Figure 4
From: Macrophages may promote cancer growth via a GM-CSF/HB-EGF paracrine loop that is enhanced by CXCL12
CXCL12-dependent transactivation of HER1 in transwell experiments. Human mononuclear phagocytes (Mø) and neutrophils (PMN, used as negative control) were stimulated with 200 ng/mL CXCL12 in the upper chamber of a transwell containing HeLa, DLD-1, Balb/c 3T3 or HUVEC target cells in the lower chamber. HeLa, DLD-1, Balb/c 3T3 and HUVEC were collected after 20 minutes of stimulation, and HER1 phosphorylation at Y1068 was measured by an ELISA using specific anti-tyrosine mAbs, expressed as phosphorylated molecules/total molecules and represented as a per cent ratio. (A) Negative controls: CXCL12 alone, stimulated PMN or unstimulated Mø were ineffectual. (B) Effect of Mø stimulation: CXCL12 led to HER1 transactivation in either HeLa, DLD-1, Balb/c 3T3 or HUVEC (p < 0.05). Pre-treatment with 100 μg/mL anti-HB-EGF neutralising Ab abolished Y1068 phosphorylation in the target cells (p < 0.05). The isotypic control of neutralising anti-HB-EGF mAb was not effective. The colour pattern of the bars refers to each type of target cell. The means ± SD of 10 experiments are depicted.