The flavonoid eupatorin inactivates the mitotic checkpoint leading to polyploidy and apoptosis.
The spindle assembly checkpoint (SAC) is a conserved mechanism that ensures the fidelity of chromosome distribution in mitosis by preventing anaphase onset until the correct bipolar microtubule-kinetochore attachments are formed. Errors in SAC function may contribute to tumorigenesis by inducing numerical chromosome anomalies (aneuploidy). On the other hand, total disruption of SAC can lead to massive genomic imbalance followed by cell death, a phenomena that has therapeutic potency. We performed a cell-based high-throughput screen with a compound library of 2000 bioactives for novel SAC inhibitors and discovered a plant-derived phenolic compound eupatorin (3',5-dihydroxy-4',6,7-trimethoxyflavone) as an anti-mitotic flavonoid. The premature override of the microtubule drug-imposed mitotic arrest by eupatorin is dependent on microtubule-kinetochore attachments but not interkinetochore tension. Aurora B kinase activity, which is essential for maintenance of normal SAC signaling, is diminished by eupatorin in cells and in vitro providing a mechanistic explanation for the observed forced mitotic exit. Eupatorin likely has additional targets since eupatorin treatment of pre-mitotic cells causes spindle anomalies triggering a transient M phase delay followed by impaired cytokinesis and polyploidy. Finally, eupatorin potently induces apoptosis in multiple cancer cell lines and suppresses cancer cell proliferation in organotypic 3D cell culture model.
VTT Technical Research Centre of Finland, Medical Biotechnology, P.O. Box 106, Turku, Finland.
Anna-Leena
AL
Salmela
Jeroen
J
Pouwels
Anu
A
Kukkonen-Macchi
Sinikka
S
Waris
Pauliina
P
Toivonen
Kimmo
K
Jaakkola
Jenni
J
Mäki-Jouppila
Lila
L
Kallio
Marko J
MJ
Kallio
D050256:Antimitotic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D064107:Aurora Kinase B; D064127:Aurora Kinases; D018929:Cell Culture Techniques; D049109:Cell Proliferation / Q000187:drug effects; D018385:Centrosome / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology*; D006367:HeLa Cells; D057166:High-Throughput Screening Assays; D006801:Humans; D007976:Leupeptins / Q000494:pharmacology; D059566:M Phase Cell Cycle Checkpoints / Q000187:drug effects*; D008297:Male; D008856:Microscopy, Fluorescence; D015739:Nocodazole / Q000494:pharmacology; D011123:Polyploidy; D011471:Prostatic Neoplasms; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology; D013871:Thiones / Q000494:pharmacology; D059008:Time-Lapse Imaging
D050256:Antimitotic Agents; D005419:Flavonoids; D007976:Leupeptins; D061988:Proteasome Inhibitors; D011743:Pyrimidines; D013871:Thiones; C103110:eupatorin; C400223:monastrol; C576921:AURKB protein, human; D064107:Aurora Kinase B; D064127:Aurora Kinases; C090464:Bub1 spindle checkpoint protein; D017346:Protein Serine-Threonine Kinases; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde; D015739:Nocodazole