XAV-939S1180

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 μM XAV-939 exposure. Treatment of human lymphoblasts with 1.0 μM 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]