AIM:To investigate the effect of c9,t11-conjugatedlinoleic acid(c9,t11-CLA)on the invasion of human gastriccarcinoma cell line and its possible mechanism ofpreventing metastasis.METHODS:Using reconstituted basement membraneinvasion,chemotaxis,adhesion,PAGE substrate zymographyand RT-PCR assays,we analyzed the abilities of invasion,direct migration,adhesion of intracellular matrix,as well asthe activity of type Ⅳ collagenase and expression of tissueinhibitor of metalloproteinase(TIMP)-1 and TIMP-2 mRNAin SGC-7901 cells which were treated with graduallyincreased concentrations(25,50,100 and 200 μmol/L)ofc9,t11-CLA for 24 h.RESULTS:At the concentrations of 200 μmol/L,100 μmol/Land 50 μmol/L,c9,t11-CLA suppressed the invasion of SGC-7901 cells into the reconstituted basement membrane by53.7 %,40.9 % and 29.3 %,respectively,in comparisonwith the negative control.Only in the 200 μmol/L c9,t11-CLA group,the chemotaxis of SGC-7901 cells was inhibitedby 16.0 % in comparision with the negative control.C9,t11-CLA also could inhibit the adhesion of SGC-7901 cells tolaminin,fibronectin and Matrigel,increase the expressionof TIMP-1 and TIMP-2 mRNA,and reduce type Ⅳ collagenaseactivities in the serum-free medium supernatant of SGC-7901 cells.CONCLUSION:c9,t11-CLA can inhibit the invasion of SGC-7901 cells at multiple procedures in tumor metastasiscascade,which may be associated with the induction ofTIMP-1 and TIMP-2 mRNA expression. AIM: To investigate the effect of c9, t11-conjugated linoleic acid (c9, t11-CLA) on the invasion of human gastric carcinoma cell line and its possible mechanism of prognostic metastasis. METHODS: Using reconstituted basement membrane invasion, chemotaxis, adhesion, PAGE substrate zymography and RT -PCR assays, we analyzed the abilities of invasion, direct migration, adhesion of intracellular matrix, as well asthe activity of type IV collagenase and expression of tissue inhibitor of metalloproteinase (TIMP) -1 and TIMP-2 mRNAin which SGC-7901 cells with gradually increasing concentrations of 25, 50, 100 and 200 μmol / L ofc9, t11-CLA for 24 h .RESULTS: At the concentrations of 200 μmol / L, 100 μmol / Land 50 μmol / L, c9, of SGC-7901 cells into the reconstituted basement membrane by 53.7%, 40.9% and 29.3%, respectively, in comparison with the negative control. Where in 200 μmol / L c9, t11-CLA group, the chemotaxis of SGC-7901 cells was inhibitedby 16.0% in comparision with the neg ative control. C9, t11-CLA also could inhibit the adhesion of SGC-7901 cells to laminin, fibronectin and Matrigel, increase the expression of TIMP-1 and TIMP-2 mRNA, and reduce type Ⅳ collagenaseactivities in the serum-free medium supernatant of SGC -7901 cells.CONCLUSION: c9, t11-CLA can inhibit the invasion of SGC-7901 cells at multiple procedures in tumor metastasis cascade, which may be associated with the induction of TIMP-1 and TIMP-2 mRNA expression.