IMMUNOHISTOCHEMICAL EXPRESSION OF CD44 AND CD56 IN MALIGNANT SALIVARY GLAND TUMORS

Introduction: Salivary gland cancers impose a huge part in oral and maxillofacial pathologies. Mucoepidermoid (MEC) and adenoid cystic carcinomas (ACC) are salivary malignancies, where (MEC) being the most common cancer. CD44, is a family of transmembrane non-kinase cell surface glycoproteins, that was broadly used as a marker for cancer stem cells (CSCs) in various malignancies. CD44 was found to be overexpressed in various types of cells including cancer stem cells (CSCs) and it has been postulated that CD44 has a part in carcinogenesis. Natural killer (NK) cells are one of the components of the innate immune system, which express the phenotypic marker CD56 in the absence of CD3, and has a vital role in tumor-cell surveillance. This study aimed to assess the expression of CD44 and CD56 in different grades of mucoepidermoid carcinomas and different patterns of adenoid cystic carcinoma, and correlate between the expressions of the markers (CD44 and CD56) in different grades and patterns of the tumors. Material &Methods: Thirty-three paraffin embedded blocks of salivary gland tumors (18 mucoepidermoid carcinoma and 15 adenoid cystic carcinoma) were selected. Those tumorswere classified into four groups: intermediate grade (IG) MEC, high grade (HG) MEC, ACC (tub-crib) and ACC (solid) patterns.Immunohistochemical staining for CD44 and CD56 was performed. Data were analyzed using SPSS (24), the independent-T test and Anova to analyze the statistical significance. Results: for CD44, inMEC group, we found no significant difference between both grades for CD44 expression, however, the difference was found to be significant between both patterns of ACC. While for CD56, the difference was statistically significant between both grades of MEC, and both patterns of ACC. Conclusion:CD44 could be promising goal for cancer therapy, mostly for CD44 expressing cancers. NK cells have a crucial role in the anti-tumor immune mechanism. Moreover, more studies are significantly demanded to assess the promising role and function of CD56 in diagnosis and prognosis of salivary gland cancers, and the tumor-cell surveillance capacity of the NK cells.