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Biomedical subjects

W E Laug

Publications and source records attributed to W E Laug.

At least 37 records · Page 2Linked to original sources
PubMed1992

Complex expression of the genes coding for plasminogen activators and their inhibitors in HeLa-smooth muscle cell hybrids.

As cells progress through the multistep process of neoplastic transformation, they eventually acquire the property of invasive behavior. Although both plasminogen activators (PA) and their inhibitors (PAI) contribute to this process, their regulation in normal and transformed cells remains poorly defined. Because somatic cell hybrids provide useful tools for examining the transformation pathway, tumorigenic and invasive HeLa cells were fused with human normal vascular smooth muscle cells and tested for invasion-related parameters, including the expression of PA and PAI genes, and matrix degradation. Both parental cell lines produced large amounts of PAI activities with no detectable PA in either cellular or secreted form. Opposite findings were obtained with the hybrid cell lines, which demonstrated the presence of receptor-bound and secreted PA but absence of enzymatically measurable PAI activities. Both urokinase-type and tissue-type PA were found in cell-associated and secreted form in the hybrid cells. In addition, expression of the urokinase-type PA receptor gene was found in the three hybrid cells and the vascular smooth muscle cells but not in the HeLa cells. Expression of active, receptor-bound and secreted PA provided the nontumorigenic hybrid cells with the enzymatic tools to degrade extracellular proteins in a plasminogen-dependent manner. Thus, the hybrid cells lost tumorigenicity while retaining the tissue-degrading capability of HeLa cells. These hybrid cell lines should prove to be important reagents for investigating the complex regulatory control of PA and PAI gene expression.

Extracellular Matrix↗
PubMed1990

Chimeric immunoglobulin-T cell receptor proteins form functional receptors: implications for T cell receptor complex formation and activation.

We constructed chimeric receptor chains in which an immunoglobulin heavy chain variable region (VH) from a phosphorylcholine-specific antibody is substituted for T cell receptor (Tcr) alpha and beta V regions. We demonstrate that the VH region joined to either the C alpha or the C beta region can form stable chimeric proteins in EL4 T cells. Both chimeric receptor chains associate with CD3 polypeptides in functional receptor complexes and respond to phosphorylcholine coupled to Sepharose beads. The VH-C alpha chimeric chain associates with the EL4 beta chain, while the VH-C beta chimeric protein appears to form either a homodimer or a heterodimer with the native EL4 beta chain. Thus, functional receptor complexes can be formed using two C beta regions, and the C alpha region may not be required for CD3 association and surface expression of Tcr complexes.

Animals↗
PubMed1990

Plasminogen activator regulation by transforming growth factor-beta in normal and neoplastic human urothelium.

Plasminogen activators (PA) are thought to participate in the invasive and metastatic processes of malignancies and are known to be modulated by certain growth factors (Danø, K; Andreasen, P.A.; Grondahl-Hansen, J.; Kristensen, P.; Nielsen, L.S.; Skriver, L. Adv. Cancer Res. 44:139-266; 1985 and Laiho, M.; Keski-Oja, J. Cancer Res. 49:2533-2553; 1989). This report describes the effect of TGF-beta on the regulation of secreted PA activity produced by human fetal urothelium and neoplastic urothelial cell lines. Epidermal growth factor was previously shown to induce substantially different effects on PA production by normal versus neoplastic urothelial (Dubeau, L.; Jones, P.A.; Rideout, W.M.; Laug, W.E. Cancer Res. 48:5552-5556; 1988). This report demonstrates that log phase normal urothelium, but not transformed cells, responded to TGF-beta (1-10 ng/mL) by diminishing the total secreted PA activity. Northern and western analyses showed that the reduction in protease activity resulted from an increased level of plasminogen activator inhibitor-1 (PAI-1) mRNA and protein. Additionally, northern analysis of total mRNA levels at varying cell densities demonstrated modulation of tPA, PAI-1, and TGF-beta transcripts in normal urothelial cells as a function of growth in vitro, suggesting the presence of an intact regulatory pathway to control extracellular proteolysis.

Blotting, Western↗
PubMed1989

Isolation of multiple types of plasminogen activator inhibitors from vascular smooth muscle cells.

Large arteries have a natural resistance to tumor cell invasion thought to be due to the production of protease inhibitors. Vascular smooth muscle cells (VSMC) representing the major cellular part of arteries were isolated from human aortas and grown in tissue culture. These cells were found to produce large amounts of inhibitors of plasminogen activators (PA). Fractionation of VSMC-conditioned medium by heparin-affigel chromatography separated three immunologically and functionally distinct PA inhibitors (PAI), namely PAI-1, PAI-2 and protease-nexin I. The three inhibitors were characterized by functional assays and immunoblotting. PA inhibitor 2 (PAI-2) had little affinity for heparin, whereas PA inhibitor 1 (PAI-1) bound to heparin and was eluted from the column at NaCl concentrations of 0.1 to 0.35 M. Protease-nexin I, eluted at NaCl concentrations of 0.5 M and higher. Most of the PAI-1 was present in the latent, inactive form. PAI-1 was further purified by ion exchange chromatography on a Mono-Q column. Partial sequencing of the purified PAI-1 confirmed its nature by matching completely with the sequence deduced from the cDNA nucleotide sequence of endothelial cell PAI-1. Thus, human VSMC produce all three presently known PAI and these can be separated in single heparin affinity purification step.

Amino Acid Sequence↗
PubMed1988

Differential regulation of plasminogen activators by epidermal growth factor in normal and neoplastic human urothelium.

The regulation of urokinase (u-PA) and tissue plasminogen activator (t-PA) in cultured normal and neoplastic urothelium was examined because plasminogen activators (PAs) are thought to be important in malignancy. Both activators were synthesized by normal urothelial cells grown in vitro under chemically defined conditions. The level of t-PA activity decreased when normal urothelial cells reached saturation density, but was stimulated more than 10-fold by the addition of epidermal growth factor (EGF) to the culture medium. Northern blot analysis showed that the regulation occurred at the transcriptional level. On the other hand u-PA activity was regulated to a lower degree by EGF and was not affected by cell density. Immunohistochemical examination of urothelial cells in histology specimens showed that t-PA was present only in the apical cells facing the lumen, suggesting that the expression of the activity might be a marker for end-stage differentiation in vivo. In contrast to normal cells, tumor cell lines made only u-PA under all conditions tested, and the levels of its expression were either unaffected or slightly decreased by EGF. Tumor cells and normal cells therefore showed substantial differences in protease regulation by EGF.

Cells, Cultured↗
PubMed1987

Improved detection of metastatic Ewing's sarcoma with the use of bone marrow scintigraphy.

Prognosis in Ewing's sarcoma is inversely related to the extent of the disease at the time of presentation. The most common sites of metastases are the lungs and skeleton. Bone marrow metastases may be present but clinically silent. We report the use of Technetium (Tc)-99m bone marrow scintigraphy to detect sites of marrow involvement by metastatic Ewing's sarcoma. This method of evaluation allowed identification of sites of involvement by Ewing's sarcoma that were not available by any other method of evaluation. In several instances, information provided by this method was pivotal in the management of these patients. Based on this small series of patients, bone marrow scintigraphy appears to be a sensitive modality in the detection of metastatic disease in patients with Ewing's sarcoma. Better understanding of the role of bone marrow scanning and its correlation with other diagnostic procedures in Ewing's sarcoma will require further study.

Adolescent↗
PubMed1987

Transient blastemia in phenotypically normal newborns.

Two normal appearing infants presented in the newborn period with elevated white blood cell counts and immature blast cells. Initial bone marrow karyotype analysis showed trisomy of chromosome 21 in all metaphases. In both patients blastemia spontaneously resolved and percentage of trisomy 21 cells decreased. One infant required multiple exchange transfusions and pericardiotomy. The other patient had undifferentiated blasts and continued to have subtle hematopoietic abnormalities greater than 2 years later. Both children have had normal growth and development. The clinical course of these patients emphasizes the need for aggressive supportive care without use of cytotoxic drugs in phenotypically normal newborns with blastemia showing trisomy 21.

Down Syndrome↗
PubMed1986

Pulmonary alveolar septal calcinosis causing progressive respiratory failure in acute lymphoblastic leukemia in childhood.

A syndrome of pulmonary alveolar septal calcinosis, pneumothorax, and pneumomediastinum, leading to rapidly progressive acute respiratory insufficiency and death was observed in 2 children with acute lymphoblastic leukemia (ALL). Primary clinical and radiological considerations in these patients were pulmonary edema and infection, and the diagnosis of pulmonary alveolar septal calcification was established only at autopsy. One patient, a 15-year-old girl, was found also to have parathyroid hyperplasia typical of familial hyperparathyroidism. The other, a 16-month-old girl, showed osteitis fibrosa of the bones and parathyroid hyperplasia of secondary type, suggesting that the pulmonary calcinosis resulted from hypercalcemia caused by a parathormone or prostaglandin-secreting tumor. The cause of pneumothorax and pneumomediastinum may have been rupture of calcified alveolar septa induced by high PEEP during ventilation of these patients. Other possible mechanisms contributing to hypercalcemia and pulmonary calcinosis in children with acute leukemia include bone resorption due to marrow infiltration, immobilization syndrome, renal failure, and administration of calcium, phosphate, or bicarbonate. This complication of acute leukemia in childhood is rare (2 patients in 430 autopsied over the period 1961-1982 at Childrens Hospital of Los Angeles). How often the process can be reversed if diagnosed before severe respiratory insufficiency is present is not known.

Adolescent↗
PubMed1986

Inhibition of tumor cell collagenolytic activity by bovine endothelial cells.

The ability of cellular vascular components including endothelial cells, smooth muscle cells, and fibroblasts to interact with the collagenolytic activity of invasive human tumor cell lines has been investigated. The human HT1080 fibrosarcoma and Bowe melanoma cells, which rapidly digest collagenous proteins in vitro, failed to dissolve them when cocultivated with bovine endothelial cells. This inhibition was not dependent on the ability of endothelial cells to form a monolayer separating the tumor cells from the collagenous substrate. In contrast, little collagenolysis inhibitory activity was detected in bovine vascular smooth muscle cells and human fibroblasts when compared to endothelial cells. Serum-free medium conditioned by endothelial cells inhibited tumor cell-mediated collagenolysis. Our data further suggest that this inhibition was mediated by secreted collagenase inhibitors, since endothelial cell-conditioned medium did not suppress the production of metalloproteinases by the tumor cells but inhibited the activities of collagenases derived from tadpole, rabbit, and human fibroblasts. Treatment of the endothelial cells with cycloheximide suppressed the collagenase inhibitory activity, demonstrating active production of collagenase inhibitors by the cells. Gel filtration chromatography of endothelial cell-conditioned medium allowed the separation of two distinct peaks with inhibitory activities for vertebrate collagenase in the molecular weight range of 70,000 to 75,000 and 30,000 to 35,000, respectively. While the inhibitor with an approximate molecular weight of 30,000 to 35,000 shared many properties with the tissue inhibitor of metalloproteinases, the high-molecular-weight inhibitor demonstrated characteristics not yet described for any collagenase inhibitor. The production and secretion of inhibitors of vertebrate collagenase by bovine endothelial cells may be of importance in the local control of collagen turnover under physiological as well as pathological conditions.

Animals↗
PubMed1985

Endothelial cells degrade extracellular matrix proteins produced in vitro.

Bovine aortic endothelial cells (BAEC) were grown on extracellular matrices produced by vascular smooth muscle cells or fetal bovine endothelial cells. The glycoprotein components of these complex substrates were degraded through activation of the serum zymogen plasminogen to plasmin, as well as by a plasminogen independent protease(s). The plasminogen independent enzyme might be a protease with elastolytic activity since the BAEC digested elastin present in smooth muscle cell derived matrices. The cells also displayed collagenolytic activity on both types of matrices. The addition of the tumor promoter 12-0-tetradecanoyl-phorbol-13-acetate (TPA) (10(-7) M) to the culture medium enhanced considerably the plasminogen activator and collagenolytic activities elaborated by BAEC resulting in an increased degradation rate of matrix glycoprotein and collagen components, whereas the elastolytic activity remained unaffected. Dexamethasone (10(-7) M), although suppressing plasminogen activator (PA) production by BAEC, did not alter their elastolytic activity allowing the cells to degrade the glycoprotein components of the matrices at an unchanged rate. The collagenolytic activity of the BAEC remained unaffected by dexamethasone. These studies demonstrate that BAEC elaborate different proteolytic enzyme activities allowing them to degrade various components of extracellular matrices. These enzymatic activities may be modulated by certain agents thus changing the degradative capabilities of the BAEC.

Animals↗
PubMed1985

Vascular smooth muscle cells inhibit the plasminogen activators secreted by endothelial cells.

Pure cultures of bovine endothelial cells (EC) produce and secrete large amounts of plasminogen activators (PA). Cocultivation of EC with vascular smooth muscle cells (SMC) resulted in a significant decrease of PA activities secreted by the EC, whereas the cellular PA activities remained unaffected. Secreted PA activities were absent in the growth medium as long as the SMC to EC ratio was 2:1 or higher. The PA inhibitory activity of the SMC was rapid and cell-to-cell contact was not necessary. The PA inhibitory activity was present in homogenates of SMC as well as in the medium conditioned by them but not in the extracellular matrix elaborated by these cells. Serum free medium conditioned by SMC neutralized both tissue type (t-PA) and urokinase like (u-PA) plasminogen activators. Gel electrophoretic analysis of SMC conditioned medium followed by reverse fibrin autography demonstrated PA inhibitory activities in the molecular weight (Mr) range of 50,000 to 52,000 similar to those present in media conditioned by bovine endothelial cells or fibroblasts. Regular fibrin zymography of SMC conditioned medium incubated with u-PA or t-PA revealed the presence of a component with a calculated approximate Mr of 45,000 to 50,000 which formed SDS resistant complexes with both types of PA. These data demonstrate that vascular SMC produce and secrete (a) inhibitor(s) of PAs which may influence the fibrinolytic potential of EC.

Animals↗
PubMed1985

Inhibition of human tumor cell-associated fibrinolysis by vascular bovine smooth muscle cells.

Fibrinolysis induced by human tumor cells producing either urokinase (u-PA) or tissue-type plasminogen activators (t-PA) was inhibited by growth in vitro of the tumor cells together with aortic bovine smooth muscle cells (SMC). Both types of plasminogen activators secreted by the tumor cells were partially or completely neutralized in such cocultivation experiments. The fibrinolysis inhibitory activities were found in living SMC, homogenates of the cells, and medium conditioned by the SMC. Incubation of medium conditioned by the SMC with media conditioned by the tumor cells followed by polyacrylamide gel electrophoresis and regular fibrin zymography resulted in sodium dodecyl sulfate-resistant inhibition of fibrinolysis. Gel electrophoretic analysis of medium conditioned by SMC followed by reverse fibrin autography revealed the presence of a single zone of lysis inhibition that corresponded to a relative molecular weight of 51,500 +/- 1,700. These results demonstrate that SMC produce and secrete a powerful inhibitor of u-PA- and t-PA-induced fibrinolysis, which may alter the invasive and degradative potential of tumor cells.

Animals↗
PubMed1984

Effects of X-irradiation on artificial blood vessel wall degradation by invasive tumor cells.

Artificial vessel wall cultures, constructed by growing arterial endothelial cells on preformed layers of rat smooth muscle cells, were used to evaluate the effects of X-irradiation on tumor cell-induced tissue degradation. Bovine endothelial cells had radiation sensitivities similar to those of rat smooth muscle cells. Preirradiation of smooth muscle cells, before the addition of human fibrosarcoma (HT 1080) cells, did not increase the rate of degradation and destruction by the invasive cells. However, the degradation rate was decreased if the cultures were irradiated after the addition of HT 1080 cells. The presence of bovine endothelial cells markedly inhibited the destructive abilities of fibrosarcoma cells, but preirradiation of artificial vessel walls substantially decreased their capabilities to resist HT 1080-induced lysis. These findings suggest that the abilities of blood vessels to limit extravasation may be compromised by ionizing radiation.

Animals↗
PubMed1983

Glucocorticoids inhibit plasminogen activator production by endothelial cells.

Confluent cultures of bovine aortic endothelial cells (BEC) were found to secrete both tissue type plasminogen activator (t-PA) and urokinase type plasminogen activator (u-PA). Exposure of the cultures to increasing concentrations of dexamethasone resulted in a time and concentration dependent inhibition of cellular and secreted u-PA. Complete inhibition of u-PA production and secretion was found at dexamethasone concentrations of 10(-8) molar or higher. Several distinct PA forms with molecular weights ranging from 10,000-20,000 to greater than 200,000 were found in the conditioned medium of untreated BEC cultures. After addition of dexamethasone (10(-7) molar) to the culture medium the PAs with molecular weights of 117,000, 58,000, 47,000, were absent suggesting that they were u-PAs, whereas the PAs with molecular weights of greater than 200,000 and 75,000 remained unchanged suggesting their t-PA origins. The PAs with lower molecular weights of 35,000, 28,000 and 10,000 to 20,000 were most likely generated from the higher molecular weight forms by limited proteolysis since they were absent when the medium was conditioned in the presence of the protease inhibitor Trasylol. The two PA types may therefore be independently regulated in BEC.

Animals↗
PubMed1983

Ethyl alcohol enhances plasminogen activator secretion by endothelial cells.

Confluent cultures of cloned bovine endothelial cells, which were derived from large vessels, produced and secreted plasminogen activator (PA) at constant rates. Exposure of these cultures to increasing concentrations of ethyl alcohol resulted in a significant augmentation of PA production and secretion. This effect, which was observed after three hours and was maximal after 18 hours of incubation, was abolished by simultaneous exposure of the cultures to cycloheximide, indicating that active protein synthesis was necessary for the observed increase of PA activity. Other aliphatic alcohols such as propanol and butanol also significantly augmented PA production and secretion by endothelial cells, whereas acetaldehyde and acetylcoenzyme A, known metabolites of ethyl alcohol, had no stimulatory effect on protease secretion by the cells. Therefore, the alcohol itself rather than its metabolites was responsible for the enhancement of PA secretion by endothelial cells. These in vitro studies may explain the increased fibrinolytic activity found in the plasma of persons consuming moderate amounts of alcohol.

Animals↗
PubMed1983

Invasive properties of primary pediatric neoplasms in vitro.

Primary solid tumors were mechanically and/or enzymatically disassociated, and the resulting suspensions of single cells and small clumps of cells were seeded onto three different substrates, i.e., tissue culture plastic, rat smooth muscle cells (SMCs), and SMC-derived extracellular matrix. Tests of the relative effectiveness of these substrates in supporting the survival and/or growth of ten different neoplasms demonstrated that only two explants remained viable for longer than 2 weeks when seeded onto tissue culture plastic while nine of the ten survived on biological substrates for 1 month or longer. Thus, tissue culture plastic was a poor substrate for primary pediatric neoplasms. In general, more than 80% of the most common solid neoplasms in childhood (brain tumor, neuroblastoma, renal tumor, rhabdomyosarcoma, osteogenic sarcoma, and Ewing's sarcoma) routinely survived or grew in long-term cultures when cultured onto SMCs or their matrix. Both substrates were effective in promoting survival and/or growth; however, cells of neuroblastomas and certain brain tumors showed a preference for a living smooth muscle substrate. Tumor cells maintained their characteristic cellular and subcellular morphology when compared with the histology of the in vivo neoplastic lesions. Light and electron microscopy of selected neoplasms cultured on SMCs for various time periods demonstrated areas of distinct cellular invasion and/or partial destruction of the SMC multilayers which correlated with the invasive potentials of the neoplasms in patients. Invasion and destruction of the SMCs were also noticed with quiescent tumor cell cultures, indicating that growth was not a necessary property of invasion. Several neoplasms were also capable of the degradation of connective tissue proteins as indicated by the hydrolysis of radiolabeled SMC matrices, but simple correlations between the extent of matrix degradation and invasive ability could not be drawn. The culture system described consistently provided for the survival and/or growth of the most common pediatric tumors for long time periods. Thus, basic biological properties of primary tumors, e.g., growth, invasive potentials, and differentiation capabilities, could be investigated routinely.

Cell Transformation, Neoplastic↗