Altered mRNA expression of specific molecular species of fucosyl- and sialyl-transferases in human colorectal cancer tissues

O-glycan recognition and function in mice and human cancers

Protein glycosylation represents a nearly ubiquitous post-translational modification, and altered glycosylation can result in clinically significant pathological consequences. Here we focus on O-glycosylation in tumor cells of mice and humans. O-glycans are those linked to serine and threonine (Ser/Thr) residues via N-acetylgalactosamine (GalNAc), which are oligosaccharides that occur widely in glycoproteins, such as those expressed on the surfaces and in secretions of all cell types. The structure and expression of O-glycans are dependent on the cell type and disease state of the cells. There is a great interest in O-glycosylation of tumor cells, as they typically express many altered types of O-glycans compared with untransformed cells. Such altered expression of glycans, quantitatively and/or qualitatively on different glycoproteins, is used as circulating tumor biomarkers, such as CA19-9 and CA-125. Other tumor-associated carbohydrate antigens (TACAs), such as the Tn antigen and sialyl-Tn antigen (STn), are truncated O-glycans commonly expressed by carcinomas on multiple glycoproteins; they contribute to tumor development and serve as potential biomarkers for tumor presence and stage, both in immunohistochemistry and in serum diagnostics. Here we discuss O-glycosylation in murine and human cells with a focus on colorectal, breast, and pancreatic cancers, centering on the structure, function and recognition of O-glycans. There are enormous opportunities to exploit our knowledge of O-glycosylation in tumor cells to develop new diagnostics and therapeutics.

Construction and identification of human fucosyltransferase 4 eukaryotic fluorenscent expression vector

AIM: To construct and identify the eukaryotic expression vector pEGFP-N1-FUT4 with en-hanced green fluorescent protein (EGFP) gene.

METHODS: The full-length fucosyltransferase 4 (FUT4) cDNA was acquired by reverse transcription-polymerase chain reaction (RT-PCR) and cloned into pEGFP-N1vector. The obtained pEGFP-N1-FUT4 was transiently transfected into cell line A431. Then the expression of FUT4 was observed under fluorescence microscope and examined by semi-quantitative RT-PCR and Western blotting.

RESULTS: The full-length human FUT4 cDNA was obtained and identified correct through sequencing and enzyme digestion. The recombinant plasmid pEGFP-N1-FUT4 was successfully constructed and FUT4 cDNA was correctly inserted into pEGFP-N1-FUT4. The expression of EGFP in A431 cells transfected with pEGFP-N1-FUT4 was observed by fluorescence microscopy. Semi-quantitative RT-PCR and Western blotting showed that FUT4 expression significantly increased after pEGFP-N1-FUT4 transfection in A431 cells in comparison with that in the controls.

CONCLUSION: The prokaryotic expression plasmid pEGFP-N1-FUT4 vector is successfully constructed, which could express FUT4 in A431 cells.