Objective      To observe the effect of combined arsenic trioxide and fenofibrate on epithelial-interstitial transformation and E-cadherin/Snail transformation factor in human pulmonary carcinoma A549 cells.       Methods      Human pulmonary carcinoma A549 cells，cultured in vitro，were divided into group A (control group) containing only DMEM culture fluid

group B (1 μmol/L arsenic trioxide treatment group)

group C (100 μmol/L fenofibrate treatment group)

and group D (1 μmol/L arsenic trioxide plus 100 μmol/L fenofibrate treatment group). After the A549 cells were exposed to arsenic trioxide

fenofibrate

arsenic trioxide

and fenofibrate

respectively

for 48 h in vitro

their inhibitory effect on proliferation，cell cycle，invasive ability of A549 cells，and expression of E-cadherin/Snail mRNA and protein in A549 cells were detected by MTT assay

flow cytometry

RT-PCR and Western blotting

respectively.       Results      The activity of A549 cells was significantly lower in group D than in groups A to C. The inhibition rate of the activity of A549 cells was (17.62±0.51)%

(28.30±0.27)% and (35.19±0.04)%

respectively

in group B

group C and group D (P0.05). Combined arsenic trioxide and fenofibrate could interference with the cell cycle and reduce the invasive ability of A549 cells with an invasive inhibition rate of (50.3±0.15)%

(56.7±0.57)% and (68.1±0.21)%

respectively

in group B

group C and group D (P0.05). RT-PCR and Western blotting showed that the expression level of E-cadherin was significantly higher while the expression level of snail was significantly lower in group D than in groups A to C (P0.05).       Conclusion      Combined arsenic trioxide and fenofibrate exerts a significant effect on epithelial-interstitial transformation of A549 cells

which may be related with the expression of E-cadherin and Snail.