PCI-24781 induces caspase and reactive oxygen species-dependent apoptosis through NF-kappaB mechanisms and is synergistic with bortezomib in lymphoma cells.

Abstract

PURPOSE:

We investigated the cytotoxicity and mechanisms of cell death of the broad-spectrum histone deacetylase (HDAC) inhibitor PCI-24781, alone and combined with bortezomib in Hodgkin lymphoma and non-Hodgkin lymphoma cell lines and primary lymphoproliferative (CLL/SLL) cells.

EXPERIMENTAL DESIGN:

Apoptosis, mitochondrial membrane potential, cell cycle analysis, and reactive oxygen species (ROS) were measured by flow cytometry, whereas caspase activation was determined by Western blot. Nuclear factor kappaB (NF-kappaB)-related mRNAs were quantified by reverse transcription-PCR, NF-kappaB-related proteins by Western blotting, and NF-kappaB DNA-binding activity by electromobility shift assay. Finally, gene expression profiling was analyzed.

RESULTS:

PCI-24781 induced concentration-dependent apoptosis that was associated with prominent G(0)/G(1) arrest, decreased S-phase, increased p21 protein, and increased ROS in Hodgkin lymphoma and non-Hodgkin lymphoma cell lines. Dose-dependent apoptosis with PCI-24781 was also seen among primary CLL/SLL cells. PCI-24781-induced apoptosis was shown to be ROS- and caspase-dependent. Combined PCI-24781/bortezomib treatment resulted in strong synergistic apoptosis in all non-Hodgkin lymphoma lines (combination indices, 0.19-0.6) and was additive in Hodgkin lymphoma and primary CLL/SLL cells. Further, PCI-24781/bortezomib resulted in increased caspase cleavage, mitochondrial depolarization, and histone acetylation compared with either agent alone. Gene expression profiling showed that PCI-24781 alone significantly down-regulated several antioxidant genes, proteasome components, and NF-kappaB pathway genes, effects that were enhanced further with bortezomib. Reverse transcription-PCR confirmed down-regulation of NF-kappaB1 (p105), c-Myc, and IkappaB-kinase subunits, where NF-kappaB DNA binding activity was decreased.

CONCLUSION:

We show that PCI-24781 results in increased ROS and NF-kappaB inhibition, leading to caspase-dependent apoptosis. We also show that bortezomib is synergistic with PCI-24781. This combination or PCI-24781 alone has potential therapeutic value in lymphoma.

• Authors: Savita Bhalla, Sriram Balasubramanian, Kevin David, Mint Sirisawad, Joseph Buggy, Lauren Mauro, Sheila Prachand, Richard Miller, Leo I Gordon, Andrew M Evens
• Journal: Clinical cancer research : an official journal of the American Association for Cancer Research (Clin Cancer Res) Vol. 15 Issue 10 Pg. 3354-65 (May 15 2009) ISSN: 1078-0432 [Print] United States
• PMID: 19417023 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Antineoplastic Agents
• Benzofurans
• Boronic Acids
• Histone Deacetylase Inhibitors
• Hydroxamic Acids
• NF-kappa B
• Pyrazines
• Reactive Oxygen Species
• Bortezomib
• Caspases
• abexinostat

Topics

• Aged
• Antineoplastic Agents (pharmacology)
• Apoptosis (drug effects, genetics)
• Benzofurans (pharmacology)
• Blotting, Western
• Boronic Acids (pharmacology)
• Bortezomib
• Caspases (metabolism)
• Cell Cycle (drug effects)
• Cell Line, Tumor
• Dose-Response Relationship, Drug
• Drug Synergism
• Female
• Flow Cytometry
• Gene Expression Profiling
• Gene Expression Regulation, Neoplastic (drug effects)
• Histone Deacetylase Inhibitors
• Humans
• Hydroxamic Acids (pharmacology)
• Lymphoma (genetics, metabolism, pathology)
• Lymphoma, Non-Hodgkin (genetics, metabolism, pathology)
• Male
• Membrane Potential, Mitochondrial (drug effects)
• Middle Aged
• NF-kappa B (metabolism)
• Pyrazines (pharmacology)
• Reactive Oxygen Species (metabolism)
• Tumor Cells, Cultured