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 of preventing 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 as the activity of type IV collagenase and expression of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 mRNA in SGC-7901 cells which were treated with gradually increased concentrations (25, 50, 100 and 200 mmol/L) of c9, t11-CLA for 24h. RESULTS: At the concentrations of 200mmol/L, 100mmol/L and 50 mmol/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 comparison with the negative control. Only in the 200 mmol/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.Chen BQ, Yang YM, Gao YH, Liu JR, Xue YB, Wang XL, ZhengYM, Zhang JS, Liu RH. Inhibitory effects of c9,t11-conjugatedlinoleic acid on invasion of human gastric carcinoma cell lineSGC-7901. World J Gastroenterol 2003;9(9):1909-1914http://www.wjgnet.com/1007-9327/9/1909.asp

AIM:To explore the inhibition of conjugated linoleic acidisomers in different purity (75% purity c9, t11-, 98% purityc9,t11- and 98% purity t10, c12-CLA) on the formation offorestomach neoplasm and cheopreventive mechanisms. METHODS: Forestomach neoplasm model induced by B(a)P in KunMing mice was established. The numbers of tumorand diameter of each tumor in forestomach were counted;the mice plasma malondialdehyde (MDA) were measuredby TBARS assay; TUNEL assay was used to analyze theapoptosis in forestomach neoplasia and the expression ofMEK-1, ERK-1, MKP-1 protein in forestomach neoplasm werestudied by Western Blotting assay.RESULTS: The incidence of neoplasm in B(a)Pgroup, 75%purity c9, t11-CLA group, 98% purity c9,t11-CLA groupand 98% purity t10, c12-CLA group was 100%, 75.0 %(P>0.05), 69.2%(P<0.05) and 53.8%(P<0.05) respectivelyand the effect of two CLA isomers in 98% purity onforestomach neoplasia was significant; CLA showed noinfluence on the average tumor numbers in tumor-bearingmouse, but significantly decreased the tumor size, the tumor average diameter of mice in 75% purity c9,t11-CLA group,98% purity c9,t11-CLA group and 98% purity t10, c12-CLAgroup was 0.157