Cancer stem-like cells contribute to paclitaxel resistance in esophageal squamous cell carcinoma

Objective: To examine the role of esophageal squamous cell carcinoma (ESCC) stem cells in paclitaxel resistance through the molecular characterization of ESCC stem cells. Methods: A resistant cell line (RR-EC109) of cells were established using intermittent induction and time increments of high-dose paclitaxel in a human esophageal squamous cell carcinoma line (EC109). The multidrug resistance of RR-EC109 cells to anticancer agents was evaluated by MTT assay. The RR-EC109 and EC109 cells were used for sphere formation assays, clonogenicity assays, stem cell gene expression, and the expression of epithelial-mesenchymal transition markers. Results: The RR-EC109 cells were established over 7 months. RR-EC109 cells had 67.258 fold resistance to paclitaxel. The percentage of sphere formation and clone proliferation ability of RR-EC109 cells was higher than that of EC109 cells (P < 0.05). The amount of side population cells in RR-EC109 cells was higher than that of EC109 cells (P < 0.05). RR-EC109 cells produced more mRNA for Bmi1, Nanog Oct4, Sox2, ABCG2, Nestin, and Ki-67 than EC109 cells (P < 0.05). E-cadherin expression was lower in RR-EC109 cells than in EC109 cells, while N-cadherin, Snail, and Twist expressions were higher in RR-EC109 cells than in EC109 cells (P < 0.05). Conclusions: Cancer stem cell (CSC)-like cells exist among paclitaxel-resistant cells in ESCC and may play a role in ESCC drug resistance.