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The Legume Inflammation Feeding Experiment is, to our knowledge, the first randomized crossover feeding trial testing the effects of a legume-enriched, low-glycemic index (GI) diet among men characterized for colorectal adenomas and insulin resistance (IR) status. This study was designed to test the effects of a legume-enriched diet compared with a healthy American (HA) diet under weight-stable conditions. The primary objective was to assess effects on C-reactive protein (CRP) and C-peptide levels. The secondary objective was to assess changes by IR status or history of adenomas. A total of 64 men who completed a colonoscopy within the previous 2 y consumed 2 diets in random order each for 4 wk separated by a washout period. The diets were a legume-enriched (250 g/d), low-GI (GI 38) diet and a high-GI (GI 69) HA diet. We measured fasting glucose, insulin, C-peptide, CRP, and soluble tumor necrosis factor-alpha receptors I and II (sTNFRI/II) at the beginning and end of the diet periods. Participants who consumed both the legume and HA diets had favorably improved CRP (-20.2 and -18.3%) and sTNFRI (-3.7 and -4.4%) concentrations, respectively. The sTNFRII concentrations declined marginally during the legume diet period (-3.8%; P = 0.060) and significantly during the HA diet period (-5.1%; P < 0.001). Fasting glucose increased significantly during both the legume (+1.8%) and HA (-2.2%) diet periods. Only the changes in glucose differed between the diet periods. Serum C-peptide and plasma insulin levels did not change in participants consuming either diet. Healthful dietary changes can improve biomarkers of IR and inflammation. [ABSTRACT FROM AUTHOR]

The present study was undertaken to test the hypothesis that the toxicity and carcinogenicity of vanadium might arise from elevation of reactive oxygen species leading to activation of the transcription factor activator protein-1 (AP-1). The AP-1 transactivation response has been implicated as causal in transformation responses to phorbol esters and growth factors. To investigate the possible activity of vanadium in the activation of AP-1, we treated mouse epidermal Jb6 P+ cells stably transfected with an AP-1 luciferase reporter plasmid with various concentrations of vanadate. This resulted in concentration-dependent transactivation of AP-1. Superoxide dismutase (SOD) and catalase inhibited AP-1 activation induced by vanadate, indicating the involvement of superoxide anion radical (O2-·),hydroxyl radical (·OH) and/or H2O2 in the mechanism of vanadate-induced AP-1 activation. However, sodium formate, a specific ·OH scavenger, did not alter vanadate-induced AP-1 activation, suggesting a minimal role for the ·OH radical. NADPH enhanced AP-1 activation by increasing vanadate-mediated generation of O2-·. N-acetylcysteine, a thiol-containing antioxidant, decreased activation, further showing that vanadate-induced AP-1 activation involved redox reactions. Calphostin C, a specific inhibitor of protein kinase C (PKC), inhibited activation of AP-1, demonstrating that PKC is involved in the cell signal cascades leading to vanadate-induced AP-1 activation. Electron spin resonance (ESR) measurements show that Hb6 P+ cells are able to reduce vanadate to generate vanadium(IV) in the presence of NADPH. Molecular oxygen was consumed during the vanadate reduction process to generate O2-· as measured by ESR spin trapping using 5,5-dimethyl-L-pyrroline N-oxide as the spin trapping agent. SOD inhibited the ESR spin adduct signal, further demonstrating the generation of O2-· in the cellular reduction of vanadate. These results provide support for a model in which vanadium, like other classes of tumor promoters, transactivates AP-1-dependent gene expression. In the case of vanadium, AP-1 transactivation is dependent on the generation of O2-· and H2O2, but not ·OH. [ABSTRACT FROM PUBLISHER]

We have reported the tumor suppressive effects of manganese-containing superoxide dismutase (MnSOD) in human breast cancer cells. In order to understand the molecular mechanism of this anti-tumor effect, we asked whether tumor suppressor gene(s), especially the ones inhibiting tumor invasion and motility, are involved in MnSOD-induced tumor suppression. Maspin is one of the serpin family of protease inhibitors that has been shown to function as a tumor-suppressor in human breast epithelium. In the present study, we demonstrated that maspin expression was up-regulated in human breast cancer MCF-7 cells that overexpress a normal MnSOD gene. The induced maspin transcripts were detected by RT-PCR and Northern blot and identified by sequencing. Maspin gene expression was induced in parallel with the level of exogenous MnSOD protein, which was induced by transfection with varied amounts of cDNA. In order to analyze cell invasion ability, which may be related to the induced maspin gene expression. MnSOD stable transfectants were tested using a matrigel invasion chamber. The invasion ability was reduced to 24% and 36% in the cloned (MCF + SOD) and pooled MnSOD-transfectants (MCF + SODp) respectively, compared with the wild-type MCF-7 cell line. In conclusion, these results suggest that overexpression of a normal MnSOD cDNA in human breast cancer cells up-regulates the gene expression of the protease inhibitor, maspin, which may play a role in the inhibitory function of MnSOD on tumor invasion. [ABSTRACT FROM PUBLISHER]