Search results for "Confluency"
showing 8 items of 8 documents
Malignant transformation of the liver tumour precursor cell line OC/CDE 22 by the four stereoisomeric fjord region 3,4-dihydrodiol 1,2-epoxides of be…
1995
In previous work we established the rat liver oval cell line OC/CDE 22 in order to study in vitro mechanisms of liver cell transformation. We have now exposed OC/CDE 22 cells to each of the four optically active fjord region dihydrodiol epoxides of benzo[c]phenanthrene to investigate their capacity for malignant transformation of liver cells. All four configurational isomers, which are among the most potent carcinogenic metabolites of polycyclic aromatic hydrocarbons tested in murine tumour models, malignantly transform OC/CDE 22 cells at a 2 microM dose level, resulting in a similar colony-forming efficiency in soft agar. Inoculation of the transformed cells into newborn syngeneic rats pro…
Cell-cell and cell-collagen interactions influence gelatinase production by human breast-carcinoma cell line 8701-BC
1995
We previously produced evidence that the human mammary-carcinoma cell line 8701-BC expresses several metalloproteinases (MMP-1, -2, -9, and -10) and their tissue inhibitors. In order to obtain a better understanding of the environmental control over gelatinolytic activities, we have tested the enzyme production of 8701-BC cells, at time intervals after plating on different collagen substrates, i.e., types I, III, IV, V and OF/LB, used as films in culture dishes. Proteinase activities, released in the conditioned culture media, were tested by zymography on SDS-PAGE, and by quantificative analyses, using 14C carboxy-methylated transferrin as substrate in a liquid incubation medium. Enzymatic …
Abstract 3940: Inactivation of the PARD3 gene is a recurrent event in lung squamous cell carcinomas and affects STAT3 activity and tumor invasiveness
2015
Abstract Correct apicobasal polarization and intercellular adhesions are essential for the appropriate development of normal epithelia. Here, we investigated the contribution of the partitioning defective 3 gene, PARD3, to the carcinogenesis of lung squamous cell carcinomas (LSCCs). Tumor-specific PARD3 alterations were found in eight per cent of the tumors, placing PARD3 among the most common tumor suppressor genes in LSCC. Some PAR3 mutant proteins prevented the formation of contacts between neighboring cells, i.e. had reduced ability to form tight junctions and actin-based protrusions. This affected subsequent downstream signaling, i.e. binding to aPKC and activation of RAC1. Further, we…
TCDD-dependent downregulation of gamma-catenin in rat liver epithelial cells (WB-F344).
2002
TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) is the most potent tumor promoter ever tested in rodents. Although it is known that most of the effects of TCDD are mediated by binding to the aryl hydrocarbon receptor (AHR), the mechanisms leading to tumor promotion still remain to be elucidated. Loss of contact-inhibition is a characteristic hallmark in tumorigenesis. In WB-F344 cells, TCDD induces a release from contact-inhibition manifested by a 2- to 3-fold increase in DNA-synthesis and the emergence of foci when TCDD (1 nM) is given to confluent cells. We focussed our interest on potential cell membrane proteins mediating contact-inhibition in WB-F344 cells, namely E-cadherin, alpha,- beta,-…
Focal adhesions and assessment of cytotoxicity
1999
Focal adhesions are highly ordered assemblies of transmembrane receptors, extracellular matrix proteins, and a large number of cytoplasmic proteins, including structural proteins, as well as tyrosine kinases, phosphatases, and their substrates. They are now accepted as a prime component of signal transduction. Because focal adhesions also play an important role in cell morphology and migration, it can be argued that their presence is indicative of healthy cells. This has been the reason for several research groups to conclude that biomaterials sustaining focal adhesion assembly are biocompatible. In this study we demonstrate that cells under cytotoxic stress may still be able to retain thei…
Drug-metabolizing enzyme activities in freshly isolated oval cells and in an established oval cell line from carcinogen-fed rats
1994
The activities of several different phase I and phase II drug-metabolizing enzymes were measured in freshly isolated oval cells from rats fed a choline-deficient/DL-ethionine-supplemented diet for 6 weeks and also in vitro in the established oval cell line OC/CDE 6. No cytochrome P450 was spectrophotometrically measurable in both preparations and two cytochrome P450-dependent monoxygenase activities, aminopyrine N-demethylase and ethoxyresorufin O-deethylase, could not be detected in the oval cells of both sources. However, cytosolic glutathione transferase, microsomal epoxide hydrolase and UDP-glucuronosyltransferase activities were clearly measurable in oval cells. Similar enzyme activiti…
Vascularization and gene regulation of human endothelial cells growing on porous polyethersulfone (PES) hollow fiber membranes.
2004
Abstract Open-cell hollow fibers made of polyethersulfone (PES) manufactured in the absence of solvents with pore diameters smaller than 100 μm were examined for vascularization by human endothelial cells. The goal of this study was to determine whether the 3-D porous character of the PES surface affected human endothelial cell morphology and functions. Freshly isolated human endothelial cells from the skin (HDMEC), from the lung (HPMEC) and from umbilical cords (HUVEC) and two human endothelial cell lines, HPMEC-ST1.6R and ISO-HAS.c1 were added to PES fibers and cell adherence and growth was followed by confocal laser scanning microscopy. Prior coating of PES with gelatin or fibronectin wa…
PARD3 Inactivation in Lung Squamous Cell Carcinomas Impairs STAT3 and Promotes Malignant Invasion.
2015
Abstract Correct apicobasal polarization and intercellular adhesions are essential for the appropriate development of normal epithelia. Here, we investigated the contribution of the cell polarity regulator PARD3 to the development of lung squamous cell carcinomas (LSCC). Tumor-specific PARD3 alterations were found in 8% of LSCCs examined, placing PARD3 among the most common tumor suppressor genes in this malignancy. Most PAR3-mutant proteins exhibited a relative reduction in the ability to mediate formation of tight junctions and actin-based protrusions, bind atypical protein kinase C, activate RAC1, and activate STAT3 at cell confluence. Thus, PARD3 alterations prevented the formation of c…