Requirement for ERK activation in acetone extract identified from Bupleurum scorzonerifolium induced A549 tumor cell apoptosis and keratin 8 phosphorylation.

Abstract

We previously demonstrated that the crude acetone extract of Bupleurum scorzonerifolium (AE-BS) 60 microg/ml has anti-proliferation activity and apoptosis effects to A549 human lung cancer cells. They can also cause tumor cell arrest in G2/M phase. To better understand its target protein in A549 cell, two-dimensional electrophoresis and liquid chromatography-tandem mass spectrometry were applied. The modification of keratin 8 was identified. By immunoblot, the expression of phosphorylated keratin 8 at Ser-73 was increased from 2.0 to 3.0-fold after AE-BS treatment 24 to 48 hr respectively as compared with untreated A549 control cells. Furthermore, the A549 cells were pretreated with 50 microM PD98059, a specific inhibitor of the upstream regulator of ERK1/2, or with the p38 kinase inhibitor 20 microM SB203580 or JNK inhibitor 20 microM SP600125 for 30 min, followed by 24 h of incubation with AE-BS, PD98059 can inhibit K8-Ser-73 hyperphosphorylation and prevented cell apoptosis which was induced by AE-BS significantly. By immunoblot, AE-BS also can induce ERK 1/2 phosphorylation. In conclusion, our data indicate that the AE-BS induced tumor apoptosis in A549 cells was related to ERK 1/2 activation. The molecular mechanism of hyperphosphorylation of K8 on Ser-73 was associated with ERK 1/2 activation rather than JNK and p38 kinase. The apoptosis induced by AE-BS may be related to K8 phosphorylation.

• Authors: Yi-Lin Chen, Shinn-Zong Lin, Wen-Liang Chang, Yeung-Leung Cheng, Horng-Jyh Harn
• Journal: Life sciences (Life Sci) Vol. 76 Issue 21 Pg. 2409-20 (Apr 08 2005) ISSN: 0024-3205 [Print] Netherlands
• PMID: 15763073 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anthracenes
• Drugs, Chinese Herbal
• Enzyme Inhibitors
• Flavonoids
• Imidazoles
• KRT8 protein, human
• Keratin-8
• Pyridines
• pyrazolanthrone
• Keratins
• Mitogen-Activated Protein Kinase 1
• Mitogen-Activated Protein Kinase 3
• SB 203580
• 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one

Topics

• Anthracenes (pharmacology)
• Apoptosis (drug effects)
• Bupleurum (chemistry)
• Chromatography, Liquid
• Drugs, Chinese Herbal (pharmacology)
• Electrophoresis, Gel, Two-Dimensional
• Enzyme Inhibitors (pharmacology)
• Flavonoids (pharmacology)
• Flow Cytometry
• Humans
• Imidazoles (pharmacology)
• Immunoblotting
• Keratin-8
• Keratins (metabolism)
• Mass Spectrometry
• Mitogen-Activated Protein Kinase 1 (metabolism)
• Mitogen-Activated Protein Kinase 3 (metabolism)
• Phosphorylation (drug effects)
• Pyridines (pharmacology)
• Tumor Cells, Cultured