Hydrogen Sulfide Lowers Proliferation and Induces Protective Autophagy in Colon Epithelial Cells

PLoS One. 2012;7(5):e37572. doi: 10.1371/journal.pone.0037572. Epub 2012 May 29.

Abstract

Hydrogen sulfide (H(2)S) is a gaseous bacterial metabolite that reaches high levels in the large intestine. In the present study, the effect of H(2)S on the proliferation of normal and cancerous colon epithelial cells was investigated. An immortalized colon epithelial cell line (YAMC) and a panel of colon cancer cell lines (HT-29, SW1116, HCT116) were exposed to H(2)S at concentrations similar to those found in the human colon. H(2)S inhibited normal and cancerous colon epithelial cell proliferation as measured by MTT assay. The anti-mitogenic effect of H(2)S was accompanied by G(1)-phase cell cycle arrest and the induction of the cyclin-dependent kinase inhibitor p21(Cip). Moreover, exposure to H(2)S led to features characteristic of autophagy, including increased formation of LC3B(+) autophagic vacuoles and acidic vesicular organelles as determined by immunofluorescence and acridine orange staining, respectively. Abolition of autophagy by RNA interference targeting Vps34 or Atg7 enhanced the anti-proliferative effect of H(2)S. Further mechanistic investigation revealed that H(2)S stimulated the phosphorylation of AMP-activated protein kinase (AMPK) and inhibited the phosphorylation of mammalian target of rapamycin (mTOR) and S6 kinase. Inhibition of AMPK significantly reversed H(2)S-induced autophagy and inhibition of cell proliferation. Collectively, we demonstrate that H(2)S inhibits colon epithelial cell proliferation and induces protective autophagy via the AMPK pathway.

MeSH terms

  • AMP-Activated Protein Kinases / metabolism
  • Animals
  • Autophagy / drug effects*
  • Autophagy-Related Protein 7
  • Cell Cycle / drug effects
  • Cell Line
  • Cell Movement / drug effects
  • Cell Proliferation / drug effects
  • Class III Phosphatidylinositol 3-Kinases / metabolism
  • Colon / metabolism*
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism*
  • Humans
  • Hydrogen Sulfide / pharmacology*
  • Intestinal Mucosa / drug effects
  • Intestinal Mucosa / metabolism
  • Mice
  • Microtubule-Associated Proteins / metabolism
  • Phagosomes / drug effects
  • Phagosomes / metabolism
  • Signal Transduction / drug effects
  • TOR Serine-Threonine Kinases / metabolism
  • Ubiquitin-Activating Enzymes / metabolism

Substances

  • Cyclin-Dependent Kinase Inhibitor p21
  • MAP1LC3B protein, human
  • Microtubule-Associated Proteins
  • TOR Serine-Threonine Kinases
  • Class III Phosphatidylinositol 3-Kinases
  • AMP-Activated Protein Kinases
  • Atg7 protein, human
  • Autophagy-Related Protein 7
  • Ubiquitin-Activating Enzymes
  • Hydrogen Sulfide