中药WCA对人胃癌细胞SGC-7901体内作用基因的筛选与验证

目的：探讨以四君子汤等健脾中药为基础的复方胃肠安(WCA)对胃癌细胞的体内作用分子机制。方法：采用人胃癌细胞SGC-7901裸小鼠皮下移植瘤模型系统评价WCA对胃癌细胞的体内抑瘤作用；链霉素抗生物素-过氧化酶法(SP法)检测增殖细胞核抗原PCNA表达,末端脱氧核苷酸转移酶介导的dUTP缺口末端标记(TUNEL法)检测凋亡指数以及SP法检测caspase-3的活化表达；cDNA array筛选出WCA组N.S.对照组差异表达2倍以上基因,Real-time Quantitative PCR验证与增殖、凋亡、分化及信号转导密切相关的19条基因的表达；SP法检测部分有差异表达的基因在细胞内的蛋白表达。结果：与对照组比较,WCA组对皮下移植瘤生长的平均抑制率为(44.32+5.67)%,3次实验WCA组的平均瘤重分别为(0.99±0.76),(1.02±0.16),(0.88±0.47) g,分别低于对照组的(1.93±0.58),(1.65±0.46),(1.63±0.52) g(P<0.05)；WCA组移植瘤PCNA阳性表达率(35.73±6.01)%、强阳性表达率(3.39±1.48)%和总阳性率(39.03±7.37)%均分别低于对照组的(53.48±9.34)%,(8.78±5.43)%,(62.26±13.80)%(P<0.05)；凋亡指数为(9.72±4.51)%高于对照组的(2.45%±1.37)%(TUNEL法)；WCA组活化caspase-3表达阳性率为(5.20±2.26)%,较对照组的(2.82±1.84)%高(P=0.0367)；与对照组比较,全基因表达谱芯片筛选出WCA组共45个2倍以上差异表达基因,其中上调表达24个,下调表达21个。35个已克隆基因,10个表达序列标签(expression sequence tag,EST)；2^-ΔΔCT法对19条目标基因的表达量进行评估,与对照组比较,表达量显著差异4倍以上的有Stat3(2^-ΔΔCT=0.16),RIPX(2^-ΔΔCT=0.18),ROD1(2^-ΔΔCT=0.23),bcl-2(2^-ΔΔCT=0.10),均为下调表达作用；WCA组P-Stat3阳性表达率(35.93±12.67)%、强阳性表达率(3.64%±1.72)%和总阳性率(39.57±13.31)%均分别低于对照组的(56.49±9.34)%,(13.16±7.06)%,(69.65±10.80)%,差异有显著性；bcl-2蛋白阳性表达率(1.62±0.82)%低于对照组的(7.53±3.73)%(P<0.05)。结论：健脾中药复方WCA在体内可抑制胃癌细胞增殖,诱导凋亡；WCA对胃癌细胞SGC-7901在核酸层次上有影响作用的已知基因主要为Stat3,RIPX,ROD1,bcl-2,均为下调表达作用；在蛋白表达水平的作用机制与抑制磷酸化的Stat3,bcl-2蛋白在细胞内的表达,上调活化caspase-3的表达有关。

Difference of gene expression profile in human gastric cancer grafted onto nude mice treated with WCA

OBJECTIVE: Chinese jianpi herbal recipe Weichangan (WCA) could increase the survival rate of advanced gastric cancer. This study was designed to investigate the molecular mechanism of WCA in treatment of gastric cancer by cDNA array, real-time quantitative PCR and immunohistochemical technique. METHOD: A human gastric adenocarcinoma cell line SGC-7901 grafted onto nude mouse was used as the animal model. The mice were divided into 3 groups, one control and the two representing experimental conditions. Animals in the two experimental groups received either WCA over a 34-day period or 5-fluorouracil (5-FU) over 6-day period starting at 8th day after grafting. Control animals received saline on an identical schedule. Animals were killed 41 days after being grafted. To assess the effect of therapy tumor weight was determined by a electron balance immediately after the animals killed. SP immunohistochemical method was used to detect the expression of proliferating cell nuclear antigen (PCNA) in xenografts. For detection of apoptotic cells, apoptotic indices (AI) were examined by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate fluorescence nick end labeling (TUNEL) method. SP method was also used to detect the expression of cleaved Caspase-3. The expression profiles in paired WCA treated gastric cancer samples and the N. S. control samples were studied by using a cDNA array representing 14, 181 cDNA clusters. The alterations in gene expression levels were confirmed by real-time quantitative PCR. SP method was used to detect the expression of Phospho-Stat3 (Tyr705) and bcl-2. RESULT: When compared with controls, tumor growth was significantly inhibited by treatment with the WCA or 5-FU (P < 0.01, respectively). The average of tumor inhibitory rate in WCA group was (44.32 +/- 5.67)% and 5-FU (47.04 +/- 11.33)%. The average labeling index (LI) for PCNA in WCA group and 5-FU group was significantly decreased compared with the control group respectively. AI of human gastric cancer xenografts in nude mice was significantly increased to (9.72 +/- 4.51)% using TUNEL method in WCA group compared with the controls (2.45 +/- 1.37)%. 5-FU group was also found a significantly increased AI compared with the controls. The expression of cleaved Caspase-3 in WCA group and 5-FU group was significantly increased compared with the control group respectively. There were 45 different expression ESTs among the control sample pool and WCA sample pool. There were 24 ESTs up-regulated in WCA samples and 21 ESTs down-regulated. These 45 ESTs contains 35 cloned genes and 11 unknown ESTs. By using Real-time Quantitative PCR, the expression level of Stat3 (2(-deltadeltaCT) = 0.16) , RIPX (2(-deltadeltaCT) = 0.18), ROD1 (2(-deltadeltaCT) = 0.23) and bcl-2 (2 (-deltadeltaCT) = 0.10) was lower in WCA group than that in control group respectively. The expression of Phospho-Stat3 (Tyr705) and bcl-2 in WCA group and 5-FU group was significantly decreased compared with the control group respectively. CONCLUSION: Chinese jianpi herbal recipe WCA could inhibit gastric cancer cell SGC-7901 growth in vivo. WCA could induce gastric cancer cell apoptosis and suppress proliferation. Its mechanisms might be involved in the down-regulation of Stat3, RIPX, ROD1 and bcl-2 gene.