Modulation of the expression of the rabbit galectin-3 gene by p53 and c-Ha-ras proteins and PMA.

Galectin-3 is a galactose-binding lectin that has been found in several mammalian tissues. Galectin-3 gene is expressed in a wide range of normal and tumoral cells. In the case of myeloid cells, its expression correlates with the differentiation of monocytes to macrophages. In the case of cancer cell lines, its expression correlates with tumorigenicity and metastatic potential. The regulation of the expression of this gene is still largely unknown. The rabbit galectin-3 gene has been isolated and characterized. Its structure revealed an organization similar to that of the murine galectin-3 gene. The genomic sequences located upstream from its 5' end, upon insertion upstream from a promoter-free reporter gene, exhibited a strong promoter activity. This activity was upregulated upon treatment of transfected smooth muscle cells with phorbol 12-myristate 13-acetate (PMA) as well as upon transfection with a EJ/ras encoding plasmid. Conversely, it was downmodulated upon transfection with wild-type p53 but not with mutated p53. The regulatory sequences involved in the positive regulation of the gene were located upon serial deletion experiments.