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B Sordat

Publications and source records attributed to B Sordat.

At least 37 records · Page 2Linked to original sources
PubMed1997

In situ stromal expression of the urokinase/plasmin system correlates with epithelial dysplasia in colorectal adenomas.

An increase of urokinase-type plasminogen activator (uPA) and a decrease of tissue-type PA (tPA) have been associated with the transition from normal to adenomatous colorectal mucosa. Serial sections from 25 adenomas were used to identify PA-related caseinolytic activities by in situ zymography, blocking selectively uPA or tPA. The distribution of uPA, tPA, and type 1 PA inhibitor mRNAs was investigated by nonradioactive in situ hybridization, and the receptor for uPA was detected by immunostaining. Low- and high-grade epithelial cell dysplasia was mapped histologically. Results show that 23 of 25 adenomas expressed uPA-related lytic activity located predominantly in the periphery whereas tPA-related activity was mainly in central areas of adenomas. In 15 of 25 adenomas, uPA mRNA was expressed in stromal cells clustered in foci that coincided with areas of uPA lytic activity. The probability of finding uPA mRNA-reactive cells was significantly higher in areas with high-grade epithelial dysplasia. uPA receptor was mainly stromal and expressed at the periphery. Type 1 PA inhibitor mRNA cellular expression was diffuse in the stroma, in endothelial cells, and in a subpopulation of alpha-smooth muscle cell actin-reactive cells. These results show that a stromal up-regulation of the uPA/plasmin system is associated with foci of severe dysplasia in a subset of colorectal adenomas.

Adenoma↗
PubMed1996

Detection of rare circulating human colon tumor cells in a nude mouse xenograft model.

A highly sensitive allele specific polymerase chain reaction was developed and applied to the detection of K-ras mutation in human colon tumor cells both in the blood and in tissues. An experimental model of human colon carcinoma cells, carrying a GAT mutation in the 12th codon of the K-ras gene, and grafted into nude mice has been selected for evaluating the occurrence of cells in the course of disseminating into the host. We have found tumor cells circulating in the blood starting 37 days following subcutaneous primary implantation. Occasional micrometastatic deposits could be detected in lymph node draining the xenograft, but no tumor cells were found in lungs and mediastinum. In this experimental model, our results indicate that the mere presence of tumor cells in the blood does not imply the full accomplishment of the multi-step metastatic process.

Animals↗
PubMed1996

Differential effect of interleukin-4 and transforming growth factor beta 1 on expression of proto-oncogenes and autocrine insulin-like growth factor II in colorectal carcinoma cells.

We have compared the effect of interleukin-4 and transforming growth factor beta 1 on proliferation and gene expression in two colorectal carcinoma cell lines, LS513 and LS1034. Transforming growth factor beta 1 was a potent inhibitor for both cells lines and virtually abolished de novo DNA synthesis. Interleukin-4 inhibited thymidine incorporation up to 60 and 45%, respectively. While both cytokines exerted a comparable cyto-inhibitory activity they displayed differential effects on proto-oncogene expression. Transforming growth factor beta 1 markedly down-regulated c-myc in LS1034 but not in LS513 cells. In contrast, expression of c-fos was induced by interleukin-4 in LS513 but not in LS1034 cells. Interestingly, in agreement with their cyto-inhibitory activity both cytokines suppressed the expression of insulin-like growth factor II in LS1034, which is an autocrine growth factor for these cells.

Cell Division↗
PubMed1996

Modulation of the plasminogen activation system by inflammatory cytokines in human colon carcinoma cells.

Inflammation may promote malignant invasion by enhancing cancer cell-associated proteolysis. Here we present the effect of inflammatory cytokines on the plasminogen activation system of eight human colon carcinoma cell lines. Tumour necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) increased in several, but not all, cell lines the production of urokinase-type plasminogen activator (uPA), tissue-type PA (tPA) and plasminogen activator inhibitor type 1 (PAI-1) as analysed by zymography, enzyme immunoassays and Northern analysis. Interleukin 6 (IL-6) had no effect. uPA receptor (uPAR) mRNA levels were also upregulated. However, each individual cell line responded differently following exposure to TNF-alpha or IL-1 beta. For example, there was a dose-dependent up-regulation of uPA and PAI-1 in SW 620 cells, whereas increased uPA production in SW 1116 cells was not accompanied by an increase in PAI-1. The TNF-alpha stimulatory effect was blocked by anti-TNF-alpha Fab fragments. All cell lines expressed both types of TNF receptor mRNAs, whereas no transcript for TNF-alpha, IL-1 beta, IL-6, IL-6 receptor or the IL-1 receptors was found. Our results demonstrate that TNF-alpha and IL-1 beta stimulate the plasminogen activation system in tumour cell but the responses differed even in cells derived from the same tissue origin.

Blotting, Northern↗
PubMed1996

Human colon carcinoma cells synthesize and secrete alpha 1-proteinase inhibitor.

Our previous results have shown that tumor cell-secreted procathepsin B can be activated by neutrophil elastase in vitro. In the present study, we addressed two questions: 1. Can neutrophil elastase be detected in human colon carcinomas, and 2. Does the co-culture of human colon carcinoma cells with neutrophils generate a cathepsin B-dependent pericellular proteolysis as assessed with radiolabeled laminin? We show that neutrophil elastase is present in colon carcinoma tissue and that its level is in good agreement with the degree of tissue infiltration by neutrophils. In co-culture experiments, elastase is released by neutrophils in a cell number dependent way, but no activation of tumor cell-secreted procathepsin B could be observed. In addition, the degradation of radiolabeled laminin by neutrophil proteinases was markedly decreased in the presence of tumor cells. These findings prompted us to search for a tumor cell-secreted elastase inhibitor. We show by enzyme activity measurements, gelatin-zymography, immunoblotting and RT-PCR that colon carcinoma cells synthesize and secrete alpha 1-proteinase inhibitor, a functional inhibitor of neutrophil elastase. The importance of this finding in the context of pericellular activation of tumor cell-secreted procathepsin B by neutrophil elastase is discussed.

Blotting, Northern↗
PubMed1995

Expression of the alpha 6, beta 1 and beta 4 integrin subunits, basement membrane organization and proteolytic capacities in low and high metastatic human colon carcinoma xenografts.

Malignant transformation is associated with alterations in both cell-cell and cell-matrix interactions. The E2 and C5 clones, derived from the human colon adenocarcinoma LoVo cell line, show, respectively, low and high metastatic capacity as experimental xenografts in vivo. In this study, we have assessed the adhesion and spreading of E2 and C5 cells on basement membrane laminin, expression of the laminin receptor integrins alpha 6 beta 1 and alpha 6 beta 4 and expression of gelatinolytic and plasminogen-dependent activities. On days 5 and 7 after subcutaneous grafting to immunosuppressed newborn rats, well-differentiated E2 tumors displayed a polarized expression of these integrin subunits, with the exception of the beta 1 subunit which remained pericellular. In contrast, C5 tumors were unorganized and the three integrin subunits remained nonpolarized and pericellular. Flow cytometry results showed that the expression of alpha 6 beta 1 and alpha 1 beta 4 integrins was weaker in the highly metastatic C5 clone than in the E2 clone whereas laminin expression was not significantly different. Under-expression and pericellular localization of these integrin receptors in C5 cells as compared to E2 cells may explain the difference in their binding and spreading capacity on laminin, organization of peritumoral basement membrane and maintenance of a differentiated phenotype. Whereas similar levels of gelatinolytic and plasminogen activator activities have been detected in the culture supernatant of the two clones, histozymograms showed that plasminogen-dependent caseinolysis appeared earlier in sections of C5 and parental tumors than in those of E2 xenografts. These results suggest that enhanced aggressiveness of C5 tumors in vivo may be linked to both an impairment of basement membrane setting due to integrin underexpression and distribution and of proteolytic activities modulated by tumor/host interactions.

Adenocarcinoma↗
PubMed1994

Latency of cathepsin B secreted by human colon carcinoma cells is not linked to secretion of cystatin C and is relieved by neutrophil elastase.

The lysosomal cysteine proteinase cathepsin B is shown to be secreted by ten human colon carcinoma cell lines and to accumulate in culture media as a latent enzyme. The cell lines also secrete a physiological inhibitor of cathepsin B, cystatin C. A significant correlation was found between secretion of the latent enzyme and the inhibitor (r = 0.755, P < 0.01). The aim of the present study was to modulate the respective secretion of the two antagonists to test whether or not latency of cathepsin B was due to the concomitant secretion of the inhibitor. SW480 colon carcinoma cells were treated with the acidotropic agent ammonium chloride, phorbol 12-myristate 13-acetate, and the inflammatory cytokines TGF-beta, TNF-alpha, and IL-1 beta. Ammonium chloride significantly increased latent cathepsin B levels without affecting the constitutive secretion of cystatin C. Phorbol 12-myristate 13-acetate induced a 4- to 5-fold increase in secreted latent cathepsin B, but did not alter significantly the accumulation of cystatin C in media. The cytokines, TGF-beta, TNF-alpha, and IL-1 beta, had no major effect on the expression of these two antagonists. Latent cathepsin B released from human carcinoma cells could be efficiently activated by neutrophil elastase at neutral pH. It is concluded that latent cathepsin B is a true proenzyme rather than an enzyme-inhibitor complex. In addition, our data from neutrophil elastase activation experiments indicate that a proteolytic system for activation of the tumor cell-secreted latent enzyme may exist in vivo.

Adenocarcinoma↗
PubMed1994

Human Co115 colon carcinoma cells potentiate the degradation of laminin mediated by tissue-type plasminogen activator.

The plasminogen activation (PA) system of human Co115 colon carcinoma cells was investigated. Analysis at the levels of protein and mRNA of cultured cells and of histozymography of tumor xenografts in nude mice showed that Co115 cells produce only tissue type PA (t-PA) and no urokinase (u-PA). Also, mRNA for the u-PA receptor and for PA inhibitor type 2 (PAI-2), but not for PAI-1, were detected. We developed a quantitative degradation assay using glutaraldehyde-immobilized 125I-laminin to investigate the capacity of Co115 cells to degrade laminin. Laminin degradation by Co115 cells was completely inhibited by 100 micrograms/ml of polyclonal anti-t-PA IgG, by the plasmin inhibitors aprotinin (100 micrograms/ml) or epsilon-aminocaproic acid (EACA; at 0.3 M), but not by antibodies against u-PA or u-PAR nor by nonimmune IgG. Cycloheximide-treated Co115 cells were unable to degrade laminin but increased laminin degradation induced by conditioned medium of Co115 cells or recombinant t-PA. No potentiation was observed when Co115 cells and laminin were kept separated by Transwell inserts. Our results suggest that Co115 human colon carcinoma cells degrade laminin by potentiating t-PA-mediated plasminogen activation at the cell surface which requires close contact between tumor cells and laminin substrate.

Animals↗
PubMed1993

The role of the urokinase receptor in extracellular matrix degradation by HT29 human colon carcinoma cells.

Urokinase (u-PA) and the urokinase receptor (u-PAR), are thought to play a critical role in the invasive and metastatic properties of cancer cells. The HT29 human colon-carcinoma cell line was selected to evaluate these aspects. HT29 cells express u-PA receptors (100,000 sites/cell, KD = 1.5 nM), but no PA activity and therefore are unable to generate plasmin in the presence of plasminogen. These cells have been transfected with a human u-PA cDNA to investigate whether secreted u-PA would enhance in vitro extracellular matrix degradation, and whether the binding of u-PA to the cell surface is determinant. Five clones were selected for stable expression of high PA activity. These clones were capable of marked plasminogen-dependent degradation of R22 smooth-muscle-cell-derived extracellular matrix, whereas the parental cell line contributed to an insignificant breakdown only. Aprotinin, polyclonal anti-u-PA IgG, recombinant PAI-2, and co-culture with human PAI-I-producing mouse L cells significantly inhibited this degradation. Furthermore, a peptide displacing u-PA from its receptor as well as 2 different polyclonal anti-u-PA receptor IgGs decreased the breakdown after 24 hr by as much as 70% and 81%, respectively. These results show that the binding of u-PA to its receptor plays an important role in in vitro matrix breakdown by HT29 u-PA transfectants.

Carcinoma↗
PubMed1993

Malignant progression of SV40-immortalised human milk epithelial cells.

A human breast epithelial cell line (Hu-MI), established by microinjecting SV40 DNA into human milk epithelial cells, exhibits the phenotype of luminal epithelial cells and is neither clonogenic nor tumorigenic. From this cell line we have selected two sublines, HuMI-T and HuMI-TTul, reflecting different stages of spontaneous transformation. HuMI-T cells grow anchorage-independently, but do not induce tumours in nude mice. HuMI-TTul cells are clonogenic as well as tumorigenic. Cells from both lines exhibit polymorphic structural and numerical chromosome aberrations. Immortalisation of normal luminal epithelial cells from human mammary gland with SV40 DNA alone may thus cause random genetic changes eventually resulting in tumorigenic cell lines. Since Hu-MI, HuMI-T and HuMI-TTul represent some of the consecutive stages taking place during cellular transformation, they are particularly suited as a novel in vitro model system to study progression of human breast cancer.

Animals↗
PubMed1992

Cystatin C and cathepsin B in human colon carcinoma: expression by cell lines and matrix degradation.

Expression of the cysteine proteinase cathepsin B and its physiological inhibitor cystatin C was analyzed in vitro in 1 human fibrosarcoma and 4 human colon carcinoma cell lines. Cystatin C antigen as well as cathepsin B activity were detected in the conditioned media of the 5 cell lines. The corresponding cell extracts expressed high levels of cathepsin B activity, whereas only trace amounts of cystatin C antigen could be found. Northern-blot analysis revealed the presence in the 5 cell lines of a 0.8-kb cystatin C mRNA transcript and 2 cathepsin B transcripts of 2.3 and 4.3 kb. Pepsin treatment of tumor-cell-released cathepsin B induced an average 7.3-fold increase in activity, indicating that the enzyme was mainly present as a latent form in conditioned medium. The pepsin-activated cathepsin B from one colon carcinoma cell line was further characterized using the cysteine proteinase inhibitors E-64, recombinant cystatin C, a cystatin-C-derived peptidyl inhibitor (Z-LVG-CHN2), and cathepsin-B-specific diazomethyl ketone inhibitors (Z-FT(OBzl)-CHN2, Z-FS(OBzl)-CHN2). This activity was totally neutralized by recombinant cystatin C, suggesting a potential for interaction between released extracellular cathepsin B and cystatin C. In vitro assays of degradation of extracellular matrix showed that cysteine proteinase inhibitors could decrease matrix degradation induced by pepsin-activated conditioned media. With colon cells, this inhibition was not observed, indicating a requirement for an extracellular activation of latent cathepsin B. Our data provide evidence that cystatin C and latent cathepsin B are both released extracellularly by colon carcinoma cells in vitro. They suggest that cystatin C and cathepsin B interactions may participate, in an as yet unelucidated way, in the modulation of the invasive phenotype of human colonic tumors.

Carcinoma↗
PubMed1992

Responsiveness of three newly established human colorectal cancer cell lines to transforming growth factors beta 1 and beta 2.

We have established 3 new human colorectal cancer cell lines (LS411N, LS513, and LS1034) from clinical biopsy samples. These lines are tumorigenic and grow s.c. as adenocarcinomas in nude mouse xenografts. Specific marker chromosomes are observed in each line. Carcinoembryonic antigen is expressed at the surface of all 3 lines, but with marked quantitative differences. Indeed, less than 10% of the cells from the HT-29 line used as a reference express carcinoembryonic antigen while more than 90% of the LS1034 cells do so. LS513 and LS1034 consistently express HLA class I antigens and intercellular adhesion molecule 1 which are not detected at the surface of the LS411N cells. No expression of HLA class II antigens DR, DQ, and DP has been measured on any of the lines. All three lines grow well in 5% fetal calf serum medium without addition of exogenous growth factors. The LS1034 line has been adapted to growth in serum-free conditions and exhibits increased clonogenicity when cells are seeded in serum-free methylcellulose medium, as compared with medium containing 5% fetal calf serum. The LS513 and LS1034 lines have proved to be of particular interest since they respond to the growth-inhibitory action of TGF-beta 1 and TGF-beta 2 in both liquid and semisolid medium. Both factors were, at pM concentrations, equipotent inhibitors of LS1034 cell proliferation. In contrast, higher concentrations of TGF-beta 1 are inhibitory for proliferation of LS513 cells, whereas TGF-beta 2 has no effect on the growth of these cells in liquid assay. On this basis, using appropriate anti-TGF-beta 1 and anti-TGF-beta 1 IgY, we developed a bioassay for TGF-beta 1 and TGF-beta 2. Two of the three lines have indeed been shown to produce latent-TGF-beta 1 activity.

Adult↗
PubMed1992

Induction of apoptosis by wild-type p53 in a human colon tumor-derived cell line.

A wild-type p53 gene under control of the metallothionein MT-1 promoter was stably transfected into human colon tumor-derived cell line EB. Repeated inductions of the metallothionein wild-type p53 gene with zinc chloride results in progressive detachment of wild-type p53 cells grown on culture dishes. Examination at both the light and electron microscopic level revealed that cells expressing wild-type p53 developed morphological features of apoptosis. DNA from both attached and detached cells was degraded into a ladder of nucleosomal-sized fragments. Expression of wild-type p53 inhibited colony formation in soft agar and tumor formation in nude mice. Furthermore, established tumors in nude mice underwent regression if wild-type p53 expression was subsequently induced. Regressing tumors showed histological features of apoptosis. Thus, regression of these tumors was the result of apoptosis occurring in vivo. Apoptosis may be a normal part of the terminal differentiation program of colonic epithelial cells. Our results suggest that wild-type p53 could play a critical role in this process.

Base Sequence↗
PubMed1990

Modulation of the malignant phenotype with the urokinase-type plasminogen activator and the type I plasminogen activator inhibitor.

Gene transfer techniques were utilized to evaluate the role of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type 1 (PAI-1) in enhancing or preventing the expression of the invasive malignant phenotype, respectively. Mouse L-cell transfectants expressing human uPA or human PAI-1 as well as mouse B16 transfectants expressing mouse uPA or human PAI-1 were generated. These transfectants were tested using a variety of experimental methods including smooth muscle cell matrix solubilization in vitro, lung colony formation in vivo and co-cultures of antagonist-expressing cells in vitro. Results from these studies provide direct evidence for an enhancing role of uPA in malignant invasion and experimental metastasis and for a modulatory role of PAI-1 in tumor cell-mediated breakdown of extracellular matrices.

Animals↗
PubMed1990

Plasminogen-activator inhibitor type 1 is a potent natural inhibitor of extracellular matrix degradation by fibrosarcoma and colon carcinoma cells.

We have analyzed the role of plasminogen-activator inhibitor type 1 (PAI-1) in the regulation of tumor cell-mediated extracellular matrix degradation. Immunocytochemical analysis revealed PAI-1 associated with microgranular and fibrillar material of the extracellular matrix and demonstrated the presence of PAI-1 as a cell surface-associated antigen. Transforming growth factor beta significantly reduced matrix degradation mediated by HT-1080 human fibrosarcoma cells. This inhibition was correlated with an increase in PAI-1 antigen expression, whereas urinary-type plasminogen activator (u-PA) secretion was unaffected. In this experimental system, PAI-1 regulated extracellular matrix breakdown, as added PAI-1 inhibited matrix solubilization, whereas monoclonal antibodies to PAI-1 increased it. A cell line (LPAI) producing high levels of biologically active PAI-1 was established by transfection of a human PAI-1 cDNA clone into mouse L cells. Coculture experiments demonstrated that LPAI cells prevented matrix degradation by Lu-PA cells (L cells expressing high levels of u-PA) or Co-115 human colon carcinoma cells (expressing tissue-type plasminogen activator). These results indicate that PAI-1 may play a critical role in the regulation of extracellular matrix degradation during tumor cell invasion.

Animals↗