title: Disruption of the Y-box binding protein-1 results in suppression of the epidermal growth factor receptor and HER-2.
abstract: The overexpression of the epidermal growth factor receptor (EGFR) and HER-2 underpin the growth of aggressive breast cancer; still, it is unclear what governs the regulation of these receptors. Our laboratories recently determined that the Y-box binding protein-1 (YB-1), an oncogenic transcription/translation factor, induced breast tumor cell growth in monolayer and in soft agar. Importantly, mutating YB-1 at Ser(102), which resides in the DNA-binding domain, prevented growth induction. We reasoned that the underlying cause for growth attenuation by YB-1(Ser(102)) is through the regulation of EGFR and/or HER-2. The initial link between YB-1 and these receptors was sought by screening primary tumor tissue microarrays. We determined that YB-1 (n = 389 cases) was positively associated with EGFR (P < 0.001, r = 0.213), HER-2 (P = 0.008, r = 0.157), and Ki67 (P < 0.0002, r = 0.219). It was inversely linked to the estrogen receptor (P < 0.001, r = -0.291). Overexpression of YB-1 in a breast cancer cell line increased HER-2 and EGFR. Alternatively, mutation of YB-1 at Ser(102) > Ala(102) prevented the induction of these receptors and rendered the cells less responsive to EGF. The mutant YB-1 protein was also unable to optimally bind to the EGFR and HER-2 promoters based on chromatin immunoprecipitation. Furthermore, knocking down YB-1 with small interfering RNA suppressed the expression of EGFR and HER-2. This was coupled with a decrease in tumor cell growth. In conclusion, YB-1(Ser(102)) is a point of molecular vulnerability for maintaining the expression of EGFR and HER-2. Targeting YB-1 or more specifically YB-1(Ser(102)) are novel approaches to inhibiting the expression of these receptors to ultimately suppress tumor cell growth.
authors.affiliation: Laboratory for Oncogenomic Research, Department of Pediatrics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Joyce
authors.initials: J
authors.lastname: Wu
authors.forename: Cathy
authors.initials: C
authors.lastname: Lee
authors.forename: Daniel
authors.initials: D
authors.lastname: Yokom
authors.forename: Helen
authors.initials: H
authors.lastname: Jiang
authors.forename: Maggie C U
authors.initials: MC
authors.lastname: Cheang
authors.forename: Erika
authors.initials: E
authors.lastname: Yorida
authors.forename: Dmitry
authors.initials: D
authors.lastname: Turbin
authors.forename: Isabelle M
authors.initials: IM
authors.lastname: Berquin
authors.forename: Peter R
authors.initials: PR
authors.lastname: Mertens
authors.forename: Thomas
authors.initials: T
authors.lastname: Iftner
authors.forename: C Blake
authors.initials: CB
authors.lastname: Gilks
authors.forename: Sandra E
authors.initials: SE
authors.lastname: Dunn
mesh_terms: D001943:Breast Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009154:Mutation; D011401:Promoter Regions, Genetic; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D051840:Y-Box-Binding Protein 1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism
chemical_list: D066246:ErbB Receptors; D018719:Erb-b2 Receptor Tyrosine Kinases; D051840:Y-Box-Binding Protein 1