The present study was conducted to investigate the effects of dehydrocostuslactone on the cell cycle distribution and apoptosis of human ovarian cancer SK-OV-3 cells and explored the mechanisms underlying these effects. Dehydrocostuslactone significantly inhibited cell proliferation in a dose-dependent manner and produced significant cell cycle arrest at the G2/M interface when applied at its IC50 (10.7 µM) for this system. Under the same conditions, dehydrocostuslactone caused a slight decrease in the expression of the cell cycle regulatory proteins CDK4 and cyclin E, as well as a small increase in the expression of the cyclin-dependent kinase inhibitor p21Cip1. In addition, the dehydrocostuslactone-induced accumulation of cells at the G2/M phase transition interface resulted in a significant decrease in CDK1 together with cyclin A and cyclin B. This cell cycle arrest induced apoptosis, as confirmed by annexin V and DAPI staining. Following exposure to dehydrocostuslactone, there was a marked increase in the expression of the apoptotic protein Bax and the downstream target p53, a tumor suppressor transcription factor protein, causing the release of cytochrome c. Based on our findings, the mechanism by which dehydrocostuslactone causes cell cycle arrest is via CDK1 down-regulation, and its induction of apoptosis appears to be related to the activation of p53 and the release of cytochrome c.

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