Salivary Agglutinin/DMBT1SAG Expression is Up-regulated in the Presence of Salivary Gland Tumors

Abstract

Salivary agglutinin (SAG) is encoded by the gene Deleted in Malignant Brain Tumors 1 ( DMBT1) and represents the salivary variant of DMBT1 (DMBT1SAG). While SAG is a bona fide anti-caries factor, DMBT1 was proposed as a candidate tumor-suppressor for brain, digestive tract, and lung cancer. Though DMBT1SAG is expressed in the salivary glands, its expression in salivary gland tumors is unknown. Here we analyzed DMBT1SAG expression in 20 salivary gland tumors and 14 tumor-flanking tissues by immunohistochemistry. DMBT1SAG in salivary gland tumors resembles the changes of expression levels known from DMBT1 in tumors in other cancer types. Particularly, DMBT1SAG was up-regulated in 10/14 tumor-flanking tissues, and a strong staining of the luminal content in the tumor and/or the tumor-flanking tissue was observed in 14/20 cases. This suggests that, in addition to its role in caries defense, SAG may serve as a potential tumor indicator and/or tumor suppressor in salivary gland tissue.