Fig. 6.

GPNMB, via the CD44 receptor, stimulates the expression and release of IL-33, which promotes stemness in the MCA-1-mock cells. a–c Real-time PCR for IL-33, IL-6, and CCL5 (AU: arbitrary units) and d–f ELISA quantification of IL-33, IL-6, and CCL5 in MCA-1-mock cells, MCA-1-GPNMB cells and their derived spheres. g, h Real-time PCR for IL-33 and CCL5 in MCA-1-mock cells treated or not treated with the supernatant from MCA-1-GPNMB cells. i Number of the MCA-1-mock cells forming spheres induced by treatment with recombinant murine IL-33 (10 ng/ml) and the inhibitory effect of blocking by the anti-mST2 mAb (4 µg/ml) or the irrelevant mAb. j Number of MCA-1-mock cells forming spheres induced by recombinant murine GPNMB (10 ng/ml) and inhibitory effect of blocking by the anti-CD44 mAb (10 µg/ml) or irrelevant mAb. MCA-1-mock cells were cultured for 7 days in IMDM medium without serum and supplemented with factors bEGF, FGF, N2, and B27. Statistical analysis: ∗p < 0.05, ∗∗p < 0.01. Unpaired t-test (a–f and i, j) and unpaired t-test with the Welch’s correction (g, h). Data are presented as the mean ± SEM