Ornithine decarboxylase (ODC) is a key enzyme in the biosynthetic pathway of polyamines and catalyzes the decarboxylation of ornithine to produce putrescine. Inhibition of ODC activity is a potential approach for the prevention and treatment of many diseases including cancer, as the expression levels and the activities of ODC in many abnormal cells and tumor cells are generally higher than those of normal cells. The discovery and evaluation of ODC inhibitors rely on the monitoring of the reaction processes catalyzed by ODC. There are several commonly used methods for analyzing the activity of ODC, such as measuring the yield of putrescine by high performance liquid chromatography, or quantifying the yield of isotope labelled carbon dioxide. However, the cumbersome operation and cost of these assays, as well as the difficulty to achieve high-throughput and real-time detection, hampered their applications. In this work, we optimized a real-time label-free method for analyzing the activity of ODC based on the macromolecule cucurbit[6]uril (CB6) and a fluorescent dye, DSMI (trans-4-[4-(dimethylamino) styryl]-1-methylpyridinium iodide). Finally, the optimized method was used to determine the activities of different ODC inhibitors with different inhibition mechanisms.
Bridged-Ring Compounds ; Imidazoles ; Ornithine ; Ornithine Decarboxylase ; Ornithine Decarboxylase Inhibitors ; Putrescine

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

A cirrhosis risk score (CRS) comprised of single nucleotide polymorphisms (SNPs) in seven genes that predicts the risk of cirrhosis in Caucasian hepatitis C has been reported. The present study was to evaluate the association of 11 separate but related SNPs and the CRS with cirrhosis risk in Chinese hepatitis B patients. A total of 563 Chinese subjects with persistent HBV infection (349 with evident liver cirrhosis and 214 without cirrhosis clinically or pathologically) were studied. The candidate SNPs were detected with a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) method. The allele frequency and genotype distribution of each polymorphism as well as the CRS value within the cirrhosis and non-cirrhosis subjects were compared. The rs2679757 polymorphism of the antizyme inhibitor 1 (AZIN1) gene was associated with the risk of cirrhosis (x2 = 6.79, P = 0.03, odds ratio for GG+AG versus AA = 1.63, 95% confidence interval = 1.13-2.35). A gene variant (rs886277) in the transient receptor potential cation channel subfamily M, member 5 gene (TRPM5) was associated with liver cirrhosis, but did not reach statistical significance (x2 = 5.77, P = 0.06). Two SNPs (rs4986791, rs62522600) are not polymorphic in Chinese. Genotype frequencies of other SNPs were not different between the cirrhosis and non-cirrhosis groups. The overall CRS values were not different between the cirrhotic and non-cirrhotic groups (median value 0.57 versus 0.62, Z = -1.05, P = 0.29). SNP rs2679757 in the AZIN1 gene is associated with the risk of HBV-related liver cirrhosis in Chinese. The CRS for Caucasian population has limited applicability for predicting liver cirrhosis in Chinese hepatitis B patients. SNPs associated with cirrhosis prognosis in hepatitis B patients and liver diseases with other etiologies warrant further clinical validation.
Adult ; Carrier Proteins ; genetics ; Female ; Gene Frequency ; Genotype ; Hepatitis B ; genetics ; Humans ; Liver Cirrhosis ; genetics ; Male ; Middle Aged ; Ornithine Decarboxylase Inhibitors ; Polymorphism, Single Nucleotide

Ornithine decarboxylase (ODC) is the rate-limiting enzyme in polyamine biosynthesis and a target for chemoprevention. Hydroxydibenzoylmethane (HDB), a derivative of dibenzoylmethane of licorice, is a promising chemopreventive agent. In this paper, we investigated whether HDB would inhibit the ODC pathway to enhance apoptosis in human promyelocytic leukemia HL-60 cells. We found ODC enzyme activity was reduced during HDB treatment. Overexpression of ODC in HL-60 parental cells could reduce HDB-induced apoptosis, which leads to loss of mitochondrial membrane potential (Deltapsim), through lessening intracellular ROS. Furthermore, ODC overexpression protected cytochrome c release and the activation of caspase-3 following HDB treatment. The results demonstrated HDB-induced apoptosis was through a mechanism of down-regulation of ODC and occurred along a ROS-dependent mitochondria-mediated pathway.
Apoptosis/*drug effects ; Caspase 3/metabolism ; Chalcones/metabolism/*pharmacology ; Chemoprevention ; Cytochromes c/biosynthesis/secretion ; Down-Regulation ; Gene Expression ; HL-60 Cells ; Humans ; Immunoblotting ; Leukemia, Myeloid/*enzymology/pathology ; Membrane Potential, Mitochondrial/drug effects ; Mitochondria/enzymology ; Ornithine Decarboxylase/antagonists & inhibitors/genetics/*metabolism ; Reactive Oxygen Species/analysis/metabolism ; Reverse Transcriptase Polymerase Chain Reaction