Search results for "TUMOR CELLS"

E-selectin modulates the malignant properties of T84 colon carcinoma cells.

2002

The extravasation of metastatic cells is regulated by molecular events involving the initial adhesion of tumor cells to the endothelium and subsequently the migration of cells in the host connective tissue. E-selectin on endothelial cells and sialyl Lewis X carbohydrate component on tumor cells are mainly involved in the adhesion of colon carcinoma cells to the endothelium of target organ. Interaction of T84 colon cancer cells to purified E-selectin in vitro caused an increase in the tyrosine phosphorylation of a number of proteins as well as the modulation of cellular properties correlated to the metastatic phenotype. Specifically, E-selectin-stimulated actin reorganization, increased coll…

Phenoloxidase-dependent cytotoxic mechanism in ascidian (Styela plicata) hemocytes active against erythrocytes and K562 tumor cells.

1997

The cytotoxic activity against rabbit erythrocytes (RE) and human K562 tumor cells by Styela plicata hemocytes was significantly related to the phenoloxidase (PO) which converts phenols to quinone and initiates the melanogenic pathway. The effector hemocyte population, separated in a Percoll density gradient band, enriched in a granulocyte type named "morula cells", was examined with RE in a hemocyte cytotoxic assay and plaque forming cell assay. Inhibition experiments with the copper chelating agents 1-phenyl-2-thiourea and tropolone, the substrate analogue sodium benzoate and sodium ascorbate support the notion that hemocyte cytotoxic activity is a PO-dependent mechanism. Treatments of he…

Exosome Involvment in Hsp60 secretion by tumor cells.

2011

The CD95/CD95 ligand system is not the major effector in anticancer drug-mediated apoptosis.

1998

Many anticancer drugs are able to induce apoptosis in tumor cells but the mechanisms underlying this phenomenon are poorly understood. Some authors reported that the p53 tumor suppressor gene may be responsible for drug-induced apoptosis; however, chemotherapy-induced apoptosis can also be observed in p53 negative cells. Recently, doxorubicin (DXR) was reported to induce CD95L expression to mediate apoptosis through the CD95/CD95L system. Thus, an impairment of such a system may be involved in drug resistance. We evaluated the in vitro antitumor activity of several cytotoxic drugs on two human p53-negative T-cell lymphoma cell lines, the HUT78-B1 CD95L-resistant cell line and the HUT78 pare…

Oxidative stress induces the expression of the major histocompatibility complex in murine tumor cells.

2001

The effect of t-butyl hydroperoxide (t-BOOH) on the induction of the Major Histocompatibility Complex (MHC) class I genes has been studied in two cell clones (B9 and G2) of the methylcholanthrene-induced murine fibrosarcoma GR9. These two clones were selected based on their different biological and biochemical behavior specially related to their tumor induction capability when injected into a BALB/c mouse. t-BOOH (0.125 mM) induced the expression of H-2 molecules in both cell clones. In B9 cell clone, in which MHC basal expression is very low or absent, t-BOOH significantly induced H-2Kd, H-2Dd and H-2Ld molecules. In G2 cell clone the expression of MHC class I genes was also enhanced by th…

Influence of Pharmacokinetic Variations on the Pharmacological Properties of Adriamycin

1972

Whenever it appears impossible to modify the chemical structure of drugs with a high and established therapeutic activity but a low chemotherapeutic index, pharmacological research has to find other ways of improving the chemotherapeutic index. This problem is particularly important in the case of antitumor drugs, thus justifying research into the most suitable choice of dosage and routes of administration, as well as into the pharmacological associations which enable tumor cells to be hit at various stages of the reproductive cycle. Alternatively, the therapeutic index could be improved by the use of antagonistic compounds (like, for example, methotrexate and folinic acid) which act upon t…

Apoptosis induced in hepatoblastoma HepG2 cells by the proteasome inhibitor MG132 is associated with hydrogen peroxide production, expression of Bcl-…

2002

This report is focused on the apoptotic effect induced by MG132, an inhibitor of 26S proteasome, in human hepatoma HepG2 cells. The results were compared with those obtained with non-transformed human Chang liver cells. MG132 reduced the viability of HepG2 cells in a time- and dose-dependent manner. The effect was in tight connection with the induction of apoptosis, as indicated by fluorescence microscopy and cytometric analysis, and was accompanied by a remarkable increase in the production of H2O2 and a reduction in mitochondrial transmembrane potential (Deltapsim). In addition cell death was prevented by antioxidants such as GSH, N-acetylcysteine or catalase. Western blot analysis showed…

Cellular uptake and in vitro antitumor efficacy of composite liposomes for neutron capture therapy.

2014

Background Neutron capture therapy for glioblastoma has focused mainly on the use of 10B as neutron capture isotope. However, 157Gd offers several advantages over boron, such as higher cross section for thermal neutrons and the possibility to perform magnetic resonance imaging during neutron irradiation, thereby combining therapy and diagnostics. We have developed different liposomal formulations of gadolinium-DTPA (Magnevist®) for application in neutron capture therapy of glioblastoma. The formulations were characterized physicochemically and tested in vitro in a glioma cell model for their effectiveness. Methods Liposomes entrapping gadolinium-DTPA as neutron capture agent were manufactur…

Proliferation of gastrointestinal carcinoma cells by T lymphocyte factors interleukin-3 and granulocyte-macrophage colony-stimulating factor

1991

Hematopoietic growth factors have been well characterized by cDNA cloning in recent years. In order to determine the influence of rhGM-CSF and rhIL-3 on epithelial cells of the gastrointestinal tract, their influence on in vitro cultured gastric and pancreas cancer cells was determined. A more than two-fold enhancement of proliferation was observed by IL-3 and GM-CSF in Mz-Sto-1 gastric and 818-4 pancreas carcinoma cells, applying a sensitive microculture system which allows precise quantification. The highest growth rates were obtained adding 1-10 ng/ml of the growth factors, but even picogram amounts were effective. Expression of mRNA for GM-CSF and IL-3 remained undetectable in the cell …

Urokinase Plasminogen Activator and Gelatinases Are Associated with Membrane Vesicles Shed by Human HT1080 Fibrosarcoma Cells

1997

Membrane vesicles are shed by tumor cells both in vivo and in vitro. Although their functions are not well understood, it has been proposed that they may play multiple roles in tumor progression. We characterized membrane vesicles from human HT1080 fibrosarcoma cell cultures for the presence of proteinases involved in tumor invasion. By gelatin zymography and Western blotting, these vesicles showed major bands corresponding to the zymogen and active forms of gelatinase B (MMP-9) and gelatinase A (MMP-2) and to the MMP-9. tissue inhibitor of metalloproteinase 1 complex. Both gelatinases appeared to be associated with the vesicle membrane. HT1080 cell vesicles also showed a strong, plasminoge…