Folia Histochemica et Cytobiologica (Apr 2010)
Expression of Cyclooxygenase-1 and Cyclooxygenase-2 in normal and pathological human oral mucosa
Abstract
Cyclooxigenase (COX) is the rate-limiting enzyme for the conversion of arachidonic acid (AA) to prostaglandins(PGs). Two isoforms of COX have been identified: COX-1 is constitutively expressed in many cells and is involved in cellhomeostasis, angiogenesis and cell-cell signalling; COX-2 is not expressed in normal condition however it is stronglyexpressed in inflammation. The oral cavity is costantly exposed to physical and chemical trauma that could lead to mucosalreactions such as hyperplasia, dysplasia and cancer. Early diagnosis is the most important issue to address for a positiveoutcome of oral cancer; therefore it would be useful to identify molecular markers whose expression is associated with thevarious stages of oral cancer progression. Since COX enzyme has been involved, with different mechanisms, in the developmentand progression of malignancies we decided to investigate the expression and localization of COX-1 and COX-2in normal human oral mucosa and three different pathologies (hyperplasia, dysplasia and carcinoma) by immunohistochemistryand RT-PCR. COX-1 mRNA and protein have been detected already in normal oral mucosa and their expressionprogressively increases from normal samples towards hyperplasia, dysplasia and finally carcinoma. On the contrary,COX-2 is not expressed in the normal tissue, starts to be expressed in hyperplasia, reaches the maximum activation in dysplasiaand then starts to be downregulated in carcinoma.