大黄素通过p53途径抑制血管平滑肌细胞增殖的实验研究

目的探讨p53途径在大黄素抑制血管平滑肌细胞增殖作用中的地位。方法通过细胞计数、老化相关β-半乳糖苷酶染色、Annexin V标记等方法观察大黄素抑制血管平滑肌细胞增殖的特点。^3H-胸苷掺入法测定DNA合成、流式细胞仪了解细胞周期变化、Western blot检测p53蛋白表达变化、基因芯片观察mRNA表达水平。结果（1）1．6～3．1μg／ml大黄素延缓细胞生长,6．3～12．5μg／ml大黄素促进细胞老化,25．0μg／ml大黄素则可显著诱导细胞凋亡。（2）大黄素干预24h后,出现非计划性DNA合成现象,这是DNA损伤的敏感性标志。p53基因和蛋白表达水平呈大黄素浓度依赖性上调。除了细胞增殖基因表达下调,其他基因表达均上调,如细胞老化基因、细胞凋亡基因、DNA损伤修复基因。（3）大黄素能够迅速渗透进入细胞,在细胞内的分布具有明显的选择性,绝大多数以颗粒形态分布于细胞胞浆中,细胞核中也有少量分布。结论大黄素通过损伤DNA激活p53途径。随着大黄素浓度升高,p53途径激活程度也随之增强并产生多种细胞增殖抑制效应,即生长停滞、细胞老化和细胞凋亡。

Involvement of p53-dependent pathway in the antiproliferative activity of emodin in human smooth muscle cell

OBJECTIVE: To investigate whether p53 pathway participates in the effect of emodin on vascular smooth muscle cell proliferation. METHODS: The effects of emodin on vascular smooth muscle cell proliferation were evaluated by cell count, senescent-associated beta-galactosidase staining, and annexin V staining. DNA synthesis was determined by (3)H-thymidine corporation, cell cycle was analyzed by FACS, the p53 protein level was measured by Western blot and cDNA expression array technology was used to demonstrate the effect of emodin on the simultaneous expression of a large number of genes in cultured vascular smooth muscle cells. RESULTS: Emodin at 1.6-3.1 microg/ml inhibited VSMC growth, at 6.3-12.5 microg/ml promoted VSMC aging and induced VSMC apoptosis at 25.0 microg/ml 24 hours after exposure. Unscheduled DNA synthesis, which was a sensitive indicator for DNA injury, was observed in VSMC following 24 hours emodin exposure. The mRNA and protein levels of p53 were up-regulated in a concentration-dependent manner. Proliferation/carcinogenesis-related genes were down-regulated and other genes related to cell senescence, apoptosis, and DNA damage/repair were up-regulated in VSMC after exposure to emodin for 24 hours. Emodin readily permeated VSMC membrane and mostly located in the cytoplasm and few of them in the nucleus. CONCLUSIONS: The p53 pathway in VSMC was activated post emodin exposure in a concentration-dependent manner and which might be responsible for the observed antiproliferative effects of emodin in vascular smooth muscle cells.