Inhibition of human endothelial cell proliferation by Gami-Jeonggi-San (Jiawei-Zhenqi-San) is accompanied by transcriptional up-regulation of p53 and Waf1 tumor suppressor genes

The effects of Gami-Jeonggi-San (GJS) on proliferation of human endothelial cell (HUV-EC-C) were investigated using a flow cytometry and a quantitative RT-PCR analysis of gene expression. An accumulation of cells at G1 phase of the cell cycle was found at 72 h after treatment (10 μl/ml) while no detectable reduction of PCNA expression was recognized. To elucidate that the cell cycle inhibitory effect of GJS stems from its capability of transcriptional regulation of the cell cycle-controlling genes, we investigated mRNA expression of p53, Waf1, PCNA, Cyclin D1, Cdc2, Histone H3, c-Myc, and c-Fos. Significantly elevated mRNA levels of the p53 tumor suppressor gene and its down-stream mediator gene, Waf1, whose increased expressions were known to trigger G1 cell cycle arrest, were observed. In contrast, a marked reduction of two early G1-specific, cell cycle stimulating genes, c-Myc and c-Fos, were found at 24 h after treatment, while there were no detectable changes in expressions of G1-S or G2-M transition-related genes, indicating the G1 specificity of GJS effect on the cell cycle. These results suggest that the pharmacological effects of GJS might be derived in part from inhibition of cellular proliferation of human endothelial cells, and that GJS inhibition of the cell cycle might stem from its regulatory capability on the transcription of the cell cycle-controlling genes, including p53 and Waf1 tumor suppressor genes.