Figure 1. EML4-ALK increases the stem-like properties and tumorigenicity of EML4-ALK-driven NSCLC cells in vitro and in vivo.
A. Sphere-forming capacity of BEAS-2B, A549, H3122 and H2228 cells in a low-density suspension culture. Original magnification, x40. B. ALK, pALK, NANOG, OCT4, SOX2, KLF4, c-MYC and β-ACTIN expression in BEAS-2B, A549, H3122 and H2228 cells in a low-density suspension culture. Original magnification, x40. (B) ALK, pALK, NANOG, OCT4, SOX2, KLF4, c-MYC and β-ACTIN expression in BEAS-2B, A549, H3122 and H2228 cells was visualized by western blot analysis with lysates from the monolayer cultured cells. (C) H3122 and H2228 cells were treated with siGFP (control) or siALK and the levels of ALK, NANOG, OCT4, SOX2, KLF4, and c-MYC proteins were analyzed. β-ACTIN was used as an internal loading control. Numbers below blots indicate expression as measured by fold change. D. Flow cytometry analysis of the frequency of ALDH1+ cells in H3122 and H2228 cells treated with siALK or siGFP (control). E. Sphere-forming capacity of H3122 and H2228 cells treated with siGFP or siALK in a low-density suspension culture. Original magnification, × 40. F. Tumorigenicity of siGFP-versus siALK-treated H3122 cells inoculated at indicated doses into 5 NOD/SCID mice per group. G. Tumors were extracted at 20 days after injection of 105 siGFP- or siALK-treated H3122 cells. Error bars represent mean ± SD. Individual data analysis was performed using two-tailed Student's t-test.