tannins and Neuroblastoma

Prion propagation is mediated by the structural alteration of normal prion protein (PrPC) to generate pathogenic prion protein (PrPSc). To date, compounds for the inhibition of prion propagation have mainly been screened using PrPSc-infected cells. Real time-quaking-induced conversion (RT-QuIC) is one alternative screening method. In this study, we assessed the propagation inhibition effects of known anti-prion compounds using RT-QuIC and compared the results with those from a PrPSc-infected cell assay. Compounds were applied to RT-QuIC reactions at 0 h or 22 h after prion propagation to determine whether they inhibited propagation or reduced amplified aggregates. RT-QuIC reactions in presence of acridine, dextran sulfate sodium (DSS), and tannic acid inhibited seeded aggregation with sporadic Creutzfeldt-Jakob disease at 0 h. After treatment at 22 h, amplified fluorescence was decreased in wells treated with either acridine or tannic acid. Compound activities were verified by western blot of RT-QuIC products and in a dye-independent conversion assay, the Multimer Detection System. Protease K-resistant PrPSc fragments (PrPres) were reduced by DSS and tannic acid in the PrPSc-infected cell assay. Importantly, these inhibitory effects were similar despite different treatment times (0 h versus 3 days). Consequentially, RT-QuIC enabled the more specific classification of compounds according to action (i.e., inhibition of prion propagation versus reduction of amplified aggregates). RT-QuIC addresses the limitations of cell-based screening methods and can be used to further aid our understanding of the mechanisms of action of anti-prion compounds.

Topics: Acridines; Anti-Infective Agents; Anticoagulants; Brain; Creutzfeldt-Jakob Syndrome; Dementia; Dextrans; High-Throughput Screening Assays; Humans; Neuroblastoma; PrPSc Proteins; Tannins; Tumor Cells, Cultured

The root of Paeonia suffruticosa ANDREWS is an important Chinese crude drug used in many traditional prescriptions. 1,2,3,4,6-Penta-O-galloyl-beta-D-glucose (PGG), a major component of this crude drug, has been shown to possess potent anti-oxidant, anti-mutagenic and anti-proliferative effects. In the present study, we examined the effect of PGG on the expression of neuronal heme oxygenase-1 (HO-1), an inducible stress protein that degrades heme to the neuroactive molecule, carbon monoxide and the anti-oxidant, biliverdin. Exposure of Neuro 2A cells to PGG (10-50 microM) resulted in a concentration- and time-dependent induction of HO-1 mRNA, and protein expressions and heme oxygenase activity. Interestingly, pretreatment of the neuronal cells with PGG resulted in enhanced cellular resistance to hydrogen peroxide. This cytoprotective effect was reversed by zinc protoporphyrin IX, an inhibitor of heme oxygenase. This study showed that PGG could protect neuronal cells from oxidative stress via the induction of HO-1 gene expression.

Topics: Animals; Antioxidants; Brain Ischemia; Cell Death; Dose-Response Relationship, Drug; Drugs, Chinese Herbal; Gene Expression Regulation, Enzymologic; Heme Oxygenase (Decyclizing); Heme Oxygenase-1; Hydrogen Peroxide; Hydrolyzable Tannins; Neuroblastoma; Neurodegenerative Diseases; Neurons; Neuroprotective Agents; Oxidative Stress; Rats; RNA, Messenger; Tannins; Tumor Cells, Cultured