Fucoidan induces cancer cell apoptosis by modulating the endoplasmic reticulum stress cascades

PLoS One. 2014 Sep 18;9(9):e108157. doi: 10.1371/journal.pone.0108157. eCollection 2014.

Abstract

Background: Cancer metastasis is the main cause leading to disease recurrence and high mortality in cancer patients. Therefore, inhibiting metastasis process or killing metastatic cancer cells by inducing apoptosis is of clinical importance in improving cancer patient survival. Previous studies revealed that fucoidan, a fucose-rich polysaccharide isolated from marine brown alga, is a promising natural product with significant anti-cancer activity. However, little is known about the role of endoplasmic reticulum (ER) stress in fucoidan-induced cell apoptosis.

Principal findings: We reported that fucoidan treatment inhibits cell growth and induces apoptosis in cancer cells. Fucoidan treatments resulted in down-regulation of the glucose regulated protein 78 (GRP78) in the metastatic MDA-MB-231 breast cancer cells, and of the ER protein 29 (ERp29) in the metastatic HCT116 colon cancer cells. However, fucoidan treatment promoted ER Ca2+-dependent calmodulin-dependent kinase II (CaMKII) phosphorylation, Bcl-associated X protein (Bax) and caspase 12 expression in MDA-MB-231 cells, but not in HCT116 cells. In both types of cancer cells, fucoidan activated the phosphorylation of eukaryotic initiation factor 2 alpha (p-eIF2α)\CCAAT/enhancer binding protein homologous protein (CHOP) pro-apoptotic cascade and inhibited the phosphorylation of inositol-requiring kinase 1 (p-IRE-1)\X-box binding proteins 1 splicing (XBP-1s) pro-survival cascade. Furthermore, CHOP knockdown prevented DNA damage and cell death induced by fucoidan.

Conclusion/significance: Fucoidan exerts its anti-tumor function by modulating ER stress cascades. Contribution of ER stress to the fucoidan-induced cell apoptosis augments our understanding of the molecular mechanisms underlying its anti-tumour activity and provides evidence for the therapeutic application of fucoidan in cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Apoptosis / drug effects*
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2 / metabolism
  • Caspase 12 / metabolism
  • Cell Proliferation
  • Cell Survival / drug effects
  • DNA Damage
  • Drug Screening Assays, Antitumor
  • Endoplasmic Reticulum Stress*
  • Endoribonucleases / metabolism
  • HCT116 Cells
  • Heat-Shock Proteins / metabolism
  • Humans
  • Phosphorylation
  • Polysaccharides / pharmacology*
  • Protein Processing, Post-Translational / drug effects
  • Protein-Serine-Threonine Kinases / metabolism
  • Signal Transduction
  • Transcription Factor CHOP / metabolism
  • bcl-2-Associated X Protein / metabolism

Substances

  • Antineoplastic Agents
  • BAX protein, human
  • DDIT3 protein, human
  • ERP29 protein, human
  • Heat-Shock Proteins
  • Polysaccharides
  • bcl-2-Associated X Protein
  • Transcription Factor CHOP
  • fucoidan
  • ERN1 protein, human
  • Protein-Serine-Threonine Kinases
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Endoribonucleases
  • CASP12 protein, human
  • Caspase 12
  • molecular chaperone GRP78

Grant support

This work was supported by the National Natural Science Foundation of China (81370524). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.