Down-modulation of Bcl-XL, release of cytochrome c and sequential activation of caspases during honokiol-induced apoptosis in human squamous lung cancer CH27 cells

Biochem Pharmacol. 2002 May 1;63(9):1641-51. doi: 10.1016/s0006-2952(02)00894-8.


Honokiol is a phenolic compound purified from Magnolia officinalis, which induced the apoptotic cell death in several types of human cancer cells. In the present study, the molecular mechanism of honokiol-mediated apoptotic process was examined in human squamous lung cancer CH27 cells. Here, we found that honokiol-induced apoptotic cell death was accompanied by upregulation of Bad and downregulation of Bcl-XL, while honokiol had no effect on the levels of Bcl-2, Bcl-XS, Bag-1, Bax and Bak proteins. Moreover, honokiol treatment caused the release of mitochondrial cytochrome c to cytosol and sequential activation of caspases. Proteolytic activation of caspase-3 and cleavage of PARP, an in vivo substrate for caspase-3, were observed in honokiol-treated CH27 cells. Furthermore, treatment with caspase inhibitors z-DEVD-fmk and z-VAD-fmk markedly blocked honokiol-induced apoptosis. These results demonstrated that modulation of Bcl-XL and Bad proteins, release of mitochondrial cytochrome c and activation of caspase-3, participated in honokiol-triggered apoptotic process in human squamous lung cancer CH27 cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents, Phytogenic / pharmacology*
  • Apoptosis / physiology*
  • Biphenyl Compounds / pharmacology*
  • Caspases / metabolism*
  • Cytochrome c Group / metabolism*
  • Enzyme Activation
  • Humans
  • Lignans*
  • Lung Neoplasms / metabolism*
  • Lung Neoplasms / pathology
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • Proto-Oncogene Proteins c-bcl-2 / physiology
  • Tumor Cells, Cultured
  • bcl-X Protein


  • Antineoplastic Agents, Phytogenic
  • BCL2L1 protein, human
  • Biphenyl Compounds
  • Cytochrome c Group
  • Lignans
  • Proto-Oncogene Proteins c-bcl-2
  • bcl-X Protein
  • honokiol
  • Caspases