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United States Department of Agriculture

Agricultural Research Service


Location: Diet, Genomics and Immunology Laboratory

2012 Annual Report

1a. Objectives (from AD-416):
The overall goal of the project is to elucidate the molecular and cellular mechanisms that respond to selected health promoting food components to reduce the risk of chronic diseases such as cancers and obesity. A secondary aim is to explore the utility of a porcine model to test the effect of health maintenance via diet and identify resulting biomarkers that reflect health status. Objective 1. Elucidate biological activities of health promoting phytochemicals from grape, soy, and cruciferous vegetables against development of breast and prostate cancer. Objective 2. Identify molecular targets and mechanisms of action of health promoting food components in animal or in vitro models of cancer and obesity. Objective 3. Ascertain the effects of specific probiotic strains in appropriate animal models of obesity. Objective 4. Identify plant polyphenols and probiotics that affect adipocyte numbers, size, and fat accumulation, and the regulation of proinflammatory mRNA stability by tristetraprolin. Objective 5. Tie together obesity, inflammation, and cancer mechanistically in appropriate animal or in vitro models.

1b. Approach (from AD-416):
Studies will evaluate if phytoalexins structurally similar to resveratrol exerts similar anti-prostate cancer effects; if soy phytoalexin glyceollins exert anti-prostate cancer effects; if phytochemicals modulate LXR-mediated pathways in prostate epithelial cells and modulate LXR-mediated pathways in macrophage. Other studies will determine if probiotic bacterial strains differ in their protective effects against chronic diseases related to obesity; regulate adipocyte numbers, size, and fat accumulation associated with the anti-inflammatory protein tristetraprolin (TTP); if obesity alters the macrophage phenotype and function in adipose tissue, colon, breast, and prostate following increased localized inflammation; and if broccoli-derived phytochemicals modulate LXR-responsive pathways in vivo. The studies will involve in vitro cell culture approaches confirmed by rodent and pig animal models.

3. Progress Report:
Continued use of in vitro and in vivo models identified biologically active compounds from the diet to test their role in prevention of chronic diseases such as obesity and cancer and to elucidate mechanisms of action. Our mechanistic studies focused on androgen receptor and liver X receptor (LXR)-mediated pathways. Androgen exposure is a risk factor for prostate cancer. The LXR receptor is responsible for cholesterol removal and is important for prevention of cardiovascular disease and prostate cancer. Glyceollins are soy-derived compounds that have been proposed to be candidate cancer preventive compounds. The effect of the glyceollins on prostate cancer is unknown. We found that the glyceollins inhibited the growth of a prostate cancer cell line. This effect of glyceollins appears to be mediated through modulation of an estrogen- but not androgen-mediated pathway and is different from other soy-derived phytochemicals. Similarly, compounds, such as indoles and thiocyanates, found in cruciferous vegetables, such as broccoli, were identified as compounds that exert inhibitory effect on breast cancer and prostate cancer cell growth in vitro. In prostate cancer cells, these compounds appeared to act independently of the LXR pathway by inhibiting an androgen receptor mediated pathway. Given the lack of effect of broccoli-derived compounds on LXR pathways, as a contingency, we examined cranberry and grape seed-based phytochemicals in a pig model. Phytochemicals from these plants have been reported to affect LXR-mediated pathways in vitro and reduce adiposity in rodent high-energy diet feeding study. These effects are currently being evaluated in vivo in a pig high-energy diet feeding study. A pig model was used to study the relationship between diet and juvenile obesity. Excess high-fructose (HFT) combined with a high-fat (HF) diet were found to increase central obesity and body weight gain in pig. These changes in fat mass were accompanied by increased total bacterial counts when compared to pigs fed basal diets. High-fructose diets induced a decrease in Bifidobacterium species and increased total coliforms. Bifidobacterium species are potentially beneficial bacteria while coliforms negatively affect intestinal health. This information provides evidence that excess calories from HFT diets exacerbate certain features of the obesogenic phenotype through increased lipidogenic activity, peripheral fat deposition, and modified intestinal bacterial populations.

4. Accomplishments
1. The anti-cancer effects of a broccoli-derived compound phenethyl isothiocyanate was examined using a mouse model of prostate cancer. The compound was found to indirectly affect tumor growth through inhibition of cell attachment factors and new blood vessel formation. Using high-through-put DNA sequence analysis technology, it was further determined that several markers of inflammation were reduced. Inflammation is an important promoter of tumor cell invasion and metastasis. This information provides mechanistic support for the potential beneficial effects of cruciferous vegetable on prostate cancer development.

2. Obesity characterized by weight gain, fat deposition, and induction of inflammatory responses has been reproduced in young pigs as a large animal model for childhood obesity. A study of the effects of high-fat (HF) and/or high-fructose (HFT) diets on molecular changes in the brain of young pigs revealed that a HF, but not a HFT diet, increased pro-inflammatory cytokine expression in the area involved in memory. This information suggested that dietary contributions of excess calories to brain dysfunction should be examined separately. It also provided an additional target organ for evaluating the negative effects of excessive caloric intake.

Review Publications
Palavalli, M.H., Natarajan, S.S., Wang, T.T., Krishnan, H.B. 2012. Inhibition of soybean seeds in warm water results in the release of copious amounts of Bowman-Birk protease inhibitor, a putative anticarcinogenic agent. Journal of Agricultural and Food Chemistry. 60:3135-3143.

Wang, T.T., Boue, S.M., Krishnan, H.B. 2011. The protective effect of soybean phytochemicals on androgen responsive human prostate cancer cells LNCaP is likely mediated through modulation of hormone/cytokine-dependent pathways. Functional Foods in Health and Disease. 1(11):457-471.

Shea-Donohue, T., Notari, L., Urban Jr, J.F., Zhao, A. 2010. Immune regulation of epithelial cell function: Implications for GI pathologies. International Dairy Journal. 20(4):248-252.

Butler, J.E., Sun, X., Wertz, N., Lager, K.M., Chaloner, L., Urban Jr., J., Francis, D.L., Nara, P.L., Tobin, G.J. 2011. Antibody repertoire development in fetal and neonatal piglets XXI. Usage of most VH genes remains constant during fetal and postnatal development. Molecular Immunology. 49(3):483-494.

Li, R.W., Li, C., Wang, T.T. 2012. Transcriptomic alterations in human prostate cancer cell LNCaP tumor xenograft modulated by dietary phenethyl isothiocyanate. Molecular Carcinogenesis. DOI: 10.1002/mc.21873.

Wu, M., Wu, R., Wang, T.T., Cheng, W. 2011. A role for p53 in selenium-induced senescence. Journal of Agricultural and Food Chemistry. 591:1182-1187.

Last Modified: 2/23/2016
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