Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P00492 (hypoxanthine-guanine phosphoribosyltransferase)
 2,385 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To test the hypothesis that mitochondrial DNA (mtDNA) is more prone to reactive oxygen species (ROS) damage than nuclear DNA, a continuous flux of hydrogen peroxide (H2O2) was produced with the glucose/glucose oxidase system. Using a horse radish peroxidase (HRPO)-based colorimetric assay to detect H2O2, glucose oxidase (GO; 12 mU/ml) produced 95 microM of H2O2 in 1 h, whereas only 46 microM of hydrogen peroxide accumulated in the presence of SV40-transformed human fibroblasts ( approximately 1 x 10(6). DNA damage was assessed in the mitochondira and three nuclear regions using a quantitative PCR assay. GO (12 mU/ml) resulted in more damage to the mitochondrial DNA (2.250 +/- 0.045 lesions/10 kb) than in any one of three nuclear targets, which included the non-expressed beta-globin locus (0.436 +/- 0.029 lesions/10 kb); and the active DNA polymerase b gene (0.442 +/- 0.037 lesions/10 kb); and the active hprt gene (0.310 +/- 0.025). Damage to the mtDNA occurred within 15 min of GO treatment, whereas nuclear damage did not appear until after 30 min, and reached a maximum after 60 min. Repair of mitochondrial damage after a 15 min GO (6 mU/ml) treatment was examined. Mitochondria repaired 50% of the damage after 1 h, and by 6 h all the damage was repaired. Higher doses of GO-generated H202, or more extended treatment periods, lead to mitochondrial DNA damage which was not repaired. Mitochondrial function was monitored using the MTT (3,(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide) assay. A 15 min treatment with 6 mU/ml of GO decreased mitochondrial activity to 80% of the control; the activity recovered completely within 1 h after damage. These data show that GO-generated H202 causes acute damage to mtDNA and function, and demonstrate that this organelle is an important site for the cellular toxicity of ROS.
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PMID:Preferential mitochondrial DNA injury caused by glucose oxidase as a steady generator of hydrogen peroxide in human fibroblasts. 944 35

During autoxidation of the pentachlorophenol (PCP) metabolite tetrachlorohydroquinone (TCHQ) the semiquinone is formed as well as reactive oxygen species (ROS). It was examined if *OH or the semiquinone are the cause of TCHQ-induced genotoxicity by direct comparison of TCHQ- and H(2)O(2)-induced DNA damage in human cells. All endpoints tested (DNA damage, DNA repair, and mutagenicity) revealed a greater genotoxic potential for TCHQ than for H(2)O(2). In the comet assay, TCHQ induced DNA damage at lower concentrations than H(2)O(2). The damaging rate by TCHQ (tail moment (tm)/concentration) was 10-fold greater than by H(2)O(2). DNA repair was lower for TCHQ than for H(2)O(2) treatment. This was shown by measuring DNA repair in the unscheduled DNA synthesis (UDS) assay and the persistence of the DNA damage in the comet assay. In contrast to H(2)O(2), TCHQ in non-toxic concentrations was mutagenic in the hypoxanthine-guanine phosphoribosyltransferase (HPRT) locus of V79 cells. Finally, there were also differences observed in cytotoxicity (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay) of TCHQ and H(2)O(2). Whereas the TCHQ cytotoxicity was enhanced during a 21h recovery phase, the H(2)O(2) cytotoxicity did not change. The results demonstrated that the pronounced genotoxic properties of TCHQ in human cells were not caused by *OH radicals but more likely by the tetrachlorosemiquinone (TCSQ) radical.
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PMID:Differences in genotoxicity of H(2)O(2) and tetrachlorohydroquinone in human fibroblasts. 1171 1

N3-o-toluyl-fluorouracil (TFu) was a potent water-insoluble prodrug of 5-fuorouracil (5-Fu). To improve the solubility of TFu, TFu loaded nanosuspension (TFu-LNS) was prepared by high-pressure homogenization method. The results of in vitro release studies showed that 5-Fu was sustained released from TFu-LNS. Then in vitro antitumor activity of TFu-LNS in terms of antiproliferative activity, induction of apoptosis and G1 cycle arrest on human breast adenocarcinoma cell line (MCF-7) and human gastric carcinoma cell line (BGC) was evaluated. The results of MTT assay showed that TFu-LNS exhibited higher antiproliferative activity against MCF-7 and BGC cells than TFu DMSO-water solution and 5-Fu solution. The apoptosis induced by TFu-LNS was assessed by Annexin V-FITC/PI double staining and Tunnel assay. And the results of two methods both clearly indicated that the superiority of TFu-LNS to TFu DMSO-water solution and 5-Fu solution in increasing the apoptosis rate of MCF-7 and BGC cells. The results of flow cytometric (FCM) analysis demonstrated that TFu-LNS could induce G1 cycle arrest of MCF-7 and BGC cells. Furthermore, in vivo pharmacokinetics study in Wistar rats indicated that TFu-LNS was capable of increasing the parameters of AUC(0-infinity) and MRT significantly by sustained releasing 5-Fu. Therefore, the overall results suggested that the TFu-LNS could enhance anti-tumor effect and hold great potential to be developed for cancer treatments.
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PMID:The in vitro anti-tumor efficacy and the pharmacokinetics of N3-o-toluyl-fluorouracil loaded nanosuspension (TFu-LNS). 2380 9