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Protective effect of pantothenic acid and related compounds against permeabilization of Ehrlich ascites tumour cells by digitonin

100%

Slyshenkov V. S., Rakowska M., Wojtczak L.

Acta Biochimica Polonica

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1996

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tom 43

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nr 2

Preincubation of Ehrlich ascites tumour cells with millimolar concentrations of pantothenic acid, pantothenol or pantethine, but not with homopantothenic acid, at 22°C or 32°C, but not at 0°C, makes the plasma membrane more resistant to the damaging effect of submillimoiar concentrations of digitonin. It is proposed that this increased resistance is due to the increased rate of cholesterol biosynthesis. In fact, incorporation of [14C]acetate into cholesterol is by 45% increased in the cells preincubated with pantothenic acid; this probably reflects elevation of the content of CoA in such cells [Slyshenkov, V.S., Rakowska, M., Moiseenok, A.G. & Wojtczak, L. (1995) Free Radical Biol. Med. 19,767-772].

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Effect of glucose and deoxyglucose on cytoplasmic concentration of free Ca2 in Ehrlich ascites tumour: studies on single cells

86%

Czyz A., Teplova V. V., Sabala P., Czarny M., Evtodienko Y. V., Wojtczak L.

Acta Biochimica Polonica

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1993

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tom 40

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nr 4

Concentration of free cytoplasmic Ca2+ ([Ca2+]i) in Ehrlich ascites tumour cells loaded with fura-2 was measured in single cells applying a video imaging system. In resting cells [Ca2+li amounted to 60 - 340 nM and was increased after addition of 10 mM D-glucose or D-2-deoxyglucose by 80 - 200 nM. This increase occurred within 30 - 60 s following addition of the sugars and lasted for several minutes. Pretreatment of the cells with thapsigargin resulted in a much smaller [Ca2+]i increase after addition of glucose or deoxyglucose and, vice versa, thapsigargin added after the sugars mobilized less Ca2+ than when added before. A possible relation of the [Ca2+]i rise evoked by glucose and deoxyglucose to the Crabtree effect is discussed.

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Ultrastructural changes of Ehrlich ascites tumor cells after intraperitoneal recombinant human tumor necrosis factor-alpha administration

72%

Terlikowski S. J., Sulkowski S. T.

Bulletin of the Veterinary Institute in Puławy

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2001

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tom 45

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nr 2

Swiss albino male mice were inoculated intraperitoneally (i.p.) with Ehrlich ascites tumor (EAT) and treated i.p. with recombinant human tumor necrosis factor-α (rhTNF-) three time a week in doses of 5, 7.5 and 10μg for 2 weeks, respectively. The effect of the cytokine on EAT was evaluated by the rate of tumor growth inhibition and ultrastructural changes in EAT cell. After the applied doses of rhTNF-α, inhibition of tumor growth was found. The number of EAT cells decreased after 7.5 and 10μg of rhTNF-α (P<0.001). Ultrastructural study demonstrated a cytotoxic effect of the cytokine on EAT cells.

4

The Crabtree effect: a new look at the old problem

72%

Wojtczak L.

Acta Biochimica Polonica

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1996

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tom 43

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nr 2

Inhibition of respiration by glucose, known as the Crabtree effect, has been observed in several tumours and some other highly glycolytic cells and tissues. Among mechanisms proposed to explain this effect were: competition between glycolysis and respiration for ADP or for inorganic phosphate, change of intracellular pH, change in the permeability of mitochondrial membranes, specific regulatory behaviour of glycolytic enzymes, and specific enzyme topography within the cell. None of these proposals alone seems satisfactory. The present article describes the research carried out in the author's laboratory, pointing to the role of Ca2+ in the mechanism of the Crabtree effect This supposition is based on the following observations: (1) in Ehrlich ascites tumour cells glucose elicits a steady increase of the cytoplasmic concentration of free Ca2+; (2) isolated Ehrlich ascites mitochondria and mitochondria within digitonin-permeabilised cells, preloaded with Ca2+, exhibit a depression of State 3 respiration and lowering of the rate of ATP synthesis; (3) ATPase activity of toluene-permeabilised Ehrlich ascites mitochondria becomes substantially inhibited at micromolar concentrations of Ca2+; (4) Ca2+ potentiates the effect of the inhibitory subunit of F1F0-ATPase. These results allow to hypothesize on the following sequence of events: (1) glucose elevates the cytoplasmic concentration of Ca2+; (2) this elicits an increased accumulation of Ca2+ in mitochondria; (3) loading of mitochondria with Ca2+ leads to an increased association of the inhibitory subunit with F1F0 which results in (4) the inhibition of coupled respiration. The importance of these mechanisms for glycolytic and rapidly proliferating cells is discussed.

Ograniczanie wyników

3 Acta Biochimica Polonica

1 Bulletin of the Veterinary Institute in Puławy

3 Wojtczak L.

1 Czarny M.

1 Czyz A.

1 Evtodienko Y. V.

1 Rakowska M.

1 Sabala P.

1 Slyshenkov V. S.

1 Sulkowski S. T.

1 Teplova V. V.

1 Terlikowski S. J.

1 2001

2 1996

1 1993

Protective effect of pantothenic acid and related compounds against permeabilization of Ehrlich ascites tumour cells by digitonin

Effect of glucose and deoxyglucose on cytoplasmic concentration of free Ca2 in Ehrlich ascites tumour: studies on single cells

Ultrastructural changes of Ehrlich ascites tumor cells after intraperitoneal recombinant human tumor necrosis factor-alpha administration

The Crabtree effect: a new look at the old problem