Tight Junction Protein (Claudin-4) and Inflammatory Regulator (COX-2) Expression in Nasopharyngeal Carcinoma: An Immunohistochemical Study

Abstract
Background: Claudin 4 is one of the tight junction proteins which considered one of the protective barriers that are mostly involved in the regulation of intercellular communication, paracellular transport and apical cell-to-cell adhesion. Over-expression of COX-2 and subsequent increase in prostaglandins (PGs) concentration have emerged in recent years as important players in cancer progression.
Aim of Study: To explore immunohisto chemically the expression of both claudin-4 and COX2 in nasopharyngeal carcinoma and correlate their expression with each other and with different clinicopathological parameters.
Material and Methods: This retrospective study was done upon formalin fixed, paraffin blocks of 32 nasopharngeal carcinoma cases and 6 non-neoplastic nasopharyngeal epithe-lium. The materials were obtained from archieves of Pathology Departement and Early Cancer Detection Unit (ECDU), Faculty of Medicine, Benha University during the years 2012- 2017. The immunohistochemical stain with Claudin 4 and COX2 was done and evaluated for each case.
Results: High expression of claudin 4 was observed in 44% of studied nasopharyngeal cases with statistically signif-icant correlation with tumor stage and distant metastasis (p<0.05). Positive expression of COX2 was detected in 75% of neoplastic group and statistically correlated with depth of tumor invasion, nodal invasion and tumor stage (p<0.05). A statistically significant correlation was detected between overexpression of COX2 and low expression of claudin4 in the studied neoplastic cases (p<0.05).
Conclusion: Claudin -4 has different tumorigenic effects besides their known adhesion attributes. Because of that, we believe that claudin 4 with other clinicopahological parameters may be a promising prognostic molecular indicator in na-sopharyngeal cancer cases and can be taken as a novel bi-omarker for the predication of distant metastasis and survival. This work also highlights COX-2 expression's potential as an indicator of cancer progression that can contribute to assess-ment of prognosis and treatment decisions. Therefore, COX-2 inhibitors may have considerable potential as therapeutic agents.