Fibroblast-derived CXCL12/SDF-1α promotes CXCL6 secretion and co-operatively enhances metastatic potential through the PI3K/Akt/mTOR pathway in colon cancer

Figure 2 Enhancement of secreted granulocyte chemotactic protein-2 levels in colon cancer cell lines and stromal cells by recombinant stromal cell-derived factor-1 and co-culture with fibroblasts. The alteration of CXCL6 secretion from colon cancer cell lines [CaCo-2 (A), WiDr (B), HT-29 (C) and DLD-1 (D)] by recombinant CXCL12 stimulation or co-culture with fibroblasts (FB) were determined by enzyme-linked immunosorbent assay in cell culture medium. Meanwhile, colon cancer cells were treated with anti-CXCL12 antibody (Ab) for 2 h, and the concentration of CXCL6 was measured by ELISA in supernatants from colon cancer cells. Effect on secretion of CXCL6 from HUVECs stimulated by recombinant CXCL12 in co-culture system with fibroblasts and the colon cancer cells DLD-1 are shown (E). The experimental detail is described in the “Materials and Methods” section. Control: colon cancer cells only; FB: fibroblasts only; CXCL12: treated with recombinant CXCL12; with FB: colon cancer cells co-cultured with fibroblasts; with FB + Ab: colon cancer cells co-cultured with fibroblasts and pre-treated with anti-CXCL12 Ab. The values are expressed as mean ± SD. Ab: Antibody; CXCL6: Granulocyte chemotactic protein-2; CXCL12: Stromal cell-derived factor-1; HUVEC: Human umbilical vein endothelial cell.