Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.1.1.17 (ornithine decarboxylase)
 6,351 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Basic fibroblast growth factor (bFGF) is a potent mitogen for various cell types. Induction of ornithine decarboxylase (ODC) activity is one of the early events triggered in proliferating cells. Our aim was to study the effect of bFGF on ODC activity and ODC mRNA expression in a pancreatic tumoral cell line, AR4-2J. Following kinetic and dose-response studies, we found that maximal stimulation (150% over control) of ODC activity occurred after 3 h of bFGF treatment (10(-9) M), the EC50 being 20 pM. To elucidate the mechanism by which bFGF stimulates ODC activity, we measured the ODC mRNA levels by Northern blot hybridization using a 32P-labeled rat cDNA probe. In AR4-2J cells treated with bFGF at 10(-9) M over 120 min, ODC mRNA expression was transiently increased by 71.6% at 60 min. Furthermore, bFGF was also able to stimulate ODC mRNA synthesis in the presence of cycloheximide. In conclusion, in AR4-2J cells of pancreatic origin, bFGF stimulates ODC gene transcription. This effect contributes to the stimulation of ODC enzymatic activity and to the proliferative effect of bFGF on this cell line.
Pancreas 1992
PMID:Effect of basic fibroblast growth factor on ornithine decarboxylase activity and mRNA expression in a pancreatic tumoral cell line (AR4-2J). 128 Mar 64

The calcium channel blocker verapamil has been previously shown to augment the chemosensitivity of pancreatic adenocarcinoma cell lines to doxorubicin by mechanisms other than changes in the intracellular accumulation, retention, or metabolism of doxorubicin. Because of our interest in polyamine biosynthesis and metabolism and the known involvement of calcium in the induction of ornithine decarboxylase (ODC) by serum refeeding of cultured cells, the effects of verapamil on the serum-stimulated ODC activity in two hamster pancreatic adenocarcinoma cell lines were examined. In plateau phase well-differentiated (WD) PaCa and poorly differentiated (PD) PaCa cells, a dose-dependent inhibition of the 4-h serum induction of ODC was seen at concentrations of 1, 5, and 10 microM verapamil. At the higher concentrations of verapamil, the inhibition of ODC induction was comparable to that achieved with 5 mM alpha-difluoromethylornithine (DFMO, a specific enzyme inhibitor of ODC) and greater than that seen with 2 mM EGTA plus calcium-depleted serum. Log phase PD PaCa cells, included for comparison, showed less ODC induction with serum and lesser degrees of inhibition of the response to serum refeeding with verapamil, DFMO, and calcium depletion. No direct inhibition of the ODC enzyme was found when verapamil was added at the time the activity was measured. Based on our present data, a possible influence of intracellular calcium pools in the verapamil effect on ODC activity is unclear. Nevertheless, the present findings suggest that verapamil's effects on cytotoxicity may be mediated (at least in part) by inhibition of the serum-mediated induction of ODC.
Pancreas 1991 Nov
PMID:Inhibitory effects of a calcium antagonist on ornithine decarboxylase induction in pancreatic cancer cell lines. 178 Mar 23

Ornithine decarboxylase (ODC) is the rate-limiting enzyme in polyamine biosynthesis. We examined circadian variations in pancreatic ODC activity and time-course effects of caerulein in fed and fasted rats. Significant circadian variations in amount of ODC activity were observed. The highest values were obtained during the dark period (1855 +/- 406 pmoles CO2/h), and the lowest during the light period (359 +/- 84 pmoles CO2/h). Caerulein treatment induced hypertrophy and hyperplasia of the pancreas in fed rats; increases in pancreatic ODC activity preceded the rise in protein and DNA contents (447 +/- 44 pmoles CO2/h and 5573 +/- 893 pmoles CO2/h, 6 and 12 h after the first injection of caerulein, respectively). In fasted rats, pancreatic ODC activity was very low (149 +/- 37 pmoles CO2/h) and caerulein treatment induced a transient increase in this activity 12 h after the first injection; hypertrophy but not hyperplasia of the pancreas was observed. In caerulein-treated fasted rats, refeeding during the night following a 48 h fasting period was not enough to increase either ODC activity or DNA content. These findings demonstrate that nutritional status is an important factor in the regulation of ODC activity and, thereby, in caerulein-induced pancreatic growth.
Pancreas 1991 Sep
PMID:Effects of feeding, fasting, and caerulein treatment on ornithine decarboxylase in rat pancreas. 194 10

The glycolytic inhibitor, 2-deoxy-D-glucose (2-DG), inhibits growth of some cancers. alpha-Difluoromethylornithine (DFMO) is an irreversible inhibitor of ornithine decarboxylase, the rate-limiting enzyme in polyamine biosynthesis. We and others have previously shown that DFMO inhibits cancer growth in a number of models. The present study was designed to investigate the effects of 2-DG alone and combined with DFMO on the growth of H2T hamster pancreatic ductal adenocarcinoma. Twenty-eight male Syrian golden hamsters were inoculated with 500,000 H2T cells, and then randomized into four groups of seven each: group 1 served as control; group 2 received DFMO (3% in drinking water); group 3 received 2-DG (500 mg/kg/day) intraperitoneally; group 4 received a combination of 2-DG and DFMO. Treatment began 5 days after tumor cell inoculation and continued for 28 days. At the end of the treatment period, the area of the H2T tumor was reduced 31% by DFMO compared with a 22% reduction caused by 2-DG. Tumor weight was significantly reduced (31%) by DFMO but not by 2-DG. Tumor contents of DNA, RNA, and protein were also reduced by DFMO but not 2-DG. Tumor concentration of the polyamines, putrescine and spermidine, were reduced by DFMO, but 2-DG did not alter levels of polyamines. The combination of DFMO and 2-DG caused a significantly greater reduction in tumor weight and putrescine content compared with DFMO alone.(ABSTRACT TRUNCATED AT 250 WORDS)
Pancreas 1989
PMID:The effects of 2-deoxy-D-glucose and alpha-difluoromethylornithine on the growth of pancreatic cancer in vivo. 249 60

Pancreatic adenocarcinoma presents a clinical and experimental challenge because of its relative resistance to conventional modes of therapy. The present study explores a novel, biologically based approach to enhancing its chemosensitivity and to overcoming its chemoresistance in a panel of pancreatic adenocarcinoma cell lines (two human lines: PANC-1 and COLO-357; and two hamster lines: WD PaCa and PD PaCa). Difluoromethylornithine (DFMO), a specific inhibitor of ornithine decarboxylase (ODC) that produces antiproliferative effects by polyamine depletion, was combined with the cytotoxic agent doxorubicin (DOX) in vitro. The inhibitory effects of DFMO were cytostatic and roughly additive to those of DOX. Although the response to the combination varied as a function of the cell lines studied and the response to DFMO as a single agent, all cell lines studied showed some increased inhibition with the combination. The most striking enhancement was seen in our most DOX-resistant cell line, WD PaCa, and also in PANC-1, a relatively sensitive cell line. Thus, the combination of DFMO and DOX shows promise as an experimental approach to the problem of drug resistance and the limited chemosensitivity of pancreatic cancer.
Pancreas 1986
PMID:Combined effects of alpha-difluoromethylornithine and doxorubicin against pancreatic cancer cell lines in culture. 310 59

The current study examines the effects of alpha-difluoromethylornithine (DFMO), an irreversible ornithine decarboxylase inhibitor, on pancreatic growth and development of rat neonates. Newborn rats were given daily subcutaneous injections of 300 or 500 mg kg-1 DFMO and killed after 7, 14, 21, and 28 days of treatment. Pancreatic weights and DNA, RNA, protein, amylase and chymotrypsin total contents (per pancreas) and concentrations were evaluated at the end of each period. Inhibition of body weight gain (30%) was maximal after 14 days of the 500 mg DFMO treatment. Pancreatic weight increase of 20% was significant after 7 days of the 300 mg DFMO treatment while deficits of 15, 20, and 14% were significant after 21 days of 300 mg DFMO and 14 and 21 days of 500 mg DFMO. Total DNA was already subnormal after one week of 500 mg DFMO with a maximal reduction of 30% after 28 days while a significant decrease of 15% was observed only after 3 weeks of 300 mg DFMO. Pancreatic hypertrophy was observed after 7 and 28 days of the 500 mg and after 14 days of the 300 mg DFMO treatment. Chymotrypsin total contents and concentrations were always preferentially affected over those of amylase. These data support the view that ornithine decarboxylase (ODC) and polyamines play an important role in cell replication and growth of the pancreatic tissue during the neonatal period.
Pancreas 1987
PMID:Implication of ornithine decarboxylase and polyamines in pancreatic growth of neonatal rats. 311 41

The present study was designed to investigate the effects of the carcinogenic agent azaserine on the induction of pancreatic and hepatic polyamine metabolism in rats. One single injection of 30 mg azaserine/kg body weight i.p. is known to induce adenoma and subsequently carcinoma, predominantly in the pancreas, after several months. Male Lewis rats were treated with either azaserine (30 mg/kg body weight i.p.) or saline and 5-10 animals per group were sacrificed 2, 6, 9, 12, 18, 24, and 48 h later. Furthermore, animals were simultaneously treated with the ornithine decarboxylase (ODC) inhibitor alpha-difluoromethylornithine (DFMO) or the polyamine oxidase inhibitor MDL 72527 and killed 6 and 12 h after azaserine injection. The azaserine-induced significant increase in pancreatic putrescine concentrations was accompanied by an increase in spermidine/spermine N1-acetyltransferase but unchanged ODC and was significantly inhibited by N, N'-bis(2,3-butadienyl)putrescine (MDL 72527) but not by DFMO. S-Adenosylmethionine decarboxylase (SAM-DC) activity was significantly decreased in the pancreata of azaserine-treated animals compared to controls. In contrast, the azaserine-induced significant increase in hepatic putrescine was lower and transient, was accompanied by an increase in ODC and SAM-DC, and was completely inhibited by simultaneous DFMO treatment but not by MDL 72527. These data show completely different patterns of activation of polyamine metabolism in the pancreas and in the liver: Azaserine treatment forms putrescine in the liver by de novo synthesis via ODC only, while azaserine-induced pancreatic putrescine is exclusively produced by the interconversion pathway via oxidation of N1-acetylspermidine.
Pancreas 1995 Jan
PMID:Dissimilar effect of the carcinogenic agent azaserine on pancreatic and hepatic polyamine metabolism in rats. 789 59

Calcium, which binds to calmodulin inside the cells, is an important mediator of various intracellular processes, including cell proliferation. We speculated that blockade of Ca2+ influx into the cells by Ca(2+)-channel blockers, such as phenytoin and verapamil, might affect the Ca(2+)-calmodulin pathway leading to suppression of cell growth. In this study, we examined the effect of phenytoin and verapamil on growth of two human pancreatic cancer cell lines, MIA PaCa-2 and CAV, in vitro and in vivo. Both phenytoin and verapamil inhibited growth of the two cell lines in a dose-dependent fashion. Phenytoin and verapamil each significantly prolonged doubling time of MIA PaCa-2 and the combination of the two drugs acted synergistically. The activity of ornithine decarboxylase, which is a rate-limiting enzyme of the polyamine pathway that is closely related to cell proliferation, was significantly inhibited by both drugs in a time-dependent fashion. Phenytoin, but not verapamil, inhibited growth of MIA PaCa-2 tumors xenotransplanted into nude mice, whereas both phenytoin and verapamil inhibited the growth of CAV tumors. Since phenytoin and verapamil are known to have fewer side effects than conventional antineoplastic drugs, these results suggest their possible use in novel therapeutic strategies.
Pancreas 1994 Mar
PMID:Inhibitory effect of calcium channel blockers on growth of pancreatic cancer cells. 819 Jul 21

We studied the effect of oral zinc administration on functional and morphological regeneration of the remnant pancreas after 80% pancreatectomy in dogs. After 80% pancreatectomy, both endo- and exocrine function (assessed by the sum of plasma immunoreactive insulin on the intravenous glucose tolerance test and amylase output on the cerulein-secretin test) markedly deteriorated, the pancreatic regeneration rate (change in weight of the remnant pancreas between the time of surgery and autopsy) was very poor, and the zinc concentration in pancreatic tissue decreased in dogs fed the standard diet. In dogs fed the high-zinc diet, pancreatic function and regeneration rate were significantly improved, and the zinc concentration in pancreatic tissue was maintained. Early cell proliferation (assessed by ornithine decarboxylase activity. DNA synthesis, and proliferating cell nuclear antigen labeling index in the remnant pancreas) after pancreatectomy was significantly enhanced in the high-zinc diet group compared to the standard diet group. Correlation analyses between parameters of early cell proliferation and zinc concentration in pancreatic tissue yielded significant positive correlations, and the zinc concentration in pancreatic tissue was significantly correlated with both endo- and exocrine function and the pancreatic regeneration rate. These results suggest that a high-zinc diet after major pancreatectomy is effective in maintaining the zinc concentration in pancreatic tissue, which not only enhance early cell proliferation in the remnant pancreas but improves pancreatic endo- and exocrine function in the late period, promoting pancreatic regeneration.
Pancreas 1997 Mar
PMID:Effect of zinc administration on pancreatic regeneration after 80% pancreatectomy. 905 88

Reversible protein phosphorylation is an important mechanism by which cells transduce external signals into biologic responses. Levels of protein phosphorylation are determined by the balanced actions of both protein kinases and protein phosphatases (PPases). However, compared with protein kinases, regulation of PPases has been relatively neglected. The insulin secretagogue L-arginine, an immediate metabolic precursor to polyamines, causes a rapid and transient decrease in PPase-1 activity in insulin-secreting RINm5F cells. We here show that polyamines dose-dependently suppress PPase-1-like activity when added to RINm5F cell homogenates at physiologic concentrations (spermine > spermidine > putrescine), while having minor and inconsistent effects on PPase-2A-like activity. The IC50 value for spermine on PPase-1-like activity was approximately 4 mM. The inhibitory effect was reproduced and of comparable magnitude on purified PPases types 1 and 2A. On the other hand, when endogenous polyamine pools were exhausted by 4 days of exposure to the specific L-ornithine decarboxylase inhibitor DL-alpha-difluoromethylornithine, there was an increase in PPase-2A-like activity. Quantitative Western analysis revealed that the amount of PPase-2A protein did not change after this treatment. It is concluded that polyamines cause time-and concentration-dependent inhibitory effects on RINm5F cell PPase activities, which may contribute to the increase in phosphorylation state that occurs after secretory stimulation.
Pancreas 2000 Jan
PMID:Polyamines regulate serine/threonine protein phosphatases in insulin-secreting cells. 1063 Mar 81


1