The proinflammatory LTB4/BLT1 signal axis confers resistance to TGF-β1-induced growth inhibition by targeting Smad3 linker region

Woo Kwang Jeon, Jiyeon Choi, Seong Ji Park, Eun Ji Jo, Young K. Lee, Seunghwan Lim, Jae Hong Kim, John J. Letterio, Fang Liu, Seong Jin Kim, Byung Chul Kim

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)41650-41666
Number of pages17
Issue number39
Publication statusPublished - 2015


  • BLT1
  • Cancer cell growth
  • LTB
  • Smad3 linker region phosphorylation
  • TGF-β1 resistance

ASJC Scopus subject areas

  • Oncology


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