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Biomedical subjects

J Varani

Publications and source records attributed to J Varani.

At least 163 records · Page 9Linked to original sources
PubMed1987

Plasminogen activator production by human tumor cells: effect on tumor cell-extracellular matrix interactions.

Cell lines derived from 3 different types of human tumor (e.g., squamous carcinomas, melanomas and gliomas) were examined for production of plasminogen activator activity and for attachment and spreading on various extracellular matrix components in the presence or absence of plasminogen. All of the squamous carcinoma and melanoma lines produced high levels of plasminogen activator activity. In contrast, 4 of 6 glioma lines had undetectable activity. Cells from all 3 tumor types attached and spread on fibrinogen-coated or fibrin-coated plastic dishes in the absence of plasminogen. In the presence of exogenous plasminogen, the attachment and spreading of the cells which produced high levels of plasminogen activator activity was inhibited. The plasminogen activator-deficient cells were much less sensitive to exogenous plasminogen. In the presence of plasminogen, attachment and spreading on fibronectin-coated dishes was also partially inhibited. In contrast, plasminogen had no effect on the attachment and spreading of the cells on type-I or -IV collagen, laminin or thrombospondin. Previous studies have shown that tumor-cell adhesion to the extracellular matrix depends on the synthesis of receptors for extracellular matrix components or on the synthesis of extracellular matrix components themselves. The present study shows that, in addition, the production of enzymes which are capable of degrading these components also influences tumor-cell adhesion to extracellular matrix moieties.

Carcinoma, Squamous Cell↗
PubMed1987

Phagocytosis of Candida albicans enhances malignant behavior of murine tumor cells.

Murine tumor cells were induced to phagocytize either Candida albicans or group A streptococcal cells. The presence of microbial particles within the tumor cell cytoplasm had no effect on in vitro tumor cell growth. However, when Candida albicans-infected tumor cells were injected into syngeneic mice, they formed tumors that grew faster, invaded the surrounding normal tissue more rapidly and metastasized more rapidly than control tumor cells. Tumor cells infected with group A streptococcal particles did not grow faster or show increased malignant behavior. These data indicate that the in vivo behavior of malignant tumor cells can be modulated by microbial particles, which are often present in the microenvironment of the growing tumor.

Animals↗
PubMed1987

Tumor type-specific differences in cell-substrate adhesion among human tumor cell lines.

Cell lines derived from human tumors of 4 different histological types (squamous carcinomas, melanomas, gliomas and a fibrosarcoma) were examined for cell-substrate adhesion on plastic culture dishes and dishes coated with 50 micrograms of type-IV collagen. In the absence of exogenous adhesion factors, the squamous carcinoma cells attached and spread more rapidly than the other cells on both substrates. Once attached, the squamous carcinoma cells were also more difficult than the other cells to remove with proteolytic enzymes/EDTA. While the cell lines derived from melanomas, gliomas and the fibrosarcoma were less adhesive than the squamous carcinoma lines in the absence of exogenous adhesion factors, these cells were highly responsive to laminin. In contrast, laminin only slightly enhanced the attachment and spreading of squamous carcinoma cells on the plastic dishes and actually inhibited attachment and spreading on the collagen-coated dishes. These results indicate that there are tumor-type-specific differences in adhesiveness among human tumor cell lines and that cells from different tumor types may have distinct mechanisms for carrying out one of the functions critical to invasion.

Carcinoma, Squamous Cell↗
PubMed1987

Modulation of fibronectin, laminin, and cellular adhesion in the transformation and differentiation of murine AKR fibroblasts.

The functional relationship between membrane/cell surface expression of fibronectin and laminin and transformation/differentiation was examined in an AKR mouse fibroblastic cell model. This model consisted of the untransformed AKR-2B cells, their chemically transformed counterpart (AKR-MCA cells) and the chemically differentiated form of the AKR-MCA cells. The transformed AKR-MCA cells were found to express more surface laminin and less fibronectin than the untransformed AKR-2B cells. The transformed AKR-MCA cells were slower to attach and spread on both plastic and type IV collagen-coated dishes in comparison to the AKR-2B cells. However, a higher percentage of the AKR-MCA cells ultimately attached and spread on the type IV collagen-coated dishes. The induction of differentiation in the AKR-MCA cells by N,N-dimethylformamide (DMF) restored fibronectin to the surface of the AKR-MCA cells but reduced laminin expression only slightly. The DMF-treated AKR-MCA cells resembled the AKR-2B cells in that they rapidly attached and spread on plastic dishes and dishes coated with type IV collagen. They also resembled the AKR-MCA cells in that a high proportion ultimately attached and spread on the collagen-coated dishes.

Animals↗
PubMed1987

Products of cells cultured from gliomas. V. Cytology and morphometry of two cell types cultured from glioma.

Explants of cells of a human glioma were evaluated with the nuclear fluorochrome 4',6-diamidino-2-phenylindole, by phase-contrast illumination, and by Giemsa staining correlated with double immunofluorescence for glial fibrillary acidic protein (GFAP) and fibronectin (FN). FN-positive (FN+) cells lacked GFAP detectable by immunofluorescence. Their mean nuclear-to-cytoplasmic ratio was large (0.192). Actual mean areas of nuclei (1,252 microns2) and cytoplasm (8,376 microns2) of FN+ cells compared with mean areas of fibroblasts suggested that the high nuclear-to-cytoplasmic ratio of FN+ cells was due to their microscopically evident reduced cytoplasmic spreading rather than to larger nuclei. Some FN+ cells showed marked variation in nuclear and nucleolar size and shape. Others had abnormal mitoses or hyperchromatic nuclei. GFAP-positive (GFAP+) cells lacked FN detectable by immunofluorescence. GFAP+ cells were smaller and less round than FN+ cells. Their usual location was growing on a layer of FN+ cells. The mean nuclear-to-cytoplasmic ratio (0.245) of GFAP+ cells was the highest in the study, surpassing the ratio of the continuous glioma line LM (0.176). Mean areas of nuclei (289 microns2) and of cytoplasm (1,350 microns2) of GFAP+ cells suggested that their high nuclear-to-cytoplasmic ratio was due to their microscopically evident reduced cytoplasmic spreading. Reduced spreading was associated with extension of long, thin cytoplasmic processes. The majority of GFAP+ cells showed marked cytoplasmic basophilia, nuclear hyperchromasia, and clumped chromatin. Features observed in both FN+ and GFAP+ cells from this high-grade astrocytoma are features associated with malignant transformation in more thoroughly studied tumor systems.

Antigens, Neoplasm↗
PubMed1987

Interaction of tumor cells with the extracellular matrix.

Cancer cell invasion of the normal tissue surrounding a growing neoplasm and the subsequent spread (metastasis) of malignant cells throughout the body is the major cause of the morbidity and mortality associated with malignant disease. At the primary tumor site, local invasion may be minimal as in the case of human malignant melanomas. Yet this tumor has the propensity to disseminate widely. On the other extreme, squamous carcinomas of the head and neck may produce a tremendous amount of host tissue destruction at the primary site. These tumors tend to be highly-invasive locally but disseminate more slowly than other forms of cancer such as malignant melanomas. In a like fashion, malignant melanomas tend to be surrounded by only minimal stroma while other tumor types produce a large amount of extracellular matrix themselves or induce matrix production by normal host tissue cells. In spite of the many tumor type specific differences which exist, recent studies in the field of cancer metastasis have identified features that are common to all invasive and metastatic tumors. This includes adhesion of invading tumor cells to host extracellular matrix structures, degradation of host tissue and active tumor cell movement through the partially degraded tissue. The critical events that occur during the invassion and metastatic processes are mediated through interactions between invading tumor cells and the extracellular matrix of the host. The expression of cell surface receptors for extracellular matrix molecules and the synthesis/expression of extracellular matrix molecules, themselves, on the surface of malignant tumor cells are thought to underline the events that are critical to the invasion and metastatic process.

Animals↗
PubMed1987

Source of iron in neutrophil-mediated killing of endothelial cells.

Recently we have shown that human neutrophils activated with phorbol ester are cytotoxic for cultured bovine pulmonary artery endothelial cells in an iron-dependent manner. By using the ferric iron chelator deferoxamine mesylate, we have now investigated the source of the iron. Pretreatment of neutrophils with deferoxamine mesylate affected neither their production of O2- nor their cytotoxicity for endothelial cells after addition of phorbol ester. However, similar pretreatment of endothelial cells with deferoxamine mesylate, followed by washing of the cells, resulted in a persistent presence of chelator associated with the endothelial cells and high degrees of protection of endothelial cells from cytotoxicity. The protection was dependent on the amount of chelator used and on the duration of exposure of the endothelial cells to the chelator. These data suggest that iron, which plays an important role in oxygen radical-mediated killing of endothelial cells by neutrophils, is derived from the target (endothelial) cells.

Animals↗
PubMed1986

Products of cells cultured from gliomas. IV. Extracellular matrix proteins of gliomas.

Five primary and 3 established human glioma cell lines were cultured with ascorbate and examined for expression of extracellular matrix components. All lines except C6 expressed collagen as assessed by silver impregnation, immunofluorescence and lectin staining and expressed laminin and fibronectin. None expressed a lectin marker for endothelial cells. Both epithelial and mesenchymal collagens were expressed. While extracellular components of glioma lines resembled those of fibroblasts more closely than other cell types, subtle differences between gliomas and fibroblasts were present. These included more laminin and collagen type-IV antigenic reactivity and more 11-12 nm diameter extracellular fibrils from individual gliomas, and slight differences in spectra of low-molecular-weight extracellular proteins assessed by gel electrophoresis. One primary and two established glioma lines analysed for DNA content were aneuploid in contrast to diploid fibroblasts. Simultaneous expression of mesenchymal and epithelial markers suggests a dual differentiation potential of glioma cells. Results do not support an endothelial origin for cells cultured from gliomas.

Carbohydrates↗
PubMed1986

Proteolytic enzymes and arachidonic acid metabolites produced by MRC-5 cells on various microcarrier substrates.

Human diploid fibroblasts were cultured on microcarriers made from DEAE-dextran, denatured collagen, DEAE-dextran linked to denatured collagen, and glass. Cells grown on these four substrates were examined for the production of proteolytic enzymes and arachidonic acid metabolites. Culture fluids from cells grown on the DEAE-dextran microcarriers contained the highest amounts of proteolytic enzyme activity. Both plasminogen-independent and plasminogen-dependent fibrinolytic activities were present and the plasminogen-dependent activity seemed to result from the presence of both urokinase and tissue plasminogen activator. Culture fluid from the cells grown on the glass microcarriers contained the least amount of protease activity, and nearly all of the plasminogen-activator activity seemed to be of the urokinase type. Protease activity in the culture fluids of cells grown on the other two substrates were intermediate. With regard to arachidonic acid metabolites, cells grown on the DEAE-dextran microcarriers produced the highest amounts of cyclooxygenase products but very low levels of lipoxygenase metabolites. Cells grown on the other three substrates produced comparable amounts of various cyclooxygenase products (lower than that produced by cells on the DEAE-dextran substrate). Cells grown on the glass microcarriers also produced detectable amounts of two lipoxygenase metabolites--leukotriene B4 and leukotriene C4. Inasmuch as both proteolytic enzymes and arachidonic acid metabolites regulate basic cell properties, the differential amounts of these metabolites observed in the culture fluids on the various substrates may contribute to the biological differences that exist on these substrates.

Arachidonic Acid↗
PubMed1986

Thrombospondin-induced attachment and spreading of human squamous carcinoma cells.

Thrombospondin (TSP) induced the attachment and spreading of human squamous carcinoma cells on plastic culture dishes and dishes coated with type I or type IV collagen. Increased adhesion was detected as early as 15 min after treatment. Dose-response studies indicated that 1-5 micrograms of TSP per 35 mm (diameter) culture dish was sufficient to induce a response and that a half-maximal response occurred at 10 micrograms of TSP/dish. The squamous carcinoma cells synthesized TSP as indicated by biosynthetic labeling experiments. TSP was secreted (or shed) into the culture medium by these cells and also became bound to the cell surface. TSP also promoted adhesion of human keratinocytes, fibroblasts and fibrosarcoma cells but did not induce attachment or spreading of human melanoma or glioma cells, although these cells did respond to laminin.

Carcinoma, Squamous Cell↗
PubMed1986

Cell growth on microcarriers: comparison of proliferation on and recovery from various substrates.

Three commercially-important types of cell were grown on four different microcarrier substrates. The cells, which included normal human diploid fibroblasts (MRC-5), primary chick embryo cells and Madin-Darby bovine kidney cells (MDBK), were compared with regard to proliferation on the substrates and with regard to recovery of viable cells from the same substrates. The substrates used included glass-coated microcarriers (Biosil), collagen microcarriers (Ventregel), DEAE-dextran microcarriers (Cytodex I) and collagen-linked DEAE-dextran microcarriers (Cytodex III). The established cell line (MDBK) grew well on all of the substrates and a high percentage of viable cells could be harvested from each substrate. The MRC-5 cells also grew well on all four substrates but high recovery rates were achieved only with cells grown on the glass-coated microcarriers or collagen microcarriers. In contrast, the primary chick embryo cells grew well only on the glass microcarriers and the recovery rate of cells harvested from this substrate was high. In some industrial operations, the re-utilization of cells after removal from the substrate is necessary. In these situations the appropriate choice of microcarriers for the cultivation of the cells may be critical.

Cell Adhesion↗
PubMed1986

Modulation of tumor cell motility by prostaglandins and inhibitors of prostaglandin synthesis.

15-Methyl-prostaglandin E1 (15-M-PGE1), a synthetic stable, prostaglandin E1 analogue was examined for ability to inhibit motility in a line of murine tumor cells. Inhibition of random motility and motility stimulated by 12-O-tetradecanoyl phorbol acetate was seen at concentrations of 15-M-PGE1 as low as 1 microM. Inhibition of laminin-stimulated motility was observed with 10 microM 15-M-PGE1. The murine tumor cells used in this study produced high levels of prostaglandins. When the cells were treated with either indomethacin or ibuprofen, prostaglandin levels (measured as prostaglandin E2 by radioimmunoassay) were reduced by greater than 95% without a corresponding increase in lipoxygenase products. When indomethacin or ibuprofen-treated cells were compared to control cells in regards to motility, they were more active. These studies show that E-series prostaglandins can modulate motility in the murine fibrosarcoma cells and suggest that the production of endogenous cyclooxygenase metabolites by the murine tumor cells may regulate, at least in part, the responsiveness of the cells to stimulation.

Animals↗
PubMed1986

In vitro and in vivo interaction between murine fibrosarcoma cells and natural killer cells.

Murine fibrosarcoma cells were examined for sensitivity to killing by natural killer (NK) and natural cytotoxic lymphocytes from mouse spleens. These tumor cell lines were sensitive to killing by effector cells which were nonadherent to plastic or nylon wool, Thy-1 negative, asialo-GM1 negative, and present in the spleens of beige mice, nude mice, and A/J mice, as well as in the spleens of normal syngeneic and allogeneic control mice. This indicates that the cytotoxic effects were due to natural cytotoxic lymphocytes rather than to NK lymphocytes, T-cells, or macrophages. Although the fibrosarcoma cells were not killed in vitro by endogenous NK cells, these tumor cells were able to "cold target" compete for Yac-1 (an NK-sensitive target) killing and to bind to asialo-GM1-positive, nonadherent spleen lymphocytes in a target cell binding assay. This suggests that the fibrosarcoma cells were recognized by NK cells. In addition, these cell lines were killed in a 4-h NK cytotoxicity assay by polyinosinic-polycytidylic acid-activated effector lymphocytes. The interaction between NK cells and the murine fibrosarcoma cells may have in vivo significance. When syngeneic mice were treated with anti-asialo-GM1 serum to eliminate NK activity and then given i.v. injections of the fibrosarcoma cells, many more lung tumors developed than in control animals. The structural basis for the recognition of the murine fibrosarcoma cells by the NK effector cells is not known. However, laminin may be involved. When the fibrosarcoma cells, which have receptors for the laminin molecule, were preincubated with laminin, they were reduced in their ability to compete for the killing of Yac-1 cells by the NK effectors and had reduced capacity to bind to NK cells in a target cell binding assay.

Animals↗
PubMed1986

Motility of rasH oncogene transformed NIH-3T3 cells.

A series of rasH oncogene-transformed cell lines were established from NIH-3T3 cells using the calcium phosphate precipitation method of transfection. The transfectant lines formed highly-invasive tumors when injected into athymic mice while the parent cells did not. When examined for motility in the micropore filter assay, all of the transfectant lines were motile in response to either laminin or fibronectin while the parent cells were not stimulated by either factor. These studies, therefore, indicate that transformation of NIH-3T3 cells with the rasH oncogene results in the generation of cells with increased capacity for motility relative to the parent cells.

Animals↗
PubMed1985

Arachidonic acid metabolism in murine fibrosarcoma cells with differing in vivo and in vitro characteristics.

Arachidonic acid metabolism was examined in a series of strongly malignant murine fibrosarcoma cell lines and in a series of weakly malignant lines isolated from the same tumors. The cells were examined in the unstimulated state and after stimulation with 12-O-tetradecanoyl phorbol acetate (TPA), laminin or fibronectin. All 3 agents were known from previous studies to induce adherence and motility in the murine fibrosarcoma cells. When the cells were prelabelled with 3H-arachidonic acid, all 3 agents stimulated the release of radioactivity into the supernatant fluids. The response to TPA was rapid while the response was slower but sustained when either laminin or fibronectin was used as the stimulating agent. This is of interest because TPA induces a rapid but transient adherence response in the same cells while laminin and fibronectin induce a slow, sustained response. Examination by radioimmunoassay procedures indicated that both control cells and stimulated cells were able to produce a variety of lipoxygenase and cyclooxygenase metabolites. In quantitative terms, the strongly malignant cells were more active than their weakly malignant counterparts. They released greater amounts of radioactivity into the supernatant fluid and produced a greater quantity of arachidonic acid metabolites, particularly prostaglandin E2, than did the corresponding weakly malignant cells. This is of interest because previous studies have shown that while both the strongly and weakly malignant cells respond in the adherence assay to TPA, laminin and fibronectin, only the strongly malignant cells demonstrate directional motility (chemotaxis and haptotaxis).

Animals↗
PubMed1985

Directional motility in strongly malignant murine tumor cells.

Laminin, fibronectin and 12-O-tetradecanoyl phorbol acetate (TPA) were examined for their ability to induce biological responses (cell-to-substrate adherence and motility) in a series of strongly malignant and weakly malignant murine fibrosarcoma cells. All three agents caused increased cell-to-substrate attachment of the cell lines. Laminin and fibronectin induced a slow but sustained response, whereas with TPA the response was rapid and transient. The 3 agents also stimulated motility in the same cells. Random motility was seen with all of the cells but directional motility was observed primarily in the strongly malignant cells. With TPA, the response was chemotactic but laminin and fibronectin induced cell migration by haptotaxis. Since laminin and fibronectin are constituents of the extracellular matrix and since malignant tumor cells must cross the extracellular space during invasion, those properties of cells which allow for migration across a substrate containing these materials may contribute to the expression of malignancy.

Animals↗
PubMed1985

Substrate-dependent differences in growth and biological properties of fibroblasts and epithelial cells grown in microcarrier culture.

Normal diploid human fibroblasts and first passage monkey kidney epithelial cells were examined for growth and metabolic activity on microcarriers made from glass and on microcarriers made from DEAE-dextran. The cells grew to a higher density (cells cm2 of surface area) on the glass microcarriers made from glass and on microcarriers made from DEAE-dextran. The cells grew to a higher density (cells/cm2 of surface area) on the glass microcarriers than they did on the DEAE-dextran microcarriers and morphological differences were observed between the cells growing on the two substrates. On the DEAE-dextran microcarriers, the cells were much more resistant to protease-mediated detachment than were the cells on the glass microcarriers. In these respects, the cells grown on the glass microcarriers were similar to cells grown in conventional monolayer culture. Interestingly, the cells grown on the DEAE-dextran microcarriers expressed higher levels of proteolytic enzyme activity than the cells grown on the glass microcarriers. Substrate-dependent differences in prostaglandin production also occurred--both in unstimulated cells and in cells stimulated with 12-0-tetradecanoyl phorbol acetate. The unstimulated cells on the glass microcarriers produced slightly higher levels of three different prostaglandins than did the cells on the DEAE-dextran microcarriers. However, after stimulation the levels were much higher in the DEAE-dextran microcarrier cultures than in the glass microcarrier cultures. In contrast to these results, there was no significant, substrate-dependent difference in the production of infectious herpes simplex virus. Taken together, these findings suggest that when commercially-useful cells such as normal fibroblasts and epithelial cells are grown in large quantities on microcarriers, the nature of the substrate may have a profound effect on the growth and physiology of the cells. They also suggest that when microcarriers are used, unexpected results based on preliminary work in conventional monolayer culture may be obtained.

Animals↗