Jee-Young Yeon

Obesity‐induced metabolic stresses in breast and colon cancer

Epidemiological studies have suggested that excess body weight gain may be a major risk factor for colon and breast cancer. A positive energy balance creates metabolic stresses, including the excess production of reactive oxygen species (ROS), hyperinsulinemia, the elevated adipokine secretion, and increased gut permeability. Obesity is a risk factor for breast cancer in postmenopausal women, and overweight women are more likely to have poor outcomes. The higher circulating concentration of insulin‐like growth factor 1 (IGF‐1) in overweight and obese women is thought to be an important mediator to promote cell proliferation and survival via the activation of phosphatidylinositol 3‐kinase (PI3K)/Akt and mitogen‐activated protein kinase (MAPK)/p38 signaling pathways. In an animal model of colon carcinogenesis, overweight mice fed a high‐fat diet exhibited a greater number of colon tumors than lean animals. The increased abdominal fat was associated with higher concentrations of leptin, insulin, and IGF‐1, which possibly mediate tumor growth. These data suggest that the metabolic burden created by excess adiposity accelerates uncontrolled cell growth and survival, thereby increasing the risk of developing breast and colon cancer.

Dietary Intake and Serum Levels of Iron in Relation to Oxidative Stress in Breast Cancer Patients

Iron may induce oxidative stress via production of reactive oxygen species, facilitating mammary carcinogenesis. This study investigated the role of iron in relation to oxidative stress as a potential risk factor in the development of breast cancer (BC). BC patients (n = 121) and healthy age-matched controls (n = 149) were entered into the study. Iron and antioxidant vitamins intakes were estimated using a quantitative food frequency questionnaire. Thirty one subjects from each group provided blood samples for measurement of serum iron, plasma malondialdehyde (MDA) and ferric reducing ability of plasma (FRAP). Total and non-heme iron intake of BC patients were lower than those of the controls. However, the serum iron level was significantly higher in BC patients. Plasma MDA levels were also significantly higher in BC patients whereas no significant difference in FRAP values were observed between the two groups. Log-transformed serum iron concentration showed no significant correlation with MDA or FRAP. These results suggest that serum iron overload may be a breast cancer risk factor possibly due to increased oxidative stress.

Diets rich in fruits and vegetables suppress blood biomarkers of metabolic stress in overweight women.

OBJECTIVE This study was performed to evaluate the effects of high vegetable-fruit (high-VF) and low vegetable-fruit (low-VF) diet on surrogate biomarkers of adiposity-related metabolic disturbances. METHODS Overweight women (n=22, 19-29 years) participated in the study between July and August, 2007 in Seoul, Korea. The intervention consisted of either high-VF diet (12 servings of VF/day) or low-VF diet (2 servings of VF/day). Plasma concentration of carotenoids and biomarkers of inflammation and oxidative stress were determined before and after each intervention period. RESULTS Study results indicated that body fat content is positively correlated with plasma interleukin (IL)-6, C-reactive protein (CRP), and leptin concentrations at baseline. Oxidative DNA damage and lipopolysaccharide (LPS)-activated production of IL-1β and IL-6 in peripheral blood mononuclear cells (PBMCs) were decreased with high-VF diet while low-VF diet increased those markers. Changes in the concentration of plasma total carotenoid and β-carotene were inversely correlated with change in plasma IL-1β concentration. Differences in IL-β production in LPS-activated PBMCs were inversely correlated with changes in plasma concentration of lutein-zeaxanthin. Also, changes in plasma total carotenoid and lycopene concentration were inversely correlated with the changes in IL-6 production in LPS-activated PBMCs. CONCLUSION Daily intake of vegetables and fruits can modify adiposity-related metabolic disturbances.