TNFα-activated stromal COX-2 signalling promotes proliferative and invasive potential of colon cancer epithelial cells

Objectives: Up to now it has been unclear whether stromal/epithelial interaction affects progression of colon cancer. This study was designed to examine effects of tumour necrosis factor alpha (TNFα)-activated stromal cyclooxygenase-2 (COX-2) signalling on proliferation and invasiveness of colon cancer epithelial cells. Materials and methods: Cyclooxygenase-2 mRNA and protein were determined by real-time PCR and western blotting and prostaglandin E₂ (PGE₂) was assayed by radioimmunoassay. Cell proliferation and invasiveness were determined by transwell chamber assays and protein kinase C (PKC) was assayed by Biotrak^™ PKC Assay System. Results: Our results indicated that TNFα, a powerful inflammatory cytokine, strongly promoted COX-2 expression and PGE₂ production in colon cancer-associated fibroblasts. Using in vitro assays for estimating proliferative and invasive potential, we discovered that activation of stromal COX-2 signalling significantly promoted proliferation and invasiveness of colon cancer epithelial cells. In addition, selective COX-2 inhibitor N-[2-(Cyclohexyloxy)-4-nitrophenyl]methanesulfonamide, blocked such proliferative and invasive effects on the cancer epithelial cells. In this process, PKC was involved in activation of COX-2 signalling in the fibroblasts. Conclusion: We conclude that activation of stromal COX-2 signalling by TNFα played a major role in promoting proliferation and invasiveness of colon cancer epithelial cells.