Trichosanthin induced apoptosis in HL-60 cells via mitochondrial and endoplasmic reticulum stress signaling pathways.
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.
Li
Jie
J
Institute 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.
Xia
Xuechun
X
Ke
Yibao
Y
Nie
Huiling
H
Smith
Mark A
MA
Zhu
Xiongwei
X
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D053471:Caspases, Initiator; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D004789:Enzyme Activation / Q000187:drug effects; D018922:HL-60 Cells; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000378:metabolism*; D008954:Models, Biological; D018832:Molecular Chaperones / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D051742:Transcription Factor CHOP / Q000378:metabolism; D015978:Trichosanthin / Q000494:pharmacology*
D000972:Antineoplastic Agents, Phytogenic; C497249:DDIT3 protein, human; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D051742:Transcription Factor CHOP; D015978:Trichosanthin; C093516:CASP4 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D053471:Caspases, Initiator