Effect of green tea extract on the induction of ornithine decarboxylase and the activation of extracellular signal-regulated kinase in bladder carcinoma ECV304 cells.
According to several studies, green tea and individual catechins can inhibit the induction of ornithine decarboxylase (ODC), the key enzyme in the biosynthesis of polyamines. It has been suggested that the inhibition of ODC induction may offer an explanation to the anticancer and chemopreventive activities of green tea. In the present study, however, treatment of bladder carcinoma ECV304 cells with green tea extract (GTE) was not able to reduce the induction of ODC by fetal calf serum. Actually, in the absence of serum, GTE provoked a dose-dependent and remarkable induction of ODC activity. The induction of ODC, which could be elicited also by (-)-epigallocatechin 3-gallate, a major green tea component, required an early activation of extracellular signal-regulated kinase 1 and 2 (ERK), and both events appeared to be dependent on an alteration of the status of cellular thiol groups. Pretreatment with specific ERK or ODC inhibitors was able to prevent a late caspase activation but hardly affected the loss of cell viability provoked by GTE. In conclusion, to our knowledge, this is the first study showing that GTE can promote ODC induction in a tumor cell line.
Facchini
Annalisa
A
Dipartimento di Biochimica G. Moruzzi, Università di Bologna, Via Irnerio 48, 40126 Bologna, Italy.
Zanella
Barbara
B
Stefanelli
Claudio
C
Guarnieri
Carlo
C
Flamigni
Flavio
F
D017209:Apoptosis; D020169:Caspases / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004790:Enzyme Induction / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D020287:In Situ Nick-End Labeling; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009955:Ornithine Decarboxylase / Q000096:biosynthesis*; D065108:Ornithine Decarboxylase Inhibitors; D010936:Plant Extracts / Q000494:pharmacology*; D013662:Tea; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000201:enzymology* / Q000473:pathology
D004791:Enzyme Inhibitors; D065108:Ornithine Decarboxylase Inhibitors; D010936:Plant Extracts; D013662:Tea; D002392:Catechin; C045651:epigallocatechin gallate; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D020169:Caspases; D009955:Ornithine Decarboxylase