Obesity occurs when a person's calorie intake exceeds the amount of energy burns, which may lead to pathologic growth of adipocytes and the accumulation of fat in the tissues. In this study, the effect and mechanism of pear pomace extracts on 3T3-L1 adipocyte differentiation and apoptosis of mature adipocytes were investigated. The effects of pear pomace extract on cell viability and the anti-adipogenic and proapoptotic effects were investigated via MTT assay, Oil red O staining, western blot analysis and apoptosis assay. 3T3-L1 preadipocytes were stimulated with DMEM containing 10% FBS, 0.5 mM 3-isobutyl-1-methylxanthine (IBMX), 5 µg/ml insulin and 1 µM dexamethasone for differentiation to adipocytes. 3T3-L1 cells were cultured with PBS or water extract of pear pomace. Water extract of pear pomace effectively inhibited lipid accumulations and expressions of PPAR-γ and C/EBPα in 3T3-L1 cells. It also increased expression of p-AMPK and decreased the expression of SREBP-1c and FAS in 3T3-L1 cells. The induction of apoptosis was observed in 3T3-L1 cells treated with pear pomace. These results indicate that pear pomace water extract inhibits adipogenesis and induces apoptosis of adipocytes and thus can be used as a potential therapeutic substance as part of prevention or treatment strategy for obesity.

BACKGROUND/OBJECTIVESThe anti-diabetic activity of pear through inhibition of α-glucosidase has been demonstrated. However, little has been reported about the effect of pear on insulin signaling pathway in obesity. The aims of this study are to establish pear pomace 50% ethanol extract (PPE)-induced improvement of insulin sensitivity and characterize its action mechanism in 3T3-L1 cells and high-fat diet (HFD)-fed C57BL/6 mice.MATERIALS/METHODSLipid accumulation, monocyte chemoattractant protein-1 (MCP-1) secretion and glucose uptake were measure in 3T3-L1 cells. Mice were fed HFD (60% kcal from fat) and orally ingested PPE once daily for 8 weeks and body weight, homeostasis model assessment of insulin resistance (HOMA-IR), and serum lipids were measured. The expression of proteins involved in insulin signaling pathway was evaluated by western blot assay in 3T3-L1 cells and adipose tissue of mice.RESULTSIn 3T3-L1 cells, without affecting cell viability and lipid accumulation, PPE inhibited MCP-1 secretion, improved glucose uptake, and increased protein expression of phosphorylated insulin receptor substrate 1 [p-IRS-1, (Tyr632)], p-Akt, and glucose transporter type 4 (GLUT4). Additionally, in HFD-fed mice, PPE reduced body weight, HOMA-IR, and serum lipids including triglyceride and LDL-cholesterol. Furthermore, in adipose tissue, PPE up-regulated GLUT4 expression and expression ratio of p-IRS-1 (Tyr632)/IRS, whereas, down-regulated p-IRS-1 (Ser307)/IRS.CONCLUSIONSOur results collectively show that PPE improves glucose uptake in 3T3-L1 cells and insulin sensitivity in mice fed a HFD through stimulation of the insulin signaling pathway. Furthermore, PPE-induced improvement of insulin sensitivity was not accompanied with lipid accumulation.

BACKGROUND/OBJECTIVESIn this study, the inhibitory effect of Erythronium japonicum extracts on the metastasis of MDA-MB-231 human breast cancer cell line was determined.MATERIALS/METHODSCells were cultured with DMSO or with 50, 75, 100 or 250 µg/ml of Erythronium japonicum methanol or ethanol extract.RESULTSBoth methanol and ethanol extracts significantly inhibited the growth and induced apoptosis of MDA-MB-231 cells in a dose-dependent manner. Erythronium japonicum extracts inhibited the adhesion of MDA-MB-231 cells. The invasion of breast cancer cells was suppressed by Erythronium japonicum extracts in a dose-dependent manner. The motility and MMP-2 and MMP-9 activities were also inhibited by both methanol and ethanol extracts.CONCLUSIONSOur results collectively indicate that Erythronium japonicum extracts inhibit the growth, adhesion, migration and invasion as well as induce the apoptosis of human breast cancer cells. Clinical application of Erythronium japonicum as a potent chemopreventive agent may be helpful in limiting breast cancer invasion and metastasis.

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