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Trifolin acetate-induced cell death in human leukemia cells is dependent on caspase-6 and activates the MAPK pathway

Fernando Torres1, José Quintana, Jesús G Díaz

  • 1Department of Biochemistry, Instituto Canario de Investigación del Cáncer (I.C.I.C.), University of Las Palmas de Gran Canaria, Plaza Dr. Pasteur s/n, 35016, Las Palmas de Gran Canaria, Spain.

Apoptosis : an International Journal on Programmed Cell Death
|April 9, 2008
PubMed

Insights

Trifolin acetate (TA), a flavonoid derivative, triggers apoptosis through intrinsic mitochondrial pathways and mitogen-activated protein kinases (MAPKs). This cell death mechanism is independent of reactive oxygen species (ROS) generation.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Background:

  • Flavonoids are natural compounds with diverse biological activities.
  • Trifolin, a naturally occurring flavonoid, can be chemically modified.
  • Understanding the mechanisms of flavonoid-induced apoptosis is crucial for drug discovery.

Purpose of the Study:

  • To investigate the apoptotic effects of trifolin acetate (TA), a derivative of trifolin.
  • To elucidate the downstream signaling pathways involved in TA-induced apoptosis.
  • To determine the role of mitochondria, MAPKs, and ROS in TA-mediated cell death.

Main Methods:

  • Induction of apoptosis in cells treated with trifolin acetate (TA).
  • Assessment of caspase activation using specific inhibitors (z-VAD-fmk, z-LEHD-fmk, z-DEVD-fmk, z-VEID-fmk).
  • Measurement of mitochondrial membrane potential (ΔΨm) and cytochrome c release.
  • Analysis of mitogen-activated protein kinases (MAPKs) pathway activation (ERK, p38, JNK) using specific inhibitors (U0126, SB203580, SP600125).
  • Evaluation of reactive oxygen species (ROS) production and the effect of antioxidants.

Main Results:

  • Trifolin acetate (TA) induced apoptosis, evidenced by caspase activation (caspase-9, -3, -6) and cytochrome c release from mitochondria without affecting mitochondrial membrane potential.
  • Overexpression of Bcl-2 or Bcl-xL abrogated TA-induced apoptosis, suggesting involvement of the intrinsic pathway.
  • Activation of extracellular signal-regulated kinases (ERK) and p38 MAPK pathways contributed to TA-induced cell death, while c-Jun NH2-terminal kinase (JNK) inhibition enhanced apoptosis.
  • Increased reactive oxygen species (ROS) were observed, but antioxidants did not prevent TA-induced cell death, indicating ROS are not pivotal.

Conclusions:

  • Trifolin acetate (TA) induces apoptosis via an intrinsic mitochondrial pathway.
  • The mitogen-activated protein kinases (MAPK) pathway, particularly ERK and p38, plays a significant role in TA-mediated apoptosis.
  • TA-induced cell death is independent of reactive oxygen species (ROS) generation.

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