Tuberc Respir Dis.  2003 Apr;54(4):403-414.

The Mechanism of Proteasome Inhibitor-Induced Apoptosis in Lung Cancer Cells

Affiliations
  • 1Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea. cgyoo@snu.ac.kr
  • 2Clinical Research Institute, Seoul National University Hospital, Korea.
  • 3Lung Institute, Medical Research Center, Seoul National University, Korea.

Abstract

BACKGROUND: Proteasome inhibitors can promote either cell survival or programmed cell death, depending on both the specific type and proliferative status of the cell. However, it is not well known whether inhibition of proteasome activity is related to apoptosis in lung cancer cells. In addition, the exact mechanisms responsible for apoptosis induced by proteasome inhibition are not well understood. In the present study, we have examined the effect of proteasome inhibition on lung cancer cells and tried to test the mechanisms that may be associated with the apoptosis of these cells.
METHODS
We examined the effect of proteasome inhibition with MG132 or PS-341 on cell survival in A549 and NCI-H157 lung cancer cells using MTT assay, and analyzed the cleavage of PARP by Western blot analysis to find evidence of apoptosis. Next, we evaluated the activation of caspase 3 by Western blot analysis and the activity of JNK by immunocomplex kinase assay. We also examined the changes in anti-apoptotic pathways like ERK and cIAP1 by Western blot analysis after inhibition of proteasome function.
RESULTS
We demonstrated that MG132 reduced cell survival by inducing apoptosis in A549 and NCI-H157 cells. Proteasome inhibition with MG132 or PS-341 was associated with activation of caspase 3 and JNK, reduced expression of activated ERK, and downregulation of cIAP1.
CONCLUSION
Apoptosis induced by proteasome inhibition may be associated with the activation of pro-apoptotic pathways like caspase 3 and JNK and the inactivation of anti-apoptotic pathways in lung cancer cells.

Keyword

Proteasome inhibitor; Apoptosis; Lung cancer

MeSH Terms

Apoptosis*
Blotting, Western
Caspase 3
Cell Death
Cell Survival
Down-Regulation
Lung Neoplasms*
Lung*
Phosphotransferases
Proteasome Endopeptidase Complex*
Proteasome Inhibitors
Bortezomib
Caspase 3
Phosphotransferases
Proteasome Endopeptidase Complex
Proteasome Inhibitors
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