Effects of Chinese Jianpi Herbs on Cell Apoptosis and Related Gene Expression in Human Gastric Cancer Grafted Onto Nude Mice

Aim: To explore the mechanism of the Sijunzi decoction and another Chinese herbal recipe (SRRS) based mainly on the Sijunzi decoction in treatment of gastric cancer.

Methods: 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 representative experimental conditions. Animals in the two experimental groups received either Sijunzi decoction or SRRS over a 40-day period starting at 1st day after grafting. Control animals received saline on an identical schedule. Animals were killed 41 days after being grafted. The effect of therapy was assessed by two ways: (1) tumor size was periodically measured during the life of the animals; (2) tumor weight was determined by a electron balance immediately after the animals killed. For detection of apoptotic cells, apoptotic indices(AI) were examined by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate fluorescence nick end labeling (TUNEL) method. Morphological alterations were observed with electron microscopy. S-P immunohistochemical method was used to detect the expression of Ki-67 in xenografts. Expression of bcl-2 and p53 was semiquantitatively detected using a reverse transcriptase-polymerase chain reaction (RT-PCR) technique.

Results: When compared with controls, tumor growth (size and weight) was significantly inhibited by treatment with the Sijunzi decoction (P<0.05) or SRRS (P<0.01). The tumor inhibitory rate in the Sijunzi decoction group was 34.33 % and SRRS group 46.53 %. AI of human gastric cancer xenografts in nude mice was significantly increased to 16.24+/-3.21 % using TUNEL method and 11.38+/-6.46 % by FACScan in the Sijunzi decoction group compared with the controls (TUNEL: 2.63+/-1.03 %, P<0.01; FACScan: 7.15+/- 1.32 %, P<0.05). SRRS group was also found a significantly increased AI by using TUNEL method and flow cytometry analysis compared with the controls (TUNEL: 13.18+/-3.05 %, P<0.05; FACScan: 11.58+/-5.71 % (P<0.05). Under electron microscope, cell shrinkage, nuclear chromatin condensation, formation of membrane blebs and apoptotic bodies were frequently observed in Sijunzi decoction group and SRRS group. The average labeling index (LI) for Ki-67 in SRRS group was significantly decreased to 8.43+/-2.22 % compared with the control group (10.37+/-4.91 %) (P<0.05). The average labeling index for Ki-67 in sijunzi decoction group was 7.95+/- 2.54 % which was lower than that of the control group, but showed no significance (P=0.07). The expression level of p53 mRNA was lower in both Sijunzi decoction group and SRRS group than that in control group (P<0.05; P<0.01). The expression of bcl-2 mRNA was also decreased in SRRS group compared with the control (P<0.01).

Conclusion: The inhibition of gastric cancer cell growth in vivo by Chinese Jianpi herbs and SRRS is related to induction of the cell apoptosis which may be involved in aberrant expression of p53 and bcl-2 genes.