Fig. 6: Targeting p38α in patient-derived stage III CRC-SCs to circumvent chemoresistance.

A Growth kinetics of CD44v6^low-enriched and CD44v6^high-enriched CRC-SCs treated with ralimetinib (10 μM) or the vehicle for up to 72 h. B Viable cell number variation in CD44v6^low- and CD44v6^high-enriched CRC-SCs treated with ralimetinib (10 μM) for 72 h. Values were normalized against those of vehicle-treated cells. C Limiting dilution assay performed on CD44v6^low-enriched and CD44v6^high-enriched CRC-SCs. The graph shows the clonogenic capacity of each cell subset. A–C CD44v6^low and CD44v6^high represent cell samples enriched for the top 20% cells with the lowest and highest expression of CD44v6, respectively. A, C *P < 0.05: CD44v6^high treated with ralimetinib vs. CD44v6^high treated with the vehicle; and ^#P < 0.05: CD44v6^low treated with ralimetinib vs. CD44v6^low treated with the vehicle. D Treatment scheme: CRC-SCs were pre-treated with ralimetinib (10 μM) for 48 h and then treated with 5-FU (2 μM), CDDP (30 μM), CPT-11 (30 μM), or trametinib (1 nM) for another 24 h in the presence of ralimetinib. E Quantification of cell viability by Cell Titer Glo in CRC-SCs #21 treated as described in (D). F Quantification of cell death by trypan blue staining in CRC-SCs #21 treated as described in (D). G Colony-forming ability of CRC-SCs #21 seeded onto double-layer soft agar and treated as described in (D). Data represent the percentage of colonies relative to DMSO-treated cells. Original magnification: 100x. H Migratory ability of growth factor-starved CRC-SCs #21 placed in the inner chamber of transwell plates and treated with the indicated compounds for 16 h. Migrating cells were fixed and counted under a fluorescence microscope. Original magnification: 100x. Tram = trametinib. *P < 0.05: treatment vs. control (DMSO); and ^#P < 0.05: combined treatment vs. corresponding single treatments.