In the present study we demonstrated that the flavonoid derivative trifolin acetate (TA), obtained by acetylation of naturally occurring trifolin, induces apoptosis. Associated downstream signaling events were also investigated. TA-induced cell death was prevented by the non-specific caspase inhibitor z-VAD-fmk and reduced by the presence of the selective caspase inhibitors z-LEHD-fmk (caspase-9), z-DEVD-fmk (caspase-3) and z-VEID-fmk (caspase-6). The apoptotic effect of TA was associated with (i) the release of cytochrome c from mitochondria which was not accompanied by dissipation of the mitochondrial membrane potential (ΔΨ m), (ii) the activation of the mitogen-activated protein kinases (MAPKs) pathway and (iii) abrogated by the over-expression of Bcl-2 or Bcl-x L. TA-induced cell death was attenuated by inhibition of extracellular signal-regulated kinases (ERK) 1/2 with U0126 and inhibition of p38 MAPK with SB203580. In contrast, inhibition of c-Jun NH 2-terminal kinase (JNK) by SP600125 significantly enhanced apoptosis. Although reactive oxygen species (ROS) increased in response to TA, this did not seem to play a pivotal role in the apoptotic process since different anti-oxidants were unable to provide cell protection. The present study demonstrates that TA-induced cell death is mediated by an intrinsic-dependent apoptotic event involving mitochondria and MAPK, and through a mechanism independent of ROS generation.
- Extracellular signal-regulated kinases
- Mitogen-activated protein kinase
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology