Inhibitory effect of epigallocatechin-gallate on brain tumor cell lines in vitro.
We investigated the effect of epigallocatechin-gallate (EGCG), the main constituent of green tea polyphenols, on human glioblastoma cell lines U-373 MG and U-87 MG, rat glioma cell line C6, and rat nonfunctioning pituitary adenoma cell line MtT/E. Cell viability was determined by assay with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), and the extent of apoptosis was studied by flow cytometric analysis. Apoptosis was also characterized by morphology using fluorescent microscopy. The role of insulin-like growth factor-I (IGF-I) was studied by assay with MTT, immunohistochemistry, and immunoradiometric assay. After 72-h exposure, a statistically significant loss of viability (P = < 0.0001) was observed at concentrations of 12.5, 25, 50, and 100 microg/ml in U-373 MG cells and U-87 MG cells. EGCG at concentrations of 50 microg/ml and higher significantly reduced the viability of C6 cells. EGCG inhibited viability of MtT/E cells only at a concentration of 100 microg/ml. Quantitative study by flow cytometry demonstrated that lower doses of EGCG (12.5, 25, 50 microg/ml) induced apoptosis in U-373 MG, U-87 MG, and C6 cells; however, only the highest dose (100 microg/ml) induced apoptosis in MtT/E cells. Compared with other cell lines, MtT/E cells showed stronger IGF-I immunoreactivity. Neutralization of IGF-I with an antihuman IGF-I antibody reduced viability of the cell lines. It can be concluded that EGCG has an inhibitory effect on malignant brain tumors, and IGF-I may be involved in the effects of EGCG.
Yokoyama
S
S
Department of Neurosurgery, Faculty of Medicine, Kagoshima University, Japan.
Hirano
H
H
Wakimaru
N
N
Sarker
K P
KP
Kuratsu
J
J
D000236:Adenoma / Q000473:pathology*; D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001932:Brain Neoplasms / Q000473:pathology*; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology*; D005909:Glioblastoma / Q000473:pathology*; D005910:Glioma / Q000473:pathology*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D010911:Pituitary Neoplasms / Q000473:pathology*; D051381:Rats; D013662:Tea / Q000737:chemistry*; D014407:Tumor Cells, Cultured / Q000187:drug effects
D016588:Anticarcinogenic Agents; D013662:Tea; D007334:Insulin-Like Growth Factor I; D002392:Catechin; C045651:epigallocatechin gallate