Nagilactone E suppresses TGF-β1-induced epithelial-mesenchymal transition, migration and invasion in non-small cell lung cancer cells

Phytomedicine. 2019 Jan;52:32-39. doi: 10.1016/j.phymed.2018.09.222. Epub 2018 Sep 26.

Abstract

Background: Non-small cell lung cancer (NSCLC) is one of the leading causes of cancer-related death around the world. Epithelial-mesenchymal transition (EMT) has been documented to increase motility and invasiveness of cancer cells, which promotes cancer metastasis.

Purpose: This study aims to investigate the inhibitory effects and mechanisms of the dinorditerpenoids and norditerpenoids isolated from the seeds of Podocarpus nagi against transforming growth factor (TGF)-β1-induced EMT.

Methods: A series of dinorditerpenoids and norditerpenoids were isolated from the seeds of P. nagi. Western blot and quantitative real-time PCR assays were performed to determine the expression levels of relative proteins and mRNA, along with immunofluorescence, Smad-binding element (SBE)-luciferase and chromatin immunoprecipitation (ChIP) assays for the mechanism study. Transwell assays were conducted to determine the effect of the compounds on cell migration and invasion.

Results: Nagilactone E (NLE) showed the superior inhibitory effect against TGF-β1-induced EMT. NLE treatment dramatically inhibited TGF-β1-induced expression of EMT markers in A549 cells. Mechanism study indicated that NLE markedly suppressed TGF-β1-induced Smad2 and Smad3 activation and nuclear translocation. SBE-luciferase and ChIP assays showed that NLE inhibited the combining of Smad3 to SBE in the promoters of the cell signaling factors. NLE co-treatment attenuated TGF-β1-induced up-regulation of the protein and mRNA levels of TGF-β receptor TβRI. Furthermore, NLE inhibited TGF-β1-stimulated cell migration and invasion, as well as up-regulation of the key signaling proteins related with migration and invasion.

Conclusion: NLE inhibited TGF-β/Smad signaling pathway, thereafter suppressed TGF-β1-induced EMT, migration and invasion in NSCLC A549 cells.

Keywords: Epithelial-mesenchymal transition; Nagilactone E; Smad; TGF-β1.

MeSH terms

  • A549 Cells
  • Carcinoma, Non-Small-Cell Lung / pathology*
  • Cell Movement / drug effects
  • Diterpenes / pharmacology*
  • Epithelial-Mesenchymal Transition / drug effects*
  • Ferns / chemistry
  • Humans
  • Lung Neoplasms / pathology*
  • Neoplasm Invasiveness
  • Seeds / chemistry
  • Signal Transduction / drug effects
  • Smad2 Protein / metabolism
  • Smad3 Protein / metabolism
  • Transforming Growth Factor beta1 / pharmacology*

Substances

  • Diterpenes
  • SMAD2 protein, human
  • SMAD3 protein, human
  • Smad2 Protein
  • Smad3 Protein
  • TGFB1 protein, human
  • Transforming Growth Factor beta1
  • nagilactone C