| The gastrointestinal tract tumor is very common in our country.It is very difficult to diagnose it in early stage.Chemotherapy and radiotherapy are the main therapies in late stage.The tumor cell can be killed by these drugs, but meanwhile the normal tissue cell also killed by these drugs.This means all the drugs have a lot of side effect,and their efficacy is very low.So it is urge to find new therapy to cure the gastrointestinal tract tumor. COX-2 frequently detected over-expressed in gastric carcinoma tissues and cell lines, was believed to play a crucial role in promotion of proliferation and angiogenesis in gastric carcinoma. Up-regulation of COX-2 might facilitate invasion of gastric carcinoma and was significantly related to the low survival rate of gastric carcinoma patients. Reduced COX-2 activity could result in decreased angiogenesis, increased apoptosis and suppressed synthesis of prostaglandins.COX-2 was closed related to gastric carcinogenesis and progression with lymph angiogenesis, however the underlying mechanisms are not fully understood.In gastric carcinoma, the expression rate COX-2 was high, COX-2 expression was positively correlated with clinical stage, and lymph node metastasis; COX-2 play an important role in the carcinogenesis and metastasis of gastric carcinoma, It is that COX-2 in gastric cancer tissues will be of significance.Objective:To study the effect of cyclooxygenase-2(COX-2) in gastric cancer and the correlation with lymph angiogenesis and prognosis.To explore the effect of cyclooxygenase-2(COX-2) gene transfection on the expression level of COX-2 in human gastric carcinoma SGC-7901 cell.To evaluate the effects of cyclooxygenase-2(COX-2)on tumour growth and lymph angiogenesis in nude mice models.Methods: 1. The expressions of VEGF-C mRNA and protein were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot in SGC-7901 cell lines by the treatment of selective COX-2 inhibitor Nimesulide at different doses. The expressions of VEGF-C protein were evaluated in SGC-7901 cells treated by PGE2 respectively.2. The constructed COX-2 gene eukaryotic expression vector was transfected into the human gastric carcinoma SGC-7901 cell by using lipofectamine transfection reagents. and the positive cell clones were obtained through G418 selection after transfection.The expressions of COX-2 mRNA and protein were detected by RT-PCR and Western blot respectively. COX-2 expression plasmid pGenesil-1-COX-2,was constructed and transfected into SGC-7901 cells.Human gastric carcinoma cells of the line SGC-7901 and human umbilical vein COX-2 cells of the line were cultured and stimulatd by the supernatant of the SGC-7901 cells transfected with pGenesil-i-COX-2,MTT method was used to detect the poliferation of the cells.3. BALB/c mice were inoclated of pGenesil-1, pGenesil-1-COX-2.Other mice were used as untreated control group.Two weeks later mice from each group were killed with the tumours taken out.exprssion of COX-2, vascular endothelial growth factor-C (VEGF-C)and and microlymphatic density (MLD).Results:1. Nimesulide could down-regulate the expressions of VEGF-C and protein in a does-dependent manner, the expressions of VEGF-C protein up-regulated by PGE-2 treatment.2.Following the transfection of the COX-2 recombination plasmid, RNA interference efficently and stably suppressed the COX-2 expression in SGC-7901 cells,and downregulation of COX-2 resulted in significantly inhibition of tumor cell growth in vitro.the growth inhibitory rates were significantly higher in specific COX-2 siRNA group than those in the control.3.Following the transfection of the COX-2 recombination plasmid,RNA interference efficently and stably suppressed the COX-2 expression in SGC-7901 cells,and downregulation of COX-2,VEGF-C,MLD resulted in significantly inhibition of tumor cell growth.the growth inhibitory rates were significantly higher in specific COX-2 siRNA group than those in the control.Conclusion:1. COX-2 over-expression can up-regulate the expression of VEGF-C. VEGF-C might promote lymph node metastasis by a lymphangiogenic pathway, than affect the prognosis of the patients with gastric cancer.2. Nimesulide could down-regulate the expressions of VEGF-C and protein in a does-dependent manner, the expressions of VEGF-C protein up-regulated by PGE-2 treatment.3. With the transfection of COX-2 gene vector by using liposome,the expression levels of COX-2 mRNA and protein is significant inhibition of tumor growth in gastric carcinoma SGC-7901 cell.4. Construction of eukaryotic expression vector expressing the specific shRNA targeting on COX-2 can supress tumour growth and with lymph angiogenesis, COX-2 gene therapy synergizes to suppress gastric carcinoma.
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