Trichosanthin induced apoptosis in HL-60 cells via mitochondrial and endoplasmic reticulum stress signaling pathways
Jie Li1, Xuechun Xia, Yibao Ke
1Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Science, Graduate School of the Chinese Academy of Sciences, Shanghai 200031, P.R. China.
Abstract:
Trichosanthin (TCS), a traditional Chinese medicine, exerts antitumor activities by inducing apoptosis in many different tumor cell lines. However, the mechanisms remain obscure. The present study focused on various caspase pathways that may be involved in TCS-induced apoptosis in leukemia HL-60 cells. Key caspases in both intrinsic and extrinsic pathways including caspase-8, -9 and -3 were activated upon TCS treatment. Additionally, TCS treatment induced upregulation of BiP and CHOP and also activated caspase-4, which for the first time strongly supported the involvement of endoplasmic reticulum stress pathway in TCS-induced apoptosis. Interestingly, although caspase-8 was activated, Fas/Fas ligand pathway was not involved as evidenced by a lack of induction of Fas or Fas ligand and a lack of inhibitory effect of anti-Fas blocking antibody on TCS-induced apoptosis. Instead, caspase-8 was activated in a caspase-9 and -4 dependent manner. The involvement of mitochondria was demonstrated by the reduction of mitochondrial membrane potential and release of cytochrome c and Smac besides the activation of caspase-9. Further investigation confirmed that caspase-3 was the major executioner caspase downstream to caspase-9, -4 and -8. Taken together, our results suggested that TCS-induced apoptosis in HL-60 cells was mainly mediated by mitochondrial and ER stress signaling pathways via caspase-3.
Insights
Trichosanthin (TCS) induces leukemia cell death by activating caspase-3 through mitochondrial and endoplasmic reticulum stress pathways. This traditional Chinese medicine
Area of Science:
- Molecular Biology
- Cell Biology
- Pharmacology
Background:
- Trichosanthin (TCS), a component of traditional Chinese medicine, exhibits antitumor properties.
- The precise molecular mechanisms underlying TCS-induced apoptosis remain largely unelucidated.
Purpose of the Study:
- To investigate the specific caspase pathways involved in TCS-induced apoptosis in leukemia HL-60 cells.
- To elucidate the roles of the intrinsic, extrinsic, and endoplasmic reticulum stress pathways in TCS's mechanism of action.
Main Methods:
- Assessing the activation of key caspases (caspase-8, -9, -3, -4) following TCS treatment.
- Evaluating the expression of endoplasmic reticulum stress markers (BiP, CHOP).
- Analyzing mitochondrial function, including membrane potential and cytochrome c release.
Main Results:
- TCS treatment activated caspase-8, -9, -3, and -4 in HL-60 cells.
- Upregulation of BiP and CHOP indicated endoplasmic reticulum stress involvement.
- Mitochondrial dysfunction was observed, with reduced membrane potential and cytochrome c release.
- Caspase-8 activation was dependent on caspase-9 and -4, not the Fas/Fas ligand pathway.
- Caspase-3 was identified as the primary executioner caspase.
Conclusions:
- TCS-induced apoptosis in leukemia cells is primarily mediated by the mitochondrial and endoplasmic reticulum stress signaling pathways.
- Caspase-3 acts as the key executioner caspase, activated downstream of caspase-9 and -4.
- These findings provide novel insights into the anticancer mechanisms of Trichosanthin.
Related Concept Videos
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01:17The Extrinsic Apoptotic Pathway