The Wnt/b-catenin pathway is a well-known oncogenic pathway. Its suppression has long been considered as an important challenge in treating cancer patients. Among colon cancer patients in particular, most patients carry an adenomatous polyposis coli (APC) mutation that leads to an aberration of Wnt/b-catenin pathway. To discover the small molecule inhibitors of the Wnt/b-catenin pathway, we conducted highthroughput screening in APC-mutant colon cancer DLD-1 cells using a transcriptional reporter assay, which identified a selective Wnt/b-catenin pathway inhibitor, K-756. K-756 stabilizes Axin and reduces active b-catenin, and inhibits the genes downstream of endogenous Wnt/b-catenin. We subsequently identified that K-756 is a tankyrase (TNKS) inhibitor. TNKS, which belongs to the PARP family, poly-ADP ribosylates Axin and promotes Axin degradation via the proteasome pathway. K-756 binds to the induced pocket of TNKS and inhibits its enzyme activity. Moreover, PARP family enzyme assays showed that K-756 is a selective TNKS inhibitor. K-756 inhibited the cell growth of APC-mutant colorectal cancer COLO 320DM and SW403 cells by inhibiting the Wnt/b-catenin pathway. An in vivo study showed that the oral administration of K-756 inhibited the Wnt/b-catenin pathway in colon cancer xenografts in mice. To further explore the therapeutic potential of K-756, we also evaluated the effects of K-756 in non-small cell lung cancer cells. Although a single treatment of K-756 did not induce antiproliferative activity, when K-756 was combined with an EGFR inhibitor (gefitinib), it showed a strong synergistic effect. Therefore, K-756, a novel selective TNKS inhibitor, could be a leading compound in the development of anticancer agents. Mol Cancer Ther; 15(7); 1525-34. Ó2016 AACR.

BacD is an ATP‐dependent dipeptide ligase responsible for the biosynthesis of L‐alanyl‐L‐anticapsin, a precursor of an antibiotic produced by Bacillus spp. In contrast to the well‐studied and phylogenetically related D‐alanine: D‐alanine ligase (Ddl), BacD synthesizes dipeptides using L‐amino acids as substrates and has a low substrate specificity in vitro. The enzyme is of great interest because of its potential application in industrial protein engineering for the environmentally friendly biological production of useful peptide compounds, such as physiologically active peptides, artificial sweeteners and antibiotics, but the determinants of its substrate specificity and its catalytic mechanism have not yet been established due to a lack of structural information. In this study, we report the crystal structure of BacD in complex with ADP and an intermediate analog, phosphorylated phosphinate L‐alanyl‐L‐phenylalanine, refined to 2.5‐Å resolution. The complex structure reveals that ADP and two magnesium ions bind in a manner similar to that of Ddl. However, the dipeptide orientation is reversed, and, concomitantly, the entrance to the amino acid binding cavity differs in position. Enzymatic characterization of two mutants, Y265F and S185A, demonstrates that these conserved residues are not catalytic residues at least in the reaction where L‐phenylalanine is used as a substrate. On the basis of the biochemical and the structural data, we propose a reaction scheme and a catalytic mechanism for BacD.

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A stereoselective synthesis of (S)-(-)-dolichol-20 ( l a ) was achieved using (Z,Z,Z,Z,Z,Z,Z,Z,€,€)-undecaprenol (ll), the C2,, block (5), and the optically active C25 block (3) as the key building blocks. Dolichols (1)1>2 have been isolated from yeast and various mammalian tissues, and shown to participate as carbohydrate

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