Structural Basis and Selectivity of Tankyrase Inhibition by a Wnt Signaling Inhibitor WIKI4

Abstract

Recently a novel inhibitor of Wnt signaling was discovered. The compound, WIKI4, was found to act through tankyrase inhibition and regulate β-catenin levels in many cancer cell lines and human embryonic stem cells. Here we confirm that WIKI4 is a high potency tankyrase inhibitor and that it selectively inhibits tankyrases over other ARTD enzymes tested. The binding mode of the compound to tankyrase 2 was determined by protein X-ray crystallography to 2.4 Å resolution. The structure revealed a novel binding mode to the adenosine subsite of the donor NAD+ binding groove of the catalytic domain. Our results form a structural basis for further development of potent and selective tankyrase inhibitors based on the WIKI4 scaffold.

Disruption of Wnt/β-Catenin Signaling and Telomeric Shortening Are Inextricable Consequences of Tankyrase Inhibition in Human Cells

“…Whereas PARP inhibitors have been proposed to be useful for sensitizing telomeres for chemical attack using other agents (34,50), our study using selective Tnks inhibitors suggests a singleagent strategy can achieve the same endpoint. Moreover, the ADbinding pocket of Tnks can accommodate diverse pharmacophores, as demonstrated here and by other efforts, thus providing a more versatile starting point than imetelstat with respect to medicinal-chemistry goals (51). Recent advances in genetic testing have also uncovered new patient cohorts associated with long telomeric length that may benefit from a Tnks inhibitor, including those with mutations in the shelterin component POT1 in familial melanoma and chronic lymphocytic leukemia (52)(53)(54), the catalytic subunit of telomerase Tert in familial and sporadic melanoma (55), and single nucleotide polymorphisms or mutations near the promoters for Tert in glioma and urothelial cancers (56,57).…”

The Poly(ADP-ribose) Polymerase Enzyme Tankyrase Antagonizes Activity of the β-Catenin Destruction Complex through ADP-ribosylation of Axin and APC2

“…6, A and B) (34,35), and also performed the complimentary experiment of co-expressing TNKS in Axin or APC2 transfected cells and monitoring ␤cat transcriptional activity (Fig. 6, C and D).…”

Discovery of potent and selective nonplanar tankyrase inhibiting nicotinamide mimics

“…15,27 ARTD1-3 were expressed as full length proteins. 27 For other proteins, the constructs used consisted of catalytic protein fragments: ARTD4…”

“…[27][28][29] All proteins were purified using a similar protocol as described before. 28,30 Cells were lysed with sonication in the presence of protease inhibitors and the proteins were purified using Ni-affinity, TEV-cleavage of the tag and size exclusion chromatography.…”

“…27 In order to keep the conditions comparable the concentration of NAD + was kept low (500 nM) during the screening and the profiling assays. A dose response curve was measured once for the best hit compounds using half-log dilutions.…”