title: Critical roles of mucin 1 glycosylation by transactivated polypeptide N-acetylgalactosaminyltransferase 6 in mammary carcinogenesis.
abstract: The structure of O-glycosylated proteins is altered in breast cancer cells, but the mechanisms of such an aberrant modification have been largely unknown. We here report critical roles of a novel druggable target, polypeptide N-acetylgalactosaminyltransferase 6 (GALNT6), which is upregulated in a great majority of breast cancers and encodes a glycosyltransferase responsible for initiating mucin-type O-glycosylation. Knockdown of GALNT6 by small interfering RNA significantly enhanced cell adhesion function and suppressed the growth of breast cancer cells. Western blot and immunostaining analyses indicated that wild-type GALNT6 protein could glycosylate and stabilize an oncoprotein mucin 1 (MUC1), which was upregulated with GALNT6 in breast cancer specimens. Furthermore, knockdown of GALNT6 or MUC1 led to similar morphologic changes of cancer cells accompanied by the increase of cell adhesion molecules beta-catenin and E-cadherin. Our findings implied that overexpression of GALNT6 might contribute to mammary carcinogenesis through aberrant glycosylation and stabilization of MUC1 and that screening of GALNT6 inhibitors would be valuable for the development of novel therapeutic modalities against breast cancer.
authors.affiliation: Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
authors.forename: Jae-Hyun
authors.initials: JH
authors.lastname: Park
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Nishidate
authors.forename: Kyoko
authors.initials: K
authors.lastname: Kijima
authors.forename: Takao
authors.initials: T
authors.lastname: Ohashi
authors.forename: Kaoru
authors.initials: K
authors.lastname: Takegawa
authors.forename: Tomoko
authors.initials: T
authors.lastname: Fujikane
authors.forename: Koichi
authors.initials: K
authors.lastname: Hirata
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Toyomasa
authors.initials: T
authors.lastname: Katagiri
mesh_terms: D001943:Breast Neoplasms / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D020869:Gene Expression Profiling; D006031:Glycosylation; D006367:HeLa Cells; D006801:Humans; D018396:Mucin-1 / Q000378:metabolism*; D017350:N-Acetylgalactosaminyltransferases / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection; D015854:Up-Regulation
chemical_list: C060192:MUC1 protein, human; D018396:Mucin-1; D017350:N-Acetylgalactosaminyltransferases