Down‐regulation of Gal 3–O‐sulfotransferase‐2 (Gal3ST‐2) Expression in Human Colonic Non‐mucinous Adenocarcinoma

Abstract

Expression levels of sulfomucin in human colonic adenocarcinomas are lower than those in normal colonic mucosa; this should be in part caused by down-regulation of expression of sulfotransferases, but it remains unclear which Gal 3-O-sulfotransferase (Gal3ST) is responsible for the biosynthesis of sulfomucin. In this study, we first examined the substrate specificities of four Gal3STs cloned so far, and found that Galβ β β β1 → → → →3GlcNAcβ β β β1 → → → → 3Galβ β β β1 → → → →4Glc (LNT) can be utilized only byGal3ST-2 as an acceptor substrate. The substrate specificity of Gal3ST-2 is closely similar to those of Gal3ST activities present in human normal mucosa and adenocarcinomas, suggesting that Gal3ST-2 is the dominant Gal3ST in colon and colonic cancer. Secondly, using LNT as a substrate, we comparatively analyzed levels of Gal3ST-2 activities in non-mucinous adenocarcinoma, mucinous adenocarcinomas, and the adjacent normal mucosa. We found that levels of Gal3ST-2 activities in non-mucinous adenocarcinoma are significantly lower than those in the adjacent normal mucosa, while those in mucinous adenocarcinomas are not significantly different from those in the adjacent normal mucosa. Moreover, we showed by a competitive RT-PCR method that expression levels of transcript for Gal3ST-2 in non-mucinous adenocarcinoma are lower than those in normal mucosa. These results suggest that Gal3ST-2 is one of the enzymes responsible for biosynthesis of sulfomucin, and that expression levels of Gal3ST-2 are down-regulated in non-mucinous adenocarcinoma.Key words: Colon cancer -Sulfomucin -Sulfotransferase -Gal3ST -Type 1Sulfomucin is a glycoprotein containing large amounts of O-linked, sulfated glycans. It is well-known that expression levels of sulfomucin in colonic cancer are markedly lower than those in the adjacent normal mucosa. 1, 2)Yamori et al.3) explored a monoclonal antibody, 91.9H, recognizing sulfated glycans in sulfomucin, and Irimura et al. 4) and Matsushita et al. 5) showed that expression levels of the epitope in colonic adenocarcinomas are indeed lower than those in normal mucosa. Thereafter, Loveless et al. 6) showed that the minimum epitope moiety is the SO 3 − →3Galβ1→3(Fucα1→4)GlcNAcβ1→3Galβ1→ structure. These results suggest that the decrease of the epitope in colon cancer is at least partly associated with that of sulfomucin. We previously showed that levels of the enzymatic activities of β1,3-galactosyltransferase, which can synthesize the backbone structure of the 91.9H antigen, are lower in colonic adenocarcinomas than in the adjacent normal mucosa. 7) Thereafter, Salvini et al. 8) showed that expression of β3GalT-V gene is down-regulated in colonic adenocarcinomas, suggesting that β3GalT-V gene is involved in biosynthesis of the 91.9H antigen and its low expression in colonic adenocarcinomas. However, it remains unclear whether or not 3-O-sulfation at the Gal residue is also down-regulated in the course of colonic carcinogenesis. Gal3ST transfers sulfate from PAPS to the C-3 position of Gal residu...

Recognition Mechanism of Galectin-4 for Cholesterol 3-Sulfate

“…The cDNA encoding the catalytic region of human Gal3ST-2 was amplified by PCR using an expression vector as the template, as reported previously (14,15). The oligonucleotide primers were 5Ј-tttgaattcGGGGGCCAGGCT-GAGGG-3Ј (forward primer) and 5Ј-tttgcggccgcAGGAGGC-CTCGTC-3Ј (reverse primer).…”

Selectins and selectin ligands in extravasation of cancer cells and organ selectivity of metastasis

“…In particular, non-malignant normal colon epithelial cells express the blood group A or B determinants as well as the Sd/a and 3 0 sulfated Lewis determinants. Upon neoplastic transformation, the synthesis of these oligosaccharides is impaired at the benefit of an increase synthesis of sialyl Lewis-a/x determinants [41,42]. Apparently, this would result from an indirect substrate competition that is dependent on the metabolic cellular context [15].…”

DNA methylation status of a distinctively different subset of genes is associated with each histologic Lauren classification subtype in early gastric carcinogenesis

“…Little is known about the functional role of GAL3ST2, a member of the galactose-3-O-sulfotransferase protein family, in human types of cancers. However, a recent series of evidence indicates that downregulation of GAL3ST2 expression is observed in colon cancers, and GAL3ST2 has also been implicated in the metastatic potential of breast and laryngeal cancers (23)(24)(25). Considering the mounting evidence on the central role of selectins such as galectin-3 in thyroid, pancreatic, colon and even GCs in relation to several relevant genes, the associative function of Gal:3-O-sulfotransferase in GCs should be emphasized and evaluated in more detail (26)(27)(28)(29).…”