Adiponectin, a hormone secreted by adipose tissue, circulates at high concentrations in human plasma. Paradoxically, plasma levels of adiponectin are approximately 50% lower in obese than in lean subjects. An association between low plasma levels of adiponectin and higher risk of developing breast and other cancers was recently reported. Obesity and overweight have also been associated with increased mortality from cancer. To test the hypothesis that adiponectin exerts direct antiproliferative and/or pro-apoptotic effects on cancer cells, we used the MCF7 human breast adenocarcinoma cell line. The proliferation rate of the MCF7 cells was measured using the MTT method, while apoptosis was examined by quantifying the DNA fragmentation using an ELISA assay. In addition, adiponectin receptor 1 (AdipoR1) and AdipoR2 mRNA expression was detected using RT-PCR. Adiponectin diminished the proliferation rate of MCF7 cells; this effect was significant after 48-96 hours of treatment. The presence of receptor expression suggested that the effect of adiponectin on cell proliferation was most likely specific and adiponectin receptor-mediated. Adiponectin induced no apoptosis of MCF7 cells over 48 hours. We conclude that adiponectin inhibits proliferation but causes no apoptosis of MCF7 breast cancer cells. These data suggest that adiponectin may represent a direct hormonal link between obesity and cancer.
Background Childhood obesity represents a major health problem of our century. The benefits of natural products, such as honey, in the management of obesity have gained renewed interest. In this study, we investigated the effect of honey on glucose and insulin concentrations in obese prepubertal girls. Materials and Methods Thirty healthy obese girls aged 10.55 (±SEM:0.34) years with a mean body mass index (BMI) above the 97th centile for age (28.58 ± 1.40 kg/m2, BMI z‐score 2.96) underwent a standard oral glucose tolerance test (OGTT) followed by an oral honey tolerance test (OHTT) 2 weeks later. Both solutions contained 75 g of glucose. Subsequently, subjects were randomized to receive either 15 g of honey or 15 g of marmalade daily, while both groups complied with dietetic instructions. Six months later all subjects were re‐evaluated with an OGTT and an OHTT. Results At the end of the study, all subjects demonstrated a significant reduction in BMI (27.57 ± 1.40, z‐score: 2.54 vs 28.58 ± 1.40 kg/m2, z‐score: 2.96, P < 0.001), however, there were no significant differences in BMI and all parameters tested between the group that received honey and the control group. The areas under the concentration–time curve for glucose and insulin for the entire population were significantly lower following ingestion of honey than glucose solution (P < 0.001) both at the beginning and at the end of study. Conclusions These findings indicate that honey does not have an effect on stimulated plasma glucose and serum insulin concentrations compared with the standard glucose solution in obese prepubertal girls.
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