International Journal of Molecular Sciences, Vol.15, No.12, 23705-23724, 2014
Lunasin Sensitivity in Non-Small Cell Lung Cancer Cells Is Linked to Suppression of Integrin Signaling and Changes in Histone Acetylation
Lunasin is a plant derived bioactive peptide with both cancer chemopreventive and therapeutic activity. We recently showed lunasin inhibits non-small cell lung cancer (NSCLC) cell proliferation in a cell-line-specific manner. We now compared the effects of lunasin treatment of lunasin-sensitive (H661) and lunasin-insensitive (H1299) NSCLC cells with respect to lunasin uptake, histone acetylation and integrin signaling. Both cell lines exhibited changes in histone acetylation, with H661 cells showing a unique increase in H4K16 acetylation. Proximity ligation assays demonstrated lunasin interacted with integrins containing alpha v, alpha 5, beta 1 and beta 3 subunits to a larger extent in the H661 compared to H1299 cells. Moreover, lunasin specifically disrupted the interaction of beta 1 and beta 3 subunits with the downstream signaling components phosphorylated Focal Adhesion Kinase (pFAK), Kindlin and Intergrin Linked Kinase in H661 cells. Immunoblot analyses demonstrated lunasin treatment of H661 resulted in reduced levels of pFAK, phosphorylated Akt and phosphorylated ERK1/2 whereas no changes were observed in H1299 cells. Silencing of alpha v expression in H661 cells confirmed signaling through integrins containing alpha v is essential for proliferation. Moreover, lunasin was unable to further inhibit proliferation in alpha v-silenced H661 cells. This indicates antagonism of integrin signaling via alpha v-containing integrins is an important component of lunasin's mechanism of action.
Keywords:lunasin;lung cancer;integrin signaling;histone acetylation;cell proliferation;Akt signaling