Inhibitory Effects of TH2 on Human Epithelial Hepatoma Cancer Cells
- VernacularTitle:藤黄新酸抑制肝癌细胞生长的机制研究
- Author:
Bo XU
;
Cheng XING
;
Min LI
;
Wei GUO
;
Jingrong CUI
- Publication Type:Journal Article
- Keywords:
TH2, proteasome, Bel-7402 cell line, apoptosis, p53
- From:
Progress in Biochemistry and Biophysics
2006;0(05):-
- CountryChina
- Language:Chinese
-
Abstract:
It has been well known that apoptosis induction and cell cycle arrest are typical biological effects observed in cancer cells after proteasome inhibition. TH2 is a new natural xanthone analogue isolated from the resin of Garcinia hurburyi tree. Here, the cell growth inhibition of TH2 on human hepatocellular carcinoma cell line (Bel-7402) was evaluated in vitro using SRB assay. The treatment of 10 ?mol/L TH2 reduced the surviving fraction from 86% (12 h) to 17.2% (48 h). To assess whether TH2 induce apoptosis, the appearance of sub-G1 peak, a specific fraction for apoptosis was detected by flow cytometry analysis. Progressive increase in the percentage of apoptotic population was observed in a dose-and time-dependent manner. Furthermore, a cleavage of poly (ADP-ribose) polymerase (PARP), a marker of early apoptosis, was observed clearly when the cells exposed to 10 ?mol/L of TH2 for 24 h by immunoblotting analysis. In vitro activities of 20 S proteasome purified from human erythrocytes on fluorogenic peptide substrates revealed that TH2 inhibited the trypsin-like, chymotrypsin-like and peptidylglutamyl peptide hydrolyzing activities in dose-dependent manner. Moreover, the turnover of tumor suppressor p53, a sign of deregulation of cell cycle progression and apoptosis induction by classical proteasome inhibitors, was disrupted in Bel-7402 cells. All these data indicate that TH2 had inhibitory effect on the proliferation of Bel-7402 cells and induction of apoptosis, which might be related to its inhibition of proteasome.
