Fig. 1

Chemoresistant ESCC possess T-ICs-like traits. a Left panel: Schematic representation of the establishment of a patient-derived xenograft mouse model to enrich clinical ESCC T-ICs. NOG mice were orthotopically implanted with clinical human ESCC cells and treated with PBS (control) or CDDP (5 mg/kg, twice a week) for 3 weeks. Tumor cells were then re-inoculated subcutaneously into NOG mice for the next round of treatment until CDDP treatment no longer reduced tumor size (fourth round of treatment). Right panel: Annexin V-FITC/PI staining of CDDP-resistant ESCC (EC-CR) and CDDP-untreated ESCC (EC-UT) cells treated with CDDP (20 μM) or DOC (1.5 nM) for 24 h. b Left table and middle graph: The frequency of T-ICs. Right graph: The estimated percentage of T-ICs among EC-CR and EC-UT cells during serial transplantations. c Representative images (left) and quantification (right) of tumorspheres formed by the indicated cells. d, e Flow cytometry analysis of the percentage of side-population cells (d) and CD90⁺ and CD271⁺ subpopulations (e) of the indicated cells. f Real-time PCR analysis of the mRNA expression of the indicated transcripts in EC-CR and EC-UT cells. Each bar represents the mean ± SD of three independent experiments. * P < 0.05