Biomedical subjects

H Klocker

Publications and source records attributed to H Klocker.

At least 55 records · Page 3Linked to original sources

PubMed1999

Epidermal growth factor (EGF) receptor blockade inhibits the action of EGF, insulin-like growth factor I, and a protein kinase A activator on the mitogen-activated protein kinase pathway in prostate cancer cell lines.

Epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) are potent mitogens that regulate proliferation of prostate cancer cells via autocrine and paracrine loops and promote tumor metastasis. They exert their action through binding to the corresponding cell surface receptors that initiate an intracellular phosphorylation cascade, leading to the activation of mitogen-activated protein kinases (MAPKs), which recruit transcription factors. We have studied the effects of EGF, IGF-I, and the protein kinase A (PKA) activator forskolin on the activation of p42/ extracellular signal-regulated kinase (ERK)2, which is a key kinase in mediation of growth factor-induced mitogenesis in prostate cancer cells. The activity of p42/ERK2 was determined by immune complex kinase assays and by immunoblotting using a phospho p44/p42 MAPK-specific antibody. EGF, IGF-I, and forskolin-induced PKA activity stimulate intracellular signaling pathways converging at the level of p42/ERK2. In the androgen-insensitive DU145 cell line, there is a constitutive basal p42/ ERK2 activity that is not present in androgen-sensitive LNCaP cells. Constitutive p42/ERK2 activity is abrogated by blockade of the EGF receptor. Hence, it is obviously caused by an autocrine loop involving this receptor. The effects of EGF on p42/ERK2 are potentiated by forskolin in both cell lines. The blockade of PKA by the specific inhibitor H89 attenuates this synergism. This finding is in contrast to those obtained in several other systems studied thus far, in which PKA activators inhibited MAPKs. p42/ERK2 in DU145 cells is highly responsive to IGF-I stimulation, whereas no effect of IGF-I on p42/ERK2 can be measured in LNCaP cells. Moreover, our results demonstrate that selective blockade of the EGF receptor in prostate cancer cells does not only inhibit the action of EGF, but also IGF-I-induced activation of the MAPK pathway and the interaction with the PKA pathway. In conclusion, these findings offer new possibilities for a therapeutical intervention in prostate cancer by targeting signaling pathways of growth factors and PKA.

Calcium-Calmodulin-Dependent Protein Kinases↗

PubMed1999

Basic fibroblast growth factor synthesis by human peritoneal mesothelial cells: induction by interleukin-1.

Peritoneal mesothelial cells are uniquely located to regulate cellular events in the peritoneal cavity and are an important source for various cytokines and growth factors. This study was conducted to analyze the capacity of human peritoneal mesothelial cells (HPMCs) to synthesize and release basic fibroblast growth factor (bFGF) and to characterize its regulation by inflammatory cytokines. HPMCs constitutively synthesized and released considerable amounts of bFGF as detected by a specific immunoassay. Almost 80% of bFGF (1547 +/- 173 pg/10(5) cells) was localized intracellularly. Approximately 20% of the bFGF (357 +/- 27 pg/10(5) cells) was associated with extracellular matrix components on the HPMC surface. Small amounts of bFGF (<1%) were detectable in tissue culture supernatants (8.4 +/- 1.4 pg/10(5) cells). Treatment of HPMCs with interleukin-1beta (IL-1beta; 1 ng/ml) resulted in a significant increase in bFGF production. The intracellular bFGF content showed a rapid but only transient increase, which was significant above background levels after 24 hours (41% increase; P < 0.05). This increase in intracellular bFGF concentration was associated with an induction of the release of bFGF. Within 96 hours, the release of bFGF to the cell surface and into the supernatant increased by 58% (564 +/- 52.4 pg/10(5) cells; P < 0.01) and by 214% (26.4 +/- 3.2 pg/10(5) cells; P < 0.001), respectively. Neither tumor necrosis factor-alpha nor interferon-gamma affected bFGF synthesis by HPMCs. Stimulation of HPMCs with IL-1beta increased steady-state levels of bFGF-specific mRNA. Immunohistochemical analyses of peritoneal tissue revealed constitutive expression of bFGF by HPMCs. This in situ expression proved to be most pronounced in areas of serosal inflammation in activated HPMCs. Our study demonstrates that HPMCs synthesize and release significant amounts of bFGF and that the expression of this growth factor is significantly up-regulated by the proinflammatory cytokine IL-1beta. The data support the view that HPMCs are key regulators of abdominal disease processes such as peritonitis, peritoneal fibrosis, or peritoneal tumor metastasis.

Cells, Cultured↗

PubMed1999

Switch from antagonist to agonist of the androgen receptor bicalutamide is associated with prostate tumour progression in a new model system.

Advanced prostate cancer is treated by androgen ablation and/or androgen receptor (AR) antagonists. In order to investigate the mechanisms relevant to the development of therapy-resistant tumours, we established a new tumour model which closely resembles the situation in patients who receive androgen ablation therapy. Androgen-sensitive LNCaP cells were kept in androgen-depleted medium for 87 passages. The new LNCaP cell subline established in this manner, LNCaP-abl, displayed a hypersensitive biphasic proliferative response to androgen until passage 75. Maximal proliferation of LNCaP-abl cells was achieved at 0.001 nM of the synthetic androgen methyltrienolone (R1881), whereas 0.01 nM of this compound induced the same effect in parental cells. At later passages (> 75), androgen exerted an inhibitory effect on growth of LNCaP-abl cells. The non-steroidal anti-androgen bicalutamide stimulated proliferation of LNCaP-abl cells. AR protein expression in LNCaP-abl cells increased approximately fourfold. The basal AR transcriptional activity was 30-fold higher in LNCaP-abl than in LNCaP cells. R1881 stimulated reporter gene activity in LNCaP-abl cells even at 0.01 nM, whereas 0.1 nM of R1881 was needed for induction of the same level of reporter gene activity in LNCaP cells. Bicalutamide that acts as a pure antagonist in parental LNCaP cells showed agonistic effects on AR transactivation activity in LNCaP-abl cells and was not able to block the effects of androgen in these cells. The non-steroidal AR blocker hydroxyflutamide exerted stimulatory effects on AR activity in both LNCaP and LNCaP-abl cells; however, the induction of reporter gene activity by hydroxyflutamide was 2.4- to 4-fold higher in the LNCaP-abl subline. The changes in AR activity were associated neither with a new alteration in AR cDNA sequence nor with amplification of the AR gene. Growth of LNCaP-abl xenografts in nude mice was stimulated by bicalutamide and repressed by testosterone. In conclusion, our results show for the first time that the nonsteroidal anti-androgen bicalutamide acquires agonistic properties during long-term androgen ablation. These findings may have repercussions on the natural course of prostate cancer with androgen deprivation and on strategies of therapeutic intervention.

Androgen Antagonists↗

PubMed1999

Prostate cancer screening in Tyrol, Austria: experience and results.

BACKGROUND: This article summarizes the experience and results of different prostate carcinoma screening projects using total prostate-specific antigen (PSA) and percent free PSA as the initial test. METHODS: The twelve projects studied included: (1) a mass screening study using PSA as the initial test in 21,079 volunteers; (2) an investigation of the usefulness of normal and age-referenced PSA cut-offs in 1,618 men; (3) a PSA-based screening study of 2,272 asymptomatic blood donors; (4) an investigation of the evidence and significance of transition zone carcinoma in 340 men with negative digital rectal examination findings; (5) determination of percent free PSA in one retrospective and two prospective studies to determine the appropriate cutpoints for percent free PSA; (6) evaluation of the diagnostic benefit of PSA transition zone density in 308 screening volunteers; (7) a study of the impact of PSA-based screening on the percentage of incidental prostate carcinoma in 1, 543 men undergoing transurethral resection of the prostate; (8) an evaluation of the changes in total PSA and pathologic stages in radical prostatectomy over 5 years in a PSA-based mass screening program; (9) a study evaluating the probability of having prostate cancer given the patient's age, total PSA and digital rectal examination findings; (10) an evaluation of the correlation between preoperative predictors and pathologic features in radical prostatectomy specimens; (11) an investigation of the correlation of total PSA with pathologic stage and tumor volume in patients undergoing radical prostatectomy with low PSA cut-off level, and (12) a study whether age has an impact on the extension of prostate cancer. RESULTS: (1) of the 21,079 volunteers, 1,618 (8%) had elevated PSA levels. Of these men, 778 (48%) underwent biopsies; 197 biopsies were positive for prostate carcinoma and 135 underwent radical prostatectomy. Ninety-five were found to be organ-confined. (2) A PSA cut-off of 2.5 ng/ml in men aged 45-49 years and of 3.5 ng/ml in men aged 50-59 years resulted in an 8% increase in the detection rate of organ-confined disease. (3) Of the 2,272 men, 284 had elevated PSA levels and prostate carcinoma was detected in 62 men. All patients underwent radical prostatectomy and histologic examination revealed organ-confined tumor in all but 8 men. (4) Ninety-eight of 340 men had biopsies positive for carcinoma; 28 of these patients (28.5%) had carcinoma that originated in the transition zone only. (5) In the retrospective study, receiver-operating characteristic curve analysis showed that by using a percent free PSA of 18% as a biopsy criterion, 37% of the negative biopsies could be eliminated although 94% of all carcinomas would still be detected. In the first prospective study, 106 of 158 men with elevated PSA levels <10.0 ng/ml were further evaluated and 37 prostate carcinomas were detected. By using a % free PSA of <22% as a biopsy criterion, 30% of the negative biopsies could be eliminated although 98% of the carcinomas would still be detected. In the second prospective study, 120 of 465 men with total PSA levels between 1.25 and 6.49 ng/ml and a % free PSA <18% were further evaluated and 27 (22.5%) were found to have prostate carcinomas. (6) Receiver-operating characteristic curve analysis for PSA transition zone density showed that by using a PSA transition zone density of >22 ng/ml/cm3 as a biopsy criterion, 24.4% of negative biopsies could be avoided without missing a single carcinoma. (7) In the prescreening era the incidence of T1a grade 1 and 2 carcinomas was 3.1% and the incidence of T1a grade 3 and T1b carcinoma was 2.3% whereas in the years after the establishment of PSA-based screening the incidence was 4.6 and 1.03% respectively. (8) The rate of organ-confined tumors increased from 28.7% in 1993 to 65.7% in 1997. (9) In this evaluation a new approach to proceed with a prostate biopsy based upon the individual risk of having prostate cancer rath

Adult↗

PubMed1999

Mechanism of androgen receptor activation and possible implications for chemoprevention trials.

Androgens are pivotal regulators of prostate cell growth, differentiation and function, and their actions are believed to be involved in prostate cancer development. The androgen-signaling pathway in the prostate gland is therefore one of the possible sites of intervention in prostate cancer prevention efforts. The central element of androgen signaling in the cell is the androgen receptor (AR), a member of the superfamily of nuclear receptors. Binding of androgen to its ligand-binding domain transforms the receptor to an active transcription factor that regulates gene expression by interacting with specific regulatory elements in the promoters of genes. In addition to this genomic action, the AR also interacts with other signaling pathways through protein-protein interaction, for example with AP-1 or Ets transcription factors. It is not only the action of androgenic hormones, but also the interactions with growth factor and protein kinase A-signaling pathways that can induce activation of AR. Moreover, these ligand-independent activators act synergistically together with low concentrations of androgens. The effects of long-term androgen deprivation on androgen signaling have been investigated in the LNCaP cell culture system. Long-term culture in a steroid-free medium results in a subline showing a hyperreactive AR characterized by increased AR expression and enhanced AR transcriptional activity in an environment with low levels of androgen hormones. It is not yet clear if similar changes also occur in normal or premalignant prostate epithelial cells and are thus relevant for prevention trials which interfere with androgen hormone signaling.

Antineoplastic Agents↗

PubMed1999

Cellular and humoral immune responses in patients with metastatic renal cell carcinoma after vaccination with antigen pulsed dendritic cells.

PURPOSE: Dendritic cells are the most potent stimulators of immune responses including antitumor responses. We performed a pilot study of cultured antigen loaded dendritic cells in patients with metastatic renal cell carcinoma. MATERIALS AND METHODS: Dendritic cells were obtained by culturing plastic adherent mononuclear cells from peripheral blood for 5 days in the presence of granulocyte-macrophage colony-stimulating factor and interleukin-4. Day 5 dendritic cells were loaded with cell lysate from cultured autologous tumor cells and with the immunogenic protein keyhole-limpet hemocyanin (KLH) which serves as a helper antigen and as a tracer molecule. During the antigen pulse dendritic cells were activated with a combination of tumor necrosis factor-alpha and prostaglandin E2. Dendritic cells were administered by 3 intravenous infusions at monthly intervals. Cellular and humoral immune responses to KLH and cell lysate were measured in vitro before and after the vaccinations. RESULTS: Preparation of 12 dendritic cell vaccines from patients with advanced renal cell carcinoma was successful. Treatment with fully activated CD83+ dendritic cells was well tolerated with moderate fever as the only side effect. Potent immunological responses to KLH and, most importantly, against cell lysate could be measured in vitro after the vaccinations. CONCLUSIONS: Our data demonstrate that a dendritic cell based vaccine can induce antigen specific immunity in patients with metastatic renal cell carcinoma. Dendritic cell based immunotherapy represents a feasible, well tolerated and promising new approach for the treatment of advanced renal cell carcinoma.

Aged↗

PubMed1998

Videoimaging of prostatic stromal-cell contraction: an in vitro model for studying drug effects.

BACKGROUND: Stromal-cell contractility is known to play an important role in the development of bladder outlet obstruction secondary to benign prostatic hyperplasia (BPH). An in vitro model of single-cell contraction was developed to investigate the effect of alpha1-adrenoceptor agonists and antagonists. METHODS: Human prostatic stromal cells were isolated from prostatectomy and cystoprostatectomy specimens. The cells were cultured in a selective medium supplemented with growth factors and steroid hormones. The culture flasks were coated with a viscous agent to allow cell contraction. Contractions were visualized by means of a cell-culture microscope fitted with a time-lapse video system. For quantitative analysis, the percentage of contracting cells was evaluated. RESULTS: Nineteen percent of the cells were found to contract without stimulation. Following incubation with doxazosin (10 nM, 100 nM, and 1 mM), there was a slight dose-dependent decrease in the number of spontaneously contracting cells, whereas adrenergic stimulation using 10 microM of phenylephrine led to a significant increase in the percentage of contracting cells (55%). Following incubation with 100 nM of doxazosin, the phenylephrine-induced effect was significantly reduced. CONCLUSIONS: This simple in vitro model of cell contraction in the prostate provides a useful means of investigating drug effects on prostatic stromal cells.

Adrenergic alpha-Agonists↗

PubMed1998

Improvement of specificity in PSA-based screening by using PSA-transition zone density and percent free PSA in addition to total PSA levels.

BACKGROUND: The clinical value of prostate-specific antigen (PSA) density in differentiating between prostate cancer and benign prostatic hyperplasia has been the subject of several studies. In this context the question has been raised about the diagnostic benefit of PSA transition-zone density (PSA-TZ density = total PSA/transition-zone volume) in the detection of prostate cancer. In the following study the value of PSA-TZ density alone and in combination with free PSA was investigated. METHODS: Between August 1995-May 1996, 308 first-line screening volunteers with elevated total PSA levels ranging from 2.5-10.0 ng/ml were evaluated. All patients underwent digital rectal examination, transrectal ultrasound, and transrectal ultrasound-guided biopsy of the prostate. Prior to these investigations, serum was obtained and total as well as free PSA levels were obtained. PSA transition-zone density (PSA-TZ density) was defined as follows: PSA-TZ density = total PSA/transition-zone volume. RESULTS: ROC curve analyses for PSA-TZ density showed that by using a PSA-TZ density of more than 0.22 ng/ml/cc as a biopsy criterion, 24.4% of negative biopsies could be avoided; ROC curve analyses for free PSA showed that by using percent free PSA <20% as a biopsy criterion, 45.5% of negative biopsies could be eliminated. When combining these two diagnostic tests, 54.2% of negative biopsies could be avoided. CONCLUSIONS: We conclude that PSA-TZ density, in addition to total and free PSA, is a new opportunity which renders it possible to calculate the likelihood of detecting prostate cancer on repeat biopsies in an individual patient.

Biopsy↗

PubMed1998

Interleukin-6 regulates prostate-specific protein expression in prostate carcinoma cells by activation of the androgen receptor.

Interleukin-6 (IL-6) levels are frequently elevated in sera of patients with metastatic prostate cancer. IL-6 receptors are expressed in prostate cancer cell lines, as well as in benign prostate hyperplasia and prostate cancer tissue specimens. The androgen receptor (AR) is a key transcription factor that is present in all stages of prostate carcinoma, even in therapy-refractory tumors. In an attempt to investigate possible cross-talk between IL-6 and androgen signal transduction cascades, we tested the effects of this cytokine on AR transcriptional activity. The regulation of AR activity by IL-6 was studied in DU-145 cells, which were cotransfected with the androgen-responsive reporter plasmid ARE2TATACAT and the AR expression vector pSG5AR. We show that IL-6 up-regulates AR activity in a ligand-independent manner, as well as synergistically, with very low doses of the synthetic androgen methyltrienolone (5-10 pM). Therefore, AR activation by IL-6 may be operative in prostate cancer patients who have decreased androgen levels because of androgen ablation therapy. The maximal induction of reporter gene activity by IL-6 alone (50 ng/ml) was 67% of that stimulated by 1 nM of methyltrienolone. The nonsteroidal antiandrogen bicalutamide (Casodex) nearly completely inhibited AR activation by IL-6. IL-6 effects on AR activity were also abolished or greatly reduced by inhibitors of protein kinase A and C and mitogen-activated protein kinase pathways. In concordance with the results obtained in DU-145 cells, IL-6 induced AR-regulated prostate-specific antigen mRNA and protein in LNCaP cells. Stimulation of prostate-specific antigen protein secretion by IL-6 was antagonized by bicalutamide and inhibitors of protein kinase A and mitogen-activated protein kinase signaling pathways. Taken together, our data show for the first time that IL-6 is a nonsteroidal activator of the AR and that this activation is implicated in the regulation of prostate-specific proteins. Keeping in mind that IL-6, its receptor, and the AR are expressed in prostate cancers, cross-talk between IL-6 and AR signaling pathways may have clinical significance.

Down-Regulation↗

PubMed1998

Expression of Lewis carbohydrate antigens in metastatic lesions from human prostatic carcinoma.

BACKGROUND: Monoclonal antibodies B1 and B3 react with Lewis(y) and related carbohydrate antigens, which are abundant in many solid tumors. These antibodies, when conjugated to a toxin, have been used to target a variety of cancers. Treatment options for advanced prostate cancer are very limited, and there is a need to develop new therapies. In this study, we have asked whether antibodies B1 and B3 react with metastatic lesions from human prostatic carcinoma. METHODS: Indirect streptavidin-biotin peroxidase immunohistochemistry was performed on formalin-fixed specimens from prostate cancer metastases. A total of 6 lymph node metastatic samples from patients who did not receive endocrine treatment and specimens of 14 distant metastases from patients who failed hormonal therapy were obtained. RESULTS: Of the samples, 6 lymph node and 11 distant metastases stained for B1. In the case of B3 staining, 6 lymph node and 10 distant metastatic lesions were positive. In about half of these metastatic samples, more than 40% of cells were immunoreactive with either antibody. Two metastatic samples stained neither for B1 nor for B3 antibody. In general, B1 staining intensity was stronger in samples in which more than 40% of cells were positive. CONCLUSIONS: Our results suggest that B1 and B3 immunoconjugates could be applied to target a substantial percentage of prostate cancer metastases.

Antibodies, Monoclonal↗

PubMed1998

Formation and sequence analysis of secretoneurin, a neuropeptide derived from secretogranin II, in mammalian, bird, reptile, amphibian and fish brains.

Secretoneurin is a recently-characterized neuropeptide derived from secretogranin II, a protein belonging to the class of chromogranins. We investigated the phylogeny of this peptide by immunoblotting and gel-filtration high performance liquid chromatography followed by radioimmunoassay of brain extracts of various species including chicken, lizard, frog and fish. In addition the amino acid sequence of secretoneurin from pig, hamster, rabbit, guinea-pig and chicken was established by reverse transcriptase polymerase chain reaction. Secretoneurin is strongly conserved during evolution, it is not only expressed in various mammalian species but found also in the brain of birds, reptiles, amphibians and fish. In all these species a significant or near complete processing of secretogranin II to secretoneurin was observed. These data provide significant evidence for the neuropeptide nature of the novel functional peptide.

Amino Acid Sequence↗

PubMed1998

Differential deactivation of human dendritic cells by endotoxin desensitization: role of tumor necrosis factor-alpha and prostaglandin E2.

The endotoxin (lipopolysaccharide)-induced cytokine response is followed by a state of unresponsiveness to lipopolysaccharide (LPS) referred to as LPS tolerance or endotoxin desensitization. LPS tolerance, which can be experimentally induced in vitro and in vivo, is also known to occur in septic disease. Here, we evaluated whether dendritic cells (DC), the most potent antigen-presenting cells, are also subject to this phenomenon. Single doses of LPS added at the initiation of DC culture inhibited in a dose-dependent fashion the production of tumor necrosis factor-alpha (TNF-alpha), interleukin-10 (IL-10), and IL-12, but not the production of IL-8, in response to a second LPS challenge in day-5 DC. In addition, the LPS-induced expression of the CD83 maturation antigen was inhibited in these cells. Moreover, the endocytic activity of DC generated in the presence of LPS was dramatically reduced. DC desensitized with LPS were potent stimulators of T-cell proliferation but poor inducers of interferon-gamma (IFN-gamma) production in the allogeneic mixed leukocyte reaction. TNF-alpha and prostaglandin E2, two major products of LPS stimulation, could replace LPS for the induction of tolerance to LPS. Moreover, treatment of desensitized DC with TNF-alpha plus prostaglandin E2 fully restored CD83 expression and partially restored IL-12 production as well as the IFN-gamma-inducing activity of DC in the mixed leukocyte reaction. Our data show that human DC are highly susceptible to the induction of LPS tolerance, which seems to be a state of differential deactivation in which some functions are impaired whereas others are retained. Tolerization at the level of the professional antigen-presenting cell by inflammatory mediators may play an important role in septic disease and in the origin of cancers associated with chronic inflammation.

Antigens, CD↗

PubMed1998

Expression, structure, and function of androgen receptor in advanced prostatic carcinoma.

BACKGROUND: Endocrine therapy for prostate cancer aims to reduce the levels of circulating androgen or to inhibit androgen action by blocking the androgen receptor in the prostate, or both. Studies in various animal and human prostate cancer models suggested that there may be a downregulation of androgen receptor during prostate cancer progression. Recent work, however, showed androgen receptor expression in all stages of prostate cancer. The presence of mutant androgen receptors in a portion of prostate cancers and receptor activation in the absence of androgen or in the presence of low androgen concentrations is discussed within this context. METHODS: This review attempts to summarize the literature on androgen receptor expression in vitro and in vivo, as well as structural and functional alterations and communication between androgen signal transduction cascade and other signaling pathways. CONCLUSIONS: Prostate tumors adapt to an environment with low androgen supply by using a hyperactive androgen receptor. The mechanisms involved are mutations of the androgen receptor generating receptors with broadened activation spectrum, increased receptor expression, and activation by interaction with other signaling pathways.

Androgen Antagonists↗

PubMed1998

Recent developments in molecular action of antihormones.

Antihormones are by definition antagonists of steroid hormone action. They interact with the ligand binding domains of steroid hormone receptors and competitively inhibit the action of the receptors by mechanisms that are not quite understood. In certain cases antihormones also exhibit agonistic activity especially in connection with certain naturally occurring receptor mutants. These observations together with findings of indiscriminate interaction of antihormones with several classes of steroid receptors have necessitated a search of more effective and reliable antihormones. Recent advances in the resolution of the crystal structure of the ligand binding domains of certain members of the steroid receptor family and identification of non-liganded activation of steroid receptors have produced considerable information that can be harnessed into a fruitful search for a new generation of antihormones.

Animals↗

PubMed1998

Measurement of serum prostate-specific membrane antigen, a new prognostic marker for prostate cancer.

OBJECTIVES: To describe current results with Western blot assay for prostate specific membrane antigen (PSMA) using 7E11.C5 antibody and the development of an additional antibody measurement for PSMA by a new sandwich immunoassay. METHODS: A population of patients from a screening group, from a difficult diagnostic group, from a pre- and postoperative radical prostatectomy group, and from a group with metastatic disease followed for a serial period, provided the serum values for a prospective assessment of PSMA by Western blot assay. A new monoclonal antibody was sought, reacting to the C-terminal region of PSMA in order to develop a sandwich radioimmunoassay. RESULTS: PSMA values in screened patients correlate with the more advanced stage of the cancers determined. In postprostatectomy patients, the PSMA value corresponds more with preoperative values and with the values of those with a poor clinical course. In difficult diagnostic cases, the PSMA value is increased, specifically in hormone-refractory cases and particularly in those cases judged by other criteria, such as the National Prostatic Cancer Project, to be in clinical progression compared with those judged to be in clinical remission. The level of PSMA value appears to be independent of homogeneous tumor volume and to be more related to that of prior hormone treatment, or to where prostate cancer cells can be documented to be outside the prostate. A new monoclonal antibody, 3F5.4G6, reacts with the extracellular domain of PSMA near the C-terminal region. This is in contrast to the previously measured antibody 7E11.C5, which reacts with an N-terminal epitope. 3F5.4G6 recognizes the same PSMA protein as does 7E11.C5. The epitopes are essentially at opposite ends of the molecule. The 3F5.4G6 antibody reacts with the LNCaP line but not with DU145, or PC3. These two antibodies to PSMA are well suited for use in a new sandwich immunoassay. CONCLUSIONS: PSMA provides a prostatic cancer serum test by using Western blot, which suggests a clinical prognostic value not seen with other markers. New antibodies, such as 3F5.4G6, reacting with the extracellular domain of PSMA combined with 7E11.C5, appear to offer an opportunity for a new sandwich immunoassay.

Antibodies, Monoclonal↗

PubMed1998

Interleukin 1beta mediates the modulatory effects of monocytes on LNCaP human prostate cancer cells.

Proliferative and secretory responses in androgen-sensitive prostate cancer LNCaP cells are regulated by steroid and peptide hormones and by differentiation-promoting substances. In the present study, we evaluated whether peripheral blood monocytes that exhibit anti-tumour activity in haematopoietic and solid tumours influence growth and secretion in the LNCaP cell line. For this purpose, LNCaP cells were incubated with monocyte-conditioned medium (MCM), and proliferation as well as expression of androgen receptor (AR) and secretion of prostate-specific antigen (PSA) were assessed. Conditioned medium from monocytes reduced proliferation in a dose-dependent manner. Incubation with 40% MCM caused a 50% reduction in cell proliferation. AR protein decreased by 70% and PSA levels in supernatants from LNCaP cells were reduced by approximately 80% following treatment with MCM. We focused on the contribution of two major products of activated monocytes, prostaglandin E2 and interleukin 1beta (IL-1beta), to the MCM modulatory action. LNCaP cells treated with prostaglandin E2 showed neither a reduction in proliferation nor a down-regulation of AR and PSA levels. The effects of MCM on cellular proliferation, AR protein and PSA secretion were abolished by pretreatment of MCM with a neutralizing anti-IL-1beta antibody. In addition, recombinant IL-1beta was able to replace MCM for the inhibition of proliferation and down-regulation of AR and PSA proteins. LNCaP cells were shown to express the IL-1beta receptor type 1, which transduces IL-1beta signal. Our findings reveal that monocyte-derived IL-1beta inhibits the proliferation of androgen-responsive prostate tumour cells and reduces AR and PSA levels.

Cell Division↗

PubMed1998

Amphiregulin is expressed in primary cultures of prostate myofibroblasts, fibroblasts, epithelial cells, and in prostate tissue.

The effect and expression of amphiregulin, a growth factor of the EGF-system was investigated in prostate primary cell cultures and in human prostate tissue. Amphiregulin increases proliferation in primary cultures of prostate myofibroblasts grown in serum-free medium. Amphiregulin mRNA is expressed in high amounts in primary cell cultures of prostate myofibroblasts, fibroblasts, epithelial cells, and in samples of prostate tissue. The data are supported by Western-blotting of amphiregulin in prostate myofibroblasts. These data call for a refocus of the expression and effects of the EGF system in the prostate.

Journal Article↗

PubMed1998

Activation of human dendritic cells by bacillus Calmette-Guerin.

PURPOSE: Dendritic cells are the most potent antigen presenting cells capable of initiating antitumor immune responses. We previously showed that bacillus Calmette-Guerin (BCG) stimulates cultured human dendritic cells. We extended these studies and tested the ability of cultured human dendritic cells to express interleukin IL-8 in response to BCG. We also investigated the T cell stimulatory potential of BCG treated dendritic cells in mixed leukocyte reactions. MATERIALS AND METHODS: Dendritic cells were obtained by culturing plastic adherent mononuclear cells from peripheral blood for 6 days in the presence of granulocyte-macrophage colony-stimulating factor and IL-4. Spontaneous and BCG stimulated IL-8 protein release into culture supernatants was measured by a quantitative immunoassay. IL-8 gene transcription was assessed by reverse transcription-polymerase chain reaction. Untreated and BCG exposed dendritic cells were compared as stimulators of allogeneic T cell proliferation, measured as [3H]thymidine incorporation. RESULTS: BCG stimulated IL-8 messenger ribonucleic acid expression and IL-8 protein release. IL-8 secretion occurred in a dose and time dependent fashion. BCG induced IL-8 release was further enhanced in the presence of indomethacin. BCG treated dendritic cells were much more potent T cell stimulators than untreated dendritic cells. CONCLUSIONS: These data demonstrate that BCG enhances the production of IL-8, a potent chemokine of T cells and granulocytes, as well as the T cell stimulatory potential of human dendritic cells.

Antibodies, Monoclonal↗