Apoptosis of human cholangiocarcinoma cells induced by ESC-3 from Crocodylus siamensis bile.

AIM: To investigate the effects of ESC-3 isolated from crocodile bile on the growth and apoptosis induction of human cholangiocarcinoma cells. METHODS: ESC-3 was isolated from crocodile bile by Sephadex LH-20 and RP-18 reversed-phase column. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay was conducted to determine the effects of ESC-3 on the proliferation of human cholangiocarcinoma cell lines (QBC939, Sk-ChA-1 and MZ-ChA-1). Giemsa staining, Hoechst 33258 and acridine orange/ethidium bromide staining showed the morphological changes of Mz-ChA-1 cells exposed to ESC-3 at different concentrations. Flow cytometry with regular propidium iodide (PI) staining was performed to analyze the cell cycle distribution of Mz-ChA-1 cells and to assess apoptosis by annexin v-fluorescein isothiocyanate (V-FITC)/PI staining. Rh123 staining was used to detect the alteration of mitochondrial membrane potential (ΔΨm). The protein levels of Bax, Bcl-2, Cdk2, cytochrome c and caspase-3 were further confirmed by Western blotting. RESULTS: ESC-3 significantly inhibited the growth of three human cholangiocarcinoma cell lines and arrested Mz-ChA-1 cell cycle at G0/G1 phase. Mz-ChA-1 cells showed typical apoptotic morphological changes after treated with ESC-3 (10 µg/mL) for 48 h. Cell death assay indicated that Mz-ChA-1 cells underwent apoptosis in a dose-dependent manner induced by ESC-3. In addition, ESC-3 treatment could downregulate the protein level of Bcl-2 and upregulate the Bax, leading to the increase in the ratio of Bax to Bcl-2 in Mz-ChA-1 cells. Meanwhile, cytochrome c was released from the mitochondria into the cytosol, which subsequently initiated the activation of caspase-3. All these events were associated with the collapse of the mitochondrial membrane potential. CONCLUSION: ESC-3, the active ingredient of crocodile bile, induced apoptosis in Mz-ChA-1 cells through the mitochondria-dependent pathway and may be a potential chemotherapeutic drug for the treatment of cholangiocarcinoma.

Apoptosis mechanism of human cholangiocarcinoma cells induced by bile extract from crocodile.

Animal bile is popularly used as a traditional medicine in China, and bile acids are their major bioactive constituents. In the present study, effects of bile extract from crocodile gallbladder on QBC939 cell growth, cell cycle, and apoptosis were investigated by MTT assay, inverted microscopy, fluorescence microscopy, transmission electron microscopy, scanning electron microscopy, PI single- and FITC/PI double-staining flow cytometry, and western blotting. Our data have revealed that bile extract inhibited cells growth significantly, and the cell cycle was arrested in G1 phase. Bile extract induced QBC939 cell apoptosis, which was associated with collapse of the mitochondrial membrane potential and increase of ROS. In bile extract-treated cells, it was observed that the expression of bcl-2 decreased and cytochrome c released to cytosol, but the expression of bax remained unchanged. The data indicated that mitochondrial pathway might play an important role in bile extract-induced apoptosis in QBC939 cells. These results provide significant insight into the anticarcinogenic action of bile extract on cholangiocarcinoma cells.

Apoptosis of human cholangiocarcinoma cell lines induced by ß-escin through mitochondrial caspase-dependent pathway.

The study aimed to evaluate the effects of ß-escin on human cholangiocarcinoma cell lines (QBC939, Sk-ChA-1 and MZ-ChA-1) and to explore its mechanisms. Cell growth, cell cycle and apoptosis were investigated, respectively, by MTT assay, single PI and FITC/PI double-staining flow cytometry, and fluorescence microscopy. The protein expression was determined by western blotting. The study revealed that ß-escin inhibited cholangiocarcinoma cell growth in a dose- and time-dependent manner, and the cell cycle of QBC939 and Sk-ChA-1 cells was arrested in the G2/M phase, and MZ-ChA-1 cells in G1 phase. Apoptosis of the three cholangiocarcinoma cell lines induced by ß-escin was associated with the collapse of the mitochondrial membrane potential and the activation of caspase-3. The apoptotic effect of ß-escin was suppressed by pancaspase inhibitor z-VAD-fmk. Molecular dissection revealed that the antiapoptotic protein bcl-2 was down-regulated after cholangiocarcinoma cell lines were treated with ß-escin, while the protein levels of bax and p53 were unchanged. Apoptosis was accompanied by an increase in reactive oxygen species (ROS). These results suggest that ß-escin induces apoptosis of cholangiocarcinoma cells through an intrinsic mitochondrial caspase-dependent pathway, and the increase in the bax/bcl-2 ratio and ROS may play important roles in ß-escin-induced apoptosis of cholangiocarcinoma cells.

Antiproliferation and apoptosis induced by tamoxifen in human bile duct carcinoma QBC939 cells via upregulated p53 expression.

Tamoxifen (TAM) is a nonsteroidal antiestrogen that has been used in the treatment of breast cancer for over 30years. Recently, it was shown that TAM also has efficacy on gastrointestinal neoplasms such as hepatocarcinoma and pancreatic carcinoma, and that the chemopreventive activities of TAM might be due to its abilities to inhibit cell growth and induce apoptosis. In the present study, we investigated the effects of tamoxifen on growth and apoptosis in the human bile duct carcinoma (BDC) cell line QBC939 using MTT assay, inverted microscopy, fluorescence microscopy, transmission electron microscopy, classic DNA fragmentation agarose gel electrophoresis assay, PI single- and FITC/PI double-staining flow cytometry, and Western blotting. Our data revealed that TAM could significantly inhibit growth and induce apoptosis in QBC939 cells. Increased expression of p53 was observed in TAM-treated cells, indicating that p53 might play an important role in TAM-induced apoptosis in QBC939 cells. These results provide significant insight into the anticarcinogenic action of TAM on BDC.