scholarly journals Feedback regulation of S-adenosylmethionine decarboxylase synthesis

1989 ◽  
Vol 257 (3) ◽  
pp. 929-931 ◽  
Author(s):  
L Persson ◽  
A R Khomutov ◽  
R M Khomutov
Keyword(s):  
Cell Growth ◽  
Marked Decrease ◽  
Potent Inhibitor ◽  
Feedback Regulation ◽  
Adenosylmethionine Decarboxylase ◽  
Ehrlich Ascites ◽  
Ehrlich Ascites Tumour ◽  
Polyamine Content ◽  
Ascites Tumour Cells ◽  
Ehrlich Ascites Tumour Cells

Treatment of Ehrlich ascites-tumour cells with 1-amino-oxy-3-aminopropane (AOAP), a potent inhibitor of ornithine decarboxylase, resulted in a marked decrease in cellular contents of putrescine and spermidine, concomitant with an arrest of cell growth. The activity of S-adenosylmethionine decarboxylase (AdoMetDC) was greatly increased in cells treated with AOAP. This increase in AdoMetDC activity was shown to be, at least partly, caused by enhanced synthesis of the enzyme, which most likely was induced by the change in cellular polyamine content.

scholarly journals Effects of S-adenosyl-1,8-diamino-3-thio-octane and S-methyl-5′-methylthioadenosine on polyamine synthesis in Ehrlich ascites-tumour cells

1989 ◽  
Vol 261 (1) ◽  
pp. 205-210 ◽  
Author(s):  
I Holm ◽  
L Persson ◽  
A E Pegg ◽  
O Heby
Keyword(s):  
Marked Decrease ◽  
Tumour Cells ◽  
Simultaneous Increase ◽  
Spermine Synthase ◽  
Ascites Tumour ◽  
Ehrlich Ascites ◽  
Ehrlich Ascites Tumour ◽  
Synthase Inhibitor ◽  
Ascites Tumour Cells ◽  
Ehrlich Ascites Tumour Cells

The rate-limiting enzymes in polyamine biosynthesis, ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (AdoMetDC), are negatively regulated by the polyamines spermidine and spermine. In the present work the spermidine synthase inhibitor S-adenosyl-1,8-diamino-3-thio-octane (AdoDATO) and the spermine synthase inhibitor S-methyl-5′-methylthioadenosine (MMTA) were used to evaluate the regulatory role of the individual polyamines. Treatment of Ehrlich ascites-tumour cells with AdoDATO caused a marked decrease in spermidine content together with an accumulation of putrescine and spermine. Treatment with MMTA, on the other hand, gave rise to a marked decrease in spermine, with a simultaneous accumulation of spermidine. A dramatic increase in the activity of AdoMetDC, but not of ODC, was observed in MMTA-treated cells. This increase appears to be unrelated to the decrease in spermine content, because a similar rise in AdoMetDC activity was obtained when AdoDATO was given in addition to MMTA, in which case the spermine content remained largely unchanged. Instead, we show that the increase in AdoMetDC activity is mainly due to stabilization of the enzyme, probably by binding of MMTA. Treatment with AdoDATO had no effects on the activities of ODC and AdoMetDC, even though it caused a precipitous decrease in spermidine content. The expected decrease in spermidine-mediated suppression of ODC and AdoMetDC was most probably counteracted by the simultaneous increase in spermine. The combination of AdoDATO and MMTA caused a transient rise in ODC activity. Concomitant with this rise, the putrescine and spermidine contents increased, whereas that of spermine remained virtually unchanged. The increase in ODC activity was due to increased synthesis of the enzyme. There were no major effects on the amount of AdoMetDC mRNA by treatment with the inhibitors, alone or in combination. However, the synthesis of AdoMetDC was slightly stimulated in cells treated with MMTA or AdoDATO plus MMTA. The present study demonstrates that regulation of neither ODC nor AdoMetDC is a direct function of the polyamine structure. Instead, it appears that the biosynthesis of the polyamines is feedback-regulated by the various polyamines at many different levels.

scholarly journals The transport and oxidation of succinate by Ehrlich ascites-tumour cells

1976 ◽  
Vol 160 (1) ◽  
pp. 121-123 ◽  
Author(s):  
T L Spencer
Keyword(s):  
Ph Dependence ◽  
Organic Anion ◽  
Tumour Cells ◽  
Cell Integrity ◽  
Carrier System ◽  
Ascites Tumour ◽  
Ehrlich Ascites ◽  
Ehrlich Ascites Tumour ◽  
Ascites Tumour Cells ◽  
Ehrlich Ascites Tumour Cells

The transport and oxidation of succinate by functionally intact Ehrlich ascites-tumour cells was investigated. On the basis of pH dependence and inhibitor sensitivity it was concluded that succinate may be transported across the cell membrane by the organic anion carrier system. Thus the ability of isolated Ehrlich cells to oxidize succinate is real, and is not necessarily a result of damage to cell integrity.

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