FUNCTIONS OF (1,3) FUCOSYLTRANFERASE GENE FAMILY

癌细胞通过血液转移会显著影响

Metastasis of cancer cells via the bloodstream significantly affects the diagnosis, treatment, and prognosis of most human malignancies. Interaction of tumor cells with the microvasculature depends on many factors, but metastatic invasion clearly requires arrest and adherence of the cell to endothelium, followed by migration and/or proliferation. Activation of endothelial cells by cytokines increases adhesion of some human melanoma and adenocarcinoma cells in vitro by a process distinct from integrin-mediated interactions. Recent experiments have shown that the fucosylated structure sialyl Lewis x can mediate adhesion of leukocytes to E-selectin (ELAM-1) and P-selectin (GMP-140/PADGEM) expressed by human endothelial cells. A related glycan, sialyl Lewis a, can also serve as a ligand for E-selectin. These carbohydrate moieties were originally described as oncodevelopmental antigens associated with some of the same malignant cells now shown to adhere to cytokine-activated endothelium. Genetic and biochemical data suggest the presence of at least six alpha(1,3)fucosyltransferase (FT) genes in humans capable of generating these related glycans. Although tissue specific expression has been demonstrated for fucosylated oligosaccharide antigens and multiple alpha(1,3)FT activities, molecular mechanisms that determine this process are not well understood. We have isolated and characterized four human alpha(1,3)FT genes, which will now be used for experiments outlined in the following specific aims: 1. Isolate and characterize remaining alpha(1,3) and alpha(1,4)FT gene(s). 2. Determine the physical maps of alpha(1,3)FT loci on human chromosomes. 3. Determine normal expression patterns of alpha(1,3)FT transcripts in human tissues. 4. Examine expression of alpha(1,3)FT transcripts in human adenocarcinoma cells capable of adhering to cytokine-activated endothelium. Demonstrate the specific alpha(1,3) or alpha(1,4) FT gene(s) involved, correlate with FT activity and oligosaccharide ligand expression, add assess selectin receptor binding. Defining the molecular basis of carbohydrate glycan expression in malignant cell adhesion events may link observations about metastasis and FT regulatory mechanisms.