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

AIM: To investigate the underlying mechanism by which CXCL12 and CXCL6 influences the metastatic potential of colon cancer and internal relation of colon cancer and stromal cells.

METHODS: Western blotting was used to detect the expression of CXCL12 and CXCL6 in colon cancer cells and stromal cells. The co-operative effects of CXCL12 and CXCL6 on proliferation and invasion of colon cancer cells and human umbilical vein endothelial cells (HUVECs) were determined by enzyme-linked immunosorbent assay, and proliferation and invasion assays. The angiogenesis of HUVECs through interaction with cancer cells and stromal cells was examined by angiogenesis assay. We eventually investigated activation of PI3K/Akt/mTOR signaling by CXCL12 involved in the metastatic process of colon cancer.

RESULTS: CXCL12 was expressed in DLD-1 cancer cells and fibroblasts. The secretion level of CXCL6 by colon cancer cells and HUVECs were significantly promoted by fibroblasts derived from CXCL12. CXCL6 and CXCL2 could significantly enhance HUVEC proliferation and migration ( P < 0.01). CXCL6 and CXCL2 enhanced angiogenesis by HUVECs when cultured with fibroblast cells and colon cancer cells ( P < 0.01). CXCL12 also enhanced the invasion of colon cancer cells. Stromal cell-derived CXCL12 promoted the secretion level of CXCL6 and co-operatively promoted metastasis of colon carcinoma through activation of the PI3K/Akt/mTOR pathway.

CONCLUSION: Fibroblast-derived CXCL12 enhanced the CXCL6 secretion of colon cancer cells, and both CXCL12 and CXCL6 co-operatively regulated the metastasis via the PI3K/Akt/mTOR signaling pathway. Blocking this pathway may be a potential anti-metastatic therapeutic target for patients with colon cancer.