Search results for "ATS"
showing 10 items of 6881 documents
Oligodendroglioma cells synthesize the differentiation-specific linker histone H1˚ and release it into the extracellular environment through shed ves…
2013
Chromatin remodelling can be involved in some of the epigenetic modifications found in tumor cells. One of the mechanisms at the basis of chromatin dynamics is likely to be synthesis and incorporation of replacement histone variants, such as the H1° linker histone. Regulation of the expression of this protein can thus be critical in tumorigenesis. In developing brain, H1° expression is mainly regulated at the post-transcriptional level and RNA-binding proteins (RBPs) are involved. In the past, attention mainly focused on the whole brain or isolated neurons and little information is available on H1° expression in other brain cells. Even less is known relating to tumor glial cells. In this st…
Mechanisms of tumor invasion: evidence from in vivo observations.
1985
The major mechanisms of tumor invasion in vivo are discussed in the present review. A special emphasis is placed on tumor dedifferentiation which has proved to be of paramount importance for the invasion process. Based on in vivo observations obtained from various human and animal tumors a concept for the mechanism of tumor invasion is proposed which mainly comprises the following basic events: the first and essential step in tumor invasion is the tumor dedifferentiation and dissociation at the invasion front. This apparently temporary and reversible process mobilizes the tumor cells out of the main tumor bulk and enables them to invade the host tissue by active locomotion. This mechanism i…
Metabolic Imaging in Microregions of Tumors and Normal Tissues With Bioluminescence and Photon Counting
1988
A method has been developed for metabolic imaging on a microscopic level in tumors, tumor spheroids, and normal tissues. The technique makes it possible to determine the spatial distribution of glucose, lactate, and ATP in absolute terms at similar locations within tissues or cell aggregates. The substrate distributions are registered in serial cryostat sections from tissue cryobiopsies or from frozen spheroids with the use of bioluminescence reactions. The light emission is measured directly by a special imaging photon counting system enabling on-line image analysis. The technique has been applied to human breast cancer xenografts, to spheroids originating from a human colon adenocarcinoma…
Role of the Ha-ras gene in the malignant transformation of rat liver oval cells.
1997
We have shown that the oval cell line OCICDE 22 can be transformed by the highly carcinogenic fiord-region diol epoxides of benzo[c]phenanthrene. Mutational activation of the ras proto-oncogene family has been proposed to be a critical event in the formation of tumors induced by polycyclic aromatic hydrocarbons. Therefore, we investigated whether in the earlier transformed OCICDE 22 cells any point mutations were detected in the ras proto-oncogene. The results indicate that the malignant transformation of OCICDE 22 cells by the 4 stereoisomeric benzo[c]phenan-threne diol epoxides in vitro is independent of activation of the Ha-ras proto-oncogene. In addition, Northern and Western blot analy…
Transplantation of prodrug-converting neural progenitor cells for brain tumor therapy
2003
Since neural progenitor cells can engraft stably into brain tumors and differentiate along the neuronal and glial line, we tested the hypothesis that transplanted cytosine deaminase (CD)-expressing ST14A cells (an immortalized neural progenitor cell line) can convert locally 5-fluorocytosine (5-FC) into 5-fluorouracil (5-FU) and produce a regression of glioma tumors. ST14A, retrovirally transduced with the E. coli CD gene, showed a strong bystander effect on glioma cells as assessed by in vitro assay. Intracerebral injection of C6 glioma cells generated a rapidly growing tumoral mass. DiI prelabeled ST14A, coinjected into the rat brain with C6 glioma cells, survived in the tumoral mass up t…
Low frequency of HLA haplotype loss associated with loss of heterozygocity in chromosome region 6p21 in clear renal cell carcinomas.
2004
HLA class I loss or downregulation is a widespread mechanism used by tumor cells to avoid tumor recognition by cytotoxic T lymphocytes favoring tumor immune escape. Multiple molecular mechanisms are responsible for these altered HLA class I tumor phenotypes. It has been described in different epithelial tumors that loss of heterozygosity (LOH) at chromosome region 6p21.3 is a frequent mechanism that leads to HLA haplotype loss, ranging between 40 and 50%, depending on the tumor entity analyzed. Here we have tested the frequency of LOH at 6p21 chromosome region in Renal Cell Carcinomas (RCC) of the clear cell and chromophobe subtype. A low frequency of HLA haplotype loss (6.6%) was found in …
Vascularity, perfusion rate and local tissue oxygenation of tumors derived from ras-transformed fibroblasts.
2007
Tumors derived from ras-transformed rat fibroblasts were investigated in order to gain insight into possible interrelationships between oncogenic transformations and therapeutically relevant parameters of the metabolic micromilieu of solid tumors in vivo. Tumors grew in nude mice after injection of in vitro-passaged cells. Growth rates, early stages of angiogenesis, perfusion and tissue oxygenation were assessed. Compared with the parental cell line, both ras transformants grew very rapidly and exhibited an early onset of angiogenesis. Perfusion rates of one ras-transformed tumor line were similar to those of the parental tumors whereas reduced flow values were detected in tumors of the oth…
External-beam radiotherapy as preparative regimen for hepatocyte transplantation after partial hepatectomy
2006
Purpose: The transplantation of donor hepatocytes is considered a promising option to correct chronic liver failure through repopulation of the diseased organ. This study describes a novel selective external-beam irradiation technique as a preparative regimen for hepatocyte transplantation. Methods and Materials: Livers of dipeptidylpeptidase IV (DPPIV)–deficient rats were preconditioned with external-beam single-dose irradiation (25 Gy) delivered to two thirds of the liver. Four days later, a one-third partial hepatectomy (PH) was performed to resect the untreated liver section, and 15 million wild-type (DPPIV + ) hepatocytes were transplanted via the spleen into the recipient livers. The …
Tissue gradients of energy metabolites mirror oxygen tension gradients in a rat mammary carcinoma model
2001
Abstract Purpose: It has been shown that oxygen gradients exist in R3230AC tumors grown in window chambers. The fascial surface is better oxygenated than the tumor surface. The purpose of the present study was to determine whether gradients exist for energy metabolites and other end points related to oxygen transport. Methods and Materials: Imaging bioluminescence was used to measure ATP, glucose, and lactate in cryosections of R3230AC tumors. Mean vessel density and hypoxic tissue fraction were assessed using immunohistochemistry. Tumor redox ratio was assessed by redox ratio scanning. Results: Lactate content and hypoxic fraction increased, whereas ATP, glucose, redox ratio, and vessel de…
Studies on the importance of microsomal epoxide hydrolase in the detoxification of arene oxides using the heterologous expression of the enzyme in ma…
1994
In order to investigate the role of the microsomal epoxide hydrolase (mEH) in the detoxification of arene oxides in the presence of a high endogenous glutathione S-transferase (GST) activity-a situation found in several organs--we expressed the rat mEH cDNA in BHK21 Syrian hamster cells. These cells have high GST activities but contain an extremely low endogenous mEH enzyme activity. We obtained several cell clones which expressed the mEH heterologously, as determined by immunoblotting. The cell clone BHK21-mEH/Mz1 had the highest level of mEH protein. Immunofluorescence showed that the level of expression was almost homogeneous throughout the cell population. Total protein isolated from th…