2'-Epi-2'-O-acetylthevetin B induces apoptosis partly via Ca(2+)-mediated mitochondrial pathway in human hepatocellular carcinoma HepG2 cells

Cell Biol Int. 2009 Sep;33(9):918-25. doi: 10.1016/j.cellbi.2009.06.013. Epub 2009 Jun 12.

Abstract

2'-Epi-2'-O-acetylthevetin B (GHSC-74), a cardiac glycoside, can be isolated from the seeds of Cerbera manghas L. We demonstrated that GHSC-74 reduced the viability of HepG2 cells in a time- and dose-dependent manner, and efficiently induced apoptosis without significantly decreasing the viability of Chang human liver cells and Swiss albino 3T3 fibroblasts, as indicated by annexin-V/PI binding assay and Hoechst 33342 staining. In addition, stimulation of HepG2 cells with GHSC-74 induced a series of intracellular events: (1) loss of mitochondrial membrane potential; (2) sustained elevation of cytosolic [Ca2+]; and (3) downregulation of Bcl-2. BAPTA-AM, a cytosolic Ca2+ chelator, partly suppressed cell death and prevented mitochondrial membrane potential from losing in GHSC-74-treated HepG2 cells. In contrast, EGTA, an extracellular Ca2+ chelator, exhibited a weaker effect as compared to that of BAPTA-AM. Taken together, the Ca(2+)-mediated mitochondrial pathway was found to be involved in GHSC-74-induced HepG2 cell apoptosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • Animals
  • Anticarcinogenic Agents / chemistry
  • Anticarcinogenic Agents / pharmacology*
  • Apocynaceae / chemistry
  • Apoptosis*
  • Calcium / metabolism
  • Cardiac Glycosides / chemistry
  • Cardiac Glycosides / pharmacology*
  • Cell Line, Tumor
  • Chelating Agents / pharmacology
  • Egtazic Acid / analogs & derivatives
  • Egtazic Acid / pharmacology
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacology*
  • Fibroblasts / drug effects
  • Membrane Potential, Mitochondrial / drug effects
  • Membrane Potential, Mitochondrial / physiology
  • Mice
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • Proto-Oncogene Proteins c-bcl-2 / antagonists & inhibitors
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • Signal Transduction / drug effects
  • Signal Transduction / physiology

Substances

  • 2'-epi-2'-O-acetylthevetin B
  • Anticarcinogenic Agents
  • Cardiac Glycosides
  • Chelating Agents
  • Enzyme Inhibitors
  • Proto-Oncogene Proteins c-bcl-2
  • 1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester
  • Egtazic Acid
  • Calcium