TNF-α enhances TGF-β-induced endothelial-to-mesenchymal transition via TGF-β signal augmentation

Cancer Sci. 2020 Jul;111(7):2385-2399. doi: 10.1111/cas.14455. Epub 2020 Jun 11.


The tumor microenvironment (TME) consists of various components including cancer cells, tumor vessels, cancer-associated fibroblasts (CAFs), and inflammatory cells. These components interact with each other via various cytokines, which often induce tumor progression. Thus, a greater understanding of TME networks is crucial for the development of novel cancer therapies. Many cancer types express high levels of TGF-β, which induces endothelial-to-mesenchymal transition (EndMT), leading to formation of CAFs. Although we previously reported that CAFs derived from EndMT promoted tumor formation, the molecular mechanisms underlying these interactions remain to be elucidated. Furthermore, tumor-infiltrating inflammatory cells secrete various cytokines, including TNF-α. However, the role of TNF-α in TGF-β-induced EndMT has not been fully elucidated. Therefore, this study examined the effect of TNF-α on TGF-β-induced EndMT in human endothelial cells (ECs). Various types of human ECs underwent EndMT in response to TGF-β and TNF-α, which was accompanied by increased and decreased expression of mesenchymal cell and EC markers, respectively. In addition, treatment of ECs with TGF-β and TNF-α exhibited sustained activation of Smad2/3 signals, which was presumably induced by elevated expression of TGF-β type I receptor, TGF-β2, activin A, and integrin αv, suggesting that TNF-α enhanced TGF-β-induced EndMT by augmenting TGF-β family signals. Furthermore, oral squamous cell carcinoma-derived cells underwent epithelial-to-mesenchymal transition (EMT) in response to humoral factors produced by TGF-β and TNF-α-cultured ECs. This EndMT-driven EMT was blocked by inhibiting the action of TGF-βs. Collectively, our findings suggest that TNF-α enhances TGF-β-dependent EndMT, which contributes to tumor progression.

Keywords: TGF-β; TGF-β type I receptor (ALK5); TNF-α; activin; endothelial-to-mesenchymal transition; epithelial-to-mesenchymal transition; integrin αv.

MeSH terms

  • Biomarkers
  • Cancer-Associated Fibroblasts / metabolism
  • Carcinoma, Squamous Cell / genetics
  • Carcinoma, Squamous Cell / metabolism
  • Carcinoma, Squamous Cell / pathology
  • Cell Line
  • Cells, Cultured
  • Endothelial Cells / metabolism
  • Epithelial-Mesenchymal Transition* / drug effects
  • Humans
  • Inflammation Mediators / metabolism
  • Mouth Neoplasms / drug therapy
  • Mouth Neoplasms / genetics
  • Mouth Neoplasms / metabolism
  • Mouth Neoplasms / pathology
  • NF-kappa B / metabolism
  • Receptor, Transforming Growth Factor-beta Type I
  • Signal Transduction* / drug effects
  • Smad2 Protein / metabolism
  • Smad3 Protein / metabolism
  • Transforming Growth Factor beta / metabolism*
  • Transforming Growth Factor beta / pharmacology
  • Tumor Microenvironment / genetics
  • Tumor Necrosis Factor-alpha / metabolism*
  • Tumor Necrosis Factor-alpha / pharmacology


  • Biomarkers
  • Inflammation Mediators
  • NF-kappa B
  • SMAD2 protein, human
  • Smad2 Protein
  • Smad3 Protein
  • Transforming Growth Factor beta
  • Tumor Necrosis Factor-alpha
  • Receptor, Transforming Growth Factor-beta Type I
  • TGFBR1 protein, human