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

ObjectivesUp 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 (TNF)-activated stromal cyclooxygenase-2 (COX-2) signalling on proliferation and invasiveness of colon cancer epithelial cells. Materials and methodsCyclooxygenase-2 mRNA and protein were determined by real-time PCR and western blotting and prostaglandin E-2 (PGE(2)) 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. ResultsOur results indicated that TNF, a powerful inflammatory cytokine, strongly promoted COX-2 expression and PGE(2) 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. ConclusionWe conclude that activation of stromal COX-2 signalling by TNF played a major role in promoting proliferation and invasiveness of colon cancer epithelial cells.