TGF-betas upregulate NCAM and L1 expression in cultured Schwann cells, suppress cyclic AMP-induced expression of O4 and galactocerebroside, and are widely expressed in cells of the Schwann cell lineage in vivo

We have examined both how the molecular phenotype of Schwann cells in vitro is regulated by transforming growth factor beta (TGF-beta), using immunohistochemistry and immunoblotting, and the distribution of TGF-beta 2 and 3 in embryonic and mature nerves and ganglia, using immunohistochemistry and in situ hybridisation. We find that TGF-beta 2 and -3 upregulate expression of the neural cell adhesion molecules NCAM and L1. In TGF-beta-treated cultures, in addition to the 140 and 120 kD isoforms known to be present in Schwann cells, small amounts of the 180 kD isoform can be detected. TGF-beta s also block cAMP-induced expression of the lipid antigens galactocerebroside (GalC) and O4, in addition to blocking expression of protein zero (P0), the major peripheral myelin glycoprotein, as previously shown. Using antibodies specific to TGF-beta 2 and -3, respectively, we confirm the presence of these proteins in myelin-forming Schwann cells and show also that TGF-beta 2 and -3 are clearly expressed by peripheral glia that are not involved in myelination. This includes Schwann cell precursors, embryonic Schwann cells, non-myelin-forming Schwann cells and satellite cells from adult nerves and ganglia, and neonatal Schwann cells in purified cultures without neurones. In situ hybridisation with a digoxygenin-labelled riboprobe reveals a strong TGF-beta 3 mRNA signal in Schwann cells, satellite cells, and some neurones. Schwann cells in culture also secrete TGF-beta in a latent form, whereas purified cultures of dorsal root ganglion neurones from 1-day-old rats secrete active TGF beta during the first 48 h in culture.

The Edinburgh randomized trial of axillary sampling or clearance after mastectomy

Between January 1980 and October 1983, 417 patients were randomized for mastectomy followed by axillary node sampling or full axillary clearance. The aim of the study was to determine whether a standard 'four-node' axillary sample, followed by careful dissection of removed tissue, could accurately indicate the extent of local treatment required. Axillary radiotherapy was given only to patients with histological involvement of sampled nodes and not to any having axillary clearance. The incidence of involved nodes was similar for both groups, as were distant relapse and survival rates. Currently 62.6 percent are alive after clearance and 65.0 percent after sampling. A non-significant increase in the rate of locoregional relapse was observed for those treated by axillary node clearance, this being due mainly to increased relapse on the unirradiated chest wall (clearance 21 percent versus sampling 12 percent in patients with node-positive disease). There was only a minor difference in axillary relapse, favouring axillary clearance (3.0 versus 5.4 percent). In patients with operable breast cancer, mastectomy with axillary node sampling gives equal control to mastectomy with axillary node clearance but, as morbidity is greater, surgical clearance of the axilla is the preferred option.

Cardiac and vascular morbidity in women receiving adjuvant tamoxifen for breast cancer in a randomised trial. The Scottish Cancer Trials Breast Group

OBJECTIVE

To determine any cardiac or vascular morbidity associated with long term treatment with tamoxifen given after mastectomy for primary breast cancer.

DESIGN

Cohort study using linkage between database of a randomised trial and statistics of Scottish hospital inpatients to identify episodes of cardiac and vascular morbidity.

SETTING

NHS hospitals in Scotland.

SUBJECTS

1312 women who had undergone mastectomy for breast cancer and who were randomised either to a treatment group to receive adjuvant tamoxifen or to a control group to be given tamoxifen only on first relapse of disease. Maximum duration of tamoxifen treatment was 14 years. Total woman years of follow up were 9943.

MAIN OUTCOME MEASURES

Randomised and observational comparisons of risk (expressed as hazard ratios) of myocardial infarction, other cardiac event, cerebrovascular disease, or thromboembolic event according to treatment allocated and between nonusers, former users, and current users of tamoxifen.

RESULTS

Use of tamoxifen was associated with lower rates of myocardial infarction. Hazard ratio for women in control group was 1.92 (95% confidence interval 0.99 to 3.73) compared with women allocated to adjuvant treatment. The association was stronger for current use: hazard ratio for non-users was 3.49 (1.52 to 8.03) compared with current users. Current users of tamoxifen, however, had higher rates of thromboembolic events:hazard ratio for non-users was 0.40 (0.18 to 0.90) compared with current users.

CONCLUSIONS

Our results provide further evidence that tamoxifen reduces the risk of myocardial infarction. Thromboembolic events should be carefully monitored in trials of tamoxifen, particularly those of prophylactic treatment, in which tamoxifen is given to healthy women.

Structure and expression of an ovine endometrial oxytocin receptor cDNA

A sheep endometrial oxytocin receptor (OTR) cDNA (1.5 kb) was isolated from a lambda-ZAP library using a reverse transcription-PCR product probe generated from oestrous endometrial mRNA. The sheep OTR cDNA shared an overall similarity of 82% with human OTR cDNA, 85% with pig OTR cDNA and 76% with rat OTR cDNA. The encoded receptor was a 391 amino acid polypeptide 94% similar to human OTR, 94% similar to pig OTR and 93% similar to rat OTR. The sheep OTR contained two additional amino acids compared with human OTR which were located in the highly GC-rich third intracytoplasmic loop. This region is thought to be associated with G protein coupling and signal transduction. Expression of the cDNA in Cos-7 cells and measurement of oxytocin-induced phosphoinositide turnover confirmed that it coded for a functional product. The affinity of the expressed receptor was comparable with that observed for the in vivo receptor.

TGF-beta s and cAMP regulate GAP-43 expression in Schwann cells and reveal the association of this protein with the trans-Golgi network

We have shown previously that growth-associated protein 43 (GAP-43) is expressed by rat Schwann cells and is restricted to non-myelin-forming Schwann cells in vivo. Here we examined the regulation of GAP-43 using agents that are known to control Schwann cell differentiation in vitro. GAP-43 protein and mRNA levels are decreased by forskolin and other agents that elevate intracellular cAMP (and promote expression of the myelinating Schwann cell phenotype). We also found that expression of GAP-43 protein but not mRNA is down-regulated by transforming growth factor betas (TGF-beta s). Moreover, TGF-beta treatment of Schwann cells results in cell clumping, process retraction and disappearance of GAP-43 from the plasma membrane, revealing that GAP-43 is associated with the Golgi apparatus. This association was confirmed by partial overlap of GAP-43 with the trans-Golgi network marker (23c) and the disruption of the Golgi with brefeldin A or monensin leading to altered GAP-43 distribution. Golgi-associated GAP-43 appeared to have the same molecular weight as the plasma membrane-associated GAP-43. Thus these results show that GAP-43 expression in Schwann cells is subject to regulation by both extracellular and intracellular signalling molecules and that Schwann cell GAP-43 is often associated with the Golgi apparatus.

Expression of c-Jun, Jun B, Jun D and cAMP response element binding protein by Schwann cells and their precursors in vivo and in vitro

In order to identify the transcription factors that may be involved in the development and differentiation of rat Schwann cells we examined the expression of c-Jun, Jun B, Jun D and the cAMP response element binding protein (CREB) in vivo and in vitro. We found that CREB was expressed at high levels throughout nerve development by both Schwann cells and their precursors. Jun family members, on the other hand, were expressed only at low levels in a few nuclei of the developing nerve. After sciatic nerve transection, however, c-Jun levels were rapidly up-regulated in many Schwann cells of the distal stump but CREB, Jun B and Jun D levels were not affected. When nerve contact was resumed after crush injury c-Jun levels returned to control values. Interestingly, unlike the situation in vivo, when Schwann cells were removed from the nerve and cultured, levels of all three Jun family members were rapidly up-regulated. This also occurred in Schwann cell precursors. In other experiments we found that Schwann cell c-Jun, but not Jun B or Jun D, expression was down-regulated by the adenylate cyclase activator, forskolin. In addition, we show that the forskolin induced down-regulation of c-Jun is not necessary for Schwann cell proliferation or myelination to occur.

Non-surgical management of early breast cancer in the United Kingdom: ductal carcinoma in situ. Clinical Audit Sub-committee of the Faculty of Clinical Oncology, Royal College of Radiologists, and the Joint Council for Clinical Oncology

This paper describes the results of a national survey on the non-surgical treatment of early breast cancer in the UK relating to the management of ductal carcinoma in-situ (DCIS), and the rationale for the current status of the UK DCIS trial. The survey shows that there is considerable clinical uncertainty, which can only be resolved by the trial.

Adjuvant therapy with 5-fluorouracil for breast cancer of likely poor prognosis: 15-year results of a randomized trial

In a trial conducted in southeast Scotland between April 1974 and December 1979, 332 women with invasive breast cancer of Stage I and II with histological evidence of node involvement, or who had operable or inoperable Stage III disease, were randomized, after primary local therapy (mastectomy, node biopsy and radiotherapy for all except the inoperable disease patients who underwent radiotherapy alone) to receive 12 4-weekly intravenous injections of 5-fluorouracil (5-FU), 700 mg/m2 or no systemic therapy. After a median follow-up of 15 years from randomization, no difference is shown between the two groups in terms of distant relapse (hazard ratio (HR) = 1.02; 95% CI 0.78-1.32), event free survival (HR = 1.23; 95% CI 0.97-1.56), or total survival (HR = 1.19; 95% CI 0.93-1.52). Locoregional relapse is significantly reduced by 5-FU administration (HR = 1.88; 95% CI 1.20-2.96). The results are similar for the trial as a whole or when mastectomy patients are considered alone. Toxicity was minimal with marrow suppression in only 19 of 147 patients receiving more than one injection; only five patients discontinued therapy due to nausea and vomiting. However, retrosternal pain occurred in 16 patients, nine of whom had their treatment curtailed as a result. Seventy-seven per cent of patients have died, the majority from breast cancer. Only 1.2% of deaths are considered attributable to cardiac causes of 5-FU is not associated with excess cardiac deaths in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of the endometrial oxytocin receptor in determining the length of the sterile oestrous cycle and ensuring maintenance of luteal function in early pregnancy in ruminants

The oxytocin receptor, a seven transmembrane domain, G protein-linked receptor molecule, plays a central role in determining the endocrine function of the ruminant uterine endometrium. During nonpregnant cycles the control of this molecule by circulating steroid hormones leads to regression of the corpora lutea. The kinetics of the mechanisms involved determine the time at which luteolysis occurs, and therefore the length of the oestrous cycle. In pregnancy, secretions of the trophoblast block endometrial oxytocin receptor gene expression and lead to luteal maintenance. An understanding of the molecular mechanisms involved in the steroidal control of oxytocin receptor gene expression will provide an explanation for the relative constancy of oestrous cycle lengths in non-pregnant animals. Unravelling the way in which trophoblast products block expression of the oxytocin receptor gene will lead to a better understanding of the reasons for the high rate of embryonic loss in domestic ruminants.

Regulation of trophoblast interferon gene expression

The trophoblast of the developing ruminant conceptus secretes large quantities (up to 100 micrograms, or 10(7) IU, per 24 h) of a number of characteristic Type I interferons. Secretion (gene expression) commences at Day 8 or 9 (in the sheep; Day 10 in cattle) and ends at about Day 22 (Day 25). The function of this material is in the inhibition of uterine prostaglandin secretion, and hence in the maintenance of the corpus luteum (the 'maternal recognition of pregnancy'). Such rapid onset and cessation of gene transcription begs questions about the function of trophoblast interferon gene promoters, and a limited number of studies have now been carried out with reporter gene constructs, with inconclusive results. It seems unlikely, however, that viral responsiveness accounts for the phenomenon, as in adult interferon genes, although the trophoblast interferons are highly active antiviral agents.

The management of operable breast cancer in Scotland surgeons' opinions. The Scottish Cancer Trials Breast Group

This report gives the responses of general surgeons in Scotland to two questionnaires. Satisfactory rates were obtained: 82% for the more detailed survey in 1988 and 62% for the second survey (1991), where nonrespondents were not followed up. In 1988 the rationale was the poor participation in the Scottish breast conservation trial while the 1991 survey further investigated the diversity of surgical opinion identified in the first. The limited trial support in 1988 was mainly due to reluctance to accept all treatment options. The majority were prepared to consider trial participation although 47% believed this compromised doctor-patient relationships. Although breast-conserving therapy was widely supported, many different views on management were encountered, both in the degree of influence of specific factors and in the decisions taken in relation to them. We believe these surveys have re-inforced a need for management guidelines, particularly as around half the patients with symptomatic breast cancer were being treated in non-specialist units.

Localization of oxytocin receptor mRNA in the ovine uterus during the oestrous cycle and early pregnancy

A synthetic 45-mer oligonucleotide corresponding to part of the ovine endometrial oxytocin receptor cDNA was hybridized to sections of ovine uterus collected from 40 ewes at different stages during the oestrous cycle, the first 3 weeks of pregnancy and seasonal anoestrus. The quantity of oxytocin receptor mRNA was measured as the optical density (OD) value on autoradiographs using image analysis. Message first appeared in the luminal epithelium on days 14-15 of the cycle, increasing to a peak OD of 0.48 at oestrus and decreasing again between days 2 and 5. Oxytocin receptor mRNA in the superficial glands, deep glands and caruncular stroma increased between day 15 and oestrous to peak OD values of 0.17, 0.11 and 0.11 respectively, declining again by day 2 and reaching basal values (OD < 0.015) by day 5. Hybridization to the myometrium tended to rise from a mean OD value of 0.01 on days 2-15 to a peak of 0.03 +/- 0.01 (mean +/- S.E.M.) on days 0-1, but the change was not significant. In pregnant ewes there was no detectable oxytocin receptor mRNA on days 14-15 in any region, but hybridization to the luminal epithelium was present in two of three ewes on day 21. In anoestrous ewes oxytocin receptor mRNA concentrations in all areas of the endometrium were approximately half those measured at oestrus. Optical density readings for oxytocin receptor mRNA in the various uterine compartments were compared with measurements of oxytocin receptors in the same regions as assessed by binding studies using the 125I-labelled oxytocin antagonist d(CH2)5[Tyr(Me)2,Thr4,Tyr-NH2(9)]-vasotocin (125I-labelled OTA). In the endometrium, receptor mRNA and 125I-labelled OTA binding patterns changed in parallel, and both sets of measurements were significantly correlated (P < 0.01). In the myometrium, a significant increase in 125I-labelled OTA binding occurred at oestrus; this was not accompanied by a similar increase in oxytocin receptor mRNA hybridization. This study helps to confirm that the previously identified cDNA clone is derived from the ovine oxytocin receptor, as patterns of oxytocin receptor mRNA expression in the endometrium closely resembled those of oxytocin binding. Maximum expression and binding both occurred at oestrus, suggesting that regulation of the oxytocin receptor gene in the uterus occurs principally at the transcriptional, rather than at the translational, level. Failure to detect a significant increase in myometrial mRNA expression at oestrus may indicate that the endometrial and myometrial oxytocin receptors are of different isoforms.

An interferon-induced Mx protein: cDNA sequence and high-level expression in the endometrium of pregnant sheep

We have cloned a 2.4-kb cDNA containing the complete coding sequence of ovine Mx from a lambda ZAP library constructed using RNA from the endometrium of a normal sheep on day 16 of pregnancy. Ovine Mx shows 80% similarity to human MxA. Human and mouse Mx are type-1 interferon (IFN)-induced genes that have previously been shown to confer resistance to influenza virus. The ovine Mx cDNA contains an open reading frame of 1962 nucleotides (nt) coding for a 653-amino-acid (aa) protein. The deduced translated sequence has consensus GTP-binding sites and similarity to the human MxA sequence (RKFLKERLARL) that has been shown to be essential for resistance against vesicular stomatitis virus (VSV). The presence of Mx mRNA was investigated by Northern blot analysis in the endometrium of non-pregnant sheep and between days 8 and 127 of pregnancy. Mx expression was detected at high levels between day 13 and day 20 of pregnancy. Furthermore, eightfold higher levels of Mx mRNA were detected in the pregnant versus the non-pregnant uterine horn in unilaterally pregnant sheep. Mx mRNA can be induced in sheep endometrium by ovine trophoblast interferon (IFN-tau).

Changes in DNA synthesis rate in the Schwann cell lineage in vivo are correlated with the precursor--Schwann cell transition and myelination

During the development of the rat sciatic nerve extensive proliferation of glial cells occurs, and there is a very substantial rearrangement of the cytoarchitecture as axons and Schwann cells assume relationships which lead to the formation of the myelinated and unmyelinated axons characteristic of adult nerve. The maturation of Schwann cells from Schwann cell precursors and the matching of Schwann cell numbers to axons is an important part of this process. We have therefore studied the proliferation of Schwann cell precursors and Schwann cells during the development of the rat sciatic nerve from embryonic day 14 to postnatal day 28 by combining bromodeoxyuridine injections of rats with double-label immunohistochemical techniques. The results reveal that DNA synthesis occurs in both Schwann cell precursors and Schwann cells throughout early nerve development. The labelling index is already substantial at embryonic day 14, but from embryonic day 17, when essentially all the glial cells have converted from precursor to Schwann cell phenotype, it rises sharply, peaking between embryonic day 19 and 20 before declining precipitously in the early postnatal period. This rapid decline in DNA synthesis coincides with the appearance of the myelin protein P0, and in individual cells DNA synthesis is incompatible with the expression of P0 protein. Nonmyelin-forming Schwann cells, which mature later in development, continue to synthesize DNA until at least postnatal day 15, but by day 28 essentially all Schwann cells in the nerve are quiescent.

Isolation and structure of a partial sheep oxytocin receptor cDNA and its use as a probe for northern analysis of endometrial RNA

The polymerase chain reaction (PCR) was used to generate a 131 bp cDNA encoding part of the sheep endometrial oxytocin receptor. The nucleotide sequence of this cDNA was 93.8% identical to the human oxytocin receptor sequence in this region. When used to probe Northern blots of sheep endometrial RNA the PCR product identified a 6.7 kb mRNA which appeared and disappeared during the oestrous cycle in parallel with the oxytocin receptor molecule as measured by ligand binding. The sheep endometrial receptor mRNA was significantly larger than the human myometrial mRNA (4.7 kb). It is suggested that the cloned cDNA described here is an appropriate probe for use where it is required to measure sheep oxytocin receptor mRNA.

GAP-43 immunoreactivity is widespread in the autonomic neurons and sensory neurons of the rat

GAP-43 is a membrane-bound phosphoprotein generally associated with axon growth during development and regeneration. Using immunohistochemical and immunoblotting techniques this study shows that GAP-43 is expressed extensively in the unperturbed adult autonomic nervous system. Strong immunoreactivity was seen in the developing and mature enteric subdivision of the autonomic nervous system and in nerves of the iris and various blood vessels. The presence of GAP-43 immunoreactivity in varicose nerve fibres, and a comparison of the labelling pattern of GAP-43 with the nerve associated marker PGP 9.5 suggests that GAP-43 is present in most or all autonomic nerve fibres in these organs. Immunoblotting of gut samples on 10% polyacrylamide gels revealed a single band of approximately 45,000 mol. wt that co-migrated with pure central nervous system GAP-43. Surgical sympathectomy experiments resulting in almost complete elimination of sympathetic fibres did not markedly affect the pattern of GAP-43 immunoreactivity in the iris, indicating that GAP-43 is expressed not only in sympathetic nerves but also in parasympathetic and sensory fibres. These findings show that GAP-43 is expressed extensively in autonomic nerves of the adult rat, at levels comparable to those seen during development. High levels of GAP-43 are not therefore restricted to development and regeneration in this part of the nervous system.

GAP-43 is expressed by nonmyelin-forming Schwann cells of the peripheral nervous system

Recently it has been demonstrated that the growth-associated protein GAP-43 is not confined to neurons but is also expressed by certain central nervous system glial cells in tissue culture and in vivo. This study has extended these observations to the major class of glial cells in the peripheral nervous system, Schwann cells. Using immunohistochemical techniques, we show that GAP-43 immunoreactivity is present in Schwann cell precursors and in mature non-myelin-forming Schwann cells both in vitro and in vivo. This immunoreactivity is shown by Western blotting to be a membrane-associated protein that comigrates with purified central nervous system GAP-43. Furthermore, metabolic labeling experiments demonstrate definitively that Schwann cells in culture can synthesize GAP-43. Mature myelin-forming Schwann cells do not express GAP-43 but when Schwann cells are removed from axonal contact in vivo by nerve transection GAP-43 expression is upregulated in nearly all Schwann cells of the distal stump by 4 wk after denervation. In contrast, in cultured Schwann cells GAP-43 is not rapidly upregulated in cells that have been making myelin in vivo. Thus the regulation of GAP-43 appears to be complex and different from that of other proteins associated with nonmyelin-forming Schwann cells such as N-CAM, glial fibrillary acidic protein, A5E3, and nerve growth factor receptor, which are rapidly upregulated in myelin-forming cells after loss of axonal contact. These observations suggest that GAP-43 may play a more general role in the nervous system than previously supposed.

Interaction between cAMP elevation, identified growth factors, and serum components in regulating Schwann cell growth

Most previous studies on Schwann cell proliferation in vitro have used serum-containing media. This complicates the analysis of agents required for cell division since serum contains an ill-defined mixture of hormones and growth factors. Serum-free medium has therefore been used to analyse the response of Schwann cell to previously identified Schwann cell mitogens. Serum factors were not necessary for DNA synthesis in response to platelet-derived growth factor, basic fibroblast growth factor, or glial growth factor, provided they were used in combination with forskolin to elevate intracellular cAMP. Transforming growth factor beta 1, a Schwann cell mitogen in serum, was not mitogenic under these conditions. Neither the growth factors nor forskolin were effective when used alone. Growth control was analysed further using long-term cultured Schwann cells that had spontaneously immortalized. Measurements of endogenous cAMP levels in short- and long-term Schwann cells revealed that long-term cells had two to three times higher basal cAMP levels. As predicted by these findings, platelet-derived growth factor, basic fibroblast growth factor, and glial growth factor stimulated DNA synthesis in long-term cells without requiring costimulation by agents which elevate cAMP (while transforming growth factor beta 1 had no effect).(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence against a role for blastocyst-secreted oxytocin in early pregnancy maintenance in sheep

Analysis of ovine conceptus RNA by slot blotting, Northern analysis and nested polymerase chain reaction failed to detect oxytocin-neurophysin prohormone mRNA. Probes used hybridized with both the 3' end of the prohormone mRNA and the oxytocin-coding sequence. Northern analysis of bovine and porcine conceptus RNA was also negative, and polymerase chain reaction demonstrated oxytocin-neurophysin mRNA in ovine corpus luteum, but not in human corpus luteum or decidua, or in ovine endometrium. Infusion of oxytocin into the uterine lumen in cyclic ewes between days 9 and 19 or 20 after oestrus failed to prolong the luteal phase of the cycle and had no effect on endometrial oxytocin receptor concentrations or uterine prostaglandin F secretion. Oxytocin administered systematically prevented luteolysis and reduced uterine prostaglandin F secretion. Taken together, these data suggest that blastocyst-derived oxytocin is unlikely to contribute to corpus luteum maintenance in early pregnancy. They are inconsistent with a previous report that the ovine blastocyst synthesizes and secretes oxytocin.