Natural polyphenols antagonize the antimyeloma activity of proteasome inhibitor bortezomib by direct chemical interaction

다국어 초록 (Multilingual Abstract)

Bortezomib is a therapeutic proteasome inhibitor with antimyeloma activity and polyphenols are well known compounds exerting antiproliferative effects against tumors. We attempted cotreatment of myeloma cells with bortezomib and polyphenols, anticipating a synergistic effect. However, the anticancer activity of bortezomib was blocked by the polyphenols. The structural features of the polyphenols correlated strikingly with their antagonistic effect; in particular, the presence or absence of a vicinal diol moiety was the key element for effective blockage of the anticancer function of bortezomib. We infer that the vicinal diols in the polyphenols interact with the boronic acid of bortezomib and convert the active triangular boronic acid of bortezomib to an inactive tetrahedral boronate, which abolishes the antimyeloma activity of bortezomib. We confirmed this hypothesis by 11B NMR spectroscopy and an in vitro assay on myeloma cell lines and primary myeloma cells from patients. Based on these findings, restriction of the intake of natural polyphenols in foods or vitamin supplements during bortezomib treatment in multiple myeloma patients should be considered.

목차 (Table of Contents)

• Contents
• Introduction 1
• Materials and methods 7
• 1. Reagents 9
• 2. Culture of the MM cell lines and primary myeloma cells 9
• 3. MM cell line characterization by fluorescence in situ hybridization (FISH) 10
• 4. MM cell line characterization by p16 methylation-specific PCR and ras sequencing 11
• 5. Cell viability assay 12
• 6. In vitro 20S proteasome activity assay 12
• 7. Isolation of CD138+ plasma cells from MM patients 13
• 8. Immunoblotting Assay 13
• 9. DPPH assay 13
• 10. Intracellular ROS detection 14
• 11. Apoptosis assessment by Annexin-V staining 14
• 12. Analysis of mitochondrial membrane potential (ΔΨm) 14
• 13. Nuclear Magnetic Resonance (NMR) Spectroscopy 15
• Results 16
• 1. Characterization of MM cell lines 16
• 2. Polyphenols inhibited the growth of MM cells and induced apoptosis 19
• 3. Polyphenols blocked antiproliferative effect and proteasome inhibitory function of bortezomib in MM cell lines 22
• 4. Polyphenols blocked bortezomib-induced apoptosis in MM cell lines 25
• 5. The inhibitory effect of polyphenols on bortezomib was also observed in primary myeloma cells from patients 30
• 6. Effect of polyphenols on bortezomib-induced intracellular ROS generation 32
• 7. Polyphenols blocked the activity of bortezomib by direct chemical interaction 36
• 8. In vitro study on the time duration of blocking effect of polyphenol 41
• Discussion 43
• References 47
• Abstract in korean 54