[Effects of Chinese herbal recipe Weichang'an in inducing apoptosis and related gene expression in human gastric cancer grafted onto nude mice].

OBJECTIVE: To investigate the mechanism of Chinese herbal recipe Weichang'an (WCA) in inducing cell apoptosis of human gastric cancer grafted onto nude mice.

METHODS: The high performance liquid chromatography was used for monitoring the stability of WCA. A human gastric cancer cell line SGC-7901 grafted in nude mouse was used as the animal model. The mice were divided into untreated group and two experimental groups. Animals in the two experimental groups received either WCA over a 34-day period or 5-fluorouracil (5-FU) over a 6-day period starting at the 8th day after grafting. Animals in the untreated group received normal saline on an identical schedule. Animals were killed 41 days after being grafted. To assess the effect of the treatment on tumor, the tumor weight was determined by the electron balance immediately after the animals were killed. SP immunohistochemical method was used to detect the expression of proliferating cell nuclear antigen (PCNA) in grafts. Apoptotic indices (AI) of the tumor cells were examined by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate fluorescence nick end labeling (TUNEL) method. SP method was also used to detect the expressions of cleaved caspase-3, caspase-8 and caspase-9. SYBR green dye I real-time quantitative polymerase chain reaction (real-time quantitative [corrected] PCR) was used to assess the related gene alterations in mRNA level. The expressions of phospho-Stat3 (Tyr705) and bcl-2 proteins were detected by using SP method.

RESULTS: Compared with the untreated group, tumor growth was significantly inhibited by treatment of WCA or 5-FU (P<0.01, respectively). The tumor inhibition rate in the WCA-treated group was 48.70% and that in the 5-FU-treated group was 60.10%. The average labeling index (LI) for PCNA in the WCA-treated group and 5-FU-treated group was significantly decreased as compared with that in the untreated group, respectively. The AI of human gastric cancer grafted in the nude mice detected by using TUNEL method was significantly increased to (9.72+/-4.51)% in the WCA-treated group, while it was (2.45+/-1.37)% in the untreated group. 5-FU-treated group was also found a significantly increased AI compared with the untreated group. The expressions of cleaved caspase-3 and caspase-9 in the WCA-treated group and 5-FU-treated group were significantly increased as compared with those in the untreated group. But caspase-8 showed no significant alteration either in the WCA-treated group or in the 5-FU-treated group. The expression levels of Stat3 (2(-)delta delta C(T))=0.16) and bcl-2 (2(-)delta delta C(T))=0.10) detected by using real-time quantitative [corrected] PCR were lower in the WCA-treated group than those in the untreated group. The expressions of phospho-Stat3 (Tyr705) and bcl-2 in the WCA-treated group were significantly decreased as compared with those in the untreated group.

CONCLUSIONS: Chinese herbal recipe WCA can inhibit gastric cancer cell SGC-7901 growth in vivo, induce gastric cancer cell apoptosis and suppress the cell proliferation. WCA induces apoptosis through the caspase-9 and caspase-3 pathway in vivo. Its mechanism might be involved in the down-regulation of Stat3 and bcl-2 genes.