Epithelial-mesenchymal Transition is Associated with Acquired Resistance to 5-Fluorocuracil in HT-29 Colon Cancer Cells

5-Fluorouracil (5-FU) is commonly used for the therapy of colon cancer; however, acquired resistance to 5-FU is a critical barrier to successful treatment and the primary cause of chemotherapy failure. Epithelialmesenchymal transition (EMT) is a process whereby cells undergo alterations in morphology and molecular characteristics promoting tumor progression and metastasis. Accumulating evidence shows that transition from epithelial to mesenchymal phenotype in cancer cells is associated with their resistance to chemotherapy. However, it is still poorly understood whether EMT is involved in acquired resistance to 5-FU. In this study, we developed an in vitro cell model, 5-FU-resistant HT-29 colon cancer cells, and characterized the differences in cellular morphology and molecular alterations between parental and resistant cells. In accord with mesenchymal-like morphology of 5-FU-resistant HT-29 cells, the expression of the mesenchymal marker fibronectin was significantly increased in these cells in comparision with that in the parental cells. Of interest, we also found a marked increase in the expression of EMT-inducing transcription factors Twist, Zeb1, and Zeb2. Finally, 5-FU-resistant cells showed enhanced migration in comparison with parental HT-29. Taken together, these results indicate that EMT could be associated with 5-FU resistance acquired by HT-29 cells. A specific role of each transcription factor found in this study will require further investigation.