A Subset of patients with papillary thyroid cancer (PTC) present with aggressive disease that is refractory to conventional treatment. Novel therapies are needed to treat this group of patients. Galectin-3 (Gal-3) is a beta-galactoside-binding protein with anti-apoptotic activity. Over 30 studies in the last 3 years have reported that Gal-3 is highly expressed in PTC relative to normal thyrocytes. In this study, we show that Gal-3 silencing with RNA interference Stimulates apoptosis, while Gal-3 overexpression protects against both TRAIL- and doxorubicin-induced apoptosis in PTC cells. The anti-apoptotic activity and chemoresistance related to Gal-3 function can be partially reversed through the inhibition of the PI3K-Akt pathway, Suggesting that Gal-3 acts, at least in part, on the PI3K-Akt axis. These observations Support further evaluation of Gal-3 as a potential therapeutic target in patients with aggressive PTC. (C) 2008 Elsevier Inc. All rights reserved.