Experimental study of DFMO on the growth and apoptosis in bladder carcinoma cells / 肿瘤研究与临床

Objective An experimental study was undertaken to observe the effects of DFMO on the growth and apoptosis in bladder carcinoma EJ cells. Methods The methods of cell culture, living camera technique, eosin dying cell counting and DNA end labeling in situ were used to observe the effects of DFMO on the growth and apoptosis in bladder carcinoma EJ cells. Results Living camera technique showed that cell growth was significantly inhibited after five days of 4 mmol/L, 6 mmol/L, 8 mmol/L of DFMO were administrated compared with that of control group, and this variation was obvious with DFMO dosage increasing. The same was observed with eosin dying cell counting. Tunel method showed that apoptosis was induced by DFMO with 4 mmol/L, 6 mmol/L, and 8 mmol/L, but 6 mmol/L seems to be a suitable dosage. All these methods showed that if exogenous putrescence was added simultaneously, there was no difference significantly compared with that of control group both in cell proliferation and apoptosis. Conclusion The proliferation of bladder carcinoma EJ cell could be inhibited by DFMO and also apoptosis could be induced by DFMO.

Effect of DFMO on the Growth of K562 Cells and Its Association with Telomerase Activity / 中国肿瘤生物治疗杂志

Objective: To investigate the effects of DFMO on the growth characteristics, apoptosis and activity of telomerase of K562 cells. Methods: The growth rate, phase distribution of cell cycle and apoptosis of treated cells with DFMO were detected by cell count, morphological assay, FCM analysis and DNA electrophoresis, respectively. The telomerase activity was examined by telomeric repeat amplification protocol(TRAP). Results: In K562 cells treated with DFMO, the growth rate was markedly retarded. The increase in G1 -phase cells and decrease in s-phase population and induction of apoptosis were observed. The activity of telomerase of treated cells was inhibited. Conclusion: The growth inhibition and apoptosis induction of K562 cells treated by DFMO were associated with suppressed telomerase activity. It is suggested that inactivation of telomerase in cancer cells conld be one of important events in antitumor molecular mechanism of inhibition of polyamine biosynthesis.

Alfa - difluoromethylornithine Reduced Protein Phosphorylation in MCF-7 Human Breast Cancer Cells / 대한암학회지

No abstract available.

Comparative Studies on the Polyarnine Involvement in MCF - 7 and MDA - MB - 231 Breast Cancer Cell Proliferation / 대한암학회지

No abstract available.

Involvement of Polyamine in Growth Hormine Secretion from the GH3 Cells / 대한내분비학회지

BACKGROUNDS: Polyamines are known to be essential for cell growth and differentiation. Recently, possible roles of the polyamine in signal transduction as neurotransmitter, modulator, or second messenger are suggested in many studies. Furthermore, it is widely studied that possible roles of polyamine are involved in the action of hormone. Thus, it was to investigate the effect of polyamines in the cell proliferation and secretion of GH from the GH cells. METHODS: Cells(5*10 cells/mL) were incubated for 3 days in DMEM containing test drugs and labeled with 20pCi/mL of [S]-methionine for 2 hr. Proteins secreted into the medium were separated by 13% SDS-gel electrophoresis, then autoradiography was performed to identify radiolabeled proteins. [S]-methionine labelled GH was identified by radioimmuno-precipitation. Total protein synthesis was determined from the radioactivity of the cell homogenate by liquid scintillation counter. The intracellular polyamine content was determined by HPLC. RESULTS: Externally added polyamines(putrescine, spermidine, spermine) induced cell proliferation in a dose-dependent manner at proper concentrations, specifically 50pM putrescine increased GH secretion, DFMO or MGBG, which is polyamine biosynthetic inhibitor, inhibited GH secretion in a dose-dependent fashion, In the cells treated with 20mM or 0.01mM MGBG, total protein synthesis were decreased only to 90 or 76% of the control levels and cell proliferation was also slightly inhibited. However the secretion of GH was severely blocked to 37% or 35% of the control. Hydrocortisone at 5 pM stimulated the secretion of GH to 153% of basal secretion, also doubled intracellular putrescine content. CONCLUSION: The present data show that externally added polyamines induced cell proliferation and GH secretion. Also, extemally added putrescine stimulated GH secretion significantly. GH secretion was inhibited by polyamine metabolic inhibitor in a dose-dependent manner and polyamine metabolic inhibitors, at proper concentrations, specifically blocked GH secretion without any significant influence on the total protein synthesis. The above results imply the involvement of polyamine in GH secretion.

Association of dexamethasone-induced apoptosis of G|1-arrest of human leukemic CEM cells with polyamine deficit

The effects of DFMO or/and putrescine on the dexamethasone-induced apoptosis of CEM cells were studied to investigate the role of polyamines in anti-leukemic glucocorticoid action. Dexamethasone-induced apoptosis was preceded by significant decreases of cellular polyamine contents and putrescine uptake activity. But DFMO produced decreases of putrescine and spermidine contents and marked increase of putrescine uptake activity, but did not induce apoptosis. However, dexamethasone and DFMO, respectively, induced G|1-arrest in cell cycle and hypophosphorylation of pRb, resulting in the increase of G|1 to S ratio and decrease of CEM cell count. DFMO enhanced the dexamethasone-induced apoptosis and G|1-arrest. On the other hand, putrescine little affected the apoptotic and G|1-arresting activities of dexamethasone, but almost suppress the effects of DFMO and also the DFMO-dependent enhancement of dexamethasone effects. These results suggested that the dexamethasone-induced apoptosis to be associated with pRb hypophosphorylation and G|1-arrest in CEM cells might be ascribed to the concomitant decreases of cellular polyamine contents and putrescine uptake activity.

Decarboxylation of arginine and ornithine by arginine decarboxylase purified from cucumber (Cucumis sativus) seedlings.

A purified preparation of arginine decarboxylase from Cucumis sativus seedlings displayed ornithine decarboxylase activity as well. The two decarboxylase activities associated with the single protein responded differentially to agmatine, putrescine and Pi. While agmatine was inhibitory (50 %) to arginine decarboxylase activity, ornithine decarboxylase activity was stimulated by about 3-fold by the guanido arnine. Agmatine-stimulation of ornithine decarboxylase activity was only observed at higher concentrations of the amine. Inorganic phosphate enhanced arginine decarboxylase activity (2-fold) but ornithine decarboxylase activity was largely uninfluenced. Although both arginine and ornithine decarboxylase activities were inhibited by putrescine, ornithine decarboxylase activity was profoundly curtailed even at 1 mM concentration of the diamine. The enzyme-activated irreversible inhibitor for mammalian ornithine decarboxylase, viz. α-difluoromethyl ornithine, dramatically enhanced arginine decarboxylase activity (3-4 fold), whereas ornithine decarboxylase activity was partially (50%) inhibited by this inhibitor. At substrate level concentrations, the decarboxylation of arginine was not influenced by ornithine and vice-versa. Preliminary evidence for the existence of a specific inhibitor of ornithine decarboxylase activity in the crude extracts of the plant is presented. The above results suggest that these two amino acids could be decarboxylated at two different catalytic sites on a single protein.