title: Cytoplasmic Localization of Proline, Glutamic Acid, Leucine-rich Protein 1 (PELP1) Induces Breast Epithelial Cell Migration through Up-regulation of Inhibitor of κB Kinase ϵ and Inflammatory Cross-talk with Macrophages.
abstract: Cytoplasmic localization of proline, glutamic acid, leucine-rich protein 1 (PELP1) is observed in ∼40% of women with invasive breast cancer. In mouse models, PELP1 overexpression in the mammary gland leads to premalignant lesions and eventually mammary tumors. In preliminary clinical studies, cytoplasmic localization of PELP1 was seen in 36% of women at high risk of developing breast cancer. Here, we investigated whether cytoplasmic PELP1 signaling promotes breast cancer initiation in models of immortalized human mammary epithelial cells (HMECs). Global gene expression analysis was performed on HMEC lines expressing vector control, PELP1-wt, or mutant PELP1 in which the nuclear localization sequence was altered, resulting in cytoplasmic localization of PELP1 (PELP1-cyto). Global gene expression analysis identified that PELP1-cyto expression in HMECs induced NF-κB signaling pathways. Western blotting analysis of PELP1-cyto HMECs showed up-regulation of inhibitor of κB kinase ϵ (IKKϵ) and increased phosphorylation of the NF-κB subunit RelB. To determine whether secreted factors produced by PELP1-cyto HMECs promote macrophage activation, THP-1 macrophages were treated with HMEC-conditioned medium (CM). PELP1-cyto CM induced changes in THP-1 gene expression as compared with control cell CM. Double conditioned medium (DCM) from the activated THP-1 cells was then applied to HMECs to determine whether paracrine signaling from PELP1-cyto-activated macrophages could in turn promote migration of HMECs. PELP1-cyto DCM induced robust HMEC migration, which was reduced in DCM from PELP1-cyto HMECs expressing IKKϵ shRNA. Our findings suggest that cytoplasmic localization of PELP1 up-regulates pro-tumorigenic IKKϵ and secreted inflammatory signals, which through paracrine macrophage activation regulates the migratory phenotype associated with breast cancer initiation.
authors.affiliation: From the Masonic Cancer Center and.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Girard
authors.affiliation: From the Masonic Cancer Center and.
authors.forename: Todd P
authors.initials: TP
authors.lastname: Knutson
authors.affiliation: From the Masonic Cancer Center and.
authors.forename: Bethanie
authors.initials: B
authors.lastname: Kuker
authors.affiliation: From the Masonic Cancer Center and.
authors.forename: Laura
authors.initials: L
authors.lastname: McDowell
authors.affiliation: From the Masonic Cancer Center and.|Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota 55455.
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Schwertfeger
authors.affiliation: From the Masonic Cancer Center and hans1354@umn.edu.|Departments of Medicine and.
authors.forename: Julie H
authors.initials: JH
authors.lastname: Ostrander
mesh_terms: D000818:Animals; D001940:Breast / Q000378:metabolism / Q000473:pathology*; D002465:Cell Movement; D056970:Co-Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051550:I-kappa B Kinase / Q000235:genetics / Q000378:metabolism*; D007249:Inflammation / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008264:Macrophages / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D056970:Co-Repressor Proteins; D016328:NF-kappa B; C438485:PELP1 protein, human; D014157:Transcription Factors; D051550:I-kappa B Kinase
keywords: NF-kB transcription factor; breast cancer; cell migration; cell signaling; inflammation; macrophage