Mechanism ascites cells

D. Garfinkel and B. Hess, Metabolic control mechanisms. VII. A detailed computer model of the glycolytic pathway in ascites cells. J. Biol. Chem. 239, 971-983 (1964). 

The nine steps involved in the purification of UMP synthase from starting tissue are outlined in figure 6.8. All steps were carried out at 0-5°C. About 200 g of Ehrlich ascites cells, a mammalian tumor rich in the desired enzymes, was suspended in buffer and processed in a tissue homogenizer, which mechanically breaks down the tissue... 

Similar to the in vitro study using Lewis lung cells, it was observed that animals pretreated with pyran had no detectable Ehrlich ascites cells in phase GgM and only a few in the S phase after 2 or 6 days (Table XIV) (60) compared to pyran untreated mice which had 58 in the S phase and 22 in the GgM phase. Consequently, the use of pyran activated macrophage resulted in a) a high overall level of tumoricidal activity both in vivo and in vitro, b) the appearance of a tumor cell population with 50 of their normal DNA content and c) a shift of tumor cells from phase GgM to G. These results indicate that a possible mechanism of activated macrophage tumoricidal activity involves the induction of tumor cells with a reduced DNA content. 

Kinetic experiments with a partially purified enzyme from Ehrlich ascites cells and with recombinant protein suggest that the reaction catalyzed by alkyl-DHAP synthase involves a ping-pong mechanism, with an activated enzyme-DHAP intermediary complex playing a central role [26]. The existence of this intermediate would explain the reversibility of the reaction since the enzyme-DHAP complex can react with either fatty alcohols (forward reaction) or fatty acids (back reaction) (Fig. 4). Acyl-DHAP acylhydrolase does not... 

HDET, L.A. Mechanism of premature polypeptide termination in a mouse ascites cell-free system programmed by EMC REA. J. Virol. (1976), 18, 788-792. 

When injected to intact or ovariectomized rats or rabbits, estrogens stimulate the uptake of a-aminoiso-butyric acid, and the free amino acid levels in the uterus are increased. Similarly, the addition of diethylstilbestrol or estradiol disulfate to an Ehrlich ascites cell in vitro stimulates the amino acid uptake by the cells. These findings are interpreted by postulating that the hormones affect amino acid transport. The hormone could, however, stimulate the penetration of the amino acid by affecting the usage of amino acids through metabolic pathways rather than by directly affecting the transport mechanism. 

Our own work (3) and that of others (2) with E. coll have shown that the de novo purine biosynthetic pathway is regulated by both a repressor molecule (pur R gene product) and by feedback inhibition. However, Chinese hamster cells are much more sensitive to feedback inhibition by adenine than E, coli and, unlike the situation in E. coli, no repression of PRPP amidotransferase or formyglycinamide biosynthesis could be detected. If repression did occur, it would have to be by a mechanism not normally associated with the purine biosynthetic pathways or at a site late in the purine bios3mthetic pathway. Moreover, the nucleotide pools of cells treated for 2 h with with actinomycin D or cycloheximide showed a substantial increase in nucleotide levels. This Increase in nucleotide concentration is probably sufficient in itself to inhibit de novo purine biosynthesis by feedback inhibition without recourse to a repression mechanism, Snyder and Henderson (10) have also reported an effect of actinomycin D on purine metabolism in Ehrlich ascites cells. In this case, there was no large effect (11% inhibition) on de novo purine biosynthesis, Snyder and Henderson (10) proposed that this decrease was due to a 29% reduction in PRPP levels as a result of increased (1,3-fold increase in ATP and 2,8-fold Increase in GTP) nucleotide pools. These observations are consistent with our data in which a 58% decrease in PRPP level is found over a 2-h period in Chinese hamster cells grown in actinomycin D, The extent of inhibition in Chinese hamster cells is much greater than that reported for Ehrlich ascites cells and may reflect a difference between cells,... 

Consideration of membrane as a target for chemotherapeutic drugs has been reviewed and relevant studies with cisplatin summarized [79]. The amino acid uptake mechanism in LI 210 cells is affected by cisplatin [80] and platinum complexes inhibit plasma membrane phosphatase activity in ascites cells [81]. Microtubule protein polymerization is also affected adversely [82]. Effects on mitochondrial functions and properties have been examined [83—86], along with studies on inhibition of sulfhydryl-containing enzymes [87—90]. 

A cytoplasmic factor is postulated to be responsible for the initiation of the S phase, and various investigators have demonstrated that DNA synthesis can be initiated by extracts of He La cells (Friedman and Mueller, 1968 Kumar and Friedman, 1972), L cells and ascites cells (Thompson and McCarthy, 1968), and embryos and eggs of Xenopus (Benbow and Ford, 1975). Although these factors are thought to be proteins, their exact nature and mechanisms of action are unknown. Recently it was suggested that diadenosine-tetra-phosphate (Ap4A) may act as an initiator of DNA replication in animal cells (Grummt, 1978). 

B. Chance, D. Garfinkel, J. Higgins, and B. Hess, Metabolic control mechanisms A solution for the equations representing interaction between glycolysis and respiration in ascites tumor cells. 

Skovsgaard T. Mechanisms of resistance to daunombicin in Ehrlich ascites tumor cells. Cancer Res 1978 38 1785-1791. 

Cell count The second important criterion of SBP is deemed to be a higher cell count (>250 polymorphonuclear neutrophils/mm ). As a result, early diagnosis is possible with a sensitivity of 92% and a specificity of 95%. A higher leukocyte count in ascitic fluid does not correlate with peripheral leukocytosis (or vice versa). Mechanical assessment of the cell count, however, also identifies lymphocytes, serosal surface cells and peritoneal macrophages. For this reason, it is imperative to distinguish the polymorphonuclear neutrophils (and possibly the number of mononuclear forms) in the ascitic fluid smear. (71, 75, 79,102,106)... 

A wide range of aldesleukin-induced adverse effects is associated with the capillary leak syndrome, which is characterized by an increase in vascular permeability with subsequent leakage of fluids and proteins into the extravascular space (4). This results in a third-space clinical syndrome, generalized or peripheral edema, weight gain, cardiovascular and pulmonary comphcations with hypotension, pericardial, and pleural effusions, ascites, oliguria, and prerenal azotemia. Symptoms usually resolve in a few days after aldesleukin withdrawal. Studies on the mechanism have raised a number of hypotheses, such as damage to the endothehal cells, release of secondary cytokines, and activation of the complement cascade (15). 

The in vivo anti-proliferative and anti-tumor activity of di-n-butyl and tri-n-butyl tin species towards Ehrlich ascites tumor IMG carcinoma, P388, and Sarcoma 180 has been reported. The cellular mechanism of the anti-proliferative activities reveals that the di-n-butyl- and tri-n-butyl-tin species selectively accumulate near to the nucleus, golgi apparatus, and endoplasmic reticulum in the cell and then destroy the structure of Golgi apparatus and endoplasmic reticulum, inhibiting the ceramide metabolism function, inositol triphosphate (IP3)-induced intracellular Ca + mobilization, and finally stopping the membrane-mediated signal transduction leading to DNA synthesis.44... 

Onozaki, K., Tomita, M., Sakurai, Y. and Ukita, T. (1972) The mechanism of the cytotoxicity of Ricinus communis phytoagglutinin toward rat ascites tumor cells. Biochem Biophys Res Commun, 48, 783-788. 

In order to clarify the mechanism of action of these compounds, their action suppressing the dehydrogenase of Ehrlich ascites carcinoma cells, and the syntheses of nucleic acids and protein by coli bacilli was examined. It was presumed from the results that the antitumour action of the compound LXII) is mainly due to the suppression of dehydrogenase action and that of compound LXIII) and compound LXIV) is due to the suppression of dehydrogenase action and syntheses of deoxyribonucleic acid, ribonucleic acid, and protein in tumour cells. 

The topology of the radical site pocket of calf thymus and mouse fibroblast ribonucleotide reductase was recently probed with a series of hydroxamate inhibitors of increasing bulkiness and will be discussed in the following section. Other mammalian sources from which ribonucleotide reductases have been isolated and more or less purified include rat Novikoff hepatoma and regenerating rat liver" rabbit bone mar-row 5,66) Ejjj-iich ascites tumor cells of mice and cultured human lymphoblast cells Some of their properties are described in Table 2. Many more animal and human cells were assayed for enzyme activity, frequently in mutant cell lines, to test for cell cycle dependence, mechanisms of metabolic regulation, drug resistance, and correlation with tumor growth rates. Representative studies of this kind, which rapidly expand in number, are summarized in Table 3. 

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