Xu Rui-Cheng, Zhou Yan-Hong, Hu Wen-Liang
Department of Cellular Biology, Medical College of Chinese People's Armed Police Forces, Tianjin, 300162, P. R. China.
Ai Zheng. 2006 Dec;25(12):1483-7.
BACKGROUND & OBJECTIVE: Antitumor effect of 9-cis retinoic acid (9-cis RA) on gastric carcinoma is unclear yet. This study was to explore the inducement effect of 9-cis RA on cell cycle arrest and apoptosis of gastric carcinoma cell line MGC803 and its mechanism.
The expression of RXRalpha, Cyclin D1, and CDK4 in MGC803 cells was detected by reverse transcription-polymerase chain reaction (RT-PCR). Cell cycle was detected by flow cytometry. The growth inhibition was analyzed by MTT assay. The apoptosis was detected by agarose gel electrophoresis and Hoechst33342/PI staining. The expression of apoptosis-associated gene Bcl-2 was detected by SP immunocytochemistry.
When treated with 0.1-10 micromol/L 9-cis RA for 96 h, the proliferation of MGC803 cells was significantly inhibited. The proportion of MGC803 cells at G1 phase was significantly increased when treated with 10 micromol/L 9-cis RA for 48, 72, and 96 h, and showed an apparent G1 phase arrest. When treated with 9-cis RA for 72 h, typical apoptotic changes, such as chromatin condensation and DNA ladder, were observed in MGC803 cells. The expression of Bcl-2 was significantly decreased in MGC803 cells when treated with 10 micromol/L 9-cis RA for 48 h. RXRalpha expression was at a low level in MGC803 cells and up-regulated when treated with 10 micromol/L 9-cis RA for 48 h (P<0.01). The expression of Cyclin D1 and CDK4 in MGC803 cells was both significantly down-regulated when treated with 10 micromol/L 9-cis RA for 96 h (P<0.01).
9-Cis RA could induce G1 phase arrest and apoptosis in MGC803 cells through down-regulating the expression of cell cycle factors Cyclin D1 and CDK4.
9-顺式维甲酸（9-cis RA）对胃癌的抗肿瘤作用尚不清楚。本研究旨在探讨9-cis RA对胃癌细胞系MGC803细胞周期阻滞和凋亡的诱导作用及其机制。
采用逆转录-聚合酶链反应（RT-PCR）检测MGC803细胞中RXRα、细胞周期蛋白D1（Cyclin D1）和细胞周期蛋白依赖性激酶4（CDK4）的表达。通过流式细胞术检测细胞周期。采用MTT法分析生长抑制情况。通过琼脂糖凝胶电泳和Hoechst33342/PI染色检测凋亡情况。采用SP免疫细胞化学法检测凋亡相关基因Bcl-2的表达。
用0.1-10 μmol/L 9-cis RA处理96小时后，MGC803细胞的增殖受到显著抑制。用10 μmol/L 9-cis RA处理48、72和96小时后，MGC803细胞在G1期的比例显著增加，并出现明显的G1期阻滞。用9-cis RA处理72小时后，MGC803细胞中观察到典型的凋亡变化，如染色质浓缩和DNA梯状条带。用10 μmol/L 9-cis RA处理48小时后，MGC803细胞中Bcl-2的表达显著降低。MGC803细胞中RXRα表达处于低水平，用10 μmol/L 9-cis RA处理48小时后上调（P<0.01）。用10 μmol/L 9-cis RA处理96小时后，MGC803细胞中Cyclin D1和CDK4的表达均显著下调（P<0.01）。
9-cis RA可通过下调细胞周期因子Cyclin D1和CDK4的表达诱导MGC803细胞发生G1期阻滞和凋亡。
