The dietary flavonoid luteolin inhibits Aurora B kinase activity and blocks proliferation of cancer cells.

In human, Aurora B is a chromosomal passenger protein that induces phosphorylation of histone and involves in spindle checkpoint and cytokinesis. Aberrant expression of Aurora B has been shown to correlate with genetic instability and carcinogenesis. In the past, Aurora B has been validated as a drug target by several studies. Here we report that the dietary flavonoid luteolin could inhibit recombinant Aurora B in radiometric activity assay (IC(50)=0.357 μM) and bind to Aurora B with a high affinity (K(D)=5.85 μM) measured by Biacore 3000. Dose-dependent down-regulation of phosphorylation on Ser10 of histone H3 was also observed in cancer cell lines after 24-h treatment, indicating that endogenous Aurora B activity was inhibited by luteolin. Furthermore, we evaluated the effects of luteolin on the survival of a panel of 23 cell lines, and found that luteolin blocked growth of HeLa cells and SW620 cells in an 8-day cell proliferation assay as well as in colony formation assay. Thus, we identified Aurora B as a novel direct target of luteolin, and our results demonstrated that targeting Aurora B by natural products may be a feasible strategy to develop low toxic anticancer agents.