Effects of galectin-3 expression on growth and tumorigenicity of the prostate cancer cell line LNCaP

BACKGROUND. Galectin-3 is a beta-galactoside-binding vertebrate lectin. In human prostate cancer, galectin-3 expression has been shown to decrease with progression of disease. In the present study, we further investigated the role of galectin-3 in this malignancy by examining the phenotype of galectin-3-transfected prostate cancer cells. METHODS. Stably transfected galectin-3-expressing cell lines were developed from the prostate cancer cell line LNCaP, which does not constitutively express this molecule. Transfected cells lines were analyzed for alterations in morphology and growth rates, and for ability to form tumors in nude mice. RESULTS. Morphologically, when compared to the parental LNCaP cells, the galectin-3 transfectants had broader, flatter cell bodies, shorter and less finely branched dendritic processes, and large nuclei with pronounced and often multiple nucleoli. The galectin-3 lilies were found to proliferate at a slower rate in vitro than either the vector control- transfected lines or parental LNCaP. When injected subcutaneously in nude mice, four of six galectin-3 lines formed tumors at a slower rate than control lines. Twenty-four tumors that formed from the transfected cell lines were examined by immunohistochemistry for galectin-3 expression, Only one tumor was found to express galectin-3, suggesting that the transfected cells which formed tumors were those which successfully down-regulated galectin-3 expression. CONCLUSIONS. In contrast to an apparent stimulatory role in some tumor types, galectin-3 is an inhibitory molecule for prostate cancer. (C) 2002 Wile -Liss, Inc.