SECRETED PROTEINS AS POTENTIAL BIOMARKERS IN ADENOID CYSTIC CARCINOMA OF THE SALIVARY GLANDS

Abstract

Secreted proteins are involved in several physiological mechanisms. In solid tumors, it can be used as diagnostic and prognostic tools. Human anterior gradient 2 (AGR2) and CD10 are proteins secreted in body fluids in prostate cancer. The main of this study was to evaluate expression of the secreted proteins AGR2 and CD10 in adenoid cystic carcinoma (ACC) of the salivary gland. A total of 20 cases of ACC of the salivary glands were examined by immunohisto-chemistry method. Female was more affected (70%) with age varying from 10 to 79. Tumor sizes ranged from 1.3 to 9 (mean 2.7 cm), located mostly in minor salivary glands and submandibular gland. Eleven cases showed neural invasion. AGR2 was typically citoplasmatic and focally expressed in 75% of cases. Its expression was observed in all solid subtype, followed by tubular (88.8%) and cribiform (55.5%). Interestingly, half of ACC exhibited AGR2 expression in the extracellular space or inside ductiform structures. Clinically, neural invasion, nodal involvement, and systemic metastasis were associated to AGR2 expression. The surface protein CD10 was also focally expressed mainly in ductal structures in solid and tubular subtypes. Interestingly, its expression was restricted only to stroma in cribriform subtype. This secreted protein was also found freely inside ductiform structures. Furthermore, peripheral nerves involved in the tumor significantly expressed CD10 (p = 0.029) in the tubular subtype. Conclusion Neural invasion may involve participation of CD10 in ACC of the salivary gland. Further studies should confirm if extracellular AGR2 and CD10 represent potential biomarkers for salivary detection as diagnostic and prognostic tools in the clinic.