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Biomedical subjects

M R Freeman

Publications and source records attributed to M R Freeman.

At least 37 records · Page 2Linked to original sources
PubMed1999

The phosphatidylinositol 3'-kinase pathway is a dominant growth factor-activated cell survival pathway in LNCaP human prostate carcinoma cells.

Intracellular signaling pathways that mediate survival of prostate carcinoma (PCa) cells are poorly understood. We examined the potential role of the phosphatidylinositol 3' kinase (PI3K) pathway as a mediator of cell survival in LNCaP human PCa cells, which express a variety of properties characteristic of human prostate cancer. LNCaP cell cultures rapidly became apoptotic when treated with the specific PI3K inhibitors, wortmannin and LY294002. In contrast, apoptosis was not induced when the cells were treated with: (a) rapamycin, an inhibitor of the ribosomal S6 kinase pp70S6K, which acts downstream of PI3K; (b) PD98059, a specific inhibitor of the extracellular signal-regulated kinase/mitogen-activated protein kinase (Erk/MAPK) kinase (MEK); or (c) the antiandrogen, Casodex; or when the cells were cultured under androgen-depleted conditions. Apoptosis induced by PI3K inhibition was attenuated by: (a) dihydrotestosterone; or (b) the ErbB1 activating ligands [epidermal growth factor (EGF), transforming growth factor alpha, or heparin-binding EGF-like growth factor]. In response to ErbB1 activation by ligand, the p85 regulatory subunit of PI3K associated specifically with ErbB3 but not detectably with ErbB1. The anti-apoptotic effect of ErbB1 activation was significantly reduced when cells were treated simultaneously with wortmannin and PD98059. These data indicate that survival signals can be evoked in LNCaP cells by several distinct pathways and can be triggered by nuclear and cell-surface receptors. Constitutive signaling through the PI3K pathway is required to prevent cell death in LNCaP, whereas activation of the Erk/MAPK and androgen response pathways is not obligatory for cell survival. These results also show that survival signals, as distinguished from mitogenic signals, can be evoked in PCa cells by ErbB1 ligands known to be synthesized within the human prostate.

Androgens↗
PubMed1999

Oxybutynin chloride inhibits proliferation and suppresses gene expression in bladder smooth muscle cells.

PURPOSE: We test the hypothesis that oxybutynin chloride inhibits bladder smooth muscle cell proliferation. MATERIALS AND METHODS: Cultured rat bladder smooth muscle cells were grown in Medium 199 supplemented with 10% fetal bovine serum in the presence of 0, 1, 10 and 100 microM. oxybutynin. Cell proliferation was assessed by counting cell numbers 48 and 96 hours after plating. To investigate the role of oxybutynin in bladder smooth muscle cell proliferation after mechanical stretch, cells were grown on silicone elastomer bottomed culture plates and subjected to cyclical stretch-relaxation for 48 hours in the presence of 10 microM. oxybutynin. Deoxyribonucleic acid synthesis was assessed by tritiated thymidine incorporation assay. To examine the effect of oxybutynin on stretch activated gene expression, bladder smooth muscle cells were subjected to stretch-relaxation for 2 hours with and without 10 microM. oxybutynin, and relative c-jun messenger (m) ribonucleic acid (RNA) levels were assessed by semiquantitative reverse transcriptase-polymerase chain reaction with normalization to glyceraldehyde-3-phosphate dehydrogenase mRNA levels. RESULTS: The serum stimulated increase in bladder smooth muscle cell growth was inhibited by oxybutynin in a dose dependent manner. In bladder smooth muscle cells there was a 4.7-fold increase in deoxyribonucleic acid synthesis after mechanical stretch, which decreased by 40% (p <0.01) when cells were stretched in the presence of oxybutynin. Stretch stimulated significant increase in c-jun mNRA levels, which was significantly decreased by oxybutynin. CONCLUSIONS: Oxybutynin chloride inhibits bladder smooth muscle cell proliferation induced by serum and mechanical stretch. A potential mechanism by which oxybutynin inhibits proliferation may be the down regulation of growth promoting genes, such as c-jun. We speculate that oxybutynin may be useful for preventing permanent hypertrophic bladder changes in addition to decreasing intravesical pressure.

Animals↗
PubMed1999

The effects of sustained hydrostatic pressure on select bladder smooth muscle cell functions.

PURPOSE: Normal bladder development is believed to depend on the active work of the bladder for storing and expelling urine. When high urinary diversion is performed in infants and the bladder no longer undergoes normal filling, bladder development may be altered, ultimately resulting in bladder dysfunction. To help better understand this relationship of bladder function with growth at the cellular level we developed a novel laboratory method for applying hydrostatic pressure to cell cultures, and we characterized the response of neonatal bladder smooth muscle cells to physiological levels of sustained hydrostatic pressure. MATERIALS AND METHODS: Neonatal ovine smooth muscle cells staining positive for desmin and alpha-smooth muscle actin were exposed to pressures of 0.3 (controls), 2, 4, 6 and 8.5 cm. water for 1, 3, 5 and 7 days. At the end of the experiments the cells were fixed, stained and counted. Mitogenic activity of the supernatant media from bladder smooth muscle cells exposed to 8.5 cm. water for 5 days (conditioned media) was tested before and after treatments of heating, freezing, passing through a heparin-sepharose affinity chromatography column or after the addition of suramin, a nonspecific growth factor inhibitor. Statistical analysis was performed using Student's t test with p <0.05 considered statistically significant. RESULTS: Exposure of bladder smooth muscle cells to sustained hydrostatic pressures of 4, 6 and 8.5 cm. water resulted in increased cell proliferation. Differences became statistically significant (p <0.05) by day 5. Also, conditioned media contained mitogenic activity that was ablated by heating, freezing, passage through a heparin-sepharose affinity chromatography column or with the addition of suramin. CONCLUSIONS: We have demonstrated a proliferative response of neonatal bladder smooth muscle after exposure to physiological levels of sustained hydrostatic pressure. This response is partially due to 1 or more transferable mitogenic factors. These data support the hypothesis that pressure associated with bladder filling is an important stimulus for detrusor development.

Animals↗
PubMed1999

Plasma levels of vascular endothelial growth factor are increased in patients with metastatic prostate cancer.

OBJECTIVES: Vascular endothelial growth factor (VEGF) is a cytokine that plays an important role in tumor angiogenesis. VEGF is overexpressed in many human cancers, including prostate cancer, but circulating levels of VEGF in patients with prostate cancer have not been reported. In this study, we analyzed plasma concentrations of VEGF in a cohort of patients with prostate cancer and compared them with a normal population. METHODS: Twenty-six healthy, cancer-free individuals and 80 patients with prostate cancer (54 patients with localized prostate cancer and 26 patients with metastatic prostate cancer [bone or lymph node positive]) were analyzed in this study. Blood was drawn in the same fashion from all individuals and deposited in tubes containing ethylenediaminetetraacetic acid as anticoagulant. Plasma was extracted and VEGF concentrations were determined using a quantitative sandwich enzyme immunoassay technique. RESULTS: Median plasma VEGF was 28.5 pg/mL (interquartile range 19.3 to 57.0) in patients with metastases; 7.0 pg/mL (interquartile range 0 to 26.5) in patients with localized disease, and 0 pg/mL (interquartile range 0 to 24) in controls. These differences were statistically significant (P <0.001). When compared group by group, the metastatic group had significantly higher plasma VEGF than the localized disease group and the control group (P = 0.003 and P <0.001, respectively). There was a tendency for plasma VEGF to be higher in the localized disease group than in the control group, a trend that almost reached statistical significance (P = 0.038). Using a cutoff of 18 pg/mL, the sensitivity and specificity of the test in differentiating between patients with and without metastatic disease was 81% and 71%, respectively. The odds of metastatic disease were almost 10 times greater for patients with VEGF values greater than 18 pg/mL than for those with values less than 18 pg/mL. There was no correlation between age and plasma VEGF values or between plasma VEGF and serum prostate-specific antigen (PSA). However, patients with serum PSA greater than 20 ng/mL had significantly higher plasma VEGF values than patients with serum PSA less than 20 ng/mL (P <0.001). No direct relation was found between Gleason sum and plasma VEGF, although VEGF levels were higher in patients with Gleason sums of 8 to 10 than in patients with lower Gleason sums. CONCLUSIONS: Our study indicates that patients with metastatic prostate cancer have higher plasma VEGF levels than patients with localized disease or healthy controls. A larger prospective study is needed to confirm the predictive utility of VEGF.

Aged↗
PubMed1999

A novel family of divergent seven-transmembrane proteins: candidate odorant receptors in Drosophila.

Although insects have proven to be valuable models for exploring the function, organization, and development of the olfactory system, the receptor molecules that bind odors have not been identified in any insect. We have developed a novel search algorithm, used it to search the Drosophila genomic sequence database, and identified a large multigene family encoding seven transmembrane domain proteins that are expressed in olfactory organs. We show that expression is restricted to subsets of olfactory receptor neurons (ORNs) for a number of these genes. Different members of the family initiate expression at different times during antennal development. Some of the genes are not expressed in a mutant of the Acj6 POU-domain transcription factor, a mutant in which a subset of ORNs show abnormal odorant specificities.

Amino Acid Sequence↗
PubMed1999

Angiogenic switch and vascular stability in human Leydig cell tumours.

The high degree of vascularisation, accompanied by the low malignancy of human Leydig cell tumours, offers an interesting model to study the neovascularisation and structural stabilisation of the vascular wall. We report here that Leydig cell tumours are characterised by an increased level of vascular endothelial growth factor (VEGF) in testicular veins, the presence of VEGF mRNA and of its receptor, KDR, and an absence of detectable VEGF receptor Flt-1, in blood vessels of tumour marginal zones and of peri-tumour areas. This is in contrast to the capillaries within normal Leydig cell clusters which demonstrate both Flt-1 and KDR. Ultrastructural destabilisation of the vascular wall, evident as a lack of basement membrane and of peri-endothelial cells was also present in nearly 85% of blood vessels of the peri-tumour areas. In contrast, approximately 89% of the blood vessels of the tumour centre region demonstrated a stabilised vascular wall including basement membrane and peri-endothelial cells. Local application of VEGF(165) to the normal testicular tissue induced significant ultrastructural destabilisation in the capillary walls which only expressed KDR. These results suggest an autocrine role of VEGF on endothelial cells of tumour blood vessels in a region-specific manner and implicate that VEGF interactions with KDR, in the absence of Flt-1, may be involved in vascular destabilisation. In addition, the finding that most (79%) of Leydig tumour blood vessels are stabilised may account for the low malignant potential of these tumours.

Journal Article↗
PubMed1999

AP-1 mediates stretch-induced expression of HB-EGF in bladder smooth muscle cells.

Mechanical induction of growth factor synthesis may mediate adaptive responses of smooth muscle cells (SMC) to increases in physical load. We previously demonstrated that cyclic mechanical stretch induces expression of the SMC, fibroblast, and epithelial cell mitogen heparin-binding epidermal growth factor-like growth factor (HB-EGF) in bladder SMC, an observation that suggests that this growth factor may be involved in compensatory bladder hypertrophy. In the present study we provide evidence that the activator protein-1 (AP-1) transcription factor plays a critical role in this mechanoinduction process. Rat bladder SMC were transiently transfected with a series of 5' deletion mutants of a promoter-reporter construct containing 1. 7 kb of the mouse HB-EGF promoter that was previously shown to be stretch responsive. The stretch-mediated increase in promoter activity was completely ablated with deletion of nucleotide positions -1301 to -881. Binding of AP-1, as evaluated by electrophoretic mobility shift assay, to a synthetic oligonucleotide containing an AP-1 binding site increased in response to stretch, and binding was inhibited by excess unlabeled DNA corresponding to nucleotides -993 to -973 from the HB-EGF promoter, a region that contains a previously recognized composite AP-1/Ets site. Stretch-induced promoter activity was significantly inhibited by site-directed mutagenesis of the AP-1 or Ets components of this site. Consistent with the promoter and gel-shift studies, curcumin, an inhibitor of AP-1 activation, suppressed the HB-EGF mRNA induction after stretch. Stretch also specifically increased mRNA levels for matrix metalloproteinase (MMP)-1, the promoter of which contains a functional AP-1 element, but not for MMP-2, the promoter of which does not contain an AP-1 element. The stretch response of the MMP-1 gene was also completely inhibited by curcumin. Collectively, these findings indicate that AP-1-mediated transcription plays an important role in the regulation of gene expression in bladder muscle in response to mechanical forces.

Animals↗
PubMed1999

Obstruction stimulates COX-2 expression in bladder smooth muscle cells via increased mechanical stretch.

Studies were performed to investigate the regulatory mechanism of bladder cyclooxygenase-2 (COX-2) expression after outlet obstruction. In situ hybridization of murine bladder tissues using COX-2-specific riboprobes demonstrated that COX-2 expression was induced predominantly in the bladder smooth muscle cells after outlet obstruction. To study the effect of increased mechanical stretch on COX isoform expression, cultured rat bladder smooth muscle cells were grown on silicone elastomer-bottomed plates coated with collagen type I and were subjected to continuous cycles of stretch/relaxation for variable duration. COX-1 mRNA levels did not change with stretch. COX-2 expression increased in a time-dependent manner after stretch, with maximal mRNA and protein levels occurring after 4 h. PGE2 levels increased more than 40-fold in the culture media after stretch, consistent with increased COX activity, and this was reduced to near completion in the presence of a COX-2 inhibitor, NS-398. Exposure to stretch over a 48-h period induced a 4.7 +/- 0.6-fold increase in tritiated thymidine incorporation rate. This increase in DNA synthesis was markedly suppressed when the cells were stretched in the presence of NS-398. We conclude that in bladder obstruction COX-2 activation occurs predominantly in the smooth muscle cells in response to mechanical stretch. Our findings also suggest that stretch-activated COX-2 expression may participate in bladder smooth muscle cell proliferation and thereby play a role in pathological bladder wall thickening after obstruction.

Animals↗
PubMed1999

Amphiregulin is coordinately expressed with heparin-binding epidermal growth factor-like growth factor in the interstitial smooth muscle of the human prostate.

Peptide growth factors have been proposed as mediators of smooth muscle-epithelial cell interactions in the human prostate; however, the identity of these molecules has not been established. In this study, we compared expression levels of messenger RNAs (mRNAs) encoding the epidermal growth factor (EGF) receptor-related receptor tyrosine kinases (ErbB1 through 4), the six EGF receptor ligands, EGF, transforming growth factor (TGF)-alpha, amphiregulin (ARG), HB-EGF, betacellulin, and epiregulin, and the related molecule heregulin-alpha, in a series of 10 prostate tissue specimens. Only EGF showed a disease-specific association, with increased mRNA levels in four of five PCa specimens in comparison to matched normal tissue from the same subject. In contrast, ARG and HB-EGF mRNAs showed a coordinate pattern of expression in 7/10 specimens that was distinct from all other growth factor or receptor genes examined and from mRNAs for prostate specific antigen, the androgen receptor and GAPDH, a house-keeping enzyme. Analysis of an additional series of benign prostatic hyperplasia and prostate cancer specimens from 60 individuals confirmed that ARG and HB-EGF mRNA levels varied in a highly coordinate manner (r = 0.93; P < 0.0001) but showed no association with disease. ARG was immunolocalized largely to interstitial smooth muscle cells (SMC), previously identified as the site of synthesis of HB-EGF in the prostate, while the cognate ARG and HB-EGF receptor, ErbB1, was localized exclusively to ductal epithelial cells and carcinoma cells. Although ARG was a relatively poor mitogen for Balb/c3T3 cells in comparison to HB-EGF, it was similar in potency to HB-EGF in stimulating human prostate epithelial cell growth, suggesting that prostate epithelia may be a physiologic target for ARG in vivo. Expression of both ARG and HB-EGF mRNAs was induced in cultured prostate SMC by fibroblast growth factor-2, a human prostate SMC mitogen linked to prostate disease. These findings indicate that ARG and HB-EGF are likely to be key mediators of directional signaling between SMC and epithelial cells in the human prostate and appear to be coordinately regulated.

Amphiregulin↗
PubMed1999

Ecdysone response genes govern egg chamber development during mid-oogenesis in Drosophila.

The steroid hormone ecdysone regulates larval development and metamorphosis in Drosophila melanogaster through a complex genetic hierarchy that begins with a small set of early response genes. Here, we present data indicating that the ecdysone response hierarchy also mediates egg chamber maturation during mid-oogenesis. E75, E74 and BR-C are expressed in a stage-specific manner while EcR expression is ubiquitous throughout oogenesis. Decreasing or increasing the ovarian ecdysone titer using a temperature-sensitive mutation or exogenous ecdysone results in corresponding changes in early gene expression. The stage 10 follicle cell expression of E75 in wild-type, K10 and EGF receptor (Egfr) mutant egg chambers reveals regulation of E75 by both the Egfr and ecdysone signaling pathways. Genetic analysis indicates a germline requirement for ecdysone-responsive gene expression. Germline clones of E75 mutations arrest and degenerate during mid-oogenesis and EcR germline clones exhibit a similar phenotype, demonstrating a functional requirement for ecdysone responsiveness during the vitellogenic phase of oogenesis. Finally, the expression of Drosophila Adrenodoxin Reductase increases during mid-oogenesis and clonal analysis confirms that this steroidogenic enzyme is required in the germline for egg chamber development. Together these data suggest that the temporal expression profile of E75, E74 and BR-C may be a functional reflection of ecdysone levels and that ecdysone provides temporal signals regulating the progression of oogenesis and proper specification of dorsal follicle cell fates.

Animals↗
PubMed1999

The dare gene: steroid hormone production, olfactory behavior, and neural degeneration in Drosophila.

Steroid hormones mediate a wide variety of developmental and physiological events in insects, yet little is known about the genetics of insect steroid hormone biosynthesis. Here we describe the Drosophila dare gene, which encodes adrenodoxin reductase (AR). In mammals, AR plays a key role in the synthesis of all steroid hormones. Null mutants of dare undergo developmental arrest during the second larval instar or at the second larval molt, and dare mutants of intermediate severity are delayed in pupariation. These defects are rescued to a high degree by feeding mutant larvae the insect steroid hormone 20-hydroxyecdysone. These data, together with the abundant expression of dare in the two principal steroid biosynthetic tissues, the ring gland and the ovary, argue strongly for a role of dare in steroid hormone production. dare is the first Drosophila gene shown to encode a defined component of the steroid hormone biosynthetic cascade and therefore provides a new tool for the analysis of steroid hormone function. We have explored its role in the adult nervous system and found two striking phenotypes not previously described in mutants affected in steroid hormone signaling. First, we show that mild reductions of dare expression cause abnormal behavioral responses to olfactory stimuli, indicating a requirement for dare in sensory behavior. Then we show that dare mutations of intermediate strength result in rapid, widespread degeneration of the adult nervous system.

Amino Acid Sequence↗
PubMed1999

Heparin-binding EGF-like growth factor expression increases selectively in bladder smooth muscle in response to lower urinary tract obstruction.

Heparin-binding epidermal growth factor-like growth factor (HB-EGF), an activating ligand for the epidermal growth factor receptor (ErbB1) tyrosine kinase and at least one isoform of the ErbB4 receptor tyrosine kinase, is synthesized by the smooth muscle of the human bladder wall. In this study we tested the hypothesis that HB-EGF plays a role in the bladder-wall thickening that occurs in response to obstructive syndromes affecting the lower urinary tract, possibly by acting as an autocrine smooth muscle cell (SMC) growth factor. HB-EGF was mitogenic for primary culture human bladder SMC, and cell growth in serum-containing medium was inhibited more than 70% by [Glu52]-diphtheria toxin/CRM197, a specific HB-EGF inhibitor, consistent with a physiologic role for HB-EGF as an autocrine bladder SMC mitogen. Human and mouse bladder SMC in vivo and cultured human bladder SMC expressed the primary HB-EGF receptor, ErbB1, but not mRNA for the secondary HB-EGF receptor, ErbB4, thereby identifying ErbB1 as the cognate HB-EGF receptor in the bladder wall. Reverse transcription-polymerase chain reaction analysis also demonstrated ErbB2 and ErbB3 expression in human bladder muscle tissue, suggesting the possibility of receptor cross-talk after ErbB1 activation. Urethral ligation in mice resulted in an increase in steady-state HB-EGF mRNA expression up to 24 hours in whole bladder tissue in comparison with ErbB1 and glyceraldehyde 3-phosphate dehydrogenase mRNA levels, which did not change in a demonstrable pattern. HB-EGF protein increased coordinately with HB-EGF mRNA levels. Dissection of bladder tissue into muscle and mucosal layers demonstrated that the increase in HB-EGF mRNA occurred predominantly in the muscle layer, with peak levels (13-fold higher than sham controls) occurring 12 hours after obstruction. These data support a physiologic role for HB-EGF as a mediator of hypertrophic bladder tissue growth.

Animals↗
PubMed1998

Extracellular calcium influx stimulates metalloproteinase cleavage and secretion of heparin-binding EGF-like growth factor independently of protein kinase C.

The phorbol ester, tetradecanoyl-phorbol 13-acetate (TPA), stimulates rapid proteolytic processing of the transmembrane, pro- form of heparin-binding epidermal growth factor-like growth factor (HB-EGF) at cell surfaces, suggesting the involvement of protein kinase C (PKC) isoforms in the HB-EGF secretion mechanism. To test this possibility, we expressed a chimeric protein, consisting of proHB-EGF fused to placental alkaline phosphatase (AP) near the amino terminus of processed HB-EGF, in NbMC-2 prostate epithelial cells. The proHB-EGF-AP chimera localized to plasma membranes and functioned as a diphtheria toxin receptor. Secreted HB-EGF-AP bound to heparin and exhibited potent growth factor activity. The presence of the AP moiety allowed highly quantitative measurements of cleavage-secretion responses of proHB-EGF to extracellular stimuli. As expected, rapid secretion of HB-EGF-AP was induced in a time- and dose-dependent manner by TPA. However, this was also observed with the Ca2+ ionophore, ionomycin, suggesting the involvement of extracellular Ca2+ ions in the secretion mechanism. Ionomycin-induced secretion was inhibited by extracellular calcium chelation but not by the PKC inhibitors, GF109203X, staurosporine, or chelerythrine. The TPA-mediated secretion effect was inhibited by staurosporine, GF109203X, and by pretreatment with TPA, but not by calcium chelation. A small secretion response was induced by thapsigargin, which releases Ca2+ from intracellular stores, but this was completely eliminated by extracellular calcium chelation. Ionomycin- and TPA-induced HB-EGF-AP secretion was not dependent on the presence of the proHB-EGF cytoplasmic domain and was specifically inhibited by the metalloproteinase inhibitors 1,10-phenanthroline and tissue inhibitor of metalloproteinase-1 (TIMP-1). These data demonstrate that extracellular Ca2+ influx activates a membrane-associated metalloproteinase to process proHB-EGF by a pathway that does not require PKC.

Alkaline Phosphatase↗
PubMed1998

Increased incidence of matrix metalloproteinases in urine of cancer patients.

Matrix metalloproteinases (MMPs) have been implicated in mechanisms of metastasis in experimental cancer models and in human malignancies. In this study, we used substrate gel electrophoresis (zymography) to determine the frequency of detection of MMPs in urine of patients with a variety of cancers. Three molecular weight classes of urinary MMPs, Mr 72,000, Mr 92,000, and high molecular weight (Mr > or = 150,000) species, were detected reproducibly and correlated with disease status. The Mr 72,000 and Mr 92,000 species were identified as MMP-2 and MMP-9, respectively, by Western blot analysis. The presence of biologically active MMP-2 (P < 0.001) or MMP-9 (P = 0.002) was an independent predictor of organ-confined cancer, and the high molecular weight species (P < 0.001) was an independent predictor of metastatic cancer. This is the first study to demonstrate that analysis of urinary MMPs may be useful in determining disease status in a variety of human cancers, both within and outside of the urinary tract.

Adult↗
PubMed1998

Heparin-binding EGF-like growth factor in the human prostate: synthesis predominantly by interstitial and vascular smooth muscle cells and action as a carcinoma cell mitogen.

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is an activating ligand for the EGF receptor (HER1/ErbB1) and the high-affinity receptor for diphtheria toxin (DT) in its transmembrane form (proHB-EGF). HB-EGF was immunolocalized within human benign and malignant prostatic tissues, using monospecific antibodies directed against the mature protein and against the cytoplasmic domain of proHB-EGF. Prostate carcinoma cells, normal glandular epithelial cells, undifferentiated fibroblasts, and inflammatory cells were not decorated by the anti-HB-EGF antibodies; however, interstitial and vascular smooth muscle cells were highly reactive, indicating that the smooth muscle compartments are the major sites of synthesis and localization of HB-EGF within the prostate. In marked contrast to prostatic epithelium, proHB-EGF was immunolocalized to seminal vesicle epithelium, indicating differential regulation of HB-EGF synthesis within various epithelia of the reproductive tract. HB-EGF was not overexpressed in this series of cancer tissues, in comparison to the benign tissues. In experiments with LNCaP human prostate carcinoma cells, HB-EGF was similar in potency to epidermal growth factor (EGF) in stimulating cell growth. Exogenous HB-EGF and EGF each activated HER1 and HER3 receptor tyrosine kinases and induced tyrosine phosphorylation of cellular proteins to a similar extent. LNCaP cells expressed detectable but low levels of HB-EGF mRNA; however, proHB-EGF was detected at the cell surface indirectly by demonstration of specific sensitivity to DT. HB-EGF is the first HER1 ligand to be identified predominantly as a smooth muscle cell product in the human prostate. Further, the observation that HB-EGF is similar to EGF in mitogenic potency for human prostate carcinoma cells suggests that it may be one of the hypothesized stromal mediators of prostate cancer growth.

Carcinoma↗
PubMed1998

Permanent impairment of embryo development by hydrosalpinges.

Recent reports suggest a deleterious effect of hydrosalpinges on pregnancy outcome for in-vitro fertilization (IVF) and improvement following surgical treatment. We compared the effect of hydrosalpinx on pregnancy outcome in 286 patients having 348 IVF cycles and followed the development of untransferred embryos for 7 days to determine if hydrosalpinges affect oocyte quality or embryo development. The delivery rate per retrieval was significantly lower for patients with hydrosalpinx, but was restored by surgical treatment to that of patients without hydrosalpinx. However, the implantation rate per embryo transferred and normal blastulation of untransferred embryos, which were significantly decreased in patients with hydrosalpinx, and growth arrest and degeneration of untransferred embryos, which were significantly increased compared to patients without hydrosalpinx, were not restored by surgical treatment of hydrosalpinges. We conclude that surgical treatment of hydrosalpinges decreases early pregnancy loss and improves pregnancy outcome, possibly by diminishing reversible deleterious effects exerted on the endometrium. As we have seen in our laboratory, hydrosalpinges may have a permanent negative influence on ovarian function, follicular development and oocyte quality since implantation of transferred embryos and normal blastulation of untransferred embryos remain low, and in-vitro growth arrest and degeneration remain high despite surgical treatment of hydrosalpinges.

Abortion, Spontaneous↗
PubMed1998

Stretch activates heparin-binding EGF-like growth factor expression in bladder smooth muscle cells.

Cultured rat bladder smooth muscle cells (SMC) were grown on collagen-coated silicone membranes and subjected to continuous cycles of stretch-relaxation. Semiquantitative RT-PCR analysis revealed a time-dependent increase in heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) mRNA levels after stretch, with maximal levels appearing after 4 h. Immunostaining for proHB-EGF revealed higher levels of HB-EGF protein in the stretched than in the nonstretched SMC. The ANG II receptor type 1 antagonist losartan markedly suppressed stretch-activated HB-EGF expression. ANG II levels were 3.3-fold higher in the stretch- than in the non-stretch-conditioned media. Stretch stimulation of bladder SMC that had been transiently transfected with an HB-EGF promoter-luciferase expression construct resulted in an 11-fold increase in reporter activity. Mechanical stretch induced a 4.7-fold increase in tritiated thymidine incorporation rate, and this was reduced by 25% in the presence of losartan. We conclude that mechanical stretch activates HB-EGF gene expression in bladder SMC and that this is mediated in part by autocrine ANG II secretion.

Angiotensin II↗