in Flemish Giant rabbits with renal insufficiency.

The metabolic management of carrier-free 74As-arsenate (As(V)) by uremic rabbits of the strain Flemish Giant was studied. Renal insufficiency was induced by nephrectomy of respectively 1 kidney (3/6 nephrectomy) and 1 kidney + 2/3 remaining kidney (5/6 nephrectomy). Marginal renal insufficiency developed in the 3/6 nephrectomized group, while animals of the 5/6 group became severely uremic. Renal excretion of 74As was reduced by 90% in 5/6 nephrectomized animals 4 h after intraperitoneal injection (i.p.) of the animals. The associated uremic syndrome caused a strong decrease in methylation capacity of inorganic arsenic (Asi). The second methylation step from monomethylarsonic acid (MMA) to dimethylarsinic acid (DMA) was more strongly affected than the first one, from arsenite (As(III)) to MMA. The increased availability of Asi led to more extensive binding to insoluble tissue constituents after 5/6 nephrectomy. The decreased renal reduction of As(V) led to a decrease in As(III) and an increase of As(V) and the associated As(V)-transferrin binding in plasma. Uptake of 74As-transferrin by the bone marrow might contribute to uremic anemia.

Adipose Tissue↗
PubMed1999

The androgen receptor amino-terminal domain plays a key role in p160 coactivator-stimulated gene transcription.

Steroid receptors are conditional transcription factors that, upon binding to their response elements, regulate the expression of target genes via direct protein interactions with transcriptional coactivators. We have analyzed the functional interactions between the androgen receptor (AR) and 160-kDa nuclear receptor coactivators. Upon overexpression in mammalian cells, these coactivators enhance the transcriptional activity of both the amino-terminal domain (NTD) and the ligand-binding domain (LBD) of the AR. The coactivator activity for the LBD is strictly ligand-controlled and depends on the nature of the DNA-binding domain to which it is fused. We demonstrate that the NTD physically interacts with coactivators and with the LBD and that this interaction, like the functional interaction between the LBD and p160 coactivators, relies on the activation function 2 (AF2) core domain. The mutation of a highly conserved lysine residue in the predicted helix 3 of the LBD (K720A), however, blunts the functional interaction with coactivators but not with the NTD. Moreover, this mutation does not affect the transcriptional activity of the full-size AR. A mutation in the NTD of activation function AF1a (I182A/L183A), which dramatically impairs the activity of the AR, has no effect on the intrinsic transcriptional activity of the NTD but interferes with the cooperation between the NTD and the LBD. Finally, p160 proteins in which the three LXXLL motifs are mutated retain most of their coactivator activity for the full-size AR, although they are no longer functional for the isolated LBD. Together, these data suggest that in the native AR the efficient recruitment of coactivators requires a functional association of the NTD with the LBD and that the binding of coactivators occurs primarily through the NTD.

Amino Acid Sequence↗
PubMed1999

Acute treatment with corticosteroids decreases IGF-1 and IGF-2 expression in the rat diaphragm and gastrocnemius.

Massive doses of methylprednisolone (M) or triamcinolone (T) induced diaphragmatic type IIx/b atrophy, resulting in a leftward shift of the force-frequency curve in rats (). To examine the role of insulin-like growth factors (IGFs) in these changes, IGF mRNA content was measured in costal diaphragm, gastrocnemius, and liver removed from 32 rats treated daily during 5 d either with saline (control, C and pair-fed, PF), M, or T (80 mg/kg). Blood samples were taken to measure IGF-1 serum levels. RNA levels were measured by Northern and dot-blots after hybridization with rat IGF-1 or IGF-2 cDNA probes labeled with alpha-32P. Compared with C (845 +/- 128 ng/ml), IGF-1 serum levels were significantly decreased in M (699 +/- 90 ng/ml, p < 0.001 versus C) and PF animals (505 +/- 33 ng/ml, p < 0.001 versus others) and even more so, in T-treated animals (273 +/- 134 ng/ml, p < 0.001 versus others). Along the same lines, IGF-1 expression in the liver was depressed after corticosteroid treatment and in PF, whereas IGF-2 mRNA content remained unchanged. Compared with C, the relative expression of IGF-1 mRNA in the diaphragm was depressed by 44% and 69% in the M and T groups, respectively (p < 0.0001 versus C), while it was unchanged in PF animals. In the gastrocnemius, IGF-1 expression was reduced after M and T (-51% and -59%, respectively, p < 0.0001 versus C) as well as in PF animals (-40%, p < 0.001 versus C). For IGF-2, a similar pattern of expression was found in the diaphragm and the gastrocnemius. Indeed, IGF-2 mRNA tended to decrease in corticosteroid-treated rats (NS) whereas it was unchanged in PF rats. We conclude that decreased IGF expression after corticosteroid treatment was similar in diaphragm and gastrocnemius and may be responsible for the diaphragmatic changes observed after steroid treatment.

Animals↗
PubMed1999

Heregulins or neu differentiation factors and the interactions between peritubular myoid cells and Sertoli cells.

Interactions between (mesenchymal) peritubular myoid cells and (epithelial) Sertoli cells play an important role in the control of Sertoli cell function and spermatogenesis. The factors involved, however, have only partially been identified. Heregulins or neu differentiation factors (NDFs) mediate mesenchymal-epithelial interactions in a variety of tissues, but their role in the testis has not been investigated. Here we demonstrate that recombinant human heregulin-alpha (Her-alpha) and Her-beta stimulate transferrin and androgen-binding protein production by cultured rat Sertoli cells up to 2.5-fold. These effects are more pronounced than those of previously identified growth factors active in this assay, such as insulin-like growth factor I and basic fibroblast growth factor. Combination with these factors results in additive effects and in marked morphological changes in the Sertoli cell cultures, including formation of tubule-like structures. Stimulation of androgen-binding protein secretion is paralleled by increased levels of the corresponding messenger RNA. This parallelism was less consistent for transferrin. Semiquantitative RT-PCR indicates that the expression of NDF-alpha and NDF-beta is more pronounced in peritubular cells than in Leydig or Sertoli cells. Conversely, the main receptors for heregulins/NDFs, HER-3 and HER-4, are predominantly expressed in Sertoli cells. A displacement assay confirms the presence of high-affinity binding sites for [125I]Her-beta on intact Sertoli cells and reveals parallel displacement curves for Her-beta, Her-alpha, and concentrated peritubular cell-conditioned medium (PTCM; estimated ED50 values: 1 ng/ml, 50 ng/ml, and 130 microg protein/ml, respectively), indicating that peritubular cells secrete one or more factors able to compete for heregulin receptors. It is concluded that heregulins/NDFs may play a role in mesenchymal-epithelial interactions in the testis. Estimates of the concentrations of heregulins in PTCM, however, make it unlikely that they contribute significantly to the effects observed with low concentrations of PTCM and ascribed to the putative mediator PModS (peritubular factor that modulates Sertoli cell function). Further investigations will be required to define the exact role of heregulins in the testis.

Androgen-Binding Protein↗
PubMed1999

Interaction of the putative androgen receptor-specific coactivator ARA70/ELE1alpha with multiple steroid receptors and identification of an internally deleted ELE1beta isoform.

Steroid-regulated gene transcription requires the coordinate physical and functional interaction of hormone receptors, basal transcription factors, and transcriptional coactivators. In this context ARA70, previously called RFG and ELE1, has been described as a putative coactivator that specifically enhances the activity of the androgen receptor (AR) but not that of the glucocorticoid receptor (GR), the progesterone receptor, or the estrogen receptor (ER). Here we describe the cloning of the cDNA for ELE1/ARA70 by RT-PCR from RNA derived from different cell lines (HeLa, DU-145, and LNCaP). In accordance with the previously described sequence, we obtained a 1845-bp PCR product for the HeLa and the LNCaP RNA. Starting from T-47D RNA, however, an 860-bp PCR product was obtained. This shorter variant results from an internal 985-bp deletion and is called ELE1beta; accordingly, the longer isoform is referred to as ELE1alpha. The deduced amino acid sequence of ELE1alpha, but not that of ELE1beta, differs at specific positions from the one previously published by others, suggesting that these two proteins are encoded by different nonallelic genes. ELE1alpha is expressed in the three prostate-derived cell lines examined (PC-3, DU-145, and LNCaP), and this expression is not altered by androgen treatment. Of all rat tissues examined, ELE1alpha expression is highest in the testis. This is also the only tissue in which we could demonstrate ELE1beta expression. Both ELE1alpha and ELE1beta interact in vitro with the AR, but also with the GR and the ER, in a ligand-independent way. Overexpression of either ELE1 isoform in DU-145, HeLa, or COS cells had only minor effects on the transcriptional activity of the human AR. ELE1alpha has no intrinsic transcription activation domain or histone acetyltransferase activity, but it does interact with another histone acetyltransferase, p/CAF, and the basal transcription factor TFIIB. The interaction with the AR occurs through the ligand-binding domain and involves the region corresponding to the predicted helix 3. Mutation in this domain of leucine 712 to arginine greatly reduces the affinity of the AR for ELE1alpha but has only moderate effects on its transcriptional activity. Taken together, we have identified two isoforms of the putative coactivator ARA70/ELE1 that may act as a bridging factor between steroid receptors and components of the transcription initiation complex but which lack some fundamental properties of a classic nuclear receptor coactivator. Further experiments will be required to highlight the in vivo role of ELE1 in nuclear receptor functioning.

Acetyltransferases↗
PubMed1999

Spermatogenesis and spermatogenic control: a state of the art.

In this short overview we summarize recent progress made in some areas of fundamental research related to spermatogenesis and its control. After a brief reminder of the main characteristics of the spermatogenic process we focus on the determinants of sperm output. Particular attention is paid to factors controlling the number of Sertoli cells, to the role of germ cell apoptosis, and to factors rendering human spermatogenesis relatively inefficient. Thereafter, we summarize recent insights on the relative role of testosterone and FSH in the endocrine control of human spermatogenesis. The potential contribution of testosterone metabolites such as 5alpha-dihydrotestosterone and 17beta-estradiol is discussed in the light of novel experimental paradigms. The contribution of cell-cell interactions to spermatogenic control is illustrated on the hand of the kit-ligand-c-kit-receptor system and the scientific and potential therapeutic potential of germ cell transplantation techniques underlined. Finally we focus on clinical and fundamental approaches which contribute to our understanding of specific genes involved in spermatogenesis. It is concluded that research in the field of spermatogenesis is rapidly expanding and that several recent findings will lead to diagnostic and therapeutic applications in the near future.

Animals↗
PubMed1998

Identification of diazepam-binding Inhibitor/Acyl-CoA-binding protein as a sterol regulatory element-binding protein-responsive gene.

Diazepam-binding inhibitor/acyl-CoA-binding protein (DBI/ACBP), a highly conserved 10-kDa polypeptide, has been implicated in various physiological processes including gamma-aminobutyric acid type A receptor binding, acyl-CoA binding and transport, steroidogenesis, and peptide hormone release. Both in LNCaP prostate cancer cells and 3T3-L1 preadipocytes, the expression of DBI/ACBP is stimulated under conditions that promote lipogenesis (treatment with androgens and insulin, respectively) and that involve the activation of sterol regulatory element-binding proteins (SREBPs). Accordingly, we investigated whether DBI/ACBP expression is under the direct control of SREBPs. Analysis of the human and rat DBI/ACBP promoter revealed the presence of a conserved sterol regulatory element (SRE)-like sequence. Gel shift analysis confirmed that this sequence is able to bind SREBPs. In support of the functionality of SREBP binding, coexpression of SREBP-1a with a DBI/ACBP promoter-reporter gene resulted in a 50-fold increase in transcriptional activity in LNCaP cells. Disruption of the SRE decreased basal expression and abolished SREBP-1a-induced transcriptional activation. In agreement with the requirement of a co-regulator for SREBP function, transcriptional activation by SREBP-1a overexpression was severely diminished when a neighboring NF-Y site was mutated. Cholesterol depletion or androgen treatment, conditions that activate SREBP function in LNCaP cells, led to an increase in DBI/ACBP mRNA expression and SRE-dependent transcriptional activation. These findings indicate that the promoter for DBI/ACBP contains a functional SRE that allows DBI/ACBP to be coregulated with other genes involved in lipid metabolism.

Animals↗
PubMed1998

Identification of the phosphatidic acid phosphatase type 2a isozyme as an androgen-regulated gene in the human prostatic adenocarcinoma cell line LNCaP.

Differential display was used to identify novel androgen-regulated genes in the human prostatic adenocarcinoma cell line LNCaP. A 322-base pair cDNA fragment that was consistently induced by the synthetic androgen R1881 revealed 100% homology with the human phosphatidic acid phosphatase type 2a isozyme very recently reported by Kai et al. (PAP-2a; Kai., M., Wada, I., Imai, S.-i., Sakane, F., and Kanoh, H. (1997) J. Biol. Chem. 272, 24572-24578). The fragment was used to clone the corresponding cDNA from a human prostate library. The deduced amino acid sequence confirmed the identity with human PAP-2a. The inducibility of PAP-2a mRNA by androgens was confirmed by Northern blot hybridization. The effect was time- and dose-dependent with a maximal stimulation (4-fold) after 24 h of treatment with 10(-9) M R1881. The steroid specificity of PAP-2a mRNA regulation was found to be in agreement with the aberrant ligand specificity of the mutated androgen receptor in LNCaP cells, supporting the involvement of the androgen receptor in the induction process. Furthermore, low basal levels of PAP-2a mRNA and absence of androgen inducibility were observed in the poorly differentiated and androgen receptor-negative cell lines PC-3 and DU-145. Induction of PAP-2a mRNA was not affected by the protein synthesis inhibitor cycloheximide and was accompanied by a marked increase in PAP-2 activity as measured by the conversion of phosphatidic acid into diacylglycerol in membrane fractions of LNCaP. Comparison of the expression of PAP-2a mRNA in 50 different human tissues revealed ubiquitous expression. The highest levels, however, were observed in the prostate. Since PAP-2 plays a pivotal role in the control of signal transduction by lipid mediators such as phosphatidate, lysophosphatidate, and ceramide-1-phosphate, the ability of androgens to stimulate the expression and activity of this enzyme in prostatic cells may provide an important opportunity for cross-talk between signaling pathways involving lipid mediators and androgens.

Adenocarcinoma↗
PubMed1998

Unidentified Factors in Jojoba Meal Prevent Oviduct Development in Broiler Breeder Females.

Supplementation of feed with jojoba meal, as a means for autonomous feed restriction, was successful in depressing feed intake and controlling body weight of broiler breeder pullets to the extent recommended by the breeder company. However, these broiler breeders never produced eggs. At the level of ovary, normal follicle development and maturation did occur. A considerable number of ovulations occurred which were not followed by oviposition. After ovulation, the ova could not be captured by the oviduct, because of the small size of the oviduct, resulting in "internal laying". The virtual absence of oviduct development cannot be explained presently but it must be due to some yet unidentified factor(s) in jojoba meal which prevent(s) the normal development of the oviduct. These factors may be acting by abnormally increasing plasma progesterone or triiodothyronin levels and/or directly by themselves interfering with oviduct development. The nature of these factors requires further investigations.

Journal Article↗
PubMed1998

Immunohistochemistry and in situ hybridization of the androgen receptor in the developing human prostate.

UNLABELLED: As it is suggested that the androgen receptor mechanism is required for prostatic development, we attempted to determine the appearance, expression and distribution of the androgen receptor in embryonic, infantile and pubertal human prostate. Using mono- and polyclonal antibodies and a digoxigenin-labeled 713 bp riboprobe, the androgen receptor expression in paraffin sections of fetal, infantile, and pubertal prostates was studied at the protein and RNA level. Under highly standardized conditions, application of the polyclonal antibodies resulted in a weak cytoplasmic and nuclear labeling of the epithelium of fetal glands. No immunoreaction was obtained with monoclonal antibodies. Applying the polyclonal antibody to pubertal and adult specimens, immunoreactivity of the androgen receptor was positive in nuclei of adluminal and basal epithelial cells, in interstitial and vascular smooth muscle cells and vascular endothelium, whereas ganglionic cells and enteroendocrine cells were negative. In situ hybridization with the digoxigenin-labeled riboprobe gave clear positive results already in epithelium of very young fetal specimens. A semiquantitative visual evaluation of in situ hybridizations showed that intermediate intensity of expression was increased in pubertal and adult specimens, whereas strong expression was reduced in prostatic epithelium. CONCLUSIONS: The essential findings are: (1) an early expression of androgen receptor mRNA in the fetal prostate; (2) no immunoreaction of monoclonal antibodies against the androgen receptor in the same specimens, (3) a decrease of androgen receptor mRNA expression, but increase in immunoreactivity of the androgen receptor protein with the onset of glandular maturation during puberty.

Adolescent↗