Expression and clinical implication of cyclooxygenase-2 and E-cadherin in oral squamous cell carcinomas

Epithelial-Mesenchymal Transition (EMT) and angiogenesis are crucial events for development of aggressive and often fatal Oral Squamous Cell Carcinomas (OSCCs). Both promote cancer progression and metastasis development, but while the former induces the loss of E-cadherin expression and, hence cadherin switching; the latter produces hematic blood vessel neo-formation and contribute to OSCC cell growth, tumor mass development, and dissemination. Cyclooxygenase-2 (COX-2) has an important role, not only in angiogenic mechanisms, but also in favoring cancer invasion. Indeed it decreases the expression of E-cadherin and leads to phenotypic changes in epithelial cells (EMT) enhancing their carcinogenic potential. Our aim is to evaluate the interplay between E-cadherin cytoplasmic delocalization, COX-2 up-regulation and COX-2 induced neo-angiogenesis in 120 cases of OSCC. We have analyzed the distribution and the number of neo-formed endothelial buds surrounding infiltrating cells that express COX-2, as well as the neo-formed vessels in chronic inflammatory infiltrate, which surround the tumor. A double immunostaining method was employed in order to verify co-localization of endothelial cell marker (CD34) and COX-2. IHC has also been used to assess E-cadherin expression. Our data demonstrate that the OSCC cells, which lose membranous E-cadherin staining, acquiring a cytoplasmic delocalization, overexpress COX-2. Moreover, we find a new CD34+ vessel formation (sprouting angiogenesis). Only basaloid type of OSCC showes low level of COX-2 expression together with very low level of neo-angiogenesis and consequent tumor necrosis. The well-known anti-metastatic effect of certain COX-2 inhibitors suggests that these molecules might have clinical utility in the management of advanced cancers.