The proinflammatory LTB4/BLT1 signal axis confers resistance to TGF-β1-induced growth inhibition by targeting Smad3 linker region.
Leukotriene B4 (LTB4) is a potent pro-inflammatory eicosanoid that is derived from arachidonic acid, and its signaling is known to have a tumor-promoting role in several cancer types. In this study, we investigated whether enhanced LTB4 signaling confers resistance to the cytostatic transforming growth factor-β1 (TGF-β1) response. We found that LTB4 pretreatment or ectopic expression of BLT1, a high affinity LTB4 receptor, fully abrogated TGF-β1-induced cell cycle arrest and expression of p15INK4B and p27KIP1. Mechanism study revealed that LTB4-mediated suppression of TGF-β1-induced Smad3 activation and growth inhibition was due to enhanced phosphorylation of Smad3 linker region (pSmad3L) through activation of BLT1-NAD(P)H oxidase (NOX)-reactive oxygen species (ROS)-epidermal growth factor receptor (EGFR)-phosphatidylinositol 3-kinase (PI3-K)-extracellular signal-activated kinase1/2 (ERK1/2)-linked signaling cascade. Furthermore, the LTB4/BLT1 signaling pathway leading to pSmad3L was constitutively activated in breast cancer cells and was correlated with TGF-β1-resistant growth of the cells in vitro and in vivo. In human breast cancer tissues, the expression level of pSmad3L (Thr179) had a positive correlation with BLT1 expression. Collectively, our data demonstrate for the first time that the induction of pSmad3L through BLT1-NOX-ROS-EGFR-PI3K-ERK1/2 signaling pathway is a key mechanism by which LTB4 blocks the anti-proliferative responses of TGF-β1, providing a novel mechanistic insight into the connection between enhanced inflammatory signal and cancer cell growth.
Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon, Republic of Korea.
Woo-Kwang
WK
Jeon
Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon, Republic of Korea.
Jiyeon
J
Choi
Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon, Republic of Korea.
Seong Ji
SJ
Park
Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon, Republic of Korea.
Eun Ji
EJ
Jo
Department of Statistics, College of Natural Sciences, Kangwon National University, Chuncheon, Republic of Korea.
Young K
YK
Lee
Department of Pediatrics, Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio, USA.
Seunghwan
S
Lim
College of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea.
Jae-Hong
JH
Kim
Department of Pediatrics, Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio, USA.
John J
JJ
Letterio
Center for Advanced Biotechnology and Medicine, Susan Lehman Cullman Laboratory for Cancer Research, Ernest Mario School of Pharmacy, Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.
Fang
F
Liu
CHA Cancer Institute and Department of Biomedical Science, College of Life Science, CHA University, Seongnam City, Republic of Korea.
Seong-Jin
SJ
Kim
Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon, Republic of Korea.
Byung-Chul
BC
Kim
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D050762:Cyclin-Dependent Kinase Inhibitor p15 / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D066246:ErbB Receptors / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D056945:Hep G2 Cells; D006801:Humans; D007975:Leukotriene B4 / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008907:Mink; D019255:NADPH Oxidases / Q000378:metabolism; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism; D010766:Phosphorylation; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism; D018102:Receptors, Leukotriene B4 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; C436291:CDKN1B protein, human; C493966:CDKN2B protein, human; D050762:Cyclin-Dependent Kinase Inhibitor p15; C513240:LTB4R protein, human; D017382:Reactive Oxygen Species; D018102:Receptors, Leukotriene B4; C497790:SMAD3 protein, human; D051900:Smad3 Protein; D053773:Transforming Growth Factor beta1; D050760:Cyclin-Dependent Kinase Inhibitor p27; D007975:Leukotriene B4; D019255:NADPH Oxidases; D058539:Phosphatidylinositol 3-Kinase; C512478:EGFR protein, human; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases
BLT1; LTB4; Smad3 linker region phosphorylation; TGF-β1 resistance; cancer cell growth