Figure 7. Regulation of c-Myc and stem cell transcription factors by CD47 ligation.

(A) c-Myc mRNA in Jurkat (JK) and CD47-deficient JinB8 Jurkat T cells (JIN). (B) Time-dependence for regulation of c-Myc mRNA expression by the CD47 ligand thrombospondin-1. Jurkat cells were treated with 2.2 nM thrombospondin-1 for the indicated times before isolating RNA and assessing c-Myc mRNA by real time PCR normalized to β2m mRNA and expressed as a ratio to normalized c-Myc levels in control cells at the corresponding time points. (C) Thrombospondin-1 effects on c-Myc mRNA in WT Jurkat and CD47-deficient (JinB8) T lymphoma cells. (D) CD47 re-expression in JinB8 cells alters expression c-Myc compared with WT Jurkat cells. (E) Effects of CD47-binding TSP1 peptide 7N3 and control peptide 604 on c-Myc mRNA expression in Jurkat T cells. (F and G) mRNA levels in thrombospondin-1-null vs. WT lung and spleen. (H) CD47 over-expression in Rat1 fibroblasts and B16 melanoma cells does not suppress growth. (I) Deregulation of translocated c-Myc in Raji Burkitt's lymphoma cells prevents growth regulation by CD47 over-expression. (*p < 0.05, **p < 0.01).