Progallin A isolated from the acetic ether part of the leaves of Phyllanthus emblica L. induces apoptosis of human hepatocellular carcinoma BEL-7404 cells by up-regulation of Bax expression and down-regulation of Bcl-2 expression.

AIM OF THE STUDY

This study was aimed to investigate the effects of Progallin A isolated from the acetic ether part of the leaves of Phyllanthus emblica L. on apoptosis in human hepatocellular carcinoma BEL-7404 cells and its possible mechanisms, and to measure the immune toxicity of Progallin A in vitro.

MATERIALS AND METHODS

Progallin A was isolated from the acetic ether part of the leaves of Phyllanthus emblica L. with column chromatography. The proliferation of spleen lymphocytes and the viability of BEL-7404 cells were assessed with MTT assay. Inverted microscope, light microscope and fluorescence microscope were utilized to observe the morphological changes of BEL-7404 cells respectively. AnnexinV/PI double labeling and TUNEL assay were used to detect early apoptosis and DNA fragmentations of BEL-7404 cells respectively. In addition, cell cycle distribution was analyzed by using flow cytometry (FCM). Bax and Bcl-2 protein levels were determined by immunofluorescence staining and western blot respectively.

RESULTS

The results showed that Progallin A had low immune toxicity and the proliferation of BEL-7404 cells was strongly inhibited by Progallin A in a time- and dose-dependent manner and that the characteristics of apoptosis of BEL-7404 cells were observed. The results also showed that apoptosis rates and the number of apoptotic cells significantly increased with prolongation of the action time. The results of flow cytometry (FCM) indicated that Progallin A induced significant G1/M and G2/M arrest of BEL-7404 cells. Immunofluorescence staining and western blot showed that the expression of Bax was found to be noticeably up-regulated and the expression of Bcl-2 was down-regulated significantly.

CONCLUSIONS

These results indicate that Progallin A has low immune toxicity in vitro and induces apoptosis of human hepatocellular carcinoma BEL-7404 cells which is related to the G1/M and G2/M arrest, and it exerts its apoptotic effect by up-regulation of Bax expression and down-regulation of Bcl-2 expression.