Effect of hyperthermia on growth of Ehrlich ascites tumor cells

Hyperthermic treatment at 43 degrees C suppressed the growth of Ehrlich ascites tumor (EAT) cells in vitro. Incubation of EAT cells at 43 degrees C for as little as 1.5 h totally abolished the transplantability of the tumor. At the same time, the rate of cellular glucose uptake, the density of glucose transporter on the cells as well as the extent of thymidine, uridine and leucine incorporation were significantly reduced.     

Mannose toxicity in Ehrlich ascites tumor cells

Mannosephosphate isomerase (MPI) showed a higher activity than hexokinase (HKM) in its ability to phosphorylate mannose in the spleen, thymus, brain, liver, striated muscles, kidneys, and testes from BALB/c mice. This led to a HKM/MPI ratio of less than 1 in all the organs and tissues mentioned. In contrast, Ehrlich ascites tumor cells obtained from the peritoneum of BALB/c mice had low MPI activity (half of the HKM activity and, therefore, a ratio of 2). Mannose, which is nontoxic to nontumor cells at a concentration of 0.1 M, induced marked in vitro mortality of the tumor cells. Incubation of Ehrlich ascites tumor cells with mannose resulted in a high accumulation of mannose-6-phosphate and a marked depletion of ATP which did not appear when the cells were incubated with glucose. These facts may explain the selective mortality caused by mannose in the tumor cells studied.     

Interaction andin vivo growth inhibition of Ehrlich ascites tumor cells by jacalin

Jacalin has been found to agglutinate Ehrlich ascites cells. The agglutination was inhibited by α-glycosides of D-Gal and β -D-Gal(1 → 3)-D-GalNAc suggesting that the lectin-ascites interaction was carbohydrate-specific. There was 21.8% inhibition of tumour (ascites) cell growthin vivo in mice administered 50μg of jacalin by injection for 6 days following intraperitoneal injection of ascites cells. Administration of 100, 150 and 200μg jacalin resulted in 40.2, 57.5 and 83% inhibition respectively. Thein vivo inhibition of tumour cells growth by jacalin was due to its preferential binding with D-Gal-α -(1 → 6) present as terminal residues in the glycoprotein on tumour cell surface.     

Effect of haemolysin of Pseudomonas aeruginosa on Ehrlich ascites tumor cells]

Haemolysin of Pseudomonas aeruginosa exerts toxic effects upon the metabolism of Ehrlich ascitic tumor cells : morphological changes appear readily ; respiration is inhibited more slowly ; the lethal effect determined by intraperitoneal injection of tumor cells is neutralized. Inhibition with human normal sera is complete for the hemolytic action, but incomplete for the cytopathic action.     

Effect of cytochalasins on F-actin and morphology of Ehrlich ascites tumor cells

Cytochalasins have been used extensively to probe the role of F-actin in different aspects of cellular function. Most of the data obtained are interpreted on the basis of the well-established depolymerizing effects of cytochalasins on F-actin preparations in vitro. However, some evidence indicates that, in intact cells, different cytochalasins can have varying effects on cell morphology and F-actin content and organization. To examine this problem in more detail, we analyzed the effects of cytochalasins on the cell morphology of and F-actin content and organization in Ehrlich ascites tumor (EAT) cells. After a 3-min exposure to 0.5 microM cytochalasin D, B, or E, F-actin content was equally reduced in all cases and this correlated with a reduction in the amount of cortical F-actin associated with the EAT cell membrane. However, only with CE was cell morphology markedly altered, with the appearance of numerous blebs. At 10 microM, blebbing was present in all conditions and the organization of cortical F-actin was disrupted. F-actin content, however, was not further reduced by this higher concentration and in CD it was identical to control levels. Exposure of EAT cells to similar concentrations of cheatoglobosin C, an analog of the cytochalasins that has little to no affinity for F-actin, resulted in a loss of F-actin content, a reduction in F-actin fluorescence, but no change in cell morphology, including a complete lack of bleb formation. Myosin II immunoreactivity, concentrated in the cortical cytoplasm colocalized with F-actin and in an area associated with the Golgi, was reduced by the high-dose cytochalasin. These results demonstrate that caution must be exercised in the use of cytochalasins to probe the role of F-actin in cellular function and that several parameters must be analyzed to obtain an accurate assessment of the effect of cytochalasin on the actin filament system.     

Nucleosidediphosphate kinase from Ehrlich ascites tumor cells

A phosphate-incorporating protein has been highly purified from the cytosol of Ehrlich ascites tumor cells (EAT cells). The nitrocellulose membrane method was used to follow the progress of the purification by quantitation of the [32P]phosphorylated form of the protein. The purified protein was identified as an NDP-kinase since it exhibited NDP-kinase activity and had enzyme characteristics in common with other NDP-kinases from various mammalian cells. The purified NDP-kinase was found to have a molecular weight of approximately 76,000 daltons. Moreover, the enzyme appears to consist of two distinct polypeptides (18,000 and 20,000 daltons). This enzyme contained 19 amino acids, with high levels of glycine (9.8%) and lysine (9.0%). The enzyme rapidly formed a [32P]phosphoenzyme when incubated with [gamma-32P]ATP in the presence of Mg2+ (1 mM) at the optimum pH of 7.5 even at low temperature (below 4 degrees C). This phosphoenzyme is an enzyme-bound, high-energy-phosphate intermediate, because ATP was formed from it on incubation with ADP in the presence of Mg2+ (1 mM). This finding suggests that the phosphoenzyme functions as an intermediate in NDP-kinase action.