Celecoxib modulates adhesion of HT29 colon cancer cells to vascular endothelial cells by inhibiting ICAM‐1 and VCAM‐1 expression

Background and purpose: Cyclooxygenase‐2 (COX‐2) is highly expressed during inflammation and can promote the progression of colorectal cancer. Interactions between cancer cells and vascular endothelial cells are key events in this process. Recently, the selective COX‐2 inhibitor, celecoxib, was shown to inhibit expression of the adhesion molecules, ICAM‐1 and VCAM‐1, in the human colon cancer cell line HT29 and to inhibit adhesion of HT29 cells to FCS‐coated plastic wells. Here, we evaluated the effects of celecoxib on adhesion of HT29 cells to human umbilical vein endothelial cells (HUVEC), mediated by ICAM‐1 and VCAM‐1, to assess further the potential protective effects of celecoxib on cancer development. Experimental approach: Celecoxib was incubated for 4 h with HT29 cells and HUVEC and adhesion was quantified by a computerized micro‐imaging system. Expression analysis of ICAM‐1 and VCAM‐1 cell adhesion molecules was performed by western blot. Key results: Celecoxib (1 n M –10 μ M ) inhibited, with the same potency, adhesion of HT29 cells to resting HUVEC or to HUVEC stimulated by tumour necrosis factor‐α (TNF‐α), mimicking inflammatory conditions. Analysis of ICAM‐1 and VCAM‐1 expression showed that celecoxib inhibited expression of both molecules in TNF‐α‐stimulated HUVEC, but not in resting HUVEC; inhibition was concentration‐dependent and maximal (about 50%) at 10 μ M celecoxib. Conclusions and implications: In conclusion, our data show that celecoxib inhibits HT29 cell adhesion to HUVEC and expression of ICAM‐1 and VCAM‐1, in stimulated endothelial cells. These effects may contribute to the chemopreventive activity of celecoxib in the development of colorectal cancer. British Journal of Pharmacology (2008) 153 , 1153–1161; doi: 10.1038/sj.bjp.0707636 ; published online 17 December 2007