Expression of interleukin 8 and its receptors in human colon carcinoma cells with different metastatic potentials

Purpose: In the present study, we examined the expression of a multifunctional cytokine, interleukin 8 (IL-8), and its receptors, CXCR1 and CXCR2, in human colon carcinoma cells with different metastatic potentials and determined their role in modulating phenotypes associated with metastasis. Experimental Design: IL-8, CXCR1, and CXCR2 protein and mRNA expression were examined using ELISA, immunocytochemistry, and reverse transcription-PCR in human colon carcinoma cells with different metastatic potentials. IL-8-mediated proliferation, migration, and tumor-endothelial cell interaction were analyzed. Results: IL-8 mRNA and protein expression was very low in Caco2 cells but elevated in KM12C cells and very high in KM12L4 cells, suggesting an association between the IL-8 production and metastatic potential. Similarly, CXCR1 and CXCR2 expression was lower in Caco2 cells than in low and high metastatic KM12C and KM12L4 cells. The recombinant human IL-8 enhanced the proliferation of colon carcinoma cells. Furthermore, proliferation of low and high metastatic cells expressing different levels of IL-8 was inhibited by neutralizing antibodies to IL-8, CXCR1, and CXCR2. We observed significant differences in the invasive potential of colon carcinoma cells expressing different levels of IL-8. In addition, we observed that IL-8 modulates adhesion of tumor cells to endothelial cells in an autocrine and paracrine manner. Conclusion: Our present data suggest an association between constitutive expression of IL-8 and aggressiveness in human colon carcinoma cells and the possible role of IL-8 in modulating different metastatic phenotypes associated with progression and metastasis.