Lupeol and stigmasterol suppress tumor angiogenesis and inhibit cholangiocarcinoma growth in mice via downregulation of tumor necrosis factor-α

PLoS One. 2017 Dec 12;12(12):e0189628. doi: 10.1371/journal.pone.0189628. eCollection 2017.

Abstract

Lupeol and stigmasterol, major phytosterols in various herbal plants, possess anti-inflammatory activities and have been proposed as candidates for anti-cancer agents, but their molecular mechanisms are still unclear. Here, we investigated the effects of lupeol and stigmasterol on tumor and endothelial cells in vitro and their anti-cancer activities in vivo. Our results demonstrated that lupeol and stigmasterol suppressed cell viability, migration, and morphogenesis of human umbilical vein endothelial cells (HUVECs) but not cholangiocarcinoma (CCA) cells. Expression analyses showed that the treatment of both compounds significantly reduced the transcript level of tumor necrosis factor-α (TNF-α), and Western blot analyses further revealed a decrease in downstream effector levels of VEGFR-2 signaling, including phosphorylated forms of Src, Akt, PCL, and FAK, which were rescued by TNF-α treatment. In vivo, lupeol and stigmasterol disrupted tumor angiogenesis and reduced the growth of CCA tumor xenografts. Immunohistochemical analyses confirmed a decrease in CD31-positive vessel content and macrophage recruitment upon treatment. These findings indicate that lupeol and stigmasterol effectively target tumor endothelial cells and suppress CCA tumor growth by their anti-inflammatory activities and are attractive candidates for anti-cancer treatment of CCA tumors.

MeSH terms

  • Animals
  • Cell Proliferation / drug effects*
  • Cholangiocarcinoma / blood supply
  • Cholangiocarcinoma / pathology*
  • Down-Regulation / drug effects*
  • Human Umbilical Vein Endothelial Cells
  • Humans
  • Mice
  • Mice, Inbred C57BL
  • Neovascularization, Pathologic / prevention & control*
  • Pentacyclic Triterpenes / pharmacology*
  • Signal Transduction
  • Stigmasterol / pharmacology*
  • Tumor Necrosis Factor-alpha / metabolism*
  • Vascular Endothelial Growth Factor A / metabolism

Substances

  • Pentacyclic Triterpenes
  • Tumor Necrosis Factor-alpha
  • Vascular Endothelial Growth Factor A
  • Stigmasterol
  • lupeol

Grants and funding

This work was supported by the Thailand Research Fund, Grant No. TRG5780200 (http://academic.trf.or.th) and Mahidol University (http://www.mahidol.ac.th) to TK. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.