Ampelopsin induces apoptosis by regulating multiple c-Myc/S-phase kinase-associated protein 2/F-box and WD repeat-containing protein 7/histone deacetylase 2 pathways in human lung adenocarcinoma cells.

Abstract

Ampelopsin (AMP), a plant flavonoid, has been reported to inhibit cell growth and/or induce apoptosis in various types of tumor. The aim of the present study was to assess the apoptosis-inducing activity of AMP in A549 human lung adenocarcinoma epithelial cells and the associated underlying mechanism. A549 cells were incubated with different concentrations of AMP in culture medium. Cell growth and apoptosis were evaluated by MTT assay and Annexin V/propidium iodide double staining and flow cytometry, respectively. In addition, western blotting and reverse transcription quantitative polymerase chain reaction analysis were used to examine the time-dependent changes in protein expression. Certain changes in apoptotic protein expression were detected following exposure to AMP, including X-linked inhibitor of apoptosis protein release, reduced B-cell lymphoma 2, myeloid cell leukemia 1 and survivin expression levels, increased Bcl-2-associated X protein expression levels and cleaved-poly ADP ribose polymerase expression. The results revealed that AMP was a potent inhibitor of A549 cell proliferation. The c-Myc/S-phase kinase-associated protein 2 (Skp2) and histone deacetylase (HDAC)1/2 pathways were found to exert an important role in AMP-induced A549 cell apoptosis, as increased levels of c-Myc mRNA and reduced levels of c-Myc/Skp2 and HDAC1 and 2 proteins following AMP treatment were observed. The levels of F-box and WD repeat-containing protein 7α (Fbw7α), Fbw7β, Fbw7γ, phosphorylated-(p-)c-Myc (Thr58) and glycogen synthase kinase 3β (GSK3β) proteins involved in c-Myc ubiquitin-dependent degradation were also analyzed. Following exposure to AMP, the expression levels of Fbw7α, Fbw7γ and GSK3β were reduced and p-c-Myc (Thr58) expression levels were increased. The results suggest that AMP exerts an anticancer effect, which is associated with the degradation of c-Myc, Skp2 and HDAC1 and 2. The ability of AMP to induce apoptosis independently of Fbwα and Fbw7γ suggests a possible use in drug-resistant cancer associated with Fbw7 deficiency. Understanding the exact underlying mechanism requires further investigation of the association between c-Myc and Fbw7α/γ reversal, and analysis of whether Thr58 phosphorylation of c-Myc is dependent on GSK3β.

• Authors: Xin-Mei Chen, Xian-Biao Xie, Qing Zhao, Fang Wang, Yang Bai, Jun-Qiang Yin, Hong Jiang, Xiao-Lin Xie, Qiang Jia, Gang Huang
• Journal: Molecular medicine reports (Mol Med Rep) Vol. 11 Issue 1 Pg. 105-12 (Jan 2015) ISSN: 1791-3004 [Electronic] Greece
• PMID: 25333250 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Cell Cycle Proteins
• F-Box Proteins
• F-Box-WD Repeat-Containing Protein 7
• FBXW7 protein, human
• Flavonoids
• Proto-Oncogene Proteins c-myc
• RNA, Messenger
• S-Phase Kinase-Associated Proteins
• ampelopsin
• Adenosine Monophosphate
• Ubiquitin-Protein Ligases
• Histone Deacetylase 2

Topics

• Adenocarcinoma (genetics, metabolism, pathology)
• Adenocarcinoma of Lung
• Adenosine Monophosphate (metabolism, pharmacology)
• Apoptosis (drug effects)
• Cell Cycle Proteins (metabolism)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• F-Box Proteins (metabolism)
• F-Box-WD Repeat-Containing Protein 7
• Flavonoids (pharmacology)
• Gene Expression Regulation, Neoplastic
• Histone Deacetylase 2 (genetics, metabolism)
• Humans
• Lung Neoplasms (genetics, metabolism, pathology)
• Membrane Potential, Mitochondrial (drug effects)
• Proto-Oncogene Proteins c-myc (genetics, metabolism)
• RNA, Messenger (genetics, metabolism)
• S-Phase Kinase-Associated Proteins (genetics, metabolism)
• Signal Transduction (drug effects)
• Ubiquitin-Protein Ligases (metabolism)