[Epigallocatechin gallate induces apoptosis in human hepatocellular carcinoma HepG2 cells via TGF/Smad signaling pathway].
OBJECTIVE
To investigate the cytotoxic effect of epigallocatechin gallate (EGCG) on human hepatocellular carcinoma cell line HepG2 cells and corresponding changes of TGF-beta1-Smad pathway.


METHODS
The cytotoxic effect of EGCG on HepG2 cells was determined by MTT assay. Cell cycle and apoptosis rate were detected by flow cytometry. RT-PCR and luciferase assay were used to verify whether TGF-beta1-Smad signaling pathway is intact in HepG2. The mRNA expression of Smad 2, Smad3, Smad4 and Smad7 was detected by real-time PCR.


RESULTS
EGCG induced apoptosis in the HepG2 cells in a time- and concentration-dependent manner. The proportion of G(1) phase cells was increased gradually as the concentration increased. However, the percentage of cells in S phase was decreased gradually. Annexin V/PI assay demonstrated that early apoptosis increased as the concentration increased, and late apoptosis also increased, when treated with high-concentration EGCG. The intact TGF-beta1-Smad pathway was verified by luciferase assay and RT-PCR. There was no significant effect of EGCG on mRNA level of Smad 2, Smad 3, and Smad 4 in HepG2 cells, but downregulated mRNA level of Smad 7.


CONCLUSIONS
EGCG can reduce apoptosis in human hepatocellular carcinoma cell line HepG2 cells. The activation of TGF-beta1-Smad signaling pathway may be involved in its cytotoxicity mechanisms.
Tong
Jin-lu
JL
Department of Gastroenterology, Renji Hospital, Shanghai Jiao Tong University, Shanghai, China.
Nie
Fang
F
Ran
Zhi-hua
ZH
Pan
Chang-qing
CQ
Xu
Xi-tao
XT
Zhu
Ming-ming
MM
Xiao
Shu-dong
SD
D016588:Anticarcinogenic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D056945:Hep G2 Cells; D006801:Humans; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D051785:Smad Proteins / Q000235:genetics / Q000378:metabolism*; D051906:Smad7 Protein / Q000235:genetics / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*
D016588:Anticarcinogenic Agents; D012333:RNA, Messenger; D051785:Smad Proteins; D051906:Smad7 Protein; D053773:Transforming Growth Factor beta1; D002392:Catechin; C045651:epigallocatechin gallate