Gene expression profiles of Ecrg4-treated mouse microglia

Esophageal cancer-related gene 4 (Ecrg4), a hormone-like peptide, is thought to be a tumor suppressor, however little is known about the mechanism of how Ecrg4 suppresses tumorigenesis. Using the mouse glioma–initiating cell models, we identified Ecrg4 acts as a tumor suppressor in vivo. To characterize the function of Ecrg4 towards microglia, an innate immune cell in central nervous system, we performed gene expression microarray analysis for primary microglia treated with or without recombinant Fc-fused Ecrg4 fragments. We demonstrate here that Ecrg4 fragments, amino acid residues 71-132 and 133-148, which are produced by the proteolitic cleavage, induced the expression of pro-inflammatory cytokines in microglia. Thus, Ecrg4 acts as a cytokine/chemokine inducer, which activates the immune cells to eradicate tumor. Primary microglia cells from C57BL/6 mice were treated with PBS alone or 20 μg/ml of recombinant Fc, Fc-fused Ecrg4(71-132), or Fc-fused Ecrg4(133-148) for 3h. Duplicate for each assays were analyzed (8 samples in total).