Genome-wide transcriptional sequencing identifies novel mutations in metabolic genes in human hepatocellular carcinoma

We report on next-generation transcriptome sequencing results of three human hepatocellular carcinoma tumor/tumor-adjacent pairs. This analysis robustly examined ∼12,000 genes for both expression differences and molecular alterations. We observed 4,513 and 1,182 genes demonstrating 2-fold or greater increase or decrease in expression relative to their normal, respectively. Network analysis of expression data identified the Aurora B signaling, FOXM1 transcription factor network and Wnt signaling pathways pairs being altered in HCC. We validated as differential gene expression findings in a large data set containing of 434 liver normal/tumor sample pairs. In addition to known driver mutations in TP53 and CTNNB1, our mutation analysis identified non-synonymous mutations in genes implicated in metabolic diseases, i.e. diabetes and obesity: IRS1, HMGCS1, ATP8B1, PRMT6 and CLU, suggesting a common molecular etiology for HCC of alternative pathogenic origin.

Induction of D-6-hydroxynicotine oxidase in resting cells of Arthrobacter oxidans

Resting cell suspensions of Arthrobacter oxidans were shown to synthesize the inducible enantiozyme, D-6-hydroxynicotine oxidase, in the presence of D-nicotine or D-6-hydroxynicotine. The corresponding L-enantiomers, as well as gamma-methylaminopropyl-(6-OH-pyridyl-3)-ketone, which is the product of the reaction catalyzed by the enzyme, were ineffective as inducers. L-6-Hydroxynicotine inhibited induction by D-nicotine and D-6-hydroxynicotine while L-nicotine inhibited induction by D-6-hydroxynicotine and had no effect on induction by D-nicotine. Enzyme induction was also found to be inhibited by glucose, 2-deoxy-D-glucose and by several intermediates of the tricarboxylic acid cycle. An absolute requirement for protein synthesis and for oxygen was also demonstrated to be necessary for the reactions involved in the covalent attachment of flavin adenine dinucleotide to pre-existing precursor protein to yield the catalytically active D-6-hydroxynicotine oxidase.

Covalently bound FAD in d-6-hydroxynicotine oxidase. Immunological studies of D- and L-6-hydroxynicotine oxidase: evidence for a D-enzyme precursor

Antersera prepared against both enantiozymes, D- and L-6-hydroxynicotine oxidase, formed precipitins in double diffusion tests with their respective antigens only. A mixture of the two antisera caused spur formation of the two precipitin lines obtained with the pure enzymes. Antiserum to L-apoprotein reacted with native L-enzyme and L-apoprotein but not with the D-sspecific enzyme. D-6-hydroxynicotine oxidase activity was inhibited by the anti-D-antiserum, leaving the L-enzyme fully active, while anti-L-antiserum inhibited the L- but not the D-specific activity. The delayed induction of D-6-hydroxynicotine oxidase as compared to the other activities of the nicotine-degrading sequence and the differential immunochemical behavior of the enantiozymes allowed the search for a D-enzyme precursor. In cells harvested 3 hours after the addition of DL-nicotine, the L-enzyme activity was present, whereas no D-enzyme activity could be detected. However, an extract of these cells did form an immunoprecipitin line with anti-D-antiserum. L-6-Hydroxynicotine oxidase, but no D-6-hydroxynicotine oxidase activity, could also be induced in Arthrobacter oxidans grown in a medium with a high glucose content and DL-nicotine as the sole nitrogen source. An extract of these L-induced cells produced the specific immunoprecipitation with anti-D-antiserum. A pulse-chase experiment with cells grown first on glucose and DL-nicotine in the presence of [14C]leucine and then in an unlabeled medium which induces D-6-hydroxynicotine oxidase activity resulted in a radioactive D-enzyme-immunoprecipitin line. From these experiments it is concluded that a precursor of the active D-enzyme is induced simultaneously with the other nicotine-degrading enzymes.