Biomedical subjects

A M Traish

Publications and source records attributed to A M Traish.

At least 37 records · Page 2Linked to original sources

PubMed1998

Preliminary report on the development and characterization of rabbit clitoral smooth muscle cell culture.

PURPOSE: Scientific model systems for physiological evaluation and investigation of pathophysiologies in clitoral function have been limited. The aim was to develop a New Zealand White rabbit clitoral corpus cavernosum smooth muscle cell culture. METHODS: Clitoral corpus cavernosum erectile tissue was harvested and placed in culture. Clitoral smooth muscle cells which migrated out from explants were grown to confluence and subcultured. Characterizations were performed by morphological and biochemical analyses. RESULTS: The cells exhibited typical morphologic characteristics of smooth muscle cells. Indirect immunofluorescence studies confirmed the presence of a-smooth muscle cell actin. Androgen and estrogen receptors were detected by specific antibodies and binding studies. The cells expressed subtypes of TGF-beta receptors. Treatment with 80 pM TGF-beta 1 24 h resulted in induction and/or increased availability of TGF-beta receptors. CONCLUSIONS: An in-vitro cell culture system using rabbit clitoral smooth muscle cells was developed. These smooth muscle cells retain their biochemical and functional integrity. This in-vitro cell culture system may facilitate studies aimed at understanding the molecular basis of female sexual function.

Animals↗

PubMed1998

A possible mechanism for alteration of human erectile function by digoxin: inhibition of corpus cavernosum sodium/potassium adenosine triphosphatase activity.

PURPOSE: Digoxin use has long been recognized to affect adversely male sexual function but the underlying mechanism is poorly understood. Digoxin is a known inhibitor of sodium/potassium adenosine triphosphatase (sodium pump), a plasma membrane enzyme that has a role in the regulation of smooth muscle tone. We investigated the effects of digoxin on human corpus cavernosum smooth muscle contractility and overall erectile function. MATERIALS AND METHODS: In human corporeal smooth muscle strips the in vitro effects of digoxin were assessed on sodium pump activity as measured by digoxin inhibitable uptake of 86rubidium, basal tone and endothelium dependent, neurogenic and nitric oxide donor induced relaxation. An in vivo prospective double-blind, placebo controlled, crossover, 4-period investigation was performed in 6 healthy male volunteers. The effects of digoxin on serum hormones, erectile function questionnaire, visual sexual stimulation and nocturnal penile tumescence were recorded. RESULTS: In vitro digoxin caused concentration dependent inhibition of 86rubidium uptake (half maximum effect at 0.01 microM.) and contraction of corporeal smooth muscle (half maximum effect at 0.8 microM.). Therapeutic concentrations of digoxin (2 nM.) also inhibited relaxation induced by acetylcholine and electrical field stimulation, which release nitric oxide from corpus cavernosum endothelial cells and nonadrenergic noncholinergic nerves, respectively. In vivo digoxin diminished penile rigidity during visual sexual stimulation and nocturnal penile tumescence testing compared to placebo without influencing libido or serum testosterone, estrogen or luteinizing hormone levels. CONCLUSIONS: Digoxin associated alteration of human erectile function may be explained, in part, by inhibition of corporeal smooth muscle sodium pump activity, which promotes contraction and impedes nitric oxide induced relaxation. Such findings suggest therapeutic use of digoxin for treatment of recurrent priapism states.

Adenosine Triphosphate↗

PubMed1998

Mechanisms of ischemia-induced cavernosal smooth muscle relaxation impairment in a rabbit model of vasculogenic erectile dysfunction.

PURPOSE: To determine the effects of hypercholesterolemia and atherosclerosis-induced chronic cavernosal arterial insufficiency on cavernosal smooth muscle tone, nitric oxide synthase (NOS) activity and cavernosal tissue synthesis of constrictor eicosanoids. To study whether inhibition of the cyclooxygenase pathway by indomethacin and tissue treatment with nitric oxide (NO) precursor L-arginine improve hypercholesterolemia and ischemia-induced impaired endothelium-dependent and neurogenic relaxation of cavernosal tissue. MATERIALS AND METHODS: New Zealand White rabbits were divided into control (n = 10, fed a regular diet), hypercholesterolemia (Hch, n = 13, fed a diet containing 0.5% cholesterol) and chronic cavernosal ischemia (CCI, n = 14) groups. The CCI group underwent balloon deendothelialization of iliac arteries and received a diet containing 0.5% cholesterol. After 16 weeks, we examined the effects of Hch and balloon de-endothelialization induced arterial occlusive disease on iliac arterial blood flow, reactivity of cavernosal tissue, cavernosal NOS activity and cavernosal tissue synthesis of constrictor eicosanoids. RESULTS: Histology revealed significant atherosclerotic arterial occlusive disease in the CCI group. Iliac artery blood flow in the CCI group was significantly reduced compared with the control and Hch groups. In the Hch and CCI groups, endothelium-dependent relaxation of cavernosal tissue to acetylcholine was significantly reduced compared with the control group. Electrical field stimulation-induced neurogenic relaxation and cavernosal NOS activity were significantly reduced in the CCI group but not in the Hch group. The basal release of cavernosal constrictor eicosanoids, prostaglandin F2alpha (PGF2alpha) and thromboxane A2 (TXA2) was significantly increased in the CCI group. Indomethacin increased endothelium-dependent relaxation in all groups and neurogenic relaxation in the CCI group, but failed to normalize the differences in relaxation between treated and control groups. In the presence of indomethacin, L-arginine improved endothelium-dependent relaxation of cavernosal tissue in the Hch group but did not normalize endothelium-dependent or neurogenic relaxations in the CCI group. Relaxation to NO donor sodium nitroprusside and papaverine was similar in cavernosal tissue from all groups. CONCLUSIONS: Impairment of endothelium-dependent relaxation by Hch occurs secondary to disruption of the NO formation in cavernosal endothelium. Improvement of endothelium-dependent relaxation by L-arginine may suggest lack of availability of L-arginine in cavernosal tissue from the Hch animals. Impairment of endothelium-dependent and neurogenic relaxation by CCI occurs secondary to disruption of the NO formation due to an alteration in the expression or activity of NOS and increased output of constrictor eicosanoids in cavernosal tissue. These studies show that Hch and atherosclerosis-induced chronic cavernosal arterial insufficiency, beyond decreasing cavernosal perfusion pressure, also adversely affect smooth muscle relaxation mechanisms in cavernosal tissue.

Animals↗

PubMed1997

Aberrant nuclear factor-kappaB/Rel expression and the pathogenesis of breast cancer.

Expression of nuclear factor-kappaB (NF-kappaB)/Rel transcription factors has recently been found to promote cell survival, inhibiting the induction of apoptosis. In most cells other than B lymphocytes, NF-kappaB/Rel is inactive, sequestered in the cytoplasm. For example, nuclear extracts from two human untransformed breast epithelial cell lines expressed only very low levels of NF-kappaB. Unexpectedly, nuclear extracts from two human breast tumor cell lines displayed significant levels of NF-kappaB/Rel. Direct inhibition of this NF-kappaB/ Rel activity in breast cancer cells induced apoptosis. High levels of NF-kappaB/Rel binding were also observed in carcinogen-induced primary rat mammary tumors, whereas only expectedly low levels were seen in normal rat mammary glands. Furthermore, multiple human breast cancer specimens contained significant levels of nuclear NF-kappaB/Rel subunits. Thus, aberrant nuclear expression of NF-kappaB/Rel is associated with breast cancer. Given the role of NF-kappaB/Rel factors in cell survival, this aberrant activity may play a role in tumor progression, and represents a possible therapeutic target in the treatment of these tumors.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1997

Binding of type II nuclear receptors and estrogen receptor to full and half-site estrogen response elements in vitro.

The mechanism by which retinoids, thyroid hormone (T3) and estrogens modulate the growth of breast cancer cells is unclear. Since nuclear type II nuclear receptors, including retinoic acid receptor (RAR), retinoid X receptor (RXR) and thyroid hormone receptor (TR), bind direct repeats (DR) of the estrogen response elements (ERE) half-site (5'-AGGTCA-3'), we examined the ability of estrogen receptor (ER) versus type II nuclear receptors, i.e. RARalpha, beta and gamma, RXRbeta, TRalpha and TRbeta, to bind various EREs in vitro . ER bound a consensus ERE, containing a perfectly palindromic 17 bp inverted repeat (IR), as a homodimer. In contrast, ER did not bind to a single ERE half-site. Likewise, ER did not bind two tandem (38 bp apart) half-sites, but low ER binding was detected to three tandem copies of the same half-site. RARalpha,beta or gamma bound both ERE and half-site constructs as a homodimer. RXRbeta did not bind full or half-site EREs, nor did RXRbeta enhance RARalpha binding to a full ERE. However, RARalpha and RXRbeta bound a half-site ERE cooperatively forming a dimeric complex. The RARalpha-RXRbeta heterodimer bound the Xenopus vitellogenin B1 estrogen responsive unit, with two non-consensus EREs, with higher affinity than one or two copies of the full or half-site ERE. Both TRalpha and TRbeta bound the full and the half-site ERE as monomers and homodimers and cooperatively as heterodimers with RXRbeta. We suggest that the cellular concentrations of nuclear receptors and their ligands, and the nature of the ERE or half-site sequence and those of its flanking sequences determine the occupation of EREs in estrogen-regulated genes in vivo .

Animals↗

PubMed1997

Intracavernosal forskolin: role in management of vasculogenic impotence resistant to standard 3-agent pharmacotherapy.

PURPOSE: We investigated forskolin, a direct adenylate cyclase activator, as an intracavernosal vasoactive agent in management of vasculogenic impotence. MATERIALS AND METHODS: Concentration responses for forskolin and prostaglandin E1 induced relaxation of phenylephrine precontracted strips of human corpus cavernosum smooth muscle were constructed in vitro. Cyclic adenosine monophosphate (cAMP) synthesis was determined with papaverine, phentolamine, prostaglandin E1 and forskolin in human corpus cavernosum smooth muscle cell cultures. Dose-dependent hemodynamic responses to intracavernosal forskolin (5 to 20 micrograms) were evaluated in a New Zealand White rabbit model. Safety and efficacy outcome data were obtained in vasculogenically impotent patients who signed informed consent and met strict inclusion and exclusion criteria that included having had standard self-injection therapies fail. RESULTS: In vitro forskolin and prostaglandin E1 alone caused concentration dependent relaxation with an EC50 of approximately 200 nm. and 16 nm., respectively. When the 2 agents were combined, the concentration response curve for relaxation shifted to the left. cAMP production was highest in cells treated with prostaglandin E1 and forskolin and was unaffected by papaverine or phentolamine. In 3 animals, equilibrium intracavernosal pressure and duration of erection had a dose dependent increase. Clinical investigation in 31 patients showed no adverse events with a mean of 14 +/- 4, range 11 to 18 months of followup. Overall 61% reported improvement in rigidity and/or erection duration using intracavernosal forskolin (98 micrograms./ml.), papaverine (29 mg./ml.), phentolamine (0.98 mg./ml.) and prostaglandin E1 (9.8 micrograms./ml.). CONCLUSIONS: Forskolin is a United States Food and Drug Administration nonapproved vasoactive agent that acts in synergism with prostaglandin E1 to induce smooth muscle relaxation. In combination with other vasoactive agents, forskolin has demonstrated preliminary safety and efficacy in patients with vasculogenic impotence resistant to standard 3-agent pharmacotherapy.

Alprostadil↗

PubMed1997

Loss of expression of a 55 kDa nuclear protein (nmt55) in estrogen receptor-negative human breast cancer.

We have identified and characterized a 55 kDa nuclear protein (referred to as nmt55) from human breast tumors and MCF-7, human adenocarcinoma breast cell line, using site-directed monoclonal antibodies. Measurements of estrogen receptors (ER) and progesterone receptors (PR), by ligand binding assays, in cytosols of 63 human breast tumors permitted classifications of these tumors into four phenotypes (ER+/PR+, ER+/ PR-, ER-/PR-, ER-/PR+). Nuclear protein (nmt55) expression in these tumors, as determined from Western blot analyses, showed a statistically significant association (p = 0.001) with tumor hormonal phenotype. Review of the pathologic characteristics of tumors analyzed suggested that lack of nmt55 expression was significantly associated with mean tumor size (p < 0.03), mean ER (p = 0.001) and mean PR (p < 0.002), but was not associated with tumor stage, grade, or type. To further study this protein, we cloned and sequenced a 2.5 kb cDNA using a monoclonal antibody to nmt55. The complete predicted open reading frame encodes a protein with 471 amino acids and a calculated molecular mass of 54,169 Da. The deduced amino acid sequence exhibited unique regions rich in glutamine, histidine, arginine, and glutamic acid. Northern blot analysis of RNA from MCF-7 cells and ER+/PR+ human breast tumors showed a 2.6 kb mRNA. Southern blot analysis suggested the presence of a single copy of this gene. Chromosomal mapping, using fluorescent in situ hybridization (FISH), located nmt55 gene to the X chromosome, region q13. The extensive homology between nmt55 and RNA binding proteins suggested that nmt55 may be involved in hnRNA splicing. The strong association observed between expression of nmt55, tumor hormonal phenotype, mean tumor size, mean ER, and mean PR content suggests that loss of nmt55 expression may be related to events involved in hormone insensitivity, tumor differentiation, and unregulated tumor cell growth and metastases.

Amino Acid Sequence↗

PubMed1997

Expression of functional alpha2-adrenergic receptor subtypes in human corpus cavernosum and in cultured trabecular smooth muscle cells.

In this study, we have identified and characterized functional alpha2-adrenergic receptor (alpha2-AR) subtypes in human corpus cavernosum and in cultured human corpus cavernosum smooth muscle cells. Analysis of total RNA, isolated from whole corpus cavernosum tissue and smooth muscle cells, by RNase protection assays, demonstrated expression of mRNA for alpha2A, alpha2B, and alpha2C adrenergic receptor subtypes in whole tissue and alpha2A and alpha2C subtypes in cultured smooth muscle cells. Binding studies with [3H]RX821002 (a highly selective and specific ligand for alpha2-adrenergic receptor) in isolated membrane fractions of human corpus cavernosum smooth muscle cells, demonstrated specific alpha2-AR binding sites with high affinity (Kd = 0.63 nM) and limited capacity (25-30 fmol/mg protein). Binding of [3H]RX821002 was displaced with the nonselective alpha-AR antagonist, phentolamine, and with the alpha-AR agonist, norepinephrine, in a dose-dependent manner, but not by the selective alpha1-AR agonist, phenylephrine. Binding of [3H]rauwolscine was also displaced by phentolamine. UK 14,304, a selective alpha2-AR agonist, inhibited forskolin-induced cyclic adenosine monophosphate (cAMP) synthesis in cultured human corpus cavernosum smooth muscle cells and induced dose-dependent contractions of tissue strips in organ bath chambers. UK 14,304-induced contractions were inhibited with alpha2-AR selective antagonists, rauwolscine and delquamine (RS 15385-197). These observations suggest that in human corpus cavernosum, norepinephrine (NE) and epinephrine may activate postsynaptic alpha2-AR subtypes, in addition to activating alpha1-AR subtypes, on smooth muscle cells, contributing to local control of human corpus cavernosum smooth muscle tone, in vivo.

Adrenergic alpha-Agonists↗

PubMed1997

G-protein-coupled receptor agonists augment adenylyl cyclase activity induced by forskolin in human corpus cavernosum smooth muscle cells.

The goal of this study was to investigate the synergistic effects between G-protein-coupled receptor agonists and forskolin-induced activation of adenylyl cyclases, in cultured human corpus cavernosum smooth-muscle cells. Treatment of human corpus cavernosum smooth-muscle cells with forskolin (0.1-10 microM) produced an increase in cAMP synthesis in a concentration-dependent manner. Forskolin-induced adenylyl cyclase activity was markedly augmented by prostaglandin E1 (PGE1) and its metabolite, PGE0, isoproterenol, carbachol, and phenylephrine. Augmentation of forskolin-induced cAMP by PGE1, and PGE0 is probably mediated by prostaglandin E receptors (EP). Enhancement of forskolin-induced cAMP synthesis by isoproterenol is mediated by beta-adrenergic receptors (beta-AR), since this activity was inhibited by propranolol. Stimulation of forskolin-induced cAMP synthesis by carbachol is attributed to activation of muscarinic acetylcholine receptors (mAChR), as demonstrated by inhibition with atropine. The augmentation of forskolin-induced cAMP synthesis by phenylephrine, an alpha1-adrenergic receptor (AR) agonist, however, was unexpected and cannot be attributed to increased intracellular Ca2+, since treatment of cells with either the Ca2+ ionophore, A23187, or 80 mM KCl did not affect forskolin-induced cAMP synthesis. Stimulation of forskolin-induced cAMP synthesis by phenylephrine is explained by its binding to beta-AR and activation of Gs protein, since this augmentation was inhibited by the beta-AR antagonist, propranolol. This observation was further supported by physiological studies in organ bath chambers, in which forskolin-induced relaxation of precontracted corpus cavernosum strips was enhanced by phenylephrine. These studies suggest that synergism between agonist-induced cAMP synthesis and forskolin is attributed to increased conformational stabilization of activated adenylyl cyclase catalytic domains by forskolin and the Gs(alpha)-subunit of activated Gs proteins.

Adenylyl Cyclases↗

PubMed1996

Site-directed estrogen receptor antibodies stabilize 4-hydroxytamoxifen ligand, but not estradiol, and indicate ligand-specific differences in the recognition of estrogen response element DNA in vitro.

Conformational differences between type I antiestrogen-liganded estrogen receptor and estradiol (E2)-liganded estrogen receptor (ER) are thought to be responsible for differentiating agonist versus antagonist ER activity at individual genes. To examine the impact of ER ligand on estrogen-response element (ERE) binding kinetics and receptor conformation, we quantitated the effect of site-directed, ER-specific antibodies raised against synthetic peptides corresponding to the DNA-binding domain of human ER on ER-ERE binding in vitro. Although 4-hydroxytamoxifen-liganded-ER (4-OHT-ER) and E2-ER bind a consensus ERE with equal high affinity, the stoichiometry of 4-OHT-ER-ERE binding at saturation is approximately 50% lower than that of E2-ER binding to all ERE sequences tested. In contrast, the ERE binding stoichiometry of tamoxifen aziridine-liganded ER (TAz-ER) is identical to that of E2-ER: one receptor dimer bound per ERE. The difference in binding stoichiometry is caused by dissociation of one molecule of 4-OHT from the ER as the dimeric receptor binds DNA. Addition of low concentrations of ER-specific polyclonal antibodies AT3A or AT3B prevented 4-OHT ligand dissociation, yielding an increase in specific 4-OHT-ER-ERE binding to a level equal to that of E2-ER- or TAz-ER-ERE binding. However, higher amounts of AT3A or AT3B inhibited specific ERE binding of both 4-OHT- and E2-ER. We conclude that differences in ER conformation when liganded with 4-OHT versus E2 are revealed by these antibodies and that such differences in receptor conformation may influence subsequent interaction of the receptor with other proteins necessary for transactivation.

Antibody Specificity↗

PubMed1996

Dissociation of 4-hydroxytamoxifen, but not estradiol or tamoxifen aziridine, from the estrogen receptor as the receptor binds estrogen response element DNA.

Estradiol-liganded estrogen receptor (E2-ER) binds EREs with a stoichiometry of one E2-ER dimer per estrogen response element (ERE). In contrast, although 4-hydroxytamoxifen (4-OHT)-liganded ER (4-OHT-ER) binds EREs with high affinity, its saturation ERE binding capacity is consistently half that of E2-ER, giving an apparent stoichiometry of one 4-OHT-ER monomer per ERE. Here we show that one molecule of 4-OHT ligand dissociates from the ER dimer apparently during the process of binding to DNA. Under equilibrium conditions, the type I antiestrogen tamoxifen aziridine (TAz), covalently attached to ER (TAz-ER), binds a single ERE with high affinity (Kd = 0.27 nM), comparable to that of E2-ER and 4-OHT-ER. In contrast to 4-OHT-ER, the ERE binding stoichiometry of TAz-ER was identical to that of E2-ER: one dimeric receptor per ERE. By measuring [3H]ligand that was initially bound to ER, a significant loss of [3H]4-OHT from ER was detected after ERE binding, whereas all [3H]E2 or [3H]TAz remained ER-bound. These results confirm that one molecule of 4-OHT ligand dissociates from the ER dimer as a consequence of ERE binding. Binding of 4-OHT and TAz are likely to induce a conformation in ER dimers that alters their capacity for gene activation. Upon ER binding to DNA, this conformation reveals itself by allowing 4-OHT dissociation, and predictably would allow TAz dissociation were it not bound covalently.

Base Sequence↗

PubMed1996

Binding of site-directed monoclonal antibodies to an epitope located in the A/B region (amino acids 140-154) of human estrogen receptor-induced conformational changes in an epitope in the DNA-binding domain.

The interactions of estrogen receptor (ER) with monoclonal antibody (Mab) F9, developed against a synthetic 30-mer hybrid oligopeptide, were determined in the presence or absence of Mab NMT-1, raised against 15-mer peptide from the N-terminal A/B region (amino acids 140- 154) or Mab 213, raised to a peptide AT3 in the DNA-binding domain (amino acids 247-263). Mab F9 bound ER and formed a complex sedimenting at the approximately 11S region of the gradients. Mabs 213 and NMT-1 bound ER and formed complexes sedimenting at approximately 7S and 9S, respectively. Preincubation of ER with Mab 213, followed by reincubation with Mab F9, resulted in a complex sedimenting at the approximately 11S region of the gradients. Similarly, preincubation of ER with Mab NMT-1 followed by reincubation with Mab F9 also produced an approximately 11S complex on the gradients. These observations suggest that binding of Mab F9 to ER induced conformational changes causing the release of Mab 213 and Mab NMT-1 from ER. Furthermore, binding of Mab NMT-1 to the A/B region of ER also produced conformational changes causing the release of Mab 213 from its epitope in the DNA-binding region. These results indicate that binding of Mab F9 and Mab NMT-1, with epitopes located within amino acids 140-154 of the A/B region of ER, induced conformational changes in the DNA-binding domain, as determined by the inability of Mab 213 to remain bound to its epitope. These data further suggest that the DNA-binding region is sensitive to conformational changes induced in the native protein.

Amino Acid Sequence↗

PubMed1996

Prostanoid production in rabbit corpus cavernosum: I. regulation by oxygen tension.

PURPOSE: To investigate the effects of oxygen tension on prostanoid synthesis in rabbit penile corpus cavernosum tissue (RCC) in organ culture. MATERIALS AND METHODS: Strips of rabbit corpus cavernosum were incubated in organ culture media under varying oxygen conditions (0%, 12% and 21% oxygen), in the presence or absence of acetylcholine and arachidonate stimulation. Prostanoids were measured in collected media by radioimmunoassay. Prostaglandin H synthase (PGHS) protein levels and mRNA PGHS expression were measured under both 0% and 21% oxygen conditions. RESULTS: Basal and acetylcholine-stimulated PGI2 release was progressively diminished as a function of diminishing oxygen tension (pO2 from approximately 165 to 25 mm.Hg). The basal and stimulated production of other prostanoids, thromboxane A2, PGF2alpha, and PGE2, was also significantly inhibited under 0% oxygen (approximately 25 mm.Hg) conditions. However, incubation under 0% oxygen did not alter PGHS protein levels nor mRNA PGHS expression. Cavernosal strips incubated under 0% oxygen but supplemented with exogenous arachidonate (10 microM.) maintained significantly lower PGI2 production than tissues exposed to 21% oxygen (approximately 165 mm.Hg). CONCLUSIONS: These data demonstrate that oxygen tension regulates prostaglandin production in corporal tissue. The reduction in prostanoid production during hypoxia can be attributed to inhibition of PGHS activity rather than the expression of the enzyme. In view of the role of PGI2 as an inhibitor of platelet aggregation and white cell-endothelial adhesion, our findings may provide mechanistic insight into the alteration in corporal blood homeostasis ischemic-hypoxic priapism.

Acetylcholine↗

PubMed1995

Identification of structurally altered estrogen receptors in human breast cancer by site-directed monoclonal antibodies.

We have developed and characterized site-directed monoclonal (MAb) and polyclonal antibodies to a specific domain in the N-terminal A/B region in order to assess estrogen receptor (ER) structural integrity in human breast tumor samples. The antibodies (Abs) reacted specifically with the native (undenatured) ER from various species. The synthetic peptides competed effectively for ER binding to the Abs, suggesting site-specificity. The Abs recognized the activated (4S) and transformed (5S) but not the unactivated, untransformed, molybdate-stabilized (8S) ER, suggesting that the epitope is inaccessible in the 8S form. Some of these Abs reacted with ER bound to its responsive elements, as determined by gel mobility shift assay. To evaluate the structural integrity of ER in breast cancer, we have utilized a) ligand binding analysis for the hormone binding domain; b) site-directed MAb to the DNA-binding domain; and c) site-directed MAb to the N-terminal transactivation domain. Analysis of ER from 29 human breast tumors revealed that 10 out of 29 tumors (35%) contained ER with intact hormone-, DNA-, and N-terminal domains. Thirteen out of 29 tumors (approximately 45%) contained ER with intact hormone binding and N-terminal domains but were defective only in the DNA-binding domain. Three out of 29 tumors (approximately 10%) contained ER defective only in the N-terminal domain. Another subgroup of tumors (3/29; approximately 10%) had ER with normal hormone binding domain but were defective in both the DNA-binding and the N-terminal activation domains.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

A heterogeneous population of alpha 1 adrenergic receptors mediates contraction of human corpus cavernosum smooth muscle to norepinephrine.

In this study we investigated the physiological properties and binding characteristics of alpha-1 adrenergic receptor (alpha 1-AR) in human corpus cavernosum (HCC) in order to identify alpha 1-AR subtypes at the functional protein level. Exposure of tissue strips to norepinephrine (NE) caused concentration-dependent contractions that were partially and noncompetitively inhibited by 10 to 100 microM. of chloroethylclonidine (CEC), an alkylating agent that specifically and irreversibly inactivates alpha 1B-AR and alpha 1C-AR subtypes. Norepinephrine-induced contractions were competitively and effectively inhibited with WB 4101, a competitive, high-affinity antagonist for alpha 1A-AR and alpha 1C-AR subtypes. The CEC-insensitive receptor subtypes bound WB 4101 with high affinity, suggesting the presence of alpha 1A-AR in HCC. Binding of [3H]prazosin and 2-[beta-(4-hydroxy-3-[125I]iodophenyl)-ethylaminomethyl]-tetralone ([125I]HEAT) to membranes of HCC treated with or without CEC demonstrated the presence of two subpopulations: a CEC-sensitive receptor population (40 to 50%), which may represent inactivation of the alpha 1B-AR and alpha 1C-AR subtypes, and a CEC-resistant receptor subpopulation, which is probably the alpha 1A-AR subtype. The physiological and biochemical properties of alpha 1-AR in HCC clearly suggest that the NE-induced contraction of HCC smooth muscle is mediated by more than one alpha 1-AR subtype. It is likely that two or possibly three receptor subtypes are involved in mediating the contraction. Further, it is possible that NE-mediated contraction of trabecular smooth muscle requires synergistic receptor-receptor receptor interactions at the second messenger or at the receptor protein level.

Alkylating Agents↗

PubMed1995

Estrogen receptor functional status in human breast cancer.

Estrogen receptors (ER) are detected in 50-85% of all breast tumors, and are clinically important because they tend to identify patients with a higher probability of responding to hormonal or endocrine manipulations. However, approximately 30-40% of all ER+ patients do not respond to hormonal manipulations. The lack of response to hormonal manipulations in ER+ patients could be the result of nonfunctional ER, as determined by its inability to recognize and bind to specific DNA-responsive elements and/or its inability to recruit other transcriptional activation factors. The functional status of ER in 34 human breast tumors was assessed determining the structural integrity of the ER DNA-binding domain using site-directed monoclonal anti-estrogen receptor antibody and sucrose density gradient analysis. Based on the fraction of ER containing an intact DNA-binding domain, the tumors were classified into three groups: group I with > 65% of intact ER, group II with > 30% of intact ER, group III with < 30% of intact ER. Clinical and pathologic data were obtained only for patients who were treated with the anti-estrogen tamoxifen and correlated with ER functional status. In group I, 11 of 13 (84.6%) patients were responsive to hormonal therapy with favorable clinical outcome; two patients had unfavorable clinical outcome. In group II, 13 of 15 patients (86.7%) had favourable clinical outcome, and two patients 13.3% had unfavorable outcome. In group III, three of six patients appeared to be hormone responsive with favorable clinical outcome, and three of the patients in this group had unfavorable response to therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Estradiol and phorbol ester cause phosphorylation of serine 118 in the human estrogen receptor.

Serine 118 is definitively identified as a major site of phosphorylation in the human estrogen receptor expressed in COS-1 cells treated with estradiol or phorbol ester. At least 30% of the estrogen receptor appears to be phosphorylated on serine 118 after treatment with estradiol or phorbol ester. Human estrogen receptor was expressed in COS-1 cells and labeled in vivo with [32P]orthophosphate in the presence of estradiol or phorbol ester. Immunopurified receptor was digested with cyanogen bromide. The most heavily labeled peptide (7 kilodaltons) was identified as amino acids 110-174 by microsequencing. Manual Edman degradation released a major portion of the 32P-label in the peptide at serine 118. A mutant with serine 118 replaced by alanine (S118A) had 80% less 32P-label in the 7 kilodalton peptide. Estrogen receptor labeled in vivo with [32P]-orthophosphate in the presence of estradiol or phorbol ester migrates electrophoretically as a doublet. The major difference between the bands is phosphorylation of serine 118 in the upshifted band. The mutant S118A does not show an upshifted band. Labeling of the estrogen receptor with [35S]methionine indicates that > or = 30% of the receptor is upshifted and suggests that > or = 30% of the receptor is phosphorylated on serine 118.

Animals↗

PubMed1995

Identification of alpha 1-adrenergic receptor subtypes in human corpus cavernosum tissue and in cultured trabecular smooth muscle cells.

Recent pharmacological and functional studies have suggested the presence of more than one alpha-1 adrenergic receptor subtype in human corpus cavernosum (HCC). In this study, we sought to identify the alpha-1 adrenergic receptor (alpha 1-AR) subtypes expressed in HCC whole tissue and in trabecular smooth muscle subcultured from this tissue. We have utilized RNase protection assays and in situ hybridization (ISH) techniques to identify and localize these receptor subtypes. RNase protection assays of mRNA isolated from whole tissue demonstrated the presence of mRNA transcripts for three alpha 1-AR receptor subtypes (alpha 1d, alpha 1b, and alpha 1a). alpha 1d-AR and alpha 1a-AR appear to be more abundant than alpha 1b-AR. The identification and localization of mRNA for alpha 1-AR subtypes in whole tissue was demonstrated by RNA protection assays and ISH analysis. Immunocytochemical analysis of alpha 1-AR by an antipeptide antibody developed against a specific amino acid sequence derived from alpha 1d-AR subtype demonstrated specific staining of the smooth muscle cells, suggesting the expression of alpha 1d-AR subtype. In cultured HCC smooth muscle cells (HCC SMC), phenylephrine,alpha 1-AR agonist stimulated Na+/K+ ATPase activity, suggesting the presence of functional alpha 1-AR. RNase protection assay of mRNA isolated from HCC SMC grown in culture further demonstrated the presence of mRNA transcripts for alpha 1d-AR and alpha 1a-AR subtypes. ISH analysis and confocal microscopy also indicate that the SMC express the alpha 1d-AR and alpha 1a-AR subtypes. The data presented suggests that HCC and SMC derived from this tissue express at least three alpha 1-AR subtypes. Identification of these receptor subtypes should allow characterization of the functional role of these receptor subtypes in regulation of trabecular smooth muscle tone and penile detumescence.

Cells, Cultured↗