Chemopreventive Property of a Soybean Peptide (Lunasin) That Binds to Deacetylated Histones and Inhibits Acetylation
Lunasin is a unique 43-amino acid soybean peptide that contains at its carboxyl end: (a) nine Asp (D) residues; (b) an Arg-Gly-Asp (RGD) cell adhesion motif; and (c) a predicted helix with structural homology to a conserved region of chromatin-binding proteins. We demonstrated previously that transfection of mammalian cells with the lunasin gene arrests mitosis, leading to cell death. Here we show that exogenous application of the lunasin peptide inhibits chemical carcinogen-induced transformation of murine fibroblast cells to cancerous foci. To elucidate its mechanism of action we show that lunasin: (a) internalizes in the cell through the RGD cell adhesion motif; (b) colocalizes with hypoacetylated chromatin; (c) binds preferentially to deacetylated histone H4 in vitro; and (d) inhibits histone H3 and H4 acetylation in vivo in the presence of a histone deacetylase inhibitor. These results suggest a mechanism whereby lunasin selectively induces apoptosis, mostly in cells undergoing transformation, by preventing histone acetylation. In support of this, lunasin selectively induces apoptosis in E1A-transfected cells but not in nontransformed cells. Finally, in the SENCAR mouse skin cancer model, dermal application of lunasin (250 μg/week) reduces skin tumor incidence by ∼70%, decreases tumor yield/mouse, and delays the appearance of tumors by 2 weeks relative to the positive control. These results point to the role of lunasin as a new chemopreventive agent that functions possibly via a chromatin modification mechanism.
Galvez AF et al. Cancer Res October 15, 2001 61; 7473
Lunasin potentiates the effect of oxaliplatin preventing outgrowth of colon cancer metastasis, binds to α(5)β(1) integrin and suppresses FAK/ERK/NF-κB signaling.
The effect of lunasin on colon cancer metastasis was studied using three human colon cancer cell lines in vitro and a liver metastasis model of colon cancer in vivo. Lunasin bound with α(5)β(1) integrin and internalized into the nucleus of KM12L4 human colon cancer cells. Lunasin (10μM) inhibited the activation of focal adhesion kinase (FAK) by 28%, 39% and 60% in RKO, HCT-116 and KM12L4 human colon cancer cells, respectively. Lunasin caused an increase in the expression of the inhibitor of kappa B alpha (IκB-α), a decrease in nuclear p50 NF-κB and a reduction in the migration of cancer cells. Lunasin (4mg/kg bw) inhibited metastasis and potentiated the effect of oxaliplatin by reducing the expression of proliferating cell nuclear antigen. Liver metastatic nodules were reduced from 28 (PBS) to 14 (lunasin, P=0.047) while combination of lunasin and oxaliplatin to 5 (P=0.004). The tumor burden was reduced from 0.13 (PBS) to 0.10 (lunasin, P=0.039) to 0.04 (lunasin+oxaliplatin, P<0.0001). Moreover, lunasin potentiated the effect of oxaliplatin in modifying expression of proteins involved in apoptosis and metastasis including Bax, Bcl-2, IKK-α and p-p65. Lunasin inhibited metastasis of human colon cancer cells by direct binding with α(5)β(1) integrin suppressing FAK/ERK/NF-κB signaling, and potentiated the effect of oxaliplatin in preventing the outgrowth of metastasis.
Dia VP et al. Cancer Lett. 2011 Dec 27;313(2):167-80. Epub 2011 Sep 10.
Lunasin Induces Apoptosis in Breast and Colon Cancer
Soy contains a variety of phytochemicals with demonstrated anticancer activity, including protease inhibitors, phytate, phytosterols, saponins, and isoflavones. Soybeans also contain bioactive proteins that exhibit anticancer activity including lectins and the most recently discovered peptide lunasin. By its involvement in allowing or denying access to genes for transcription, acetylation is pivotal in the process of turning genes on and off. Lunasin has a binding affinity for regions of nucleosomes that are not fully acetylated. The negatively charged amino acids of Lunasin have a natural attraction to positively charged amino acid in histones. During acetylation, the positive charge on histones is neutralized. When this occurs, genes involved in cell proliferation (e.g. oncogenes) are "turned on" or activated, resulting in tumors or cancer. Lunasin can bind to hypo acetylated histones (histones that still have the positive charge) in different regions of chromosomes, blocking or preventing their acetylation. This blocking action helps keep cancer related genes switched “off”.
The chromatin binding affinity of Lunasin is believed to the underlying mechanism responsible for the cancer-preventing property of Lunasin. A series of studies strongly suggests that chromatin modification is linked with tumor suppression pathways. When delivered to the proper target tissue Lunasin may play a role in preventing or "silencing" the expression of genes that lead to tumor formation, intervening primarily at the initiation and promotion-and possibly other stages of carcinogenesis (Lunasin nd).
Lunasin is a unique 43-amino acid soybean peptide that contains at its carboxyl end: (a) nine Asp (D) residues; (b) an Arg-Gly-Asp (RGD) cell adhesion motif; and (c) a predicted helix with structural homology to a conserved region of chromatin-binding proteins. We demonstrated previously that transfection of mammalian cells with the lunasin gene arrests mitosis, leading to cell death (Galvez et alk 2001).
Lunasin, a novel seed peptide, sensitizes human breast cancer MDA-MB-231 cells to aspirin-arrested cell cycle and induced apoptosis
Breast cancer is one of the most common tumors in women of Western countries. The high aggressiveness and therapeutic resistance of estrogen-independent breast tumors have motivated the development of new strategies for prevention and/or treatment. Combinations of two or more chemopreventive agents are currently being used to achieve greater inhibitory effects on breast cancer cells. This study reveals that both aspirin and lunasin inhibit, in a dose-dependent manner, human estrogen-independent breast cancer MDA-MB-231 cell proliferation. These compounds arrest the cell cycle in the S- and G1-phases, respectively, acting synergistically to induce apoptosis. To begin elucidating the mechanism(s) of action of these compounds, different molecular targets involved in cell cycle control, apoptosis and signal transduction have been evaluated by real-time polymerase chain reaction (RT-PCR) array. The cell growth inhibitory effect of a lunasin/aspirin combination is achieved, at least partially, by modulating the expression of genes encoding G1 and S-phase regulatory proteins. Lunasin/aspirin therapy exerts its potent pro-apoptotic effect is at least partially achieved through modulating the extrinsic-apoptosis dependent pathway. Synergistic down-regulatory effects were observed for ERBB2, AKT1, PIK3R1, FOS and JUN signaling genes, whose amplification has been reported as being responsible for breast cancer cell growth and resistance to apoptosis. Therefore, our results suggest that a combination of these two compounds is a promising strategy to prevent/treat breast cancer (Hsieh et al 2010) .
Lunasin induces apoptosis and modifies the expression of genes associated with extracellular matrix and cell adhesion in human metastatic colon cancer cells
Scope: Lunasin is an arginine-glycine-aspartic acid (RGD) cancer preventive peptide. The objective was to evaluate the potential of lunasin to induce apoptosis in human colon cancer cells and their oxaliplatin-resistant (OxR) variants, and its effect on the expression of human extracellular matrix and adhesion genes.
Methods and results: Various human colon cancer cell lines which underwent metastasis were evaluated in vitro using cell flow cytometry and fluorescence microscopy. Lunasin cytotoxicity to different colon cancer cells correlated with the expression of α5b1 integrin, being most potent to KM12L4 cells (IC50 = 13 μM). Lunasin arrested cell cycle at G2/M phase with concomitant increase in the expression of cyclin-dependent kinase inhibitors p21 and p27. Lunasin (5–25 μM) activated the apoptotic mitochondrial pathway as evidenced by changes in the expressions of Bcl-2, Bax, nuclear clusterin, cytochrome c and caspase-3 in KM12L4 and KM12L4-OxR. Lunasin increased the activity of initiator caspase-9 leading to the activation of caspase-3 and also modified the expression of human extracellular matrix and adhesion genes, downregulating integrin α5, SELE, MMP10, integrin β2 and COL6A1 by 5.01-, 6.53-, 7.71-, 8.19- and 10.10-fold, respectively, while upregulating COL12A1 by 11.61-fold.
Conclusion: Lunasin can be used in cases where resistance to chemotherapy developed (Dia et al 2011).
Dia VP, & de Mejia EG. Molecular Nutrition & Food Research. (2011) DOI: 10.1002/mnfr.201000419
Galvez AF, Chen N, Macasieb J, & de Lumen BO. Chemopreventive Property of a Soybean Peptide (Lunasin) That Binds to Deacetylated Histones and Inhibits Acetylation. Cancer Res October 15, 2001 61; 7473-8.
Hsieh C-C, Hernández-Ledesma B, & de Lumen BO. Chemico-Biological Interactions. Volume 186, Issue 2, 30 July 2010, Pp 127-34. doi:10.1016/j.cbi.2010.04.027