AIM:To evaluate the relationship between uPA,PAI-1,CEA,PI3K and metastatic potential in three colorectal tumorcell lines.METHODS:Metastatic model in nude rats was establishedby variants HT-29c and HT-29d cell lines and the metastaticpotential of two tumor cell variants was compared.Urokinase-type plasminogen activator (uPA) andplasminogen activator inhibitor type 1 (PAI-1) weredetermined using ELISA in colorectal carcinoma WiDr,HT-29 and HT-29d cell lines with different metastatic potentials.Expression of carcinoembryonic antigen (CEA) andphosphoinositide 3-kinase (PI3-Kinase) was analyzed usingimmunohistochemistry (IHC) in these cell lines in vitro andin vivo.CEA expression was compared using fluorescenceactivated cell sorter (FACS) in vitro.RESULTS:The number of HT-29d cells arrested in liverdramatically decreased within the initial 24 hours afterinjection.The taking rate of liver metastases in the variantHT-29d increased as compared with parental HT-29 cells(70 % versus 50 %) and a variant HT-29b cells (70 % versus60 %),and extensive organs were synchronously involvedin metastases.The uPA concentration of variant HT-29d cellline was significantly higher than that of the non-metastaticWiDr and the low metastatic HT-29 cell lines.The variantHT-29d cells produced stronger PI3-kinase expression ascompared with the non-metastatic WiDr cells and the lowmetastatic HT-29 cells in vivo.CONCLUSION:The selected variant HT-29d cell exhibitedan enhanced metastatic potential.The level of uPA and PAI-1 is positively correlated with the metastatic capacity of tumorcells.The expression of PI3-kinase correlates with tumordevelopment and metastasis. AIM: To evaluate the relationship between uPA, PAI-1, CEA, PI3K and metastatic potential in three colorectal tumor cells lines. METHODS: Metastatic model in nude rats was established by variants HT-29c and HT-29d cell lines and the metastatic potential of two tumors cell variants was compared to Urokinase-type plasminogen activator (uPA) andplasminogen activator inhibitor type 1 (PAI-1) weredetermined using ELISA in colorectal carcinoma WiDr, HT- 29 and HT- 29d cell lines with different metastatic potentials. Expression of carcinoembryonic antigen ( CEA) and phosphoinositide 3-kinase (PI3-Kinase) was analyzed using immunohistochemistry (IHC) in these cell lines in vitro and in vivo. CEA expression was compared using fluorescence activated cell sorter (FACS) in vitro. in liverdramatically decreased within the initial 24 hours after injection. The taking rate of liver metastases in the variant HT-29 d increased as compared with parental HT-29 cells (70% versus 50%) and a variant HT-29b cells (70% versus 60%), and extensive organs were synchronously involved in metastases. The uPA concentration of variant HT-29d cellline was significantly higher than that of the non-metastatic WiDr and the low metastatic HT-29 cell lines. variant HT-29d cells were harvested for enhanced PI3-kinase expression ascompared with the non-metastatic WiDr cells and the lowmetastatic HT-29 cells in vivo. CONCLUSION: The selected variant HT-29d cell exhibited enhanced metastatic potential. The level of uPA and PAI-I is positively correlated with the metastatic capacity of tumor cells. The expression of PI3-kinase correlates with tumor development and metastasis.