XAV-939

312, 31

1.0 uM

XAV-939 specifically inhibits tankyrase PARP activity. XAV-939 dramatically decreases DNA-PKcs protein levels, confirming the critical role of tankyrase poly-ADP-ribosylation activity in maintaining stability of the DNA-PKcs protein. The greatest reduction of DNA-PKcs protein levels (< 25% relative expression compared to DMSO treated controls) occurs at 12 hours with 1.0 uM XAV-939 exposure. Treatment of human lymphoblasts with 1.0 uM XAV-939 results in marked elevation of tankyrase 1 levels. [1] XAV-939 is axin stabilizing agent. XAV-939 stimulates beta-catenin degradation by stabilizing axin, the concentration-limiting component of the destruction complex. XAV-939 stabilizes axin by blocking the poly-ADP-ribosylating enzymes tankyrase 1 and tankyrase 2. Both tankyrase isoforms interact with a highly conserved domain of axin and stimulate its degradation through the ubiquitin-proteasome pathway. XAV-939 deregulates the Wnt/b-catenin pathway which has been implicated in many cancers. [2]

XAV-939 is solubilized in DMSO at 55 C to make a 10 mM stock solution which may be diluted later to a working concentration of 100 uM. WTK1 lymphoblasts treated with either DMSO or 1.0 uM XAV-939 for 8 hours are loaded into independent wells of a 4-20% gradient SDS-PAGE every 2 hours over the course of 6 hours. At each time point, DMSO and XAV-939 samples are loaded into wells immediately adjacent to the prior time point. The corresponding load times at 0, 2 and 4 hours results in total run times of 2, 4 and 6 hours respectively. The gel is analyzed via western blot for DNA-PKcs following completion of the final run time and is quantified after normalization to actin loading controls.

XAV-939 (NVP-XAV939) selectively inhibits Wnt/β-catenin-mediated transcription through tankyrase1/2 inhibition with IC50 of 11 nM/4 nM in cell-free assays, regulates axin levels and does not affect CRE, NF-κB or TGF-β.