Growth inhibition and cell cycle arrest effects of epigallocatechin gallate in the NBT-II bladder tumour cell line.
OBJECTIVE
To examine the growth inhibition and cell cycle arrest effects of epigallocatechin gallate (EGCG), a major constituent of green tea polyphenols, on the NBT-II bladder tumour cell line.


METHODS
Growth inhibition and cell cycle arrest effects of EGCG were evaluated by the tetrazolium assay, flow cytometry and apoptotic DNA ladder tests. The cell cycle-related oncogene and protein expressions in NBT-II bladder tumour cells, when incubated with EGCG, were detected with reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis.


RESULTS
EGCG inhibited growth of the NBT-II bladder tumour cells in a dose- and time-dependent manner. Flow cytometry showed a G0/G1 arrest in cells when cultured with EGCG at doses of 10, 20 or 40 micro mol/L for 48 or 72 h. The apoptotic DNA ladder test showed that EGCG at 10 micro mol/L induced early apoptosis after 48 h of incubation. A down-regulation of cyclin D1 was detected by RT-PCR when the cells were incubated with EGCG (20 micro mol/L for 48 h. EGCG also down-regulated protein expression of cyclin D1, cyclin-dependent kinase 4/6 and phosphorylated retinoblastoma protein, in both a time- and dose-dependent manner, when detected by Western blot.


CONCLUSIONS
EGCG had growth inhibition and cell-cycle arrest effects in NBT-II bladder tumour cells by down-regulating the cyclin D1, cyclin-dependent kinase 4/6 and retinoblastoma protein machinery for regulating cell-cycle progression.
Chen
J J
JJ
Department of Pharmacology, Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
Ye
Z-Q
ZQ
Koo
M W L
MW
D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use*; D028241:Camellia sinensis; D002392:Catechin / Q000031:analogs & derivatives* / Q000627:therapeutic use*; D002453:Cell Cycle / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D004354:Drug Screening Assays, Antitumor; D005434:Flow Cytometry; D006801:Humans; D008517:Phytotherapy / Q000379:methods*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy* / Q000473:pathology
D000972:Antineoplastic Agents, Phytogenic; D002392:Catechin; C045651:epigallocatechin gallate