The relationship between oxidation stress and phosphoinositide 3-kinase (PI3K) signaling in pancreatic ␤-cell dysfunction remains unclear. Mercury is a well-known toxic metal that induces oxidative stress. Submicromolar-concentration HgCl 2 or methylmercury triggered reactive oxygen species (ROS) production and decreased insulin secretion in ␤-cell-derived HIT-T15 cells and isolated mouse islets. Mercury increased PI3K activity and its downstream effector Akt phosphorylation. Antioxidant Nacetyl-L-cysteine (NAC) prevented mercury-induced insulin secretion inhibition and Akt phosphorylation but not increased PI3K activity. Inhibition of PI3K/Akt activity with PI3K inhibitor or by expressing the dominant-negative p85 or Akt prevented mercury-induced insulin secretion inhibition but not ROS production. These results indicate that both PI3K and ROS independently regulated Akt signaling-related, mercury-induced insulin secretion inhibition. We next observed that 2-or 4-week oral exposure to low-dose mercury to mice significantly caused the decrease in plasma insulin and displayed the elevation of blood glucose and plasma lipid peroxidation and glucose intolerance. Akt phosphorylation was shown in islets isolated from mercury-exposed mice. NAC effectively antagonized mercury-induced responses. Mercury-induced in vivo effects and increased blood mercury were reversed after mercury exposure was terminated. These results demonstrate that low-dose mercury-induced oxidative stress and PI3K activation cause Akt signaling-related pancreatic ␤-cell dysfunction.

Lung cancers are among the most common cancers in the world, and the search for effective and safe drugs for the chemoprevention and therapy of pulmonary cancer has become important. In this study, bovine lactoferrin (bLF) was used in both in vitro and in vivo approaches to investigate its activity against lung cancer. A human lung cancer cell line, A549, which expresses a high level of vascular endothelial growth factor (VEGF) under hypoxia, was used as an in vitro system for bLF treatment. A strain of transgenic mice carrying the human VEGF-A165 (hVEGF-A165) gene, which induces pulmonary tumors, was used as an in vivo lung cancer therapy model. We found that bLF significantly decreased proliferation of A549 cells by decreasing the expression of VEGF protein in a dose-dependent manner. Furthermore, oral administration of bLF at 300 mg/kg of body weight 3 times a week for 1.5 mo to the transgenic mice overexpressing hVEGF-A165 significantly eliminated expression of hVEGF-A165 and suppressed the formation of tumors. Additionally, treatment with bLF significantly decreased the levels of proinflammatory cytokines, such as tumor necrosis factor-α, and antiinflammatory cytokines, such as IL-4 and IL-10. Levels of IL-6, which is both a proinflammatory and an antiinflammatory cytokine, were also reduced. Treatment with bLF decreased levels of tumor necrosis factor-α, IL-4, IL-6, and IL-10 cytokines, resulting in limited inflammation, which then restricted growth of the lung cancer. Our results revealed that bLF is an inhibitor of angiogenesis and blocks lung cell inflammation; as such, it has considerable potential for therapeutic use in the treatment of lung cancer.

Our results showed that oral administration of pLF-enriched milk to mice led to broad-spectrum antimicrobial activity in the digestive tract and protected the mucosa of the small intestine from injury, implying that pLF can be used as an effective SDD regimen.