Binding of galectin-1 (gal-1) on trophoblast cells and inhibition of hormone production of trophoblast tumor cells in vitro by gal-1.

Galectin-1 (gal-1), a member of the mammalian beta-galactoside-binding proteins, recognizes preferentially Galbeta1-4GlcNAc sequences of oligosaccharides associated with several cell surface glycoconjugates. As demonstrated histochemically, the lectin recognizes appropriate glycoepitopes on the syncytiotrophoblast and on chorionic carcinoma cells (BeWo). Freshly isolated trophoblast cells and trophoblast tumor cells Jeg3 did not bind gal-1. BeWo cells in contrast to Jeg3 form a syncytium in vitro and synthesize progesterone as well as hCG. BeWo cells were used as an approach to study the effects of gal-1 on hormone production. The lectin decreased cellular hCG and progesterone production as well as hCGbeta gene transcription as measured by real-time RT-PCR. Gal-1 mediated inhibition of cellular progesterone production was reduced in the presence of a Thomsen-Friedenreich (TF)-polyacrylamide conjugate. Inhibition of cellular hCG and progesterone production was also induced by anti-TF monoclonal antibodies. The results demonstrate that ligation of Galbeta1-4GlcNAc and Galbeta1-3GalNAc (TF) epitopes on BeWo cells may have regulatory effects on hCG and progesterone production.