Objective      To determine the effects of silencing T lymphoma invasion and metastasis inducing factor 1 (Tiam1) on the invasion and metastasis capability of esophageal carcinoma cell line EC9706 in vitro and the chemotherapeutic sensitivity of EC9706 to 5-fluorouracil

(5-FU).       Methods      EC9706 cells were transfected with Tiam1 siRNAs. In 48 h after transfection

Tiam1 mRNA and protein levels were evaluated by RT-PCR and Western blotting. The invasion and metastasis ability of EC9706 cells were checked by Boyden chamber assay and wound healing assay. CCK-8 assay was used to test the inhibitory actions on EC9706 cells after the cells were treated with different concentrations of 5-FU and Tiam1 siRNA together. The apoptosis of EC9706 cells was assayed by TUNEL.       Results      Tiam1 siRNA2 and siRNA3 could inhibit the mRNA and protein expression of Tiam1 efficiently in EC9706 cells compared with control groups after 48 h (

P

0.05). The results of Boyden chamber assay and wound healing assay showed that the invasion and metastasis ability of EC9706 cells transfected with Tiam1 siRNA3 for 48 h decreased greatly compared with that in control groups (

P

0.05). The growth inhibitory rates of EC9706 cells treated with different concentrations of 5-FU and Tiam1 siRNA3 together were much higher than those treated with different concentrations of 5-FU alone (

P

0.05). The apoptotic rates of EC9706 cells treated with 10 μg/mL 5-FU and Tiam1 siRNA together were also higher than those in control groups (

P

0.05).       Conclusion      Inhibiting the expression of Tiam1 decreases the invasion and metastasis abilities of EC9706 cells greatly and increases the chemotherapeutic sensitivity of EC9706 cells to 5-FU.