IDENTIFICATION OF NOVEL CHEMOTYPES TARGETING β‐CATENIN IN HEPATOCELLULAR CARCINOMA

Hepatocellular carcinoma (HCC) is the 3 rd leading cause of death by cancer worldwide. Aberrant β‐catenin activation is implicated in 30% of HCC making it an attractive therapeutic target. Very few chemical inhibitors of Wnt pathway currently exist even in the preclinical arena. Here we report identification of 2 novel small molecules that effectively target β‐catenin. Using morphological similarity search applied to an existing small molecule that inhibits β‐catenin interaction to a histone acetyltransferase, and a cut‐off of 0.7, we identified 24 compounds, which was further narrowed to 17 after in silico ADME/toxicity filtering. Top 2 candidates were used to assess effect on Wnt signaling in HepG2, Hep3B and Huh7 human hepatoma cells through the use of TOPflash luciferase reporter assay and MTT viability assay. Safety of these agents was tested on primary human hepatocytes. There was a significant decrease in TOPflash reporter activity in all hepatoma cells but especially in HepG2 cells that harbor mutant β‐catenin gene at concentrations ranging from 200–25μM as well as a concomitant decrease in cell viability. Molecular analysis showed a significant decrease in downstream β‐catenin targets such as cyclin‐D1 and Glutamine synthetase, whereas total β‐catenin levels remained unaffected. Primary human hepatocyte exposed to the inhibitors at 200μM over 48 hours did not exhibit any loss of viability. Thus, we have identified 2 potent novel chemotypes that specifically inhibit Wnt signaling in hepatoma cells and lead to their decreased survival and proliferation and will be of relevance in additional preclinical studies.