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Adenosine-induced caspase-3 activation by tuning Bcl-XL/DIABLO/IAP expression in HuH-7 human hepatoma cells

Dongqin Yang1, Takahiro Yaguchi, Takashi Nakano

  • 1Division of Bioinformation, Department of Physiology, Hyogo College of Medicine, Nishinomiya, Japan.

Cell Biology and Toxicology
|January 12, 2010
PubMed

Insights

Extracellular adenosine disrupts mitochondrial membrane potential in hepatoma cells. Adenosine triggers cell death by activating caspase-3 and caspase-8, bypassing normal apoptotic inhibition pathways.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Pharmacology

Background:

  • Extracellular adenosine influences cellular functions.
  • Adenosine's role in hepatoma cell apoptosis is not fully understood.
  • HuH-7 cells are a Fas-deficient human hepatoma cell line.

Purpose of the Study:

  • To elucidate the mechanism of adenosine-induced apoptosis in HuH-7 cells.
  • To investigate the role of mitochondrial membrane potential and caspases in adenosine-mediated cell death.
  • To identify key proteins and pathways involved in adenosine's apoptotic signaling.

Main Methods:

  • Assessing mitochondrial membrane potential changes.
  • Analyzing mRNA and protein expression of Bcl-X(L), IAP2, and DIABLO.
  • Investigating caspase activation (caspase-3, -7, -8, -9) using specific inhibitors and overexpression techniques.
  • Utilizing dipyridamole, an adenosine transporter inhibitor.

Main Results:

  • Extracellular adenosine disrupted mitochondrial membrane potential in HuH-7 cells.
  • Adenosine downregulated Bcl-X(L) and IAP2 expression while upregulating DIABLO.
  • Adenosine activated caspase-3 and caspase-8, leading to cell death, independent of caspase-9 activation in some instances.
  • Overexpression of Bcl-X(L) or IAP2 inhibited caspase-3 activation.

Conclusions:

  • Intracellular adenosine activates caspase-3 by overcoming IAP inhibition, influenced by decreased IAP2 and increased DIABLO expression.
  • Adenosine-induced apoptosis in HuH-7 cells involves caspase-8 activation and mitochondrial damage.
  • This study provides deeper insight into the adenosine-induced apoptotic pathway in human hepatoma cells.

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