Relationship between lunasin's sequence and its inhibitory activity of histones H3 and H4 acetylation

Abstract

[Scope]: Dysfunction of histone acetyltransferases (HATs) or histone deacetylases (HDACs) involved in histones acetylation has been associated with cancer. Inhibitors of these enzymes are becoming potential targets for new therapies. [Methods and Results]: This study reports by Western-Blot analysis, that peptide lunasin is mainly an in vitro inhibitor of histone H4 acetylation by P300/cAMP-response element-binding protein (CBP)-associated factor (PCAF), with IC50 values dependent on the lysine position sensitive to be acetylated (0.83 μM (H4-Lys 8), 1.27 μM (H4-Lys 12) and 0.40 μM (H4-Lys 5, 8, 12, 16)). Lunasin is also capable of inhibiting H3 acetylation (IC50 of 5.91 μM (H3-Lys 9) and 7.81 μM (H3-Lys 9, 14)). Studies on structure-activity relationship establish that lunasin's sequence are essential for inhibiting H4 acetylation whereas poly-D sequence is the main active sequence responsible for H3 acetylation inhibition. Lunasin also inhibits H3 and H4 acetylation and cell proliferation (IC50 of 181μM) in breast cancer MDA-MB-231 cells. Moreover, this peptide decreases expression of cyclins and cyclin dependent kinases-4 and -6, implicated in cell cycle pathways. [Conclusion]: Results from this study demonstrates lunasin's role as modulator of histone acetylation and protein expression that might contribute on its chemopreventive properties against breast cancer.