title: Identification of a novel cell death receptor mediating IGFBP-3-induced anti-tumor effects in breast and prostate cancer.
abstract: Insulin-like growth factor-binding protein-3 (IGFBP-3), a major regulator of endocrine actions of IGFs, is a p53-regulated potent apoptotic factor and is significantly suppressed in a variety of cancers. Recent epidemiologic studies suggest that IGFBP-3 contributes to cancer risk protection in a variety of cancers, and a polymorphic variation of IGFBP-3 influences cancer risk, although other studies vary in their conclusions. Some antiproliferative actions of IGFBP-3 have been reported to be independent of IGFs, but the precise biochemical/molecular mechanisms of IGF-independent, antiproliferative actions of IGFBP-3 are largely unknown. Here we report a new cell death receptor, IGFBP-3R, that is a single-span membrane protein and binds specifically to IGFBP-3 but not other IGFBP species. Expression analysis of IGFBP-3 and IGFBP-3R indicates that the IGFBP-3/IGFBP-3R axis is impaired in breast and prostate cancer. We also provide evidence for anti-tumor effect of IGFBP-3R in vivo using prostate and breast cancer xenografts in athymic nude mice. Further in vitro studies demonstrate that IGFBP-3R mediates IGFBP-3-induced caspase-8-dependent apoptosis in various cancer cells. Knockdown of IGFBP-3R attenuated IGFBP-3-induced caspase activities and apoptosis, whereas overexpression of IGFBP-3R enhanced IGFBP-3 biological effects. IGFBP-3R physically interacts and activates caspase-8, and knockdown of caspase-8 expression or activity inhibited IGFBP-3/IGFBP-3R-induced apoptosis. Here, we propose that IGFBP-3R represents a novel cell death receptor and is essential for the IGFBP-3-induced apoptosis and tumor suppression. Thus, the IGFBP-3/IGFBP-3R axis may provide therapeutic and prognostic value for the treatment of cancer.
authors.affiliation: Department of Pathology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia 23298-0662, USA.
authors.forename: Angela R
authors.initials: AR
authors.lastname: Ingermann
authors.forename: Yong-Feng
authors.initials: YF
authors.lastname: Yang
authors.forename: Jinfeng
authors.initials: J
authors.lastname: Han
authors.forename: Aki
authors.initials: A
authors.lastname: Mikami
authors.forename: Amanda E
authors.initials: AE
authors.lastname: Garza
authors.forename: Lathika
authors.initials: L
authors.lastname: Mohanraj
authors.forename: Lingbo
authors.initials: L
authors.lastname: Fan
authors.forename: Michael
authors.initials: M
authors.lastname: Idowu
authors.forename: Joy L
authors.initials: JL
authors.lastname: Ware
authors.forename: Ho-Seong
authors.initials: HS
authors.lastname: Kim
authors.forename: Dae-Yeol
authors.initials: DY
authors.lastname: Lee
authors.forename: Youngman
authors.initials: Y
authors.lastname: Oh
mesh_terms: D000818:Animals; D017209:Apoptosis; D001483:Base Sequence; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D053181:Caspase 8 / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D055785:Gene Knockdown Techniques; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009368:Neoplasm Transplantation; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D014183:Transplantation, Heterologous
chemical_list: C552964:IGFBP-3R protein, human; C515497:IGFBP3 protein, human; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D011956:Receptors, Cell Surface; C505530:CASP8 protein, human; D053181:Caspase 8