A polysaccharide from Glycyrrhiza inflata Licorice inhibits proliferation of human oral cancer cells by inducing apoptosis via mitochondrial pathway

Tumour Biol. 2015 Jun;36(6):4825-31. doi: 10.1007/s13277-015-3135-6. Epub 2015 Feb 8.

Abstract

In the present study, we isolated and characterized a water-soluble polysaccharide (GIP1) from the roots of Glycyrrhiza inflata. The goal of this study was to investigate the anti-tumor effect of GIP1 on the human oral cancer SCC-25 cell line and to explore the possible mechanism. Our experimental result showed that GIP1 (50, 100, and 200 μg/mL) specifically decreased cell viability of SCC-25 cells in a concentration-dependent manner via the induction of apoptosis. Furthermore, Western blot analysis showed that exposure of SCC-25 cells to GIP1 led to down-regulation of anti-apoptotic protein Bcl-2 and up-regulation of pro-apoptotic protein Bax, thus causing a loss of mitochondrial membrane potential and the release of cytochrome c to the cytosol. Moreover, we observed activation of the initiator caspaes-9, and the effector caspases-3, but not caspase-8. Concomitantly, GIP1-induced apoptosis can be blocked by caspase-3- or caspase-9-specific inhibitor, but not caspase-8 inhibitor. As well, the cleaved poly (ADP-ribose) polymerase, as a caspae-3 substrate, occurred in SCC-25 cells following GIP1 treatment at three concentrations. Collectively, our results showed that the GIP1 induced apoptosis in SCC-25 cells involving a caspase-dependent mitochondrial signaling pathway.

MeSH terms

  • Apoptosis / drug effects*
  • Cell Line, Tumor
  • Cell Proliferation / drug effects*
  • Cell Survival / drug effects
  • Gene Expression Regulation, Neoplastic / drug effects
  • Glycyrrhiza / chemistry
  • Humans
  • Membrane Potential, Mitochondrial / drug effects
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • Mouth Neoplasms / drug therapy*
  • Polysaccharides / administration & dosage*
  • Polysaccharides / chemistry
  • Proto-Oncogene Proteins c-bcl-2 / biosynthesis
  • Signal Transduction / drug effects
  • bcl-2-Associated X Protein / biosynthesis

Substances

  • Polysaccharides
  • Proto-Oncogene Proteins c-bcl-2
  • bcl-2-Associated X Protein