Fig. 1

Phenotypic characteristics of Caco-2 and Caco-2 CR cells. a The sensitivity of a panel of CRC cell lines (HCT116, SW620, Caco-2 and HCT8) to cetuximab treatment was assessed by CCK8 assays. CRC cells were incubated with graded concentrations (0–200 μg/ml) of cetuximab for 48 h. Six replicates were used for each concentration, and the experiment was repeated at least three times. Data are presented as mean ± SD. b Cell viability was assessed by CCK8 assays in Caco-2 and Caco-2 CR cells treated with various concentrations of cetuximab (0–200 μg/ml) for 48 h. Each concentration had six replicates, and the experiment was repeated at least three times. Data are presented as mean ± SD. **P < 0.01 by two-way ANOVA. c Flow cytometry was performed in Caco-2 and Caco-2 CR cells with cetuximab treatment (100 μg/ml and 200 μg/ml) for 48 h. All experiments were repeated three times, and data are presented as mean ± SD. **P < 0.01 by Student’s t test. ^##P < 0.01 by one-way ANOVA followed by Dunnett’s test. d Caco-2 and Caco-2 CR cells were treated with or without 200 μg/ml cetuximab (CTX) for 48 h. Apoptosis was detected by a TUNEL assay. Scale bar = 100 μm. e The cell cycle was assessed by flow cytometry in Caco-2 and Caco-2 CR cells after 48 h of treatment with cetuximab (200 μg/ml). All experiments were repeated three times, and data are presented as mean ± SD. *^/#P < 0.05, **^/##P < 0.01 by Student’s t test. f The percentage of EGFR-, ERBB3-, and c-MET-positive cells and the MFI were determined by GALLIOUS flow cytometry in Caco-2 and Caco-2 CR cells. All experiments were repeated three times, and data are presented as mean ± SD. *P < 0.05, **P < 0.01 by Student’s t test. g Flow cytometry analysis showed the expression of stemness biomarkers of CRC cells, CD44 and CD133, in Caco-2 and Caco-2 CR cells. All experiments were repeated three times, and data are presented as mean ± SD. *P < 0.05 by Student’s t test