Figure 2
From: Macrophages may promote cancer growth via a GM-CSF/HB-EGF paracrine loop that is enhanced by CXCL12
CXCL12 modifies HB-EGF expression in mononuclear phagocytes. Human mononuclear phagocytes (Mø) were cultured alone or in the presence of 200 ng/mL CXCL12. Cells were collected after 20 minutes, 2 hours and 24 hours; cell-free supernatants were collected after 24 hours and the levels of soluble HB-EGF protein were measured using a specific ELISA. (A) Flow cytometric analysis showing that CXCL12-stimulated Mø released HB-EGF (after 20 minutes) and up-regulated its expression (after 24 hours). (B) Northern blot analysis on Mø and neutrophils (PMN, used as negative control) collected after 2 hours of stimulation with CXCL12. Only Mø produced detectable levels of HB-EGF mRNA in basal conditions, and HB-EGF transcripts were up-regulated upon stimulation. After 24 hours, the mRNA up-regulation persisted (data not shown). (C) CXCL12 treatment induced Mø to release HB-EGF into the culture medium (p < 0.05). Representative pictures or the means ± SD out of 10 experiments are shown.