[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.