Salivary gland tumors comprise a heterogeneous group of lesions presenting different histological features and diverse clinical behavior. Pleomorphic adenoma is the most common benign tumor of major salivary glands. It shows a marked histological diversity with epithelial, myoepithelial, and mesenchymal components in a variety of patterns. Although it presents a slow progression, without treatment can cause significant morbidity and even death. Mucoepidermoid carcinoma is the most common malignant tumor of the salivary glands. Local recurrence rates range from 7% to 26% and distant metastasis rates range from 6% to 15%. Tight junctions (TJ) are considered one of the major structures in the establishment and maintenance of cell polarity having important physiological function in the formation of tubular organs, including the salivary glands. Some studies have demonstrated an association between tumor behavior and protein expression of tight junctions, particularly claudins. Claudins are transmembrane proteins important for the maintenance of cell adhesion and polarity and act as selective barriers. Changes in claudin expression have been detected in several tumors and appear to be related to progression and invasion. However, few studies have evaluated the role of claudins in the development of salivary gland tumors. In this study, using Real Time RT-PCR we have analyzed the expression of claudins-1, -3, -4, -5, -7, -11 in a series of 40 salivary gland tumor samples (20 cases of pleomorphic adenoma and 20 cases of mucoepidermoid carcinoma) and 10 samples of normal salivary glands tissue samples. Increased expression of claudin-1 and claudin-7 was observed in mucoepidermoid carcinoma when compared to pleomorphic adenoma (p=0.010 and p=0.001, respectively). Decreased expression of claudin-3 and claudin-11 was observed in mucoepidermoid carcinoma when compared to pleomorphic adenoma (p=0.005 and p=0.030, respectively). Regarding mucoepidermoid carcinoma tissue samples, we have evaluated the presence/absence of CRTC1/MAML2 fusion and demonstrated that 57.9% of the cases were positive for the presence of the fusion. Claudin-7 expression was associated with the presence of the fusion (p=0.048) and the absence of the fusion was associated with high histological grade tumors (p=0.023). Our study provides evidence of alterations in the expression of claudins in salivary gland tumors demonstrating that regulation of tight junction components is an important feature in salivary gland tumors behavior. CNPq Research Grant 443243/2014-0

Citation Format: Maria L. Arrojo, Claudia Arruda, Luiz P. Kowalski, Fernando A. Soares, Silvia V. Lourenço, Cláudia M. Coutinho-Camillo. Differential expression of claudins between benign and malignant salivary gland tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4036.