Regulation of Wnt Singaling Pathway by Poly (ADP-Ribose) Glycohydrolase (PARG) Silencing Suppresses Lung Cancer in Mice Induced by Benzo(a)pyrene Inhalation Exposure

Benzo(a)pyrene (BaP) is a polycyclic aromatic hydrocarbon that specifically causes cancer and is widely distributed in the environment. Poly (ADP-ribosylation), as a key post-translational modification in BaP-induced carcinogenesis, is mainly catalyzed by poly (ADP-ribose) glycohydrolase (PARG) in eukaryotic organisms. Previously, it is found that PARG silencing can counteract BaP-induced carcinogenesis in vitro, but the mechanism remained unclear. In this study, we further examined this process in vivo by using heterozygous PARG knockout mice (PARG+/−). Wild-type and PARG+/− mice were individually treated with 0 or 10 μg/m3 BaP for 90 or 180 days by dynamic inhalation exposure. Pathological analysis of lung tissues showed that, with extended exposure time, carcinogenesis and injury in the lungs of WT mice was progressively worse; however, the injury was minimal and carcinogenesis was not detected in the lungs of PARG+/− mice. These results indicate that PARG gene silencing protects mice against lung cancer induced by BaP inhalation exposure. Furthermore, as the exposure time was extended, the protein phosphorylation level was down-regulated in WT mice, but up-regulated in PARG+/− mice. The relative expression of Wnt2b and Wnt5b mRNA in WT mice were significantly higher than those in the control group, but there was no significant difference in PARG+/− mice. Meanwhile, the relative expression of Wnt2b and Wnt5b proteins, as assessed by immunohistochemistry and Western blot analysis, was significantly up-regulated by BaP in WT mice; while in PARG+/− mice it was not statistically affected. Our work provides initial evidence that PARG silencing suppresses BaP induced lung cancer and stabilizes the expression of Wnt ligands, PARG gene and Wnt ligands may provide new options for the diagnosis and treatment of lung cancer

Combustion kinetics of the coke on deactivated dehydrogenation catalysts

The coke combustion kinetics on the deactivated catalysts for long chain paraffin dehydrogenation was studied by the thermogravimetry and differential thermogravimetry (TG–DTG) technique. The amount and H/C mole ratio of the coke were determined by the TG and elemental analysis. And the comprehensive coke combustion model and catalytic combustion mechanism were also proposed. The results showed that three types of coke existed, which were located on the metal sites (C1) and the support sites surrounding (C2) and far from Pt (C3), respectively. The reaction order with respect to carbon was 1, 1/3 and 3/4, and to oxygen was 0, 1/2 and 3/4, respectively for the coke C1, C2 and C3. Moreover, the corresponding activation energy was 31, 107 and 127 kJ/mol, respectivel

Hydrogen peroxide modified Mg-Al-O oxides supported Pt-Sn catalysts for paraffin dehydrogenation

In this work, a new method to prepare Mg-Al-O oxide by co-precipitation method with addition of H2O2 was developed. The application of Mg-Al-O as a support of Pt-Sn catalysts for paraffin dehydrogenation was investigated. Characterization results indicated that modification of H2O2 (i) enlarged the pore structure and decreased the density and mechanical strength of the Mg-Al-O oxide and (ii) increased the platinum dispersion, weakened the acidity of the Pt-Sn/Mg-Al-O catalysts. Dehydrogenation of n-dodecane results showed that modification of H2O2 (iii) improved the paraffin conversion and olefin selectivity; (iv) inhibited the coke deposition on the catalyst and (v) extended the catalyst life-time. (C) 2015 Elsevier B.V. All rights reserved