No abstract available.
Cell Line* ; Colorectal Neoplasms* ; Eflornithine* ; Humans*

No abstract available.
Breast Neoplasms* ; Breast* ; Eflornithine* ; Estrogens ; Humans* ; MCF-7 Cells ; Phosphorylation* ; Polyamines

OBJECTIVETo characterize the role of plating densities and alpha-difluoromethylornithine (DFMO) on the proliferation of IEC-6 cells in vitro.

METHODSIEC-6 cells were seeded in 96-well microplates at various densities in the presence or absence of DFMO. Cells were counted and their proliferative capability was monitored Days 1 to 7 with MTT assay at an optical density of 570 nm.

RESULTSThere was a positive relationship between cell number and OD value (r = 0.954, P < 0.01). Higher plating densities (> 0.5 x 10(4) cells/well) inhibited the growth of cells on Day 2. When the density reaches 4 x 10(4) cells/well, the OD value increased gradually and reached a peak on Day 5. After that, the OD value began to fall. The growth of IEC-6 cells was limited at a low density (0.2 x 10(4) cells/well) on Day 4. DFMO caused a complete inhibition of proliferation of IEC-6 cells on Days 1 to 3.

CONCLUSIONProliferation of IEC-6 cells is related to plating density and incubation time. It is inhibited by DFMO, but is reversible when the incubation time is prolonged.

Animals ; Antineoplastic Agents ; pharmacology ; Cell Count ; Cell Division ; drug effects ; Cell Line ; Eflornithine ; pharmacology ; Time Factors

PURPOSE: Growth factors stimulate protein phosphorylation resulting in transmission of mitogenic signals. In breast cancer, protein kinases and their substrate proteins are importnat in cell proliferation and phathogenesis. Polymine is known as a mediator of stimuli-induced proliferation in many cell systems. In the present study, we report the importance of polyamines in protein phosphorylation in MCF-7 human breast cancer cells. MATERIALS AND METGODS: Protein phosphorylation study was done by incubating cells in the DMEM containing [gamma-(32)P]-ATP. Quantitation of phosphorylation was analysed by fluorescene image analyzer. Tyrosine phosphorylation was detected by anti-phosphotyrosine antibody. Shc was detected by radioimmunoprecipitation and Western blotting. RESULTS: E2, TGF-alpha, and EGF enhanced the protein phosphorylation in very similar pattern. Among those proteins, 67 kDa protein was most strongly phosphorylated. But the most prominent tyrosine phosphoprotein was 52 kDa protein. DFMO at 5 mM strongly inhibited the phosphorylation of the most proteins. Externally added polyamine could recover the inhibitory effect of DFMO in protein phosphorylation. Among the 5 major tyrosine phosphoproteins, 52 and 46 kDa proteins appeared to be Shc proteins. CONCLUSION: Polyamines modulate signal transduction in relation with estrogen receptor and EGF receptor through multiple steps of protein phosphorylations. Tyrosine phosphorylation of Shc proteins were most significantly influenced by polyamines in growth factor-stimulate breast cancer cell proliferation.
Blotting, Western ; Breast Neoplasms* ; Breast* ; Cell Proliferation ; Eflornithine ; Epidermal Growth Factor ; Estrogens ; Humans* ; Intercellular Signaling Peptides and Proteins ; MCF-7 Cells ; Phosphoproteins ; Phosphorylation* ; Polyamines* ; Protein Kinases ; Receptor, Epidermal Growth Factor ; Signal Transduction ; Transforming Growth Factor alpha ; Tyrosine

OBJECTIVETo study the effect of polyamine biosynthesis inhibition on growth characteristics of human lung carcinoma cells and its correlation with the expression of human lung carcinoma associated antigen ALT-04ag gene.

METHODSThe gene expression was detected by RT-PCR and immunocytochemical tests. The cell growth characteristics were studied by cell growth curves, morphological observation, FCM analysis and DNA electrophoresis.

RESULTSHuman lung squamous carcinoma cells L78 treated with 5 mmol/L alpha-difluoromethylornithine (DFMO) for 5 days showed significant growth inhibition and apoptosis induction. The mRNA and protein expressions of ALT-04ag gene in the cells were downregulated, while these changes resulted from DFMO treatment were prevented by provision of DFMO along with exogenous putrescine.

CONCLUSIONThe effect of polyamine biosynthesis inhibition induced by DFMO restrains the growth characteristics and promotes apoptosis of human lung carcinoma L78 cells, which is associated with down regulation of ALT-04ag gene expression.

Antigens, Neoplasm ; biosynthesis ; genetics ; Apoptosis ; Carcinoma, Squamous Cell ; pathology ; Cell Division ; Down-Regulation ; Eflornithine ; pharmacology ; Gene Expression Regulation, Neoplastic ; Humans ; Lung Neoplasms ; pathology ; Oncogene Proteins ; genetics ; RNA, Messenger ; biosynthesis ; genetics ; Tumor Cells, Cultured

OBJECTIVE: To explore the mechanism of alpha-difluoromethylornithine (DFMO) inhibiting ODC activity in the cortex and hippocampus in rats. METHODS: Forty male rats was randomly divided into ischemal control group and DFMO pretreatment group. DFMO was given intravenously half an hour before global cerebral ischemia, and expression of ODC mRNA was measured by comparative reverse transcription-polymerase chain reaction (RT-PCR) in the cortex and hippocampus in rats after 2, 4, 6 h and 8 h of reperfusion. The variations of the expression of ODC mRNA were studied in the DFMO pretreatment group and the ischemal control group respectively. RESULTS: After 2, 4 and 6 h of reperfusion, the expression of ODC mRNA in the cortex and hippocampus in the pretreatment group was lower than that in the ischemia control group significantly (P <0.05, P <0.01), but not at 8 h reperfusion (P > 0.05). CONCLUSION DFMO suppressed the expression of ODC mRNA after different lengths of reperfusion following 10-minute global cerebral ischemia in rats and it may be one of the ways for DFMO to inhibit ODC activity.
Animals ; Brain Ischemia ; metabolism ; Cerebral Cortex ; metabolism ; Eflornithine ; pharmacology ; Hippocampus ; metabolism ; Male ; Ornithine Decarboxylase ; biosynthesis ; genetics ; Ornithine Decarboxylase Inhibitors ; RNA, Messenger ; biosynthesis ; genetics ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; metabolism