title: Ras promotes transforming growth factor-β (TGF-β)-induced epithelial-mesenchymal transition via a leukotriene B4 receptor-2-linked cascade in mammary epithelial cells.
abstract: Inflammation and inflammatory mediators are inextricably linked with epithelial-mesenchymal transition (EMT) through complex pathways in the tumor microenvironment. However, the mechanism by which inflammatory mediators, such as the lipid inflammatory mediators, eicosanoids, contribute to EMT is largely unknown. In the present study we observed that BLT2, leukotriene B4 receptor-2, is markedly up-regulated by oncogenic Ras and promotes EMT in response to transforming growth factor-β (TGF-β) in mammary epithelial cells. Blockade of BLT2 by the BLT2 inhibitor LY255283 or by siRNA reduced EMT induced by Ras in the presence of TGF-β. In addition, stimulation of BLT2 by the addition of a BLT2 ligand, such as leukotriene B4, restored EMT in the presence of TGF-β in human immortalized mammary epithelial MCF-10A cells. We further searched BLT2 downstream components and identified reactive oxygen species and nuclear factor κB as critical components that contribute to EMT. Taken together, these results demonstrate for the first time that a BLT2-linked inflammatory pathway contributes to EMT. This provides valuable insight into the mechanism of EMT in mammary epithelial cells. In addition, considering the implications of EMT with the stemness of cancer cells, our finding may contribute to a better understanding of tumor progression.
authors.affiliation: From the College of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea.
authors.forename: Hyunju
authors.initials: H
authors.lastname: Kim
authors.affiliation: From the College of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea.
authors.forename: Jung-A
authors.initials: JA
authors.lastname: Choi
authors.affiliation: From the College of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea jhongkim@korea.ac.kr.
authors.forename: Jae-Hong
authors.initials: JH
authors.lastname: Kim
mesh_terms: D001943:Breast Neoplasms / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D042361:Mammary Glands, Human / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D018102:Receptors, Leukotriene B4 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013777:Tetrazoles / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: C485878:LTB4R2 protein, human; D016328:NF-kappa B; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D018102:Receptors, Leukotriene B4; D013777:Tetrazoles; D016212:Transforming Growth Factor beta; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases; C402799:NOX1 protein, human; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); C063823:LY 255283
keywords: BLT2; Epithelial-Mesenchymal Transition (EMT); NADPH Oxidase; NF-κB (NF-KB); Ras Protein; Reactive Oxygen Species (ROS); TGF-β