title: Surfactant protein D suppresses lung cancer progression by downregulation of epidermal growth factor signaling.
abstract: Surfactant protein D (SP-D) is a member of the collectin family that has an important role in maintaining pulmonary homeostasis. In this study, we demonstrated that SP-D inhibited the proliferation, migration and invasion of A549 human lung adenocarcinoma cells. We found that SP-D suppressed epidermal growth factor (EGF) signaling in A549 cells, H441 human lung adenocarcinoma cells and human EGF receptor (EGFR) stable expression CHO-K1 cells. A binding study using (125)I-EGF demonstrated that SP-D downregulated the binding of EGF to EGFR. A ligand blot indicated that SP-D bound to EGFR, and a lectin blot suggested that EGFR in A549 cells had both high-mannose type and complex type N-glycans. We purified the recombinant extracellular domain of EGFR (soluble EGFR=soluble EGFR (sEGFR)), and demonstrated that SP-D directly bound to sEGFR in a Ca(2+)-dependent manner. The binding of SP-D to sEGFR was suppressed by EDTA, mannose or N-glycopeptidase F treatment. Mass spectrometric analysis indicated that N-glycans in domain III of EGFR were of a high-mannose type. These data suggest that SP-D reduces EGF binding to EGFR through the interaction between the carbohydrate recognition domain of SP-D and N-glycans of EGFR, and downregulates EGF signaling. Our finding suggests the novel type of regulation system of EGF signaling involving lectin-to-carbohydrate interaction and downregulation of ligand binding.
authors.affiliation: 1] Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo, Japan [2] Department of Respiratory Medicine and Allergology, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Hasegawa
authors.affiliation: Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.affiliation: Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ariki
authors.affiliation: Department of Molecular Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan.
authors.forename: D
authors.initials: D
authors.lastname: Asakawa
authors.affiliation: Department of Molecular Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Tajiri
authors.affiliation: Department of Molecular Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Wada
authors.affiliation: Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, Wako, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Nishitani
authors.affiliation: Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Takamiya
authors.affiliation: 1] Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo, Japan [2] Department of Respiratory Medicine and Allergology, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Saito
authors.affiliation: 1] Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo, Japan [2] Department of Respiratory Medicine and Allergology, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Uehara
authors.affiliation: 1] Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo, Japan [2] Department of Urology, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Hashimoto
authors.affiliation: 1] Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo, Japan [2] Department of Urology, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kurimura
authors.affiliation: Department of Respiratory Medicine and Allergology, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kuroki
mesh_terms: D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D045744:Cell Line, Tumor; D006224:Cricetinae; D003412:Cricetulus; D015536:Down-Regulation; D004815:Epidermal Growth Factor / Q000235:genetics / Q000378:metabolism*; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D037663:Pulmonary Surfactant-Associated Protein D / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D009363:Neoplasm Proteins; D037663:Pulmonary Surfactant-Associated Protein D; D004815:Epidermal Growth Factor; C512478:EGFR protein, human; D066246:ErbB Receptors; D002118:Calcium