Objective    To discuss the epithelial-mesenchymal transition (EMT) of human colon cancer cell line SW480 and its effect on tumor drug resistance to chemotherapy drugs and targeted drugs.     Methods    SW480 cells were treated with cetuximab (C225)

5-fluorouracil (5-FU)

and C225 and 5-Fu combination

separately. Cell morphology was observed. Immunofluorescence assay was employed to detect the cytoskeleton changes as

well as the expression difference of E-cadherin and vimentin before and after treatment. Western blotting was used to inspect the expression of E-cadherin

vimentin

multidrug resistance-associated protein (MRP)

and P-glycoprotein (P-gp) of SW480 cells in an experimental group (C225 and 5-FU treated)

a negative control group (untreated)

and a positive control group (TGF-β1 induced).

In-vitro

drug susceptibility test (by cell counting kit-8

CCK-8 colorimetry) was adopted to examine the survival of SW480 cells with or without drug treatment.     Results    The cell morphology of SW480 cells after separate treatment with C225

5-FU

and C225 and 5-FU combination showed EMT. Immunofluorescence assay results indicated changes in SW480 cell cytoskeleton and an arrangement polarity increase of filamin

E-cadherin downregulation

and vimentin upregulation

accompanied by upregulation of both MRP and P-gp. The SW480 cells treated with C225 and 5-FU combination possessed a significantly reduced survival rate as compared with those treated with C225 or 5-FU separately (

P

<

0.05).     Conclusion    Combined or separate application of targeted drugs and chemotherapy drugs on SW480 cells can induce EMT that influences tumor drug resistance.