title: Up-regulation of plasma membrane-associated ganglioside sialidase (Neu3) in human colon cancer and its involvement in apoptosis suppression.
abstract: Human plasma membrane-associated sialidase (Neu3) is unique in specifically hydrolyzing gangliosides, thought to participate in cell differentiation and transmembrane signaling, thereby playing crucial roles in the regulation of cell surface functions. We have discovered levels of mRNA for this sialidase to be increased in restricted cases of human colon cancer by 3- to 100-fold compared with adjacent nontumor mucosa (n = 32), associated with significant elevation in sialidase activity in tumors (n = 50). In situ hybridization showed the sialidase expression in epithelial elements of adenocarcinomas. In cultured human colon cancer cells, the sialidase level was down-regulated in the process of differentiation and apoptosis induced by sodium butyrate, whereas lysosomal sialidase (Neu1) was up-regulated. Transfection of the sialidase gene into colon cancer cells inhibited apoptosis and was accompanied by increased Bcl-2 and decreased caspase expression. Colon cancer exhibited a marked accumulation of lactosylceramide, a possible sialidase product, and addition of the glycolipid to the culture reduced apoptotic cells during sodium butyrate treatment. These results indicate that high expression of the sialidase in cancer cells leads to protection against programmed cell death, probably modulation of gangliosides. This finding provides a possible sialidase target for diagnosis and therapy of colon cancer.
authors.affiliation: Division of Biochemistry, Research Institute, Department of Surgery, Miyagi Prefectural Cancer Center, Natori, Miyagi 981-1293, Japan.
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Kakugawa
authors.forename: Tadashi
authors.initials: T
authors.lastname: Wada
authors.forename: Kazunori
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yamanami
authors.forename: Kiyoaki
authors.initials: K
authors.lastname: Ouchi
authors.forename: Ikuro
authors.initials: I
authors.lastname: Sato
authors.forename: Taeko
authors.initials: T
authors.lastname: Miyagi
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D003110:Colonic Neoplasms / Q000201:enzymology*; D015536:Down-Regulation; D015870:Gene Expression; D006801:Humans; D008875:Middle Aged; D009439:Neuraminidase / Q000235:genetics*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012333:RNA, Messenger; D014162:Transfection; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
chemical_list: D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; C465436:Neu3 protein, human; D009439:Neuraminidase; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases