Galectin-3 immunoprofile in adenoid cystic carcinoma and polymorphous low-grade adenocarcinoma of salivary glands

Adenoid cystic carcinoma (ACC) and polymorphous low-grade adenocarcinoma (PLGA) are malignant neoplasms of salivary glands, which are similar in histologic patterns but very different in clinical behavior, treatment and prognosis. Galectin-3 is a multifunctional protein of a growing family of beta-galactoside-binding animal lectins, which is implicated in a variety of biological events such as tumor cell adhesion, proliferation, differentiation and angiogenesis. This protein was found to be implicated in cellular transformation and a correlation between its expression and cancer progression and metastasis has been described. The aim of this study was to determine the galectin-3 immunoprofile in 14 cases of ACC (2 cases of tubular subtype, 4 cases of solid subtype and 8 cases of cribriform subtype) and in 12 cases of PLGA with different histologic patterns, including lobular, tubular and cribriform aspects. Moreover, slides of normal salivary glands were included. In normal salivary glands there was strong nuclear and cytoplasmic staining for galectin-3 in ductal luminal cells. ACC showed specific staining in luminal cells mainly in the nuclei. In the tubular subtype of ACC, galectin-3 strongly stained luminal cells of the ductiform structures. The cribriform and solid subtypes showed a few positive luminal cells of small ducts present in the cribriform structures and in solid nests respectively. In the cases of PLGA, independent of the histologic architecture, all tumor cells revealed a positive cytoplasmic reaction. Galectin-3 expression seems to be related to cell differentiation more than to tumor progression and prognosis in the neoplasms studied.