Epigallocatechin-3-gallate suppresses the expression of HSP70 and HSP90 and exhibits anti-tumor activity in vitro and in vivo.
BACKGROUND
Epigallocatechin-3-gallate (EGCG), one of the major catechins in green tea, is a potential chemopreventive agent for various cancers. The aim of this study was to examine the effect of EGCG on the expression of heat shock proteins (HSPs) and tumor suppression.


METHODS
Cell colony formation was evaluated by a soft agar assay. Transcriptional activity of HSP70 and HSP90 was determined by luciferase reporter assay. An EGCG-HSPs complex was prepared using EGCG attached to the cyanogen bromide (CNBr)-activated Sepharose 4B. In vivo effect of EGCG on tumor growth was examined in a xenograft model.


RESULTS
Treatment with EGCG decreased cell proliferation and colony formation of MCF-7 human breast cancer cells. EGCG specifically inhibited the expression of HSP70 and HSP90 by inhibiting the promoter activity of HSP70 and HSP90. Pretreatment with EGCG increased the stress sensitivity of MCF-7 cells upon heat shock (44 degrees C for 1 h) or oxidative stress (H2O2, 500 microM for 24 h). Moreover, treatment with EGCG (10 mg/kg) in a xenograft model resulted in delayed tumor incidence and reduced tumor size, as well as the inhibition of HSP70 and HSP90 expression.


CONCLUSIONS
Overall, these findings demonstrate that HSP70 and HSP90 are potent molecular targets of EGCG and suggest EGCG as a drug candidate for the treatment of human cancer.
Department of Pathology, Chosun University, College of Dentistry, Gwangju 501-759, Republic of Korea.
Phan L C H B
PL
Tran
Soo-A
SA
Kim
Hong Seok
HS
Choi
Jung-Hoon
JH
Yoon
Sang-Gun
SG
Ahn
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000378:metabolism / Q000494:pharmacology*; D001665:Binding Sites; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002392:Catechin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018384:Oxidative Stress / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000187:drug effects; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D047368:Tumor Burden / Q000187:drug effects
D000972:Antineoplastic Agents, Phytogenic; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D000255:Adenosine Triphosphate; D002392:Catechin; C045651:epigallocatechin gallate