Figure 5. GAS6 overexpression increases CSCs through activation of Mer signaling in PCa cells.

(A, B) Percent of cells expressing the CSC phenotype in coculture of PCa^Control or PCa^GAS6OE with osteoblasts as quantified by FACS analysis. Data in Figure 5A, 5B are representative of mean with s.d. (Student's t-test). (C) The sphere formation of PCa^Control cells or PCa^GAS6OE cells in suspended sphere culture conditions following the treatment with a Mer inhibitor, UNC1062. Bar = 50 μm. (D) Quantification of prostatospheres in suspended sphere culture condition. *Denotes p < 0.05 between vehicle vs. a Mer inhibitor, UNC1062 treatments by Student's t-test. (E, F) MTT assays of PCa^Control cells or PCa^GAS6OE following the treatment with a Mer inhibitor, UNC1062 at 3 day cultures in adherent culture conditions. N.S. denotes no significance (p > 0.05) between vehicle vs. a Mer inhibitor, UNC1062 treatments by Student's t-test. (G, H) % CSC from DTC population in bone marrow at 24 hours after intracardiac injection of PCa^Control cells or PCa^GAS6OE in SCID mice (n = 5) as quantified by FACS analysis. Data are representative of mean with s.d. (Student's t-test). (I) Left panel: Immunofluorescence staining of p-Mer (red)/GAS6 (green) in PCa cells in bone marrow of a PCa patient. Blue, DAPI nuclearstain. Bar = 50 μm. Right panel: p-Mer (red)/GAS6 (green) positive cells (white arrows) in the magnification of the white rectangle from left panel. Bar = 20 μm.