title: Muc4 is required for activation of ErbB2 in signet ring carcinoma cell lines.
abstract: Signet-ring cell carcinoma is one of the most malignant tumors, classified histologically as a poorly differentiated adenocarcinoma. The ErbB2/ErbB3 complex is often constitutively activated, which suggests that the ErbB2/ErbB3 signaling pathway may be important for malignancy of this tumor. However, the mechanism underlying this activation has not been understood. Here, we show that ErbB2 and Muc4 bind in signet ring carcinoma cells, which was not seen in highly differentiated adenocarcinoma cell lines. ErbB3 was suggested to be a substrate of ErbB2 because knockdown of ErbB2 resulted in less phosphorylation of ErbB3. Inhibition of expression of Muc4 at the cell surface by the treatment of the cells with benzyl-GalNac, an inhibitor of mucin secretion, blocked phosphorylation of ErbB3, suggesting that activity of ErbB2 depends on the expression of Muc4. These results supply the biochemical backgrounds in recent studies suggesting the contribution of Muc4 in the tumorigenesis.
authors.affiliation: Division of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yokoyama
authors.forename: Bin-Hai
authors.initials: BH
authors.lastname: Shi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kawai
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Konishi
authors.forename: Ryota
authors.initials: R
authors.lastname: Andoh
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tachikawa
authors.forename: Sayoko
authors.initials: S
authors.lastname: Ihara
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Fukui
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics; D018279:Carcinoma, Signet Ring Cell / Q000473:pathology; D002454:Cell Differentiation; D002460:Cell Line; D045744:Cell Line, Tumor; D006801:Humans; D007668:Kidney; D055264:Mucin-4; D009077:Mucins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D012334:RNA, Neoplasm / Q000235:genetics; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D020893:Receptor, ErbB-3 / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection
chemical_list: D055264:Mucin-4; D009077:Mucins; D012334:RNA, Neoplasm; D018719:Erb-b2 Receptor Tyrosine Kinases; D020893:Receptor, ErbB-3; D011994:Recombinant Proteins; C524658:MUC4 protein, human